JPH08239609A - Recording fluid - Google Patents

Abstract

PURPOSE: To obtain an ink jet recording fluid which emits red light when irradiated with ultraviolet rays and gives a record excellent in water resistance by compounding a specific phosphor material, a water-sol. solvent capable of dissolving the phosphor material, and water. CONSTITUTION: This recording fluid is prepd. by compounding 0.005-3.0wt.% [tetra-4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedionato] europium complex which is represented by the formula. has a tetra-n-butylammonium salt as the counterion, and emits red light of 600-650nm when irradiated with ultraviolet rays of 254-365nm as a phosphor material, 20-70wt.% water-sol. solvent (e.g. N-methyl-2-pyrrolidone) capable of dissolving the phosphor material, water, and if necessary a binder component and other additives, to give a soln.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording liquid which becomes visible when irradiated with ultraviolet rays. More specifically, the present invention relates to a recording liquid for inkjet which emits red light when irradiated with ultraviolet rays and has excellent water resistance.

[0002]

2. Description of the Related Art Conventionally, as ink jet recording liquids, water-soluble dyes such as acid dyes, direct dyes and basic dyes are dissolved in a glycol solvent and water (JP-A-53-6).
1412, JP-A-54-89811, JP-A-55-65.
269) is often used. As the water-soluble dye, those having high solubility in water are generally used in order to obtain stability of the recording liquid. Therefore, the ink jet recorded matter generally has poor water resistance, and there is a problem that spillage of water easily causes bleeding of the dye in the recorded portion.

In order to improve such poor water resistance,
Attempts have been made to change the structure of the dye and to prepare a recording liquid having a strong basicity (JP-A-56-57862). Further, it has also been attempted to improve the water resistance by making good use of the reaction between a recording paper and a recording liquid (JP-A-50-4900).
4, JP-A-57-36692, JP-A-59-2069
6, JP-A-59-146889). Although these methods have a remarkable effect on a specific recording paper, they lack versatility in that they are restricted by the recording paper, and when a non-specific recording paper is used, a water-soluble dye is used. In many cases, the recording liquid used cannot obtain sufficient water resistance of the recorded matter.

Recording liquids having good water resistance include those in which an oil-soluble dye is dispersed or dissolved in a high boiling point solvent, and those in which an oil-soluble dye is dissolved in a volatile solvent. Therefore, it is difficult to prepare such a recording liquid because there are various restrictions on materials that can be visualized by making the recorded material emit light. In addition, inks have been developed that can be visualized by special light and can be read by a sensor, which is difficult to confirm with ordinary light in various special applications. Hitherto, a fluorescent whitening agent that emits a purple color has been used for such applications. Since such a fluorescent whitening agent is a water-based dye, it has a drawback that the recorded matter is inferior in water resistance. Moreover, since the fluorescent whitening agent is widely used for paper, fiber, etc., it is difficult to distinguish it from those emitted light. In addition, the fluorescent pigment obtained by granulating the fluorescent dye with resin is a mixture of the fluorescent dye and resin, and can be dissolved like an dye by using an organic solvent, but it also has absorption in the visible range. Therefore, even when the fluorescent light is not applied, the displayed characters and figures can be visually confirmed by a person, and it cannot be used as a material for so-called hidden ink.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide an ink jet recording liquid capable of obtaining a recorded product having good water resistance which is irradiated with ultraviolet rays and emits red light.

[0006]

That is, the present invention is an ink jet recording liquid containing a fluorescent material represented by the following formula, a water-soluble solvent capable of dissolving the fluorescent material, and water.

Embedded image

The fluorescent material emits red light of 600 to 650 nm when irradiated with ultraviolet rays of 254 to 365 nm. When it is not irradiated with ultraviolet rays, it is not colored because it is not colored, and it is useful as a so-called hidden ink material. The fluorescent material is produced by reacting a 4,4,4-trifluoro-1- (2-thienyl) -1,3-butanedione compound and europium perchlorate with sodium hydroxide in acetone. Tetra 4,4,4-trifluoro-1- (2- having a tetra-n-butylammonium salt as a counter ion
(Thienyl) -1,3-butanedionate] europium complex, which is colorless under visible light and has the property of developing a red color under ultraviolet light, and has a large emission intensity and light resistance. Also excellent in sex. Since the fluorescent material has almost no solubility in water, but has sufficient solubility in a solvent, the recorded material has good water resistance, and is very suitable as a fluorescent material for inkjet intended for hidden printing.

In the present invention, since the fluorescence intensity of the fluorescent material is high, the desired detection as a hidden print can be made by using 0.005 to 3% by weight in the recording liquid. If it is less than this range, it becomes difficult to read the light emission, and if it is more than this range, precipitation is likely to occur and a trouble such as clogging of the nozzle opening is likely to occur.

As the water-soluble solvent, acetone, methyl ethyl ketone, cyclohexanone and other ketone-based solvents, ethyl acetate and other ester-based solvents, which are excellent in the solubility of the fluorescent material,
Dimethylsulfoxide, N-methyl-2-pyrrolidone, γ-butyl lactone, dioxane and the like are used. Especially, N-methyl-2-pyrrolidone and γ-butyl lactone have excellent solubility in a fluorescent material and are compatible with water. It is desirable because it has excellent compatibility and has a relatively low volatility, which makes it difficult to plug the nozzle opening. It is also preferable in terms of odor.
In the present invention, water does not contribute to the dissolution of the fluorescent material, but it is preferable to use 20 to 70% as a solvent component of the recording liquid. This water has a function of reducing the odor, flammability, etc. of the solvent component of the recording liquid, and has an appropriate evaporating property. From the viewpoint of making the recording liquid aqueous, it is preferable to use 20 to 70%. If 70% or more of water is used, the solubility of the fluorescent material is lowered, and the fluorescent material having sufficient fluorescence intensity cannot be used.

The recording liquid of the present invention can be used in various printers and various printers by selecting the type of solvent, the presence or absence of a binder, the type, the amount, etc., and adjusting the viscosity, surface tension, electric conductivity, drying property, etc. It can be applied to the recording medium of. The characteristics of the recording liquid differ depending on the printer, but generally the viscosity is 0.8-15 cps and the surface tension is 2
0-60 dyn / cm is preferable. When used in a continuous type printer, it is desirable to adjust the conductivity to about 0.1 to 20 mS. When an absorbent recording material such as paper is used, it is preferable to use the following recording liquid. That is, the fluorescent material of the present invention, a solvent, and if necessary, a binder component, an additive and the like are dissolved to prepare a recording liquid.

The binder component is for fixing the fluorescent material favorably, has good solubility in the above-mentioned solvent and water, and as the one capable of appropriately adjusting the viscosity of the recording liquid, the following resins are listed. be able to. That is, polyvinyl alcohol, polyvinylpyrrolidone,
Carboxymethyl cellulose, hydroxymethyl cellulose, natural resin (eg, gum arabic, gelatin), water-soluble or water-dispersible acrylic resin, styrene-acrylic resin, polyester resin, polyamide resin, polyurethane resin, etc. are used.

These resins are not always necessary for a recording medium such as permeable paper. However, it is necessary when recording is performed on a non-permeable recording medium, and is 0.5 to 10% by weight in the recording liquid.
Preferably, 1 to 5% by weight is used. If the amount is less than this amount, the fluorescent material cannot be sufficiently fixed to the impermeable recording medium. If the amount is more than this amount, the ejection stability of the recording liquid may be deteriorated. In addition, since the resin layer is thickly covered around the fluorescent material, there is a possibility that the emission of the fluorescent material may be reduced, and the generation of fluorescent light due to the resin may be an obstacle. If a resin is used, stronger water resistance can be obtained in the recorded matter.

The solvent used in the present invention is as follows for preventing the recording liquid from drying at the nozzle portion, solidifying the recording liquid, and preventing stable ejection of the recording liquid and drying of the nozzle over time. A solvent can also be added and used. Such solvents include ethylene glycol, diethylene glycol, propylene glycol, triethylene glycol, polyethylene glycol, glycerin, tetraethylene glycol, dipropylene glycol, ketone alcohol, diethylene glycol monobutyl ether,
Ethylene glycol monobutyl ether ethylene glycol monoethyl ether, 1,2-hexanediol,
Examples include substituted pyrrolidone, 2,4,6-hexanetriol, tetrafurfuryl alcohol, 4-methoxy-4methylpentanone and the like. Further, alcohols such as methanol, ethanol and isopropyl alcohol can be used for the purpose of speeding up the drying of the recording liquid on paper. These solvents may be used alone or as a mixture to prepare a recording liquid.
Used in the range of up to 50%.

When the material to be printed with the recording liquid is like paper,
A penetrant can be added in order to stop the permeation of the recording liquid into the paper and accelerate the apparent drying property. As such penetrant, glycol ether such as diethylene glycol monobutyl ether, alkylene glycol, polyethylene glycol monolauryl ether, sodium lauryl sulfate, sodium dodecylbenzenesulfonate, sodium oleate, sodium dioctylsulfosuccinate and the like can be used. These are 5% of the recording liquid
The following amount of use has a sufficient effect, and if the amount of use is more than this, blurring of printing and paper drop (print through) occur, which is not preferable.

An antifoaming agent may be added to prevent the circulation or movement of the recording liquid or the generation of bubbles during the production of the recording liquid. To improve the ejection stability of the recording liquid and the recorded image, the following surfactants may be added and used. As such a surfactant, an anionic, nonionic, cationic or amphoteric surfactant can be used. Examples of the anionic activator include fatty acid salt, alkyl sulfate ester salt, alkyl aryl sulfonate, alkyl naphthalene sulfonate, dialkyl sulfonate, dialkyl sulfosuccinate, alkyl diaryl ether disulfonate, alkyl phosphate, poly Examples thereof include oxyethylene alkyl ether sulfate, polyoxyethylene alkylaryl ether sulfate, naphthalene sulfonic acid formalin condensate, polyoxyethylene alkyl phosphate ester salt, glycerol borate fatty acid ester, and polyoxyethylene glycerol fatty acid ester.

As the nonionic activator, polyoxyethylene alkyl ether, polyoxyethylene alkylaryl ether, polyoxyethylene oxypropylene block copolymer, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, Examples thereof include glycerin fatty acid ester, polyoxyethylene fatty acid ester, polyoxyethylene alkylamine, fluorine-based and silicon-based nonionic activators. Examples of the cationic activator include alkylamine salts, quaternary ammonium salts, alkylpyridinium salts, alkylimidazolium salts and the like. Examples of the zwitterionic activator include alkylbetaine, alkylamine oxide, phosphadylcholine and the like.

The recorded matter of the present invention is difficult to visually identify, but it is also possible to use a coloring agent to facilitate the identification of the recorded matter. Therefore, general pigments and dyes can be used together with the fluorescent material in the recording liquid. However, 3% of the recording liquid is required to fully exhibit the fluorescent characteristics.
Hereafter, it is necessary to stop using less than 2%. The dyes include metal-containing dyes, disperse dyes, direct dyes,
Acid dyes, oil dyes and the like are used. These dyes
Purified dyes free of inorganic salts are preferred.

For the production of the recording liquid, a fluorescent material, a solvent, water, a resin, an additive, etc. are mixed, dissolved by stirring, and diluted, if necessary, mixed with other additives for recording. Produce a liquid. The mixing and stirring can be performed by a high-speed dispersing machine, an emulsifying machine, etc., in addition to the usual stirring using a stirrer. The mixed recording liquid should be diluted before or
After that, it is sufficiently filtered with a filter having a pore size of 3 μm or less. It is preferable to filter with a filter of 1.0 μ or less. Filtration by centrifugation may be used prior to filtration of the filter, which reduces clogging during filtration by the filter and prolongs the service life of the filter.

Since the recording liquid produced by the present invention has remarkably good water resistance, it is suitable for use as an inkjet recording liquid, and can be used for hidden letters, symbols, cardboard markings, numbering, bar codes, etc. of documents in offices. It can be used in the field of recorded matter that is difficult to recognize and that has a security function. Further, the water resistance is better than that of a recording liquid produced by a dye such as a fluorescent whitening agent, and it is possible to form a special image having excellent storability of recorded matter.

[0020]

EXAMPLES The present invention will be described in more detail based on the following examples. In the examples, parts and% represent parts by weight and% by weight, respectively.

[Example 1] The following raw materials were mixed to prepare an aqueous recording liquid. Fluorescent material 0.3 parts N-methyl-2-pyrrolidone 66.0 parts Purified water 23.7 parts Ethylene glycol 10.0 parts After dissolving the fluorescent material with N-methyl-2-pyrrolidone, purified water and ethylene glycol Was added, and the mixture was stirred for 20 minutes with a stirrer and then filtered through a 0.45μ membrane filter to prepare a recording liquid. The viscosity was 4 cps. This recording liquid was colorless and transparent, and had little solvent odor. This recording liquid was put in a cartridge of "thinkjet" manufactured by Hewlett-Packard Co., and recording was performed on plain paper. When the recorded matter was irradiated with ultraviolet rays of 254 nm, orange red emission (around 620 nm) was confirmed. When water was dripped on the recording surface and ink bleeding was examined, there was no ink bleeding or runoff, and it had sufficient water resistance.

Example 2 The following raw materials were mixed to prepare an aqueous recording liquid. Fluorescent material 0.5 parts N-methyl-2-pyrrolidone 55.0 parts Sodium thiocyanate 1.0 part Ethylene glycol 5.5 parts Isopropyl alcohol 5.0 parts Purified water 35.0 parts Fluorescent material N-methyl-2 After dissolving with pyrrolidone, purified water in which sodium thiocyanate was dissolved and ethylene glycol were added, and the mixture was stirred with a stirrer for 20 minutes and then filtered with a 0.45 µ membrane filter to prepare a recording liquid. The viscosity was 2.3 cps. This recording liquid was colorless and transparent, and had little solvent odor. This recording liquid was put in a "Hitachi IJ Printer" manufactured by Hitachi Ltd., and recording was performed on plain paper. 254n for recorded material
When ultraviolet rays of m were irradiated, reddish orange emission could be confirmed. When water was dripped on the recording surface and ink bleeding was examined, there was no ink bleeding or runoff, and it had sufficient water resistance.

[Example 3] The following raw materials were mixed to prepare an aqueous recording liquid. Fluorescent material 0.5 part N-methyl-2-pyrrolidone 57.0 parts Sodium thiocyanate 1.0 part Ethylene glycol 5.5 parts Polyvinyl alcohol 1.0 part Isopropyl alcohol 2.0 parts Purified water 35.0 parts Fluorescent material Was dissolved in N-methyl-2-pyrrolidone, purified water in which sodium thiocyanate and polyvinyl alcohol were dissolved and ethylene glycol were added, and the mixture was stirred with a stirrer for 20 minutes and then filtered with a 0.80μ membrane filter. A recording liquid was prepared. The viscosity is 2.
It was 9 cps. This recording liquid was colorless and transparent, and had little solvent odor. This recording liquid was put in a "Hitachi IJ Printer" manufactured by Hitachi Ltd., and recording was performed on plain paper. When the recorded matter was irradiated with ultraviolet rays of 365 nm,
A reddish orange emission could be confirmed. When water was dripped on the recording surface and ink bleeding was examined, there was no ink bleeding or runoff, and it had sufficient water resistance.

Example 4 The following raw materials were mixed to prepare an aqueous recording liquid. Fluorescent material 1.0 parts Dimethyl sulfoxide 2.0 parts N-methyl-2-pyrrolidone 70.0 parts Ethyl alcohol 3.0 parts Purified water 20.0 parts Sodium thiocyanate 1.0 parts Dissolve in a stirrer for 30 minutes After that, it was filtered with a 0.45μ membrane filter to prepare a recording liquid. The viscosity is 1.
It was 9 cps. This recording liquid was put in a "Hitachi IJ Printer" manufactured by Hitachi, Ltd. to record on the surface of an aluminum plate. When the recorded matter was irradiated with ultraviolet rays of 254 nm, reddish orange emission could be confirmed.

Example 5 Fluorescent material 0.7 part Resin (Nippon Polymer's Riocryl PC-52, solid content 40%) 1.0 part N-methyl-2-pyrrolidone 60.0 parts Purified water 25.5 parts Glycerin 10.0 parts Manufacturing was performed by adding fluorescent material, resin solution and N-methyl-2-pyrrolidone to dissolve them well, and after dissolving, dilute with the remaining solvent and add sodium thiocyanate to adjust the recording liquid. It was Then, filtration was carried out with a 0.8 μ membrane filter, and a “thinkjet” cartridge manufactured by Hewlett-Packard Co. was put in a “Hitachi IJ Printer” manufactured by Hitachi, Ltd. to record on the surface of the paper. When the recorded matter was irradiated with ultraviolet rays of 254 nm, reddish orange emission could be confirmed. When water was dripped on the recording surface and ink bleeding was examined, there was no ink bleeding or runoff, and it had sufficient water resistance.

Example 6 The following raw materials were mixed to prepare an aqueous recording liquid. Fluorescent material 0.5 parts Diethylene glycol monobutyl ether 5.0 parts Dimethyl sulfoxide 5.0 parts N-methyl-2-pyrrolidone 50.0 parts Purified water 30.0 parts After dissolving for 20 minutes with a stirrer, 0.45 μm A recording liquid was manufactured by filtering with a membrane filter. This recording liquid was put in a cartridge of "thinkjet" manufactured by Hewlett-Packard Co., and recording was performed on plain paper. 254n for recorded material
When ultraviolet rays of m were irradiated, reddish orange emission (around 620 nm) was confirmed. When water was dripped on the recording surface and ink bleeding was examined, there was no ink bleeding or runoff, and it had sufficient water resistance.

Example 7 The following raw materials were mixed to prepare an aqueous recording liquid. Fluorescent material 0.9 parts Diethylene glycol monobutyl ether 5.0 parts Dimethyl sulfoxide 1.0 part Ethylene glycol 2.0 parts Isopropyl alcohol 5.0 parts N-methyl-2-pyrrolidone 60.0 parts Purified water 25.9 parts After dissolving with a stirrer for 20 minutes, it was filtered with a 0.45μ membrane filter to prepare a recording liquid. The viscosity is 2.
It was 6 cps. This recording liquid was put in "Marsh LCP" manufactured by Marsh Co., and recording was performed on a cardboard. When the recorded matter was irradiated with ultraviolet rays of 254 nm, orange red emission (around 620 nm) was confirmed. When water was dripped on the recording surface and ink bleeding was examined, there was no ink bleeding or runoff, and it had sufficient water resistance.

[0028]

According to the present invention, it is possible to obtain a recorded material having good water resistance while using water as a medium. This recorded material is
It is possible to perform recording that is difficult to distinguish from the background such as paper, and because it emits red light due to ultraviolet light, it can be used as a special recorded matter for reading with sensors, hidden characters, printing regarding security, etc.

Front Page Continuation (72) Inventor Michiko Tamano 2-33 Kyobashi, Chuo-ku, Tokyo Toyo Inn Co., Ltd. (72) Inventor Masaki Yaginuma 2-3-3 Kyobashi, Chuo-ku, Tokyo Toyo Inn Ki Manufacturing Co., Ltd.

Claims (3)

[Claims] 1. An ink jet recording liquid containing a fluorescent material represented by the following formula, a water-soluble solvent capable of dissolving the fluorescent material, and water. Embedded image 2. The ink jet recording liquid according to claim 1, which contains 0.005 to 3.0% of a fluorescent material. 3. The ink jet recording liquid according to claim 1, wherein N-methyl-2-pyrrolidone is used as the water-soluble solvent.