JPH05117568A - Fluorescent ink for marking pen - Google Patents

Abstract

PURPOSE:To obtain the title ink suitable for heat-sensitive paper, etc., providing holograph free from change of color by dispersing specific fluorescent pigment into an aqueous medium. CONSTITUTION:For example, preferably 10-30wt.% fluorescent pigment having >=70wt.% cumulative distribution percentage of particles having 0.2-3.0mum particle diameter is dispersed into an aqueous medium comprising >=50wt.% water and 1-40wt.% wetting agent such as ethylene glycol to give the objective ink.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is suitable for use in fluorescent ink for marking pens for underlining a fluorescent color on a desired portion of a document, especially for thermal paper applied to facsimiles and other OA equipment. Fluorescent ink for marking pens that can be used.

[0002]

2. Description of the Related Art This type of fluorescent ink mainly uses an ink in which a fluorescent pigment is dispersed in an aqueous medium. The fluorescent pigment used usually contains a fluorescent dye and acrylic acid, methacrylic acid or the like. Fine particles of a combination of a polymer with a monomer and an average particle diameter of about 0.1 to 0.15 μm
The range is. When a fluorescent ink containing such fine particles of fluorescent pigment is applied to thermal paper, the pigment particles penetrate into the coated portion of the thermal paper and contact with a colorless dye (leuco dye), which is a color source, to develop color. In many cases, the underlined part is darkened, and the darkened part becomes darker with the passage of time, eventually causing the underlying character to be unreadable.

[0003]

DISCLOSURE OF THE INVENTION It is an object of the present invention to provide a fluorescent ink for a marking pen which, when applied to the above-mentioned thermal paper, has no discoloration immediately afterward and does not cause a blackening phenomenon over time. is there.

[0004]

The fluorescent ink of the present invention comprises a fluorescent pigment having an average particle size of 0.2 to 3.0 μm dispersed in an aqueous medium containing water, a wetting agent and, if necessary, various additives. The composition is The aqueous medium has a water content of 50% by weight or more, and the wetting agent is selected from glycerin, ethylene glycol, propylene glycol and the like, and is added in the range of 1 to 40% by weight in the total ink composition. The addition of an excessive amount of wetting agent tends to decolor the print on the thermal paper. If necessary, a surface active agent, an antiseptic agent, a rust preventive agent, a pH adjusting agent, etc. may be added in a small amount of about several wt% or less in the total ink composition. The fluorescent pigment is used in the range of 10 to 30% by weight in the entire ink composition, and has an average particle size of 0.
It is essential that the pigment particles are in the range of 2 to 3.0 μm. It is preferable that the cumulative distribution ratio of pigment particles having a particle diameter of 0.2 to 3.0 μm is 70% or more. Penetration of pigment particles into the coated portion of the thermal paper decreases as the particle size increases, but when the particle size exceeds 3 μm, the opacity of the handwriting increases, making it difficult to see the underlying print and marking pen It is not preferable because it tends to block the capillary ink passage of the pen tip, and the size of the pigment particles is appropriately within the above range.

[0005]

In the fluorescent ink of the present invention, the fluorescent pigment used has an average particle size of 0.2 to 3.0 μm, and the average particle size of the fluorescent pigment particles used in conventional fluorescent inks is about 0.1. Since it is larger than 0.15 μm to 0.15 μm, when applied to a paper surface, microscopically, it forms a handwriting in a state where the pigment is deposited in layers in the surface. Similarly, when applied to thermal paper, most of the pigment particles remain on the surface without penetrating into the coated area, and the contact with the leuco dye in the coated area is significantly reduced. Opportunity runs out. Therefore, no substantial discoloration is recognized in the handwriting, and the darkening does not proceed even with the passage of time.

[0006]

EXAMPLES Example inks and comparative example inks having the following compositions were prepared, and a predetermined amount of each sample ink was filled in a pen having a 4 mmφ rod-shaped pen body made of a fiber bundle resin processed body and a fiber bundle ink storage body. And used as a sample pen. Each sample ink was prepared by adding an aqueous medium composed of a mixed liquid of water and a wetting agent into the fluorescent pigment dispersion liquid which was being stirred, and stirring the mixture until it was sufficiently homogeneous. Table 1 shows the composition and physical properties of the sample ink.

[Table 1] The numerical values of the compositions in the table are all parts by weight, and the content of the raw material fluorescent pigment dispersion is an aqueous dispersion in which the fluorescent pigment is dispersed in water by a surfactant. Details of each fluorescent pigment liquid are as follows. A: Product name SW-15 (Shin Loihi Co., Ltd.) Yellow fluorescent pigment 42% by weight, average particle diameter 0.8 μm Cumulative distribution ratio of particles with particle diameter 0.2 to 2.0 μm 100
% B: trade name SW-17 (Shin Loihi Co., Ltd.) pink fluorescent pigment 42% by weight, average particle size 0.8 μ
m Cumulative distribution ratio of particles having a particle diameter of 0.2 to 2.0 μm 100
% C: Trade name Lumicor NKW-3005 (Nippon Fluorescent Co., Ltd.) Yellow fluorescent pigment 42% by weight, average particle size 0.11 μm D: Trade name Rumicol NKW-3007 (Nippon Fluorescent Co., Ltd.) Pink fluorescent pigment 41% by weight, Average particle size 0.11
μm

Next, printed thermal paper (Panafax ultra-sensitive UG-0001B4 manufactured by Matsushita Electric Transmission Co., Ltd.)
A line was drawn on each print with the sample pen, and immediately after one week and one month, the state of the color of the handwriting line was observed. The results are shown in Table 2.

[Table 2] The contents of the symbols in the table are as follows. ○: No discoloration was observed, △: Discoloration was observed, ×:
Noticeable discoloration

[0008]

As can be seen from the results shown in Table 2, even when the fluorescent ink of the present invention is applied to thermal paper, no discoloration of the handwriting line is observed immediately after writing for one month. Of course, the original function, that is, the effect of conspicuously raising the print without hiding the print is maintained. In Comparative Examples 1 to 3, the same fluorescent pigment was used, but there was a difference in the timing of discoloration (the No. 2 ink was significantly discolored immediately after) because the wetting agent was applied to the paper coating area. It is considered that this is due to the difference in the penetrability, but the fluorescent ink of the present invention using a pigment having a relatively large particle size is not substantially affected by the type of wetting agent.

Claims (2)

[Claims] 1. A fluorescent ink for a marking pen, comprising a fluorescent pigment having an average particle size of 0.2 μm to 3.0 μm dispersed in an aqueous medium. 2. The fluorescent pigment has a particle diameter of 0.2 μm to 3.0.
The fluorescent ink for a marking pen according to claim 1, wherein the cumulative distribution ratio of particles in the range of μm is 70% or more.