JP2007277545A - Diluting liquid for inkjet recording liquid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a diluting liquid for diluting an inkjet recording liquid which has good print drying property and adhesion with respect to paper and non-porous media to be recorded, specially which has an aptitude for obtaining a recording liquid superior in solubility for a luminescence material and good in jetting stability. <P>SOLUTION: This diluting liquid is for diluting an inkjet recording liquid containing a polyketone resin comprising 5-40 wt.% of water, 95-60 wt.% of n-propyl alcohol and 0-50 wt.% of ethanol; and a solvent comprising water and an alcohol. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a diluting liquid for diluting an ink jet recording liquid having good print drying and adhesion to paper and a non-porous recording medium.

2. Description of the Related Art Conventionally, in various special applications, recording liquids that are difficult to confirm with visible light but have been visualized with special light or that can be read by a sensor have been developed. In such applications, a fluorescent whitening agent such as a fluorescent whitening agent is used, but the fluorescent whitening agent is a water-based dye and has a disadvantage of poor water resistance. In addition, the fluorescent whitening agent generally emits purple light and is widely used for paper, fiber, etc., and therefore has a drawback that it is difficult to distinguish from such light emission.

Japanese Patent Publication No. 54-22336 discloses a recording liquid that emits reddish orange light when irradiated with ultraviolet rays. This recording liquid is a recording liquid mainly composed of water and hydrophilic glycol ethers. In applications where printing is performed at high speed, the amount of water is large, and drying of glycol ethers is slow. Drying could not be obtained. In particular, when the recording medium is a non-porous film other than paper, a particularly sufficient drying speed cannot be obtained.

Japanese Examined Patent Publication No. 8-26264 discloses a recording liquid with good drying properties that emits reddish orange light by ultraviolet rays. These use xylene and methyl ethyl ketone as solvents. Therefore, adhesion to non-porous films, etc. is good, but the solvent used is composed only of flammable solvents that do not contain water. There were restrictions.

Japanese Patent Laid-Open No. 2000-160083 uses 70% or more of alcohol in place of the solvent such as methyl ethyl ketone, and is a recording liquid with less odor than methyl ethyl ketone. However, this recording liquid consists only of alcohol, which is a flammable solvent. In terms of flammability, the recording liquid needs to be handled at least as much as the methyl ethyl ketone recording liquid, and requires attention.
JP 2000-160083 A

The present invention is an ink jet recording which has a sufficient adhesion to a non-porous recording medium, has a low odor, is excellent in drying properties, and has good water resistance in consideration of flammability. A dilution liquid for diluting the liquid is provided.

That is, the present invention is a solvent comprising polyketone resin, water and alcohol, characterized by comprising 5 to 40% by weight of water, 95 to 60% by weight of n-propyl alcohol, and 0 to 50% by weight of ethanol. The present invention relates to a diluting liquid for diluting an ink jet recording liquid containing.

According to the present invention, a recording liquid excellent in solubility of the fluorescent material and having good ejection stability can be obtained, and a recorded matter having good water resistance can be obtained. This recorded material can be recorded that is difficult to distinguish from the recording medium such as paper. Also, since red light is emitted by ultraviolet light, optical reading with a sensor, hidden characters, security as a special recorded material. It can be used for printing.

（式中、Ｘは、置換基を有してもよいメチル基、置換基を有してもよいフリル基、置換基を有してもよいフェニル基、置換基を有してもよいナフチル基または置換基を有してもよいチオニル基を表し、Ｙは、（ｎ−Ｃ₄ Ｈ₉ ）₄ Ｎまたは（Ｈ₂ Ｏ）ｎを表す。 The fluorescent material that can be used for the ink jet recording liquid in which the diluent of the present invention is diluted is a tetra-n-butylammonium salt represented by formula (1) or a europium complex having water as a counter ion, and X is substituted. Examples of the substituent include a lower alkyl group, a phenyl group, a halogen atom, and a hydroxyl group.
(Formula 1)

(In the formula, X is a methyl group which may have a substituent, a furyl group which may have a substituent, a phenyl group which may have a substituent, or a naphthyl group which may have a substituent. or a substituent represents an thionyl group, Y represents an _{(n-C 4 H 9)} 4 n or (H ₂ O) n.

  Specific examples of the fluorescent material of the present invention include tetra [4,4,4-trifluoro-1- (2-furanyl) -1,3-butanedionate] europium complex, tetra [4,4,4-tri Fluoro-1-phenyl-1,3-butanedionate] europium complex, tetra [4,4,4-trifluoro-1- (2-thionyl) -1,3-butanedionate] europium complex, tetra [4 , 4,4-trifluoro-1-naphthyl-1,3-butanedionate] europium complex, tetra [4,4,4-trifluoro-1-methyl-1,3-butanedionate] europium complex, and the like. These compounds are colorless or light yellow in visible light, and have a property of developing red color under ultraviolet light, have high emission intensity and excellent durability. It also has solubility in solvents.

The fluorescent material of the present invention comprises 4,4,4-trifluoro-1- (2-furanyl) -1,3-butanedione compound, 4,4,4-trifluoro-1-phenyl-1,3-butanedione compound 4,4,4-trifluoro-1- (2-thionyl) -1,3-butanedione compound, 4,4,4-trifluoro-1-naphthyl-1,3-butanedione compound, 4,4,4 -It can be produced by reacting butanedione compounds such as trifluoro-1-methyl-1,3-butanedione compound and europium perchlorate in acetone together with sodium hydroxide.

Since the fluorescent material of the present invention has high emission intensity, it can be detected as a printed matter by using 0.2 to 3% by weight in the recording liquid. If it is less than this, the reading of light emission is not sufficient, and if it is more than this, the trace of recording becomes easy to distinguish. The recording liquid can be adjusted to a recording liquid suitable for a printer by using a fluorescent material and a solvent, but the type of solvent, the presence or absence of the binder resin, the type, the amount, etc. can be adjusted according to the recording medium.

As the polyketone resin of the present invention, a polyketone resin having a hydroxyl value of 100 to 300 mmg KOH / g, which is a polycondensation product of one or more ketones selected from acetone, methyl ethyl ketone or clohexanone and formaldehyde is suitable.

The polyketone resin of the present invention not only fixes on paper, but also has good fixability on a recording medium such as a non-porous film. Moreover, it does not color when it is used as a solution, and is excellent in solvent releasability.

Furthermore, the polyketone resin of the present invention has a moderate compatibility with water, and is characterized by the fact that the phenomenon of whitening during drying hardly occurs in the recording liquid drying using alcohols that easily absorb water as a solvent. have. This is an extremely important characteristic particularly in applications that require stealth (invisibility) on the surface of the recording medium, and the polyketone resin of the present invention can exhibit performance that satisfies this requirement. . The polyketone resin is excellent in fixability even on a non-porous recording medium with little internal stress due to volume shrinkage during drying.

The polyketone resin used in the present invention has sufficient solubility in a solvent system composed of water and alcohol, and exhibits good water resistance after drying. Further, since the solubility is excellent, the viscosity of the resin solution is relatively low, and it is possible to adjust the low-viscosity recording liquid required for the inkjet recording liquid. Moreover, since it is excellent in re-solubility in a solvent, high reliability is ensured in the continuous discharge property with a printer. As described above, by using a polyketone resin, it is possible to form a recording liquid excellent in the balance of ejection stability in a printer, fixability on a recording medium, and water resistance.

The polyketone resin of the present invention has a hydroxyl value of 100 to 300 mgKOH / g, preferably 130 to 280 mgKOH / g, and a softening point of 60 to 130 ° C, preferably 90 to 105 ° C, in order to improve the balance of the above properties. As the molecular weight, it is preferable to use a resin having a weight average molecular weight of 300 to 5,000, preferably 500 to 3,000.

The polyketone resin of the present invention is used in an inkjet recording liquid in an amount of 3 to 35% by weight, preferably 5 to 30% by weight. If the amount is less than the lower limit, it is not preferable because the fluorescent material cannot be sufficiently fixed to the non-permeable recording medium. If the amount is larger than this upper limit, the viscosity of the recording liquid increases and the ejection stability decreases. In addition, since the resin layer covers the periphery of the fluorescent material thickly, there is a possibility that the emission of the compound may be lowered, and the generation of fluorescence due to the resin may be an obstacle, which is not preferable.

The polyketone resin of the present invention may be used alone, but may be used by mixing with other resins in order to adjust the fixing property, the viscosity of the recording liquid, the solubility and the like. Examples of these resins include cellulose-based, phenol-based, epoxy-based, epoxyphenol-based, polyester-based, polyamide-based, polyurethane-based, butyral-based, silicon-based, rosin, and rosin-modified resins (phenol-modified, maleic acid-modified, fumarate). Acid-modified etc.), acrylamide, alkyd, shellac, acrylic, styrene-acrylic resins, etc. can be exemplified, and those having good solubility in the mixed solvent of the present invention and capable of adjusting the viscosity of the recording liquid appropriately are selected. To do. These resins can be used at 0 to 3% by weight in the recording liquid.

As the solvent of the present invention, it is preferable to use an alcohol-based solvent from the viewpoints of excellent solubility of the fluorescent material and odor and hygiene. When the drying property on the recording medium is particularly important, it is possible to use only alcohol as a solvent component, but consideration of flammability, drying property and fixing property on the recording medium, and From the viewpoint of balance of solubility of the fluorescent material, it is more preferable to use an alcohol-based mixed solvent containing water. Examples of such alcohol include methanol, ethanol, n-propyl alcohol, and iso-propyl alcohol.

The solvent of the present invention is preferably a mixed system of water and n-propyl alcohol, or a mixed system of water, n-propyl alcohol and ethanol. When the water content is high, precipitation due to a decrease in the solubility of the polyketone resin may be induced. Therefore, in order to obtain a stable recording liquid, n-propyl alcohol 10-60 with respect to 5-30 parts by weight of water. It is preferable to adjust as a weight part and ethanol 0-50 weight part. Moreover, it is preferable that the ratio of water and n-propyl alcohol is 5-30: 30-60 by weight ratio. By adjusting in this way, it becomes an inkjet recording liquid that maintains good solubility of the fluorescent material and the resin, has excellent drying properties on the recording medium, and is preferable in terms of flammability, odor, and safety and health.

In addition to the above, the solvent of the present invention contains 0 to 5% of a solvent such as N-methyl-2-pyrrolidone, γ-butyllactone, methyl isobutyl ketone, etc. in order to increase the dissolution stability of the resin and the fluorescent material. % Can also be used in combination. However, the combined use of these solvents may cause a decrease in drying properties, and when high-speed drying properties are important, it is preferable to keep the amount used to a minimum.

Further, an antifoaming agent can be added to the ink jet recording liquid of the present invention in order to prevent the circulation or movement of the recording liquid or the generation of bubbles during the production of the recording liquid. Furthermore, an anionic, nonionic, cationic or amphoteric surfactant can be used for improving the ejection stability of the recording liquid and the recorded image.

Specific examples of anionic activators include fatty acid salts, alkyl sulfate esters, alkyl aryl sulfonates, alkyl naphthalene sulfonates, dialkyl sulfonates, dialkyl sulfosuccinates, alkyl diaryl ether disulfonates, alkyl phosphoric acids. Salt, polyoxyethylene alkyl ether sulfate, polyoxyethylene alkyl aryl ether sulfate, naphthalenesulfonic acid formalin condensate, polyoxyethylene alkyl phosphate ester salt, glycerol borate fatty acid ester, polyoxyethylene glycerol fatty acid ester, etc. It can be illustrated.

Specific examples of the nonionic activator include polyoxyethylene alkyl ether, polyoxyethylene alkyl aryl ether, polyoxyethylene oxypropylene block copolymer, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, Nonionic active agents such as glycerin fatty acid ester, polyoxyethylene fatty acid ester, polyoxyethylene alkylamine, fluorine-based and silicon-based can be exemplified.

Specific examples of the cationic activator include alkylamine salts, quaternary ammonium salts, alkylpyridinium salts, alkylimidazolium salts and the like.

Specific examples of the amphoteric activator include alkyl betaines, alkylamine oxides, phosphadylcholines and the like.

In the inkjet recording liquid of the present invention, it is preferable to add a silicon compound for the purpose of appropriately spreading the recording liquid on a non-porous recording medium such as a film and preventing repelling. Preferably, by adding a silicon compound represented by the formula (2) in the range of 0.01 to 0.5% by weight in the recording liquid, dot formation is improved and image formation that enables high-precision optical reading is possible. Can be realized.
Formula (2)

The ink jet recording liquid of the present invention is difficult to identify when it is a recorded material, but it is also possible to easily identify the recorded material using a colorant. For this reason, general pigments and dyes can also be used together with the compound. However, in order to sufficiently exhibit the fluorescence characteristics, it is necessary to stop the use of 3% by weight or less, preferably 2% by weight or less of the recording liquid. Examples of the dye that can be added include oil-based dyes, metal-containing dyes, and disperse dyes. These dyes are preferably purified dyes from which inorganic salts have been removed.

The I ink jet recording liquid of the present invention is obtained by mixing a fluorescent material, a solvent, a resin, and additives as necessary, stirring and dissolving, and further diluting and mixing other additives as necessary. . For stirring and dissolving, a high-speed disperser, an emulsifier and the like can be used in addition to a stirrer using a normal stirring blade. The solution thus obtained is sufficiently filtered through a filter having a pore size of 3 μm or less, preferably 1 μm or less before or after dilution to give a recording solution. Prior to filtration of the filter, filtration by centrifugation can also be used, which can reduce production clogging and reduce the number of filter replacements, resulting in production efficiency.

Further, the properties of the ink jet recording liquid of the present invention can be adjusted for viscosity, surface tension, conductivity, drying property, etc. depending on the type of printer, but in general, the viscosity is 0.8 to 15 mPa · s, the surface tension is 20 to 45 mN / m.

When the inkjet recording liquid of the present invention is used in a continuous type printer, the conductivity is set to 0.1 to 20 millisiemens (mS / cm), and further to 0.5 to 10 millisiemens (mS / cm). It is preferable to adjust. As the conductivity adjusting agent, sodium thiocyanate, potassium thiocyanate, ammonium thiocyanate, lithium nitrate, tetrabutylammonium bromide and the like can be used, and tetrabutylammonium bromide is particularly preferable from the viewpoint of stability over time. Such a conductivity adjusting agent is preferably used in the recording liquid in an amount of 5% by weight or less, preferably 0.2 to 5% by weight.

When the inkjet recording liquid of the present invention is used in a continuous type printer, the solvent in the recording liquid is volatilized by continuous use by discharging and collecting the recording liquid, the solid content of the recording liquid is concentrated with time, and the viscosity is increased. Rises. For this reason, the inkjet recording liquid of the present invention requires a diluting liquid for replenishing the volatile components in the recording liquid and adjusting the solubility and viscosity of the resin and the fluorescent material. Since the highly volatile alcohol component tends to decrease from the mixed solvent of the recording liquid, the diluent preferably has a composition containing more volatile alcohol component than the recording liquid. As such a diluent, a diluent comprising 5 to 10 parts by weight of water, 95 to 70 parts by weight of n-propyl alcohol, and 0 to 50 parts by weight of ethanol is suitable.

The inkjet recording liquid of the present invention is a variable information and high-speed printing of barcodes for the purpose of optical reading, recording of hidden characters and symbols in office documents, cardboard marking and numbering, and recording of barcode information that is difficult to recognize It can be used in a wide range of fields such as recording with a security function. Also, the recorded matter of the recording liquid of the present invention has better water resistance than a recorded matter obtained from a recording solution containing a dye such as a fluorescent brightening agent as a fluorescent material. It can also be used for special image forming applications that are required.

[Example]
Hereinafter, the present invention will be described in more detail based on examples. In the examples, parts and% represent parts by weight and% by weight, respectively.

[Synthesis of Fluorescent Materials (1) and (2)] 12.8 parts of perchloric acid (60% aqueous solution) was added to 3.6 parts of europium oxide and 10 parts of water, followed by stirring at room temperature for 30 minutes. This aqueous solution was placed in a mixture of 16.5 parts of 4,4,4-trifluoro-1- (2-thionyl) -1,3-butanedione, 3.2 parts of sodium hydroxide, 5 parts of water and 250 parts of acetone. The solution was added dropwise at room temperature and stirred for 1 hour. After completion of the reaction, acetone was removed by an evaporator, and the produced yellow pasty solid was dissolved in 50 parts of ethanol and dropped into 300 parts of water with stirring. The precipitated white solid was separated by filtration and dried to obtain 15.5 parts of the fluorescent material (1). Dissolve 10 parts of this fluorescent material (1) in 200 parts of ethanol, add 6 parts of tetra-n-butylammonium bromide, stir at room temperature for 1 hour, then add 500 parts of water, and filter the precipitated solid. It dried under reduced pressure at 0 degreeC and obtained 11.5 parts of fluorescent materials (2).

[Synthesis of fluorescent materials (3) and (4)] 12.8 parts of perchloric acid (60% aqueous solution) was added to 3.6 parts of europium oxide and 10 parts of water, and the mixture was stirred at room temperature for 30 minutes. This aqueous solution was placed in a mixture of 16.5 parts of 4,4,4-trifluoro-1- (2-phenyl) -1,3-butanedione, 3.2 parts of sodium hydroxide, 5 parts of water and 250 parts of acetone. The solution was added dropwise at room temperature and stirred for 1 hour. After completion of the reaction, acetone was removed by an evaporator, and the produced yellow pasty solid was dissolved in 50 parts of ethanol and dropped into 300 parts of water with stirring. The precipitated white solid was separated by filtration and dried to obtain 15.5 parts of fluorescent material (3). Dissolve 10 parts of this fluorescent material (3) in 200 parts of ethanol, add 6 parts of tetra-n-butylammonium bromide, stir at room temperature for 1 hour, and then filter out the precipitated solid with 500 parts of water added. It dried under reduced pressure at 0 degreeC and obtained 11.5 parts of fluorescent materials (4).

[Example 1] A recording liquid was prepared by mixing the following raw materials. Fluorescent material (1) 1.5 parts Polyketone resin (1) 15.0 parts (K-1717 manufactured by LAWTER; hydroxyl value 270 mg KOH / g, softening point 100 ° C.) n-propyl alcohol 59.0 parts water 23.45 parts Sodium thiocyanate 1.0 part Silicon additive 0.05 part The raw material was sufficiently dissolved by a stirrer and then filtered through a membrane filter having a pore diameter of 0.80 μm to obtain a recording liquid having a viscosity of 5.3 mPa · s. This recording liquid was put into a “Hitachi IJ printer” manufactured by Hitachi, Ltd. and recorded on a transparent polystyrene film.

The recorded material could not be identified under visible light, but red light emission (615 nm ± 5 nm) was confirmed when irradiated with ultraviolet light. Water was dripped onto the recording surface to check for bleeding of the recording liquid. However, the recording liquid did not bleed or flow out and had sufficient water resistance.

When continuous printing of the recording liquid was performed, an increase in the viscosity of the recording liquid was observed. Therefore, the diluent (1) was added according to the consumption of the recording liquid. The addition of the diluent (1) was supported by adding about 0.6 times the consumption of the recording liquid. Thereby, the viscosity of the recording liquid could be maintained as in the initial printing.

[Example 2] A recording liquid was prepared by mixing the following raw materials.

Fluorescent material (2) 1.5 parts Polyketone resin (1) 15.0 parts (K-1717 manufactured by LAWTER; hydroxyl value 270 mg KOH / g, softening point 100 ° C.) n-propyl alcohol 29.0 parts Ethanol 30.0 parts Water 19.45 parts Methyl isobutyl ketone 4.0 parts Sodium thiocyanate 1.0 part Silicon additive 0.05 parts The raw material is sufficiently dissolved in a stirrer and then filtered through a membrane filter having a pore size of 0.8 μm to obtain a viscosity. A recording liquid of 4.3 mPa · s was obtained.

This recording solution was put into a “Hitachi IJ printer” manufactured by Hitachi, Ltd. and recorded on a polystyrene film. Since the viscosity of the recording liquid was increased by continuous printing of the recording liquid, the diluent (2) was added according to the consumption of the recording liquid. Dilution liquid (2) was added by adding about 0.6 times the consumption of the recording liquid. Thereby, the viscosity of the recording liquid could be maintained as in the initial printing. When the recorded matter was irradiated with ultraviolet rays, red emission with orange was confirmed. Water was dripped onto the recording surface to check for bleeding of the recording liquid. However, the recording liquid did not bleed or flow out and had sufficient water resistance. The recording liquid was drawn down on a polyester film, a treated polypropylene film, a treated polyolefin film or the like to confirm drying, but there was no whitening phenomenon on the dry surface.

Examples 3 to 9 Recording liquids having the composition shown in Table 1 were prepared in the same manner as in Example 1.

[Comparative Examples 1-6] Recording liquids having the composition shown in Table 2 were prepared in the same manner as in Example 1.

[Adjustment of Diluent] A solvent was mixed with the composition shown in Table 3, and filtered through a filter having a pore size of 0.8 μm to prepare a diluted solution.

[Description of raw material name of recording liquid]
X in formula (1) Y in formula (1)
Fluorescent material (1): Thionyl group Water fluorescent material (2): Thionyl group Tetrabutylammonium salt fluorescent material (3): Phenyl group Water fluorescent material (4): Phenyl group Tetrabutylammonium salt fluorescent material (5): Furyl group Tetrabutylammonium salt fluorescent material (6): Naphtyl group Tetrabutylammonium salt polyketone resin (1): K-1717 manufactured by LAWTER (hydroxyl value 270 mg KOH / g, softening point 100 ° C.) Polyketone resin (2): K manufactured by LAWTER -1717B (hydroxyl value 135 mg KOH / g, softening point 95 ° C.) TBAB: The recording liquids obtained in the tetrabutylammonium bromide examples and comparative examples were evaluated as follows. The results are shown in Tables 4 and 5.

[Evaluation method] Filterability: The amount of filtration during vacuum filtration with a 0.80 μm membrane filter (4.5 cmφ) is 1 liter or more. Water resistance: Bleeding, flowing out, and stickiness of recording liquid when immersed in water for 3 minutes. Adhesion: peel test with mending tape (manufactured by 3M). Dot shape: The shape of the dot on the polystyrene film was confirmed with a microscope. Whitening: A dried state when the recording liquid is drawn down on the surface of the polyester film and dried.

The recording liquid of Comparative Example 1 has a strong methyl ethyl ketone odor and a low flash point. The recording liquid of Comparative Example 2 has a low flash point and poor water resistance due to the resin. The recording liquid of Comparative Example 3 uses a part of water, but the dot shape is insufficient. Water resistance based on resin is also weak. In the recording liquid of Comparative Example 4, the solvent is only alcohol, and the dot formation is insufficient. In the recording liquid of Comparative Example 5, the solvent is only alcohol and the flash point is low. The recording liquid of Comparative Example 6 is extremely slow to dry on the film surface.

Claims (1)

An ink jet recording liquid comprising a polyketone resin and a solvent comprising water and alcohol, characterized by comprising 5 to 40% by weight of water, 95 to 60% by weight of n-propyl alcohol, and 0 to 50% by weight of ethanol. Diluent for diluting.