JPH01245072A - Fluorescent ink composition for ink jet - Google Patents

Abstract

PURPOSE:To provide the title composition outstanding in chemical resistance such as resistance to oil and water, capable of giving recording printed images of excellent clearness and recognizability, comprising a colorant made up of a mixture of white pigment with a fluorescent coloring matter, a binder, an organic solvent and an electrical conductivity-imparting agent. CONSTITUTION:The objective composition comprising (A) a colorant made up of a mixture of a white pigment (pref., titanium dioxide <=1.0mum in mean particle size) with pref. 0.5-5wt.% (based on said pigment) of a fluorescent coloring matter, (B) a binder (e.g., pyroxylin, rosin-modified xylene resin), (C) an organic solvent (pref., consisting mainly of ketone or alcohol), and (D) an electrical conductivity-imparting agent [e.g., alkali (alkaline earth) halide].

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to an ink composition for IJ (ink jet), and more specifically to a fluorescent ink composition for IJ that provides recorded images with excellent clarity and visibility. Regarding.

(Prior Art and Problems) - Conventionally, the fJ recording method is becoming widely used, and the ink used in this method consists of a liquid medium and a colorant.

As the coloring agent for the ink, a dye soluble in the liquid medium is used to prevent clogging of the IJ nozzle. Images recorded using these dye inks can form clear images on white substrates such as paper, but when recorded on black, gray, or other dark-colored substrates, the dye A clear recorded image cannot be formed due to the low hiding power of 1゜ Fluorescent dyes, which are very clear and have excellent visibility, are used especially when used for marking, but fluorescent dyes have particularly low hiding power. Therefore, it could not be used for marking items with a non-white base.

Therefore, an object of the present invention is to provide a fluorescent ink composition for IJ that can provide excellent clarity and visibility even to articles having a colored base.

(Means for Solving the Problems) In order to achieve the above object, the present inventor has conducted extensive research and found that a fluorescent ink composition for IJ can achieve the object of the present invention by using a white pigment in combination with a fluorescent dye. The present invention was completed by discovering that a product can be obtained.

That is, the present invention provides a fluorescent ink composition for IJ containing a colorant, a binder, an organic solvent, and a conductivity imparting agent, wherein the colorant is a mixture of a white pigment and a fluorescent dye. It is a thing.

(Function) By using a white pigment in combination with a fluorescent dye, all or part of the fluorescent dye is adsorbed to the white pigment, and even if recorded on a dark-colored background, the dark-colored background is hidden, making it clear and visible. This allows for large markings. Furthermore, since the fluorescent dye is adsorbed to the white pigment, the recorded image also has excellent chemical resistance such as oil resistance and water resistance.

(Preferred Embodiments) Next, the present invention will be described in more detail by citing preferred embodiments.

The white pigment used in the present invention may be any conventionally known white pigment such as titanium oxide or lead oxide, and is not particularly limited, but titanium oxide is particularly preferred. It is generally preferable to use such a white pigment in an amount of 5 to 30% by weight in the ink composition.

Examples of fluorescent dyes used as part of the coloring agent in the present invention include brilliant sulfoflavin FF.
, Basic Yellow HG, Eosin, Rhodamine 6G
, Rhodamine B, Rhodamine B Base, Hudson Yellow D-250, / Lugen Red 49, Lumogen Yellow, Lumogen Brilliant Yellow, Lumogen Yellow Orange, Lumogen Red Orange, etc. (Any conventionally known products can be used, Furthermore, fluorescent pigments obtained by dissolving these fluorescent dyes in a thermosetting resin, curing and pulverizing them can also be used in the same manner. The proportion of these fluorescent dyes to be used may be any concentration as long as it provides a sufficient coloring density to the recorded matter; If the concentration is too high, the fluorescence intensity may actually decrease, which is not preferable. If the amount of fluorescent dye is 5% by weight or less of the white pigment within the above range, almost all of the fluorescent dye will be adsorbed to the white pigment, making it possible to provide markings with high oil resistance and water resistance.

Further, the binder used in the present invention has the function of improving the dispersion stability of the pigment particles dispersed in the ink and adhering the pigment particles attached to the recording medium, for example, Binders and plasticizers such as nitrified cotton, rosin-modified maleic acid resin, xylene resin, rosin-modified xylene resin, ester gum, ketone resin, DOP, DO3, etc. can be used. These binders etc. are colorants 100%
It is preferable to use 1 part of 50 to 150Ti per part by weight.

Further, the conductivity imparting agent used in the present invention is added to impart conductivity to the ink composition, and any salt that is soluble in the solvent constituting the ink can be used. Examples of such salts include alkali metal and alkaline earth metal halides, nitrates, thiocyanates, and the like.

However, when considering the dispersion stability of the pigment, potassium thiocyanate, sodium thiocyanate, or lithium nitrate is preferable. The amount added is approximately 0.2% to 3% by weight of the ink composition.
A range that accounts for % by weight is preferred.

As the solvent in the present invention, any solvent may be used as long as it dissolves well all the components of the ink composition except the pigment and quickly evaporates after printing.

The solvent used for this purpose is preferably a ketone and/or alcohol as the main solvent, such as acetone, methyl ethyl ketone, methyl isobutyl ketone, methanol, ethanol, isopropanol, and ethyl formate, ethyl acetate, etc. Ester solvents can also be used together.

These solvents are also used to adjust physical properties such as viscosity of the ink composition, and preferably account for about 80 to 90% by weight of the ink composition.

As a method for dispersing fluorescent dyes and white pigments, fluorescent dyes,
A pigment, a binder, and a solvent are mixed, and this is dispersed using a known dispersion means such as a ball mill or a sand grinder to obtain a mill base in which the average particle diameter of the pigment is 1.0 μm or less, preferably 0.5 μm or less, and this It is preferable to add an organic solvent and other necessary components to adjust the concentration, viscosity, and other physical properties, and if coarse particles remain in the dispersion, they can be sufficiently removed by filtration, centrifugation, etc. should be kept.

Although the ink composition of the present invention is constituted by the above-mentioned components and methods, other known additives such as various activators and anti-settling agents can be used as appropriate.

(Examples) Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples. In the text, parts or percentages are based on weight unless otherwise specified.

Example 1 Rutile titanium oxide (manufactured by Ishihara Sangyo) 10 parts Hudson Yellow D-250 (manufactured by Dayglo) 0.5 parts Nitrocellulose L174 (manufactured by Daicel) 10 parts Rosin-modified maleic acid (Hitachi Chemical) 4 parts cyclohexanone 15 parts ethyl acetate
5 parts ethanol
10 parts 1 Ingredients were dispersed twice using a sand grind mill, mixed with 45 parts of ethanol containing 1.5 parts of sodium thiocyanate, and filtered with suction through a 3 μm filter to remove coarse particles. A composition was obtained.

The above ink has an average particle diameter of 0.5 μm, a viscosity of 6, and an Ocp
, specific resistance 950Ω・C11, specific gravity 0.9 and surface tension 2
It had a physical property value of 3 dyne/cm.

When this ink was used to print on an ABS resin plate colored black using an IJ printer, clear markings with excellent visibility were possible.

On the other hand, when no white pigment was used in the above composition, the print was hardly visible.

Example 2 Rutile type titanium oxide (manufactured by Ishihara Sangyo) 10 parts Rhodamine B base 1 part Nitrified cotton SS 1
/8 (manufactured by Daicel) 9 parts Rosin-modified maleic acid resin (manufactured by Hitachi Chemical) 3 parts Methyl ethyl ketone 10 parts Methyl alcohol 40 parts Dispersion was performed using the above tube ball mill to obtain a mill base. To this was added a solution of 1.5 parts of sodium thiocyanate (domestic chemical special grade) dissolved in a mixture of 60 parts of ethanol, 20 parts of ethyl acetate, and 4 parts of DOP (manufactured by Tokyo Kasei), and the mixture was filtered under reduced pressure through a 3 μm filter. Viscosity6. A fluorescent ink composition for IJ of the present invention having a specific resistance of 700 Ω·CI and a surface tension of 23 dyne/cta was obtained.

When this ink was used to print on an ABS resin plate colored red using an IJ printer, clear markings with excellent visibility were possible.

On the other hand, when no white pigment was used in the above composition, the print was hardly visible.

(Effect) According to the present invention as described above, by using a white pigment in combination with a fluorescent dye, all or a part of the fluorescent dye is adsorbed to the white pigment, and even when recorded on a dark-colored base, a dark-colored image can be obtained. It hides the underlying material and enables clear and highly visible markings.

Furthermore, since the fluorescent dye is adsorbed to the white pigment, the recorded image also has excellent chemical resistance such as oil resistance and water resistance.

Claims (3)

[Claims] (1) A fluorescent ink composition for IJ containing a colorant, a binder, an organic solvent, and a conductivity imparting agent, wherein the colorant is a mixture of a white pigment and a fluorescent dye. (2) The fluorescent ink composition for IJ according to claim 1, wherein the white pigment is titanium oxide having an average particle diameter of 1.0 μm or less. (3) The amount of fluorescent dye is 0.5 to 5% by weight of the white pigment
The fluorescent ink composition for IJ according to claim 1.