JPH0346502B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to improved aqueous inkjet recording ink compositions.

In inkjet recording, in order to perform good recording, various conditions are required for the ink used.

First, it is necessary that the viscosity, surface tension, specific conductivity, and density of the ink be within appropriate ranges as ink physical property values depending on the droplet generation method and the droplet flying direction control method. Furthermore, during long-term storage, long-term use, or recording suspension, precipitation must not occur due to chemical changes, and the physical properties of the ink must not change. The discharge nozzle of a recording device generally has a diameter of 10
The diameter is approximately 60 μm, and if the nozzle is clogged due to precipitation, droplets cannot be ejected. Even if the nozzle is not completely clogged, if solid matter or sticky matter adheres to the vicinity of the nozzle, or if the physical properties of the ink that were adjusted to the desired values during ink formulation change, recording performance, ejection stability, and ejection response may deteriorate. descend.

It is also desired that the recorded image has sufficiently high contrast and clarity. In conventional inks, when an attempt is made to increase the contrast of an image by increasing the dye content in the ink, the ejection nozzle tends to become clogged. Therefore, there is a need for dyes that have high solubility in the solvent used in ink and a high extinction coefficient.

It is also necessary to dry quickly after printing. Conventional ink contains a large amount of wetting agent to prevent nozzle clogging due to drying of the ink inside the nozzle during printing pauses. Special paper with high quality is used. As a result, not only does image smearing occur significantly, but it also becomes impossible to use many types of ordinary paper.

In addition, it is naturally required that recorded images have water resistance, light resistance, and abrasion resistance.

Although many proposals have been made so far as inkjet recording inks, in practice no one has been obtained that fully satisfies all of the above conditions.

The present invention was made in view of the current situation, and it is an object of the present invention to provide an ink composition for inkjet recording that satisfies all of the above conditions.

That is, the gist of the present invention is an aqueous inkjet recording ink characterized by containing at least one dye represented by the following structural formulas (1) to (1). As the anthraquinone dye, those of the following structural formula (a) are useful.

(However, A is a hydrogen atom, a benzene ring, an alkyl group having 1 to 2 carbon atoms, or a benzene ring substituted with an alkyl group having 1 to 2 carbon atoms, X ₁ to X ₄ are hydrogen,
Halogen atom, methyl group, hydroxyl group, carboxyl group, sulfonate group, amino group, -NH・CH ₃ or
Either NH-A, hydroxyl group, carboxyl group, or sulfonate group is a sodium salt. n
is 1 to 18. ) Specific examples of such compounds include the following.

As the azo dye, those having the following structural formula (b) or (c) are useful.

Specific examples of such compounds include the following.

As a pyrazolone dye, the following structural formula (d) or (v) is used.
are useful.

(However, n is 1 to 18.) (However, A ₁ to _{A 5} are a methyl group, a hydroxyl group, an amino group, a sulfon group, or a carboxyl group, the sulfon group is a sodium salt or a quaternary ammonium salt, the carboxyl group is a sodium salt, and D ₁ to _{D 4} are at least one or more amino groups,
Benzene ring that can be substituted with a hydroxyl group or a sulfonate group or a sodium salt of a sulfonate group, n is 1 to 18
It is. ) Specific examples of such compounds include the following.

As the phthalocyanine dye, those having the following structural formula (f) are preferable.

(However, n is 1 to 18.) Specific examples of such compounds include the following.

As the fluorescein dye, those having the following structural formula (g) are preferable.

(However, A ₁ and A ₂ are hydrogen atoms, methyl groups, hydroxyl groups, or amino groups, sulfonate groups, and carboxyl groups, or sulfonate groups, carboxyl groups, and hydroxyl groups are sodium salts, and D is an oxygen atom or N
( _C2H5 ) _{2- ,} and _X1 to _X7 are a hydrogen atom, a halogen atom, a sodium sulfonate group, or a sodium hydroxide group. n is 1-18. ) Specific examples of such compounds include the following.

As a triphenylmethane dye, the following structural formula (H) is used.
The one is good.

(However, E ₁ to E ₃ are hydrogen atoms or H(O-CH ₂ -CH ₂ ) _o -O- [n=1 to 18], and A is a hydrogen atom or a hydroxyl group, an amino group, a sulfonate group, a carboxyl group, sulfonate group, carboxyl group, or hydroxyl group is a sodium salt, and D ₁ ,
D ₂ is an amino group, a hydroxyl group, a sulfonate group, or -
A hydrocarbon represented by a benzene ring or C _n H _2n+1 which can be substituted with O-(CH ₂ -CH ₂ -O) _o H, and m is 0, 1 or 2. ) Specific examples of such compounds include the following.

As an inkjet recording ink composition,
The basic components are a dye compound solvent and a wetting agent, and the ink of the present invention also has the same basic structure. The amount of the dye compound added is preferably 0.5 to 20% by weight, preferably 1.0 to 10% by weight.

The solvent that can be used is generally water, but is not limited thereto.

In the present invention, the following water-soluble organic solvents are preferably used in combination.

For example, alkyl alcohols having 1 to 4 carbon atoms such as ethyl alcohol, propyl alcohol, and butyl alcohol; Ether solvents such as ethylene glycol monoethyl ether and ethylene glycol diethyl ether; Polyhydric alcohols such as ethylene glycol, diethylene glycol, and propylene glycol Alcohol: An amine or amide solvent such as alcohol amine or formamide.

Furthermore, an aqueous solvent consisting of a mixture of these water-soluble organic solvents and water may also be used.

As the wetting agent used in the present invention, many of those commonly known in the technical field related to the present invention are effective, but among these, thermally stable ones are particularly effective. Preferably used. Specific examples of such wetting agents include polyalkylene glycols such as polyethylene glycol and polypropylene glycol; examples of such wetting agents include polyalkylene glycols such as polyethylene glycol, polypropylene glycol, etc.; Alkylene glycols containing carbon atoms; for example, ethylene glycol methyl ether, diethylene glycol methyl ether,
Lower alkyl ethers of diethylene glycol such as diethylene glycol methyl ether and diethylene glycol ethyl ether; glycerin; lower alkoxy triglycols such as methoxy triglycol and ethoxy triglycol; N-vinyl-2-pyrrolidone oligomer; and the like.

These wetting agents may be added in necessary amounts as desired to satisfy the desired characteristics of the recording medium liquid, but the amount added is usually 0.1 to 40wt based on the total weight of the recording medium liquid. %, preferably 0.1~25wt
%, preferably 0.2 to 15 wt%.

Moreover, the above-mentioned wetting agents may be used alone or in combination of two or more types under conditions that they do not adversely affect each other.

In the present invention, various additives are used to provide more remarkable recording characteristics. Such additives include preservatives, fungicides, chelating reagents, rust inhibitors, ultraviolet absorbers, antioxidants, viscosity modifiers, surface tension modifiers, PH modifiers, resistivity modifiers, and infrared absorbers. Examples include.

For example, examples of the chelating reagent include alkali metal salts such as ethylenediaminetetraacetic acid, nitrilotriacetic acid, hydroxyethylethylenediaminetriacetic acid, diethylenetriaminepentaacetic acid, and uramildiacetic acid.

Examples of the rust preventive include acidic sulfite, sodium thiosulfate, ammonium thioglycolate, diisopropylammonium nitrite, pantaerythritol tetranitrate, dicyclohexylammonium nitrite, and the like.

As ultraviolet absorbers, benzotriazole,
Examples include acetophenone and benzyl.

The viscosity modifier and surface tension modifier are mainly used to flow through the nozzle at a sufficient flow rate depending on the recording speed, to prevent the recording medium liquid from flowing around the nozzle orifice, and to the recording member. It is added to prevent bleeding (spreading of spot diameter) when applied.

As the viscosity modifier and the surface tension modifier, all commonly known agents can be used as long as they are effective and do not adversely affect the liquid medium and recording material used.

Specifically, suitable examples of the viscosity modifier include polyvinyl alcohol, hydroxypropyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose, water-soluble acrylic resin, polyvinylpyrrolidone, gum arabic starch, and the like.

Surface tension modifiers preferably used in the present invention include anionic, cationic, and nonionic surfactants, and specifically,
Anionic systems include polyethylene glycol ether sulfate and ester salts, and cationic systems include polyethylene glycol ether sulfate and ester salts.
-Vinylpyridine derivatives, poly-4-vinylpyridine derivatives, nonionic polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene alkyl esters, polyoxyethylene sorbitan monoalkyl esters, polyoxyethylene alkyl amines, etc. Can be mentioned. In addition to these surfactants,
Diethanolamine, propanolamine, amino acids such as morpholinic acid, basic substances such as ammonium hydroxide, sodium hydroxide, N-methyl-2
Substituted pyrrolidones such as -pyrrolidone are also effectively used.

Two or more of these surface tension adjusting agents may be used as necessary, within a range that does not adversely affect each other or other constituent components, so that a recording medium liquid having a desired value of surface tension is prepared. You may use a mixture.

The amount of these equal surface tension adjusters to be added is determined as appropriate depending on the type, other constituent components of the recording medium liquid to be prepared, and desired recording characteristics. whereas normally it is 0.0001
~0.1 part by weight, preferably 0.001 to 0.01 part by weight.

Specific examples of the PH adjuster include lower alkanolamines, monovalent hydroxides such as alkali metal hydroxides, ammonium hydroxide, and the like.

These PH adjusters are added in a necessary amount so that the recording medium liquid to be prepared has a desired PH value.

The PH adjuster is used to maintain the chemical stability of the prepared recording medium liquid, for example, to maintain a predetermined PH value in order to prevent changes in physical properties due to long-term storage and to prevent sedimentation and aggregation of the recording agent and other components. Appropriate amount is added.

As the PH adjuster suitably used in the present invention, almost any PH adjuster can be mentioned as long as it can control the PH value to a desired value without adversely affecting the recording medium liquid to be prepared.

Specific examples of the resistivity adjuster include inorganic salts such as ammonium chloride, sodium chloride, and potassium chloride, water-soluble amines such as triethanolamine, and quaternary ammonium salts.

In the case of recording in which the recording medium liquid droplets do not need to be charged, the specific resistance value of the recording medium liquid may be arbitrary.

Next, specific examples will be described.

Example 1 Compound (3) above 3 parts by weight diethylene glycol 10 Polyethylene glycol (#400) 15 N-methyl-2-pyrrolidone 2 Water Remainder The above components were stirred and mixed at 70°C for 4 hours, and 0.5μ A recording liquid was obtained by pressure filtration using a membrane filter (manufactured by Millipore).

Example 2 Compound (6) above 3 parts by weight ethylene glycol 5 Diethylene glycol 20 Diethylene glycol-n-butyl ether
2 parts by weight N-methyl-2-pyrrolidone 1 water balance The above components were stirred and mixed at 80° C. for 5 hours and filtered under pressure using a 0.5 μm membrane filter to obtain a recording liquid.

Example 3 Compound (10) 3 parts by weight polyethylene glycol (#400) 20 Glycerin 5 Diethylene glycol-n-butyl ether
2. Water (Remainder) The above components were stirred and mixed at 70° C. for 5 hours and filtered under pressure using a 0.5μ membrane filter to obtain a recording liquid.

Example 4 Compound of (11) above 3 parts by weight ethylene glycol 15 Polyethylene glycol (#600) 5 parts by weight diethylene glycol ethyl ether 2 Water Residual The above ingredients were stirred and mixed at 80°C for 4 hours and filtered through a 0.5μ membrane filter. A recording liquid was obtained by pressure filtration.

Example 5 Compound (13) above 3 parts by weight diethylene glycol 5 Triethylene glycol 10 Polyethylene glycol 10 2-pyrrolidone 2 Water Remaining The above ingredients were stirred and mixed at 60°C for 4 hours and added through a 0.5μ membrane filter. A recording liquid was obtained by pressure filtration.

Example 6 Compound (15) 3 parts by weight polyethylene glycol (#400) 15 Glycerin 5 parts by weight diethylene glycol-n-butyl ether
2. Water (remainder) The above components were stirred and mixed at 60° C. for 5 hours, and filtered under pressure using a 0.5μ membrane filter (manufactured by Millipore) to obtain a recording liquid.

Example 7 Compound of (17) 3.5 parts by weight Ethylene glycol 5 Propylene glycol 5 Polyethylene glycol 15 N-methyl-2-pyrrolidone 2 Water The remaining components were stirred and mixed at 70°C for 4 hours, and 0.5μ A recording liquid was obtained by pressure filtration using a membrane filter (manufactured by Millipore).

Example 8 Compound of (20) 2.5 parts by weight diethylene glycol 5 Polypropylene glycol 5 parts by weight Polyethylene glycol 3 2-pyrrolidone 3 Water The above components were stirred and mixed at 60°C for 5 hours, and filtered through a 0.5μ membrane filter. A recording liquid was obtained by pressure filtration.

Example 9 Compound (23) 3 parts by weight Ethylene glycol 20 Glycerin 5 Ethylene glycol diethyl ether 1 2-pyrrolidone 1 Water The above components were stirred and mixed at 70°C for 4 hours, and filtered through a 0.5μ membrane filter. A recording liquid was obtained by pressure filtration.

Example 10 Compound of (27) above 3 parts by weight diethylene glycol 15 Butylene glycol 10 parts by weight Ethoxy glycol 3 Water The balance The above components were stirred and mixed at 70°C for 5 hours, and filtered under pressure using a 0.5μ membrane filter. A recording liquid was obtained.

Example 11 Compound (31) above 2.5 parts by weight Diethylene glycol 5 Triethylene glycol 5 Polyethylene glycol (#400) 10 N-methyl-2-pyrrolidone 2 Water Residual ingredients were stirred and mixed at 70°C for 5 hours. Then, pressure filtration was performed using a 0.5μ membrane filter (manufactured by Millipore) to obtain a recording liquid.

Example 12 Compound of (33) above 3 parts by weight Ethylene glycol 5 Diethylene glycol 10 Glycerin 5 parts by weight Diethylene glycol ethyl ether 3 Remaining water The above ingredients were stirred and mixed at 80°C for 3 hours, and filtered through a 0.5μ membrane filter. A recording liquid was obtained by pressure filtration.

Example 13 Compound of (37) 2.5 parts by weight Diethylene glycol 10 Triethylene glycol 5 Polyethylene glycol (#400) 5 Diethylene glycol methyl ether 3 Water Residual The above components were stirred and mixed at 70°C for 5 hours to give 0.5 parts by weight. μ
A recording liquid was obtained by pressure filtration using a membrane filter.

Example 14 Compound of the above (39) 3.5 parts by weight polypropylene glycol 5 parts by weight ethylene glycol 5 〃 Polyethylene glycol (#400) 10 〃 Diethylene glycol ethyl ether 2 〃 2-pyrrolidone 1 〃 Water Balance The above ingredients were heated at 80°C for 4 hours. Stir to mix, 0.5μ
A recording liquid was obtained by pressure filtration using a membrane filter.

Example 15 Compound of the above (42) 3 parts by weight Ethylene glycol 5 Triethylene glycol 15 2-pyrrolidone 2 Water Balance The above components were stirred and mixed at 70°C for 5 hours to give 0.5μ
A recording liquid was obtained by pressure filtration using a membrane filter.

Example 16 Compound of (35) above 3 parts by weight Ethylene glycol 5 Triethylene glycol 5 Polyethylene glycol (#400) 10 Ethylene glycol diethyl ether 2 Water Remainder The above ingredients were stirred and mixed at 70°C for 5 hours, and 0.5 A recording liquid was obtained by pressure filtration using a μ membrane filter (manufactured by Millipore).

Example 17 Compound of the above (62) 3.5 parts by weight diethylene glycol 5 Polyethylene glycol (#400) 15 2-pyrrolidone 2 Water The remaining components were stirred and mixed at 70°C for 4 hours, and filtered through a 0.5μ membrane filter (Millipore). A recording liquid was obtained by pressure filtration using a filter (manufactured by Co., Ltd.).

Example 18 Compound of the above (74) 3 parts by weight ethylene glycol 5 Triethylene glycol 5 Polyethylene glycol (#400) 10 Diethylene glycol-n-butyl ether
2. Water (Remainder) The above components were stirred and mixed at 80° C. for 4 hours, and filtered under pressure using a 0.5μ membrane filter (manufactured by Millipore) to obtain a recording liquid.

Example 19 Compound of (52) above 3 parts by weight diethylene glycol 10 〃 Polypropylene glycol (#400) 5 〃 Glycerin 5 〃 N-Methyl-2-pyrrolidone 1.5 〃 Water Remainder The above components were stirred and mixed at 70°C for 3 hours, and 0.5 A recording liquid was obtained by pressure filtration using a μ membrane filter (manufactured by Millipore).

Example 20 Compound of (6) above 3.5 parts by weight diethylene glycol 10 Polyethylene glycol 15 Diethylene glycol-n-butyl ether
2 N-Methyl-2-pyrrolidone 1 Water Remainder The above components were stirred and mixed at 70°C for 4 hours, and filtered under pressure using a 0.5μ membrane filter (manufactured by Millipore) to obtain a recording liquid.

When various tests were conducted using the inks of the above examples, the following results were obtained, indicating that the inks were excellent as inkjet recording inks.

1. Image clarity and image drying properties: When the ink was jet-recorded on commercially available high-quality paper using a nozzle with an inner diameter of 30 μm at a particle generation frequency of 100 KHz, a clear image was obtained. The drying time of the recorded material was within 10 seconds at room temperature and humidity.

2. Storage: The ink was sealed in a glass container and stored at -20°C for 1 month, at 4°C for 1 month, at 20°C for 1 year, and at 90°C for 1 week, but no precipitation was observed. Ta. Further, no change was observed in the physical properties or color tone of the ink.

3. Jetting stability: The jet recording described in 1) above was carried out continuously for 1,500 to 2,000 hours, and stable recording was achieved without any clogging of the nozzle or change in the jetting direction.

In the conventional ink prepared with a dye that does not add -(CH ₂ -CH ₂ -O) _o H groups, clogging and a change in the ejection direction occurred after about 1000 hours.

4 Injection response: After recording the jet according to 1) above,
After being left at room temperature and humidity for one month and at 40°C and 30% RH for one week, the jet recording in 1) was performed again, and as in 3) above, stable recording was achieved.

Claims (1)

[Claims] 1. The hydrogen atom in the hydroxyl group of the dye is (-CH ₂ -CH ₂ -O) _o H group (however, n = 1 to 18)
1. An aqueous inkjet recording ink characterized by containing at least one dye represented by the following structural formulas (a) to (h) substituted with: (However, A is a hydrogen atom, a benzene ring, an alkyl group having 1 to 2 carbon atoms, or a benzene ring substituted with an alkyl group having 1 to 2 carbon atoms, X ₁ to X ₄ are hydrogen,
Either a halogen atom, a methyl group, a hydroxyl group, a carboxyl group, a sulfonate group, an amino group, _-NH.CH3 or NH-A, or a hydroxyl group, a carboxyl group, or a sulfonate group is a sodium salt. ) (However, A ₁ to _{A 5} are a methyl group, a hydroxyl group, an amino group, a sulfon group, or a carboxyl group, the sulfon group is a sodium salt or a quaternary ammonium salt, the carboxyl group is a sodium salt, and D ₁ to _{D 4} are at least one or more amino groups,
A benzene ring which can be substituted with a hydroxyl group or a sulfonate group or a sodium salt of a sulfonate group. ) (However, A ₁ and A ₂ are hydrogen atoms, methyl groups, hydroxyl groups, or amino groups, sulfonate groups, and carboxyl groups, or sulfonate groups, carboxyl groups, and hydroxyl groups are sodium salts, and D is an oxygen atom or N
( _C2H5 ) _2- , and _X1 to _X7 are a hydrogen atom, a halogen atom, or _a sodium sulfonate group. ) (However, E ₁ to _{E 2} are hydrogen atoms or H(O-
_CH2 - _CH2 )n-O-, at least one of which is H(O- _CH2 - _CH2 )n-O-, and A is a hydrogen atom, a hydroxyl group, an amino group, a sulfonate group,
The carboxyl group, sulfonate group, carboxyl group, or hydroxyl group is a sodium salt, and D ₁ , D ₂
is a hydrocarbon represented by C _n H _2n+1 or a benzene ring which can be substituted with an amino group, a hydroxyl group or a sulfonate group, and m is 0, 1 or 2. )