JP2002088292A - Ink composition and printed matter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink composition which does not impair the appearance of an article even when used for printing on the article, makes it possible to detect a printed mark at a high sensitivity without being influenced by the color of a base material, has high printability and shelf stability, and can be excited with ultraviolet rays. SOLUTION: The ink composition contains an organic fluorescent coloring matter that is substantially invisible in a visible light region and that can be excited by ultraviolet rays to emit light in a visible light region, a noncolored pigment, and a vehicle, wherein the vehicle comprises a hardly volatile vehicle having a boiling point of 200 deg.C or higher.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultraviolet excitation type ink composition suitable for a printing method such as a dot impact type printer, a stamp type printer, a stamp, etc., and a printed matter produced using this ink composition. It is.

[0002]

2. Description of the Related Art In recent years, information such as a manufacturer and a product name of an article is displayed as a bar code or certain characters, numbers, and symbols, and the pattern and information are displayed using a bar code reader or an OCR (Opti).
It is often used for reading by optical detection methods such as cal Character Reader) and used for total sales of products and analysis of distribution. Recently, not only products using such barcode systems and OCR systems have been found, but also applications to file management have been made. For example, in the automatic sorting of mail, a system for distributing articles by code management is used, and in banks, a system for printing character and numerical information on forms and using the information to sort and manage the information is introduced.

Conventionally, in a barcode system, a method of printing a barcode such as black on a white background using a printing method such as an ink jet printer, an impact printer, a thermal transfer printer, offset printing, gravure printing, and screen printing. It's being used. However, since this method reads information using the difference in reflectance between the barcode and the base, there is a drawback that reading becomes extremely difficult when the article becomes dirty. In addition, since reflected light in the visible light region is used, there is a disadvantage that the appearance of the article is necessarily impaired. Furthermore, OC
Even in the R system, information such as characters, numbers, and symbols is printed in blue or black, so that there is a problem that the information reading rate decreases and the appearance of articles is impaired.

[0004] In order to solve such a problem that the reading rate of information in the barcode system or the OCR system is lowered or the appearance of articles is impaired, a method using an ink composition containing a fluorescent dye has been used or proposed. . In particular, when a printed material is prepared using an ink composition containing a fluorescent dye that emits light in the visible light region when excited by ultraviolet light, the printed material is substantially invisible in the visible light region, and thus is printed without impairing the appearance of the article. There are advantages that can be done. Also, while being readable by machine,
Since the light-emitting region is a visible light region, there is also an advantage that the presence of a printed matter can be visually recognized, and attention has been paid as an alternative to a bar code such as black and white.

For example, Japanese Patent Laying-Open No. 58-49764 proposes a method for outputting information for a machine using an invisible ink for an ink jet printer containing an ultraviolet absorbing dye. In addition, Japanese Patent Publication 4-64
In the '517 publication, information is provided by an ink jet printer using an ink composition containing a fluorescent dye that emits fluorescence other than blue-violet and blue, and when reading information recorded with this ink under ultraviolet irradiation,
A method of reading information through a filter that cuts blue-violet and blue light has been proposed.

[0006]

However, the printed matter produced using the above-described ink composition containing a fluorescent dye cannot read information because of insufficient fluorescence emission intensity upon irradiation with ultraviolet rays. There was a practical problem. In particular, when the base color of the article is a dark color such as black, blue, green, or red, or when the article is added with a fluorescent whitening agent, or when the article has a rough surface, the output of the read signal is output. However, there is a drawback that the size of the image becomes smaller. Also, when the base color of the article has black ruled lines, letters, numbers, and symbols,
Because the reading output varied partially, there were some places that could not be recognized.

Therefore, as an effective method for improving the fluorescence emission intensity, there has been proposed a method of increasing the amount of a fluorescent dye added to an ink composition or adding a non-colored pigment for concealing a base. I have. For example, Japanese Patent Application Laid-Open No. 1-24
Japanese Patent No. 5072 proposes a fluorescent ink composition for inkjet containing a mixture of a white pigment and a fluorescent dye, a binder, an organic solvent, and a conductivity imparting agent. Also, in Japanese Patent Application Laid-Open No. 9-174966, an ink jet printer is used to print on the surface of a printing medium using an aqueous fluorescent ink containing a fluorescent dye and transparent solid fine particles having a particle size of 1 μm or less. There has been proposed a fluorescent marking method characterized in that fluorescent light is emitted by irradiating excitation energy.

However, in the ink composition used in the ink jet printer, the solid substances such as fluorescent dyes, white pigments, and transparent solid fine particles are increased or the solid substances having a large particle diameter are increased in order to improve the fluorescence emission intensity. When it is contained, there arises a problem that the nozzle is clogged and the ejection of the ink is not stable, and a problem that the solid substance is settled and the preservability of the ink is poor. For this reason, it has been difficult to improve the fluorescence emission intensity due to the increase in the solid substance and the particle size. Therefore, development of an ink composition having high printability and storage stability and a printed matter having a high output of an information reading signal by a barcode system or an OCR system have been demanded.

In view of such circumstances, the present invention is substantially invisible in the visible light range, does not impair the appearance of the article even when printed on the article, and furthermore, prints the printed mark with a base color. It is an object of the present invention to provide an ultraviolet-excitation ink composition which can be detected with high sensitivity without being affected by the ink and has high printability (printing naturally includes printing) and high storage stability. The present invention also provides a bar code system and an O
It is an object of the present invention to provide a printed material in which a CR system outputs a high output of an information reading signal.

[0010]

Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object, and as a result, have found that an organic fluorescent dye that emits visible light when excited by ultraviolet light and a non-colored pigment have a boiling point. According to the ink composition dissolved and / or dispersed in a non-volatile vehicle at 200 ° C. or higher, printability and storage stability are high, and a printed matter obtained by printing this on an article impairs the appearance of the article. The present invention was found to improve the fluorescence emission intensity and reading output upon irradiation of ultraviolet rays without any problem, and completed the present invention.

That is, the present invention provides an ink containing an organic fluorescent dye that is substantially invisible in the visible light region and emits light in the visible light region when excited by ultraviolet light, a non-colored pigment, and a vehicle. In the ink composition, the vehicle is a non-volatile vehicle having a boiling point of 200 ° C. or more. The above-mentioned non-colored pigment is a general term for a white pigment and a transparent pigment.

The present invention also provides an ink composition having the above constitution, in particular, an ink composition wherein the organic fluorescent dye is a europium compound having an emission center wavelength of 615 ± 20 nm when excited by ultraviolet rays. An ink composition having a fluorescent dye content of 0.1 to 50% by weight; an ink composition in which the organic fluorescent dye is present as particulate matter having an average particle diameter of 10 to 10,000 nm; Ink composition having a weight ratio to the fluorescent dye (weight of non-colored pigment / weight of organic fluorescent dye) of 1/10 to 50/10, wherein the non-colored pigment is calcium carbonate, magnesium carbonate, calcium magnesium carbonate , Silicates,
An ink composition that is at least one selected from silica, alumina, aluminum hydroxide, barium sulfate, calcium sulfate, titanium dioxide, zinc pigment, and non-colored resin particles can be provided. Further, the present invention relates to a printed matter, characterized in that the article has a printed layer composed of the ink composition of each of the above constitutions on an article.

In the present invention, as described above, an organic fluorescent dye which is excited by ultraviolet rays and emits light in a visible light region and a non-colored pigment are dissolved and / or dispersed in a non-volatile vehicle having a boiling point of 200 ° C. or higher. The ink composition of the present invention thus configured has a high boiling point of the vehicle and does not evaporate, so that it has no adverse effect on the human body, can be used in an office environment, and furthermore, the solvent volatilization and solid content can be reduced. Since sedimentation is suppressed, the storage stability of the ink is excellent, and the printability is also excellent.

Since the ink composition of the present invention has such excellent ejection stability and storage stability, it can be applied to a printing method using an ink jet printer, but a more preferable printing method is a dot impact method. Printers, stamp printers, stamps, and the like. In a bank, a dot impact type printer prints character and numerical information on a form, and the information can be used preferably in a system for sorting and managing the information. Further, the printed matter is substantially invisible and does not impair the appearance of the article, and the readout signal shows a high output regardless of the base color of the article.
Excellent for file management by CR system. Further, in the automatic sorting of mail, it can be used for a system for distributing articles by code management.

[0015]

DETAILED DESCRIPTION OF THE INVENTION The organic fluorescent dye used in the present invention is:
A dye substantially invisible in the visible light region (wavelength 400 to 700 nm) and excited by ultraviolet light (wavelength less than 400 nm) to be in the visible light region (wavelength 400 to 700 nm).
Is a dye having an emission center wavelength. Although the emission color is not particularly limited, it is red (preferably at a wavelength of 615 ± 20).
nm) are preferred because they emit visible light with excellent detectability.

The reason why the organic fluorescent dye emitting red light is excellent is that a cheap and easily available silicone photodiode can be used for detecting the light emission. In other words, this diode has a higher light-receiving sensitivity for visible light on a longer wavelength side than on a shorter wavelength side, and thus has higher detection sensitivity for long-wavelength red visible light. In addition, generally used white paper contains a fluorescent whitening agent, and may emit blue light when irradiated with ultraviolet light. In the case of using an organic fluorescent dye that emits red light, since the emission wavelength of red is separated from the emission wavelength of blue from the optical brightener, even when printed on white paper to which an optical brightener has been added. The luminescence of the dye can be detected with high sensitivity.

As described above, as the organic fluorescent dye of the present invention, a red-emitting organic fluorescent dye which has no absorption in the visible light region and is excited by ultraviolet rays and has a light emission center wavelength in a long wavelength region around 600 nm is preferable. Used
A typical example thereof is a metal complex having a rare earth element such as europium or samarium as a light emission center and a ligand having a large number of π electrons as a counter ion.
Among these, a europium compound having a large light emission amount is particularly preferable.

Specifically, it has no absorption in the visible light region of 400 to 700 nm, and is therefore substantially invisible in the visible light region, and 615 ±
Including europium having an emission center wavelength at 20 nm,
This includes tenoyl trifluoroacetone, naphthoyl trifluoroacetone, benzoyl trifluoroacetone,
Methylbenzoyltrifluoroacetone, furoyltrifluoroacetone, pivaloyltrifluoroacetone,
Metal complexes having hexafluoroacetylacetone, trifluoroacetylacetone, fluoroacetylacetone, heptafluorobutanoylpivaloylmethane and the like as ligands are exemplified. Among these, a europium compound having a ligand of tenoyltrifluoroacetone, naphthoyltrifluoroacetone, or methylbenzoyltrifluoroacetone having a large light emission amount is most preferable.

Such organic fluorescent dyes include, for example,
J. Am. Chem. Soc. Volume 186, 5117
Page, 1964 (Melby etc.) and Tokuhei 6-1526
No. 9 can be synthesized. Also,
Commercially available products of such organic fluorescent dyes include, for example,
"Rumilux CD335" manufactured by Rieder de Haan,
“CD331” and “CD332”, Mitsui Chemicals, Inc.
"ER-120", "ER-122", and the like.

In the present invention, such an organic fluorescent dye is used in an amount of 0.1 to 50% by weight based on the total amount of the ink composition.
Is preferable. That is, the content is preferably 0.1% by weight or more in order to secure a suitable fluorescence emission intensity, and the content is preferably 50% by weight or less in order to obtain suitable ink storability.

In the present invention, a non-colored pigment is used in order to reduce the absorption of the emitted ultraviolet light or the fluorescent light emitted from the fluorescent dye into the base. As the non-colored pigment, non-colored inorganic pigments and non-colored resin particles can be used. These non-colored inorganic pigments and non-colored resin particles may be either hollow particles or non-hollow particles. These may be used alone or as a mixture of two or more.

Non-colored inorganic pigments include calcium carbonate, magnesium carbonate, calcium magnesium carbonate, silicates (kaolin, clay, zeolite, talc, aluminum silicate, calcium silicate, etc.), silica, alumina, aluminum hydroxide , Barium sulfate, calcium sulfate, titanium dioxide, zinc pigments (lithopone, zinc sulfide,
Zinc oxide). Non-colored resin particles include acrylic polymers such as acrylates and methacrylates, vinyl aromatic hydrocarbon polymers such as polystyrene, styrene- (meth) acrylic acid copolymers, and styrene-acrylonitrile copolymers. Polymer, polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyamide, polyacetal,
Benzoguanamine resin, alkyd resin, melamine resin,
There is an aromatic sulfonamide resin.

In the present invention, the amount of the non-colored pigment used is
The weight ratio between the non-colored pigment and the organic fluorescent dye (weight of the non-colored pigment / weight of the organic fluorescent dye) is preferably 1/10 to 50/10. When the weight ratio is less than 1/10, the effect of improving the fluorescence emission intensity by concealing the base is reduced. Can not be obtained.

In the present invention, a non-volatile vehicle having a boiling point of 200 ° C. or higher is used as a vehicle for dissolving and / or dispersing the organic fluorescent dye and the non-colored pigment. Using such a volatile vehicle,
(1) The above-mentioned vehicle is hardly volatilized, so that the ink can be used in an office environment. (2) Since the viscosity of the above-mentioned vehicle is high, sedimentation of solid substances such as fluorescent dyes and non-colored pigments can be prevented. Storage stability is improved,
(3) Since the concentration of the fluorescent dye can be set to a high value, an effect is exhibited when the fluorescence emission intensity increases.

The above-mentioned vehicle includes higher fatty acids (oleic acid, linoleic acid, linolenic acid, isostearic acid, etc.), animal and vegetable oils (linseed oil, castor oil, rapeseed oil, soybean oil, tallow oil, etc.) which are liquid at room temperature. Paraffin, machine oil, polyoxyethylene, polyoxypropylene, alkyl ether, polyoxyethylene alkyl ether,
Polyoxypropylene alkyl ether, polyethylene glycol, polypropylene glycol, glycerin,
Sorbitanic acid esters, benzyl alcohol, phenyl cellosolve, 1,3-dimethyl-2-imidazolidinone and the like.

One of these vehicles may be used alone, or two or more of them may be used in combination.
The viscosity (25 ° C) of the vehicle used is 10 mPa · s
１1 kPa · s is preferable, and 20 mPa · s〜100 P
a · s is more preferred, and 20 mPa · s to 5 Pa · s is even more preferred. When the viscosity is less than 10 mPa · s, solid substances such as non-colored pigments are liable to precipitate and storage stability is deteriorated. When it exceeds 1 kPa · s, solid substances such as non-colored pigments are difficult to disperse.

In the present invention, the organic fluorescent dye is used by dissolving or dispersing it in the above-mentioned vehicle. In particular, in order to impart good light fastness and weather resistance to the ink composition and its printed matter, an organic fluorescent dye in the above-described vehicle has an average particle diameter of 10 to 10.
Desirably, it is present as 10,000 nm granules. If the average particle size is smaller than 10 nm, the emission intensity is likely to deteriorate with time, and if the average particle size is larger than 10,000 nm,
Problems such as sedimentation of the dye in the ink composition and dropping of the dye from the printed matter are likely to occur.

The organic fluorescent dye composed of the above-mentioned particulate matter has an average particle diameter of 10 after the dispersion step in the preparation of the ink composition.
It may be in the range of up to 10,000 nm, and not all of the granules need to have a uniform particle size. The above average particle diameter means that the ink composition is prepared in the same proportion of a solvent in about 1,000.
The sample prepared by diluting it twice was placed in a cell having a diameter of 12 mm, and 5 mW of He-Ne was added at room temperature by a dynamic light scattering method.
This is a value measured by using a laser under the conditions of a measurement angle of 90 degrees and a cumulative number of 100 times.

The ink composition of the present invention comprises, as essential components, the above-mentioned organic fluorescent dye, non-colored pigment and
It contains a non-volatile vehicle at a temperature of at least 0 ° C., and various additives can be appropriately selected and compounded as optional components as required.
For example, organic fluorescent dyes and non-colored pigments are used as articles
Various binder resins can be used in order to fix the resin.
Also, a surface conditioner, an antifoaming agent, a dispersant, a viscosity adjuster, a crosslinking agent, a fungicide, a preservative, a rust preventive, an antistatic agent, a lubricant, an ultraviolet absorber, an antioxidant, a charge adjuster, Various known additives such as a pH adjuster can be blended.

The binder resin is preferably one having low reactivity with the organic fluorescent dye and improving printability by a printer or the like and durability of the printed layer. Usually, those which are stably dissolved in the above-mentioned vehicle are used, but those which are emulsified and dispersed may be used. Specifically, rosin resin,
There are phenol resin, petroleum resin, ketone resin, alkyd resin, maleic acid resin, butyral resin, polyamide resin, shellac, and the like, and one or more of them are used. It is desirable to use these binder resins in a proportion of usually 0.1 to 50 parts by weight with respect to 1 part by weight of the organic fluorescent dye. When the content is 0.1 parts by weight or more, a suitable binding force can be secured, and when the content is 50 parts by weight or less, a suitable emission intensity of the printed matter can be maintained.

The ink composition of the present invention can be prepared by various known stirring devices, dispersers,
It can be easily prepared by using a centrifuge, a filter or the like. In particular, to disperse organic fluorescent dyes and non-colored pigments in a vehicle, a ball mill,
A method of uniformly mixing and dispersing using a disperser such as a sand mill, a bead mill, and a roll mill is employed.

In the present invention, the above-described ink composition is printed on the surface of various articles including postal items such as forms and postcards by a printing method such as a dot impact printer, a stamp printer, and a stamp. , A print layer formed of a desired mark such as a bar code or certain characters, numbers, and symbols is formed into a printed material.

The printed matter thus produced does not impair the appearance of the article as an invisible printed layer because the organic fluorescent dye in the printed layer has no light-emitting and light-absorbing components in the visible light region. Moreover, when the printed matter is irradiated with ultraviolet light, the fluorescent dye in the print layer is excited and emits light in the visible light region, which can be visually recognized, and a silicone photodiode or the like is used as the photoelectric conversion element. If light emission is detected by a reader, desired mark information can be read with high sensitivity.

[0034]

Next, an embodiment of the present invention will be described in more detail. However, the present invention is not limited only to the following examples. In the following, “parts” means “parts by weight”.

Example 1 To 60 parts of castor oil (boiling point of 200 ° C. or more), 20 parts of a petroleum resin (“Quinton 1500” manufactured by Zeon Corporation) was added and dissolved by heating to form a resin solution. An organic fluorescent dye [Lumilux CD33 manufactured by Rieder de Haan Co., Ltd.]
5 "(a europium compound which is substantially invisible in the visible light region and emits red light when excited by ultraviolet light, excitation wavelength: 365 nm, emission wavelength: 615 nm)] and titanium oxide [produced by Titanium Industry Co., Ltd.] "Kronos KA
-10 "] and dispersed by a planetary ball mill for 4 hours, so that the organic fluorescent dye has an average particle diameter of 800
An ultraviolet-excited ink composition was prepared, which was present as nanometer particles.

Example 2 To 50 parts of oleic acid (boiling point: 360 ° C.) and 17 parts of 1,3-dimethyl-2-imidazolidinone (boiling point: 226 ° C.), rosin resin [Ester gum AA manufactured by Arakawa Chemical Co., Ltd.]
L "]], and dissolved by heating to obtain a resin solution. To this, 10 parts of an organic fluorescent dye ("Lumilux CD335" manufactured by Rieder de Hahn, the same as in Example 1) was added and dissolved, and benzoguanamine resin [Nippon Shokubai Co., Ltd. M30 "], and the mixture was dispersed for 4 hours by a planetary ball mill to prepare an ultraviolet-excitation ink composition in which the organic fluorescent dye was present in a dissolved state.

Comparative Example 1 An ultraviolet-excitation ink composition was prepared in the same manner as in Example 1 except that 5 parts of titanium oxide was not used.

Comparative Example 2 Instead of castor oil 60 parts, methyl ethyl ketone (boiling point 8
(0 ° C.) An ultraviolet-excitation ink composition was prepared in the same manner as in Example 1 except for using 60 parts.

For each of the ink compositions prepared in Examples 1 and 2 and Comparative Examples 1 and 2, the storage stability of the ink, the fluorescence emission intensity of the printed matter, the light fastness of the printed matter,
The printability of the printer was evaluated. The results were as shown in Table 1.

<Storability of Ink> 50 cc of the ink composition was placed in a glass bottle and left in a constant temperature bath at 60 ° C. for 24 hours. The state of the ink composition was observed and evaluated according to the following criteria. . 〇: No sediment is observed. △: Sedimentation of organic fluorescent dye and non-colored pigment is slightly observed. X: Organic fluorescent dye and non-colored pigment are clearly sedimented.

<Fluorescence Emission Intensity of Printed Material> The ink composition was applied to a concealing rate test paper (JIS K5400) using a # 4 bar coater, dried, and then subjected to a fluorescence spectrophotometer [JASCO Corporation The light emission intensity was measured by “FP750” manufactured by Toshiba Corporation. The measurement was performed at two places: a white background and a black background. The larger the value is, the higher the fluorescence emission intensity is.

<Light resistance of printed matter> The test sample used in the measurement of the above-mentioned "fluorescence emission intensity of printed matter" was used.
"Xenon weatherometer Ci65" manufactured by Atlas
After irradiating with light for 1 hour, the emission intensity was measured with a fluorescence spectrophotometer (“FP750” manufactured by JASCO Corporation). The measurement was performed on a white background portion, and a maintenance ratio by comparison before and after irradiation, that is, [(emission intensity after irradiation / emission intensity before irradiation) × 100 (%)] was calculated. The larger the value, the better the light resistance.

<Printability of printer> Nylon, width 8
mm of ink composition on fabric ink ribbon
Impregnated at a rate of 4 g / m ² , mounted in a cassette, and manufactured by Seiko Epson Corporation
After printing on woodfree paper according to "P-80", the printed matter was irradiated with black light to observe the state of the printed matter, and evaluated according to the following criteria. 〇: Printed matter is good ×: Light emission intensity of printed matter is low, and dropping and blurring are observed

[0044]

As is evident from the results in Table 1 above, both ink compositions of Examples 1 and 2 have good ink storability, excellent printability in a printer, and a high quality printed matter ( In particular, the ink composition of Example 1 in which the fluorescence emission intensity of the black background portion is good, and in which the organic fluorescent dye is present as particulate matter in a bulk state, has the above-mentioned fluorescence emission intensity which is high, and the light resistance of the printed matter is also high. It turns out that it is excellent.

On the other hand, the ink composition of Comparative Example 1 containing no non-colored pigment has a low fluorescence emission intensity on a black background, and uses a non-volatile vehicle having a boiling point of 200 ° C. or more. In the ink composition of Comparative Example 2, the organic fluorescent dye and the non-colored pigment were remarkably sedimented, and the storage stability of the ink and the printability of the printer were poor. Notably inferior.

[0047]

As described above, according to the present invention, an organic fluorescent dye which is substantially invisible in the visible light region and which emits light in the visible light region when excited by ultraviolet light, and a non-colored pigment having a boiling point of 200 By dissolving and / or dispersing in a non-volatile vehicle of at least
Practical, with high storage stability and excellent printability, capable of printing desired marks on an article without impairing its appearance, and capable of detecting printed marks with high sensitivity without being affected by the underlying color It is possible to provide an ultraviolet-excitation type ink composition having extremely high value and a printed material thereof.

Continuation of the front page F term (reference) 4J039 AB04 AB05 AB06 AD01 AD03 AD05 AD08 AD09 AD10 AD11 AE01 AE03 AE06 AE07 AE08 AE10 BA13 BA16 BA18 BA21 BA22 BA30 BA31 BA32 BA35 BA39 BC01 BC07 BC12 BC13 BC19 BC51 BE01 EA28 EA29 GA24 EA42 GA44 GA34

Claims (7)

[Claims] 1. An ink composition comprising an organic fluorescent dye which is substantially invisible in a visible light region and emits in a visible light region when excited by ultraviolet light, a non-colored pigment, and a vehicle, An ink composition wherein the vehicle is a non-volatile vehicle having a boiling point of 200 ° C. or higher. 2. The organic fluorescent dye is excited by ultraviolet rays and
2. The ink composition according to claim 1, which is a europium compound having an emission center wavelength at 5 ± 20 nm. 3. The ink composition according to claim 1, wherein the content of the organic fluorescent dye is 0.1 to 50% by weight. 4. An organic fluorescent dye having an average particle size of 10 to 10,
The ink composition according to any one of claims 1 to 3, which is present as a particulate matter having a particle size of 000 nm. 5. The weight ratio of the non-colored pigment to the organic fluorescent dye (weight of non-colored pigment / weight of organic fluorescent dye) is 1/10.
5. The ink composition according to claim 1, wherein the ratio is from 50/10. 6. The non-colored pigment is selected from the group consisting of calcium carbonate, magnesium carbonate, calcium magnesium carbonate, silicate, silica, alumina, aluminum hydroxide, barium sulfate, calcium sulfate, titanium dioxide, zinc pigment and non-colored resin particles. The ink composition according to claim 1, wherein the ink composition is at least one selected from the group consisting of: 7. A printed matter comprising a printed layer comprising the ink composition according to claim 1 on an article.