JPH068416A - Inkjet recording method - Google Patents

Abstract

(57) [Summary] [Structure] A head having a water-repellent treatment applied to a nozzle orifice of a head for ejecting the ink with an ink containing at least a component insoluble in water. The water-insoluble component may be a resin component having a hydrophilic group and a hydrophobic group, or a pigment. [Effect] It was possible to provide a recording method which satisfies the weaknesses of ink jet recording such as water resistance and light resistance, and can realize high printing quality and compatibility with plain paper. Even if the ink contains water-insoluble components due to the water repellent treatment, the reliability can be secured by the conventional cleaning system.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording method for ejecting and recording ink according to an electric signal,
An object of the present invention is to provide an ink jet recording method which sufficiently satisfies the required characteristics of ink jet recording, such as high print quality, water resistance, and compatibility with plain paper.

[0002]

2. Description of the Related Art Ink jet recording methods have been under research and development because of their low noise, high speed recording, high density recording, and easy colorization. For those inkjet recording inks, safety, reliability,
For the reason of printing quality and the like, a water-based ink in which a water-soluble dye is dissolved in a water-soluble medium is currently used. However, due to the widespread use of laser printers, the demand for high printing quality such as graphics has increased, and the demand for improved water resistance and light resistance, which are the drawbacks of ink jet printers that have used water-based inks, and compatibility with plain paper, have yet to be addressed. It is hard to say that it has sufficient characteristics.

Conventionally, ink has been improved to solve such drawbacks. JP-A-3-16317
No. 5 discloses an ink containing water and a colorant, which contains at least a component which is not soluble in water to achieve high printing quality and improved water and light resistance.
Further, JP-A-64-31877 discloses a weight average molecular weight of 10
Inks have been disclosed that improve water resistance by adding hydroxypropylated polyethyleneimine having from 00 to 10,000. Furthermore, JP-A-3-767
68 contains an aqueous medium, a styrene-maleic acid copolymer as a dispersant, and a specific pigment, whereby an inkjet recording liquid excellent in light resistance of a recorded image, water resistance, storage stability of a recording liquid, and the like is obtained. It is disclosed. Although various inks have been studied in this way, the fact is that they have not been put to practical use yet. That is, even if a system that can realize water resistance or high printing quality as high as laser is realized as an ink, problems have occurred in reliability as a printer, particularly clogging and ejection reliability. Therefore, it is necessary to design the ink composition into a system that takes clogging into consideration, and it is not possible to create a realistic system in terms of fast drying and compatibility with plain paper, and still water resistance to light, high print quality, quick drying, and plain paper. Printers that meet the requirements for compatibility have not been realized. Further, with respect to the recording head used in the ink jet recording method, higher density, higher speed, improved ejection stability, etc. are being advanced. JP-A-59-17
No. 6059 discloses a head in which a fluorocarbon plasma polymerized film having an unsaturated bond is used as a water-repellent film, and by making the nozzle surface water-repellent, deterioration of print quality due to defective ejection direction of ink droplets is improved. It is suggested that you can.
Further, in Japanese Patent Laid-Open No. 63-3963, there is no study on the head shape by matching with ink such as a head block or the like which has been subjected to water repellent treatment by nickel electroforming containing a tetrafluoride resin.

[0004]

Therefore, the present invention provides an ink jet recording method that satisfies the requirements for plain paper, high printing quality, water resistance, and light resistance while satisfying the reliability of clogging. To provide.

[0005]

As a result of repeated studies to solve this problem, the inventors of the present invention have found that in order to satisfy the water resistance, the light resistance, and the high printing quality comparable to that of a laser, the water-insoluble material does not dissolve in water. It is an essential condition that the ink has a pigment added as a resin component or a colorant, and the nozzle orifice is clogged by using a recording head having a water repellent treatment,
It has been found that an inkjet recording method that realizes ejection reliability can be provided. That is, as a result of performing clogging evaluation using various kinds of ink and leaving conditions, and heads of various kinds of nozzle orifice materials, clogging reliability is greatly influenced by the wettability of the nozzle orifice and ink, and water It has been found that in the case of an ink to which an insoluble compound is added, solidification due to drying always occurs at the nozzle orifice. In the case of an inkjet printer, in the case of ejection failure due to such clogging of the nozzle orifice, a normal ejection state is restored by automatically or by a user performing a recovery operation called cleaning. Cleaning is an operation of sucking ink from the outside of the nozzle orifice or an operation of increasing the pressure in the nozzle orifice, and recovers by discharging foreign matter in the nozzle orifice and the thickened ink from the nozzle with a certain pressure. It is an operation that causes it. It has been found that it is a head having a nozzle orifice that has been subjected to a water repellent treatment, which has poor wettability with ink, that can cleanly remove the solidified nozzle deposits by such a returning operation. When the nozzle orifice is subjected to the water repellent treatment, the solidified ink can be completely discharged without adhering to the nozzle orifice, and the reliability comparable to that of the conventional water-based ink can be realized.

First, the ink used in the present invention will be described in detail. The ink used in the present invention contains at least a component insoluble in water. The colorant may be any of water-soluble dyes and pigments, and as the water-soluble dye, an acid dye, a direct dye, an edible dye, or the like can be selected according to the purpose in terms of hue, color density, water resistance, light resistance, and the like. . Inorganic pigments (carbon black) and organic pigments (azo pigments, phthalocyanine pigments, etc.) can be used as the pigment. The addition amount is color tone,
Considering the concentration and the like, it is desirable to add 0.5 to 20% by weight. If it is 0.5% by weight or less, a practical concentration cannot be obtained, and if it exceeds 20% by weight, the storage stability is adversely affected. When a pigment is used as a colorant, the water-insoluble component used in the present invention can be used by dispersing the pigment itself as a water-insoluble component, or in combination with another water-insoluble component. As the water-insoluble component other than the colorant, vinyl ester-based, acrylic ester-based, methacrylic acid ester-based, styrene-based, olefin-based, and hydrophilic functional groups such as amino groups, carboxyl groups, amide groups, and hydroxyl groups A homo- or copolymer resin emulsion of the monomer or the like, an organic ultrafine particle having an internal three-dimensional crosslinked structure, a microemulsion, a colloidal dispersion, or a natural or synthetic wax emulsion such as paraffin wax, microcrystalline wax, polyethylene wax or carnauba wax. Can be used. It is also possible to use inorganic ultrafine particles such as colloidal silica. The solvent used in the present invention is ion-exchanged water,
As the water-soluble organic solvent, alkyl alcohols having 1 to 4 carbon atoms, ketones, keto alcohols, ethers, polyalkylene glycols, glycerin, lower alkyl ethers of polyhydric alcohols, and the like are used.

Further, as the water-soluble resin, glue, gelatin, casein, albumin, alginic acid, carboxymethyl cellulose, hydroxyethyl cellulose, polyvinylpyrrolidone, polyvinyl alcohol, saccharides and the like can be used in combination with the water-insoluble component. Further, known dispersants, surface tension adjusting agents, antifungal agents, chelating agents and the like which have been conventionally used can be added as required.

Next, the recording head used in the present invention will be described. The nozzle orifice of the head used in the present invention is not particularly limited as long as it is water-repellent. As the material of the head used in the present invention, any material can be used as long as it can be made into a head, such as glass, silicon, metal, further plastic, and photosensitive resin. Further, even if the nozzle is made of the same material as the pressure chamber, the nozzle plate may be made of another material. For water repellent treatment, coating with fluororesin, eutectoid plating with fluororesin, or
Various treatment techniques such as fluorosilane treatment, aminosilane treatment, and fluorocarbon plasma polymerized film having an unsaturated bond can be used depending on the purpose. FIG. 1 shows a sectional view of a first head used in the present invention.
Reference numeral 1 is a nozzle plate made of nickel, and 6 is a water repellent film obtained by eutectoid plating of a fluororesin and nickel. The head material shown by 5 is plastic such as polysulfone and polycarbonate. Specifically, the eutectoid plating is performed according to the following procedure. Eutectoid plating of Ni and PTFE was performed on the outer surface of a nickel plate having an ink discharge nozzle formed by punching with a press, using a plating solution having the following composition under the following conditions.

[0009]

[Table 1]

After plating under the above conditions, it is placed in a furnace at 350 ° C. for 30 minutes to melt the PTFE exposed on the surface of the eutectoid plating layer, and the plating surface is completely covered with PTFE. To obtain a water repellent film. The film thickness was 3 μm.

FIG. 2 shows a sectional view of the second head used in the present invention. The nozzle orifice 2 is formed of the same material as the head material forming the cavity 3.
The material forming the cavity is glass, a photosensitive resin, or the like. The water repellent film of No. 6 is a solvent-soluble fluoropolymer film. The solvent-soluble fluoropolymer membrane is specifically obtained by the following procedure. 2% by weight of Cytop (registered trademark of Asahi Glass Co., Ltd.) is dissolved in a fluorine-based solvent in which it is dissolved.

A head, which is hermetically sealed so that the solution does not become clogged in the processing solution, is dipped horizontally with respect to the nozzle to deposit a film. Thereafter, the film is baked at a temperature equal to or higher than the glass transition point of the film to obtain the target water repellent film.

FIG. 3 shows a sectional view of a third head used in the present invention. Reference numeral 1 denotes a nozzle plate made of the same material as that of the head, the cavity and the like. Specifically, polysulfone, polycarbonate, amorphous polyolefin or the like can be used. The water-repellent treatment film 6 is formed by utilizing plasma polymerization of tetrafluoroethylene gas having an unsaturated bond to form a strong and thin film on the nozzle surface. Specifically, a film was produced by the following procedure. Using a general plasma device, gas pressure 0.3 Torr, applied voltage 0.25 W / cm ² , high frequency 13.6 MH
The film was treated for 15 minutes under the conditions of z and gas C2F4 to obtain the desired water repellent film.

[0014]

The present invention will be described in detail with reference to the following examples. First, five types of ink compositions used in the present invention are shown below. The composition is shown in% by weight.

[0015]

[Table 2]

Compositions other than Boncoat are placed in a stirring vessel and stirred at 80 ° C. for 3 hours. When the temperature has dropped sufficiently,
Add bon coat and stir further. After stirring, pressure filtration was performed using a 1 μm membrane filter to prepare a recording ink.

[0017]

[Table 3]

The organic ultrafine particles, carbon black, and nonionic dispersant are dispersed for 15 hours using a paint shaker, transferred to a stirrer, polyethylene glycol # 200 is added, and the mixture is further stirred for 1 hour. After stirring, pressure filtration was performed using a 1 μm filter to obtain a recording liquid having an average particle size of 0.2 μm.

[0019]

[Table 4]

Similar to the ink 1, the components other than the polyethylene wax emulsion were put in a stirring container and kept at 80 ° C. for 3 days.
Stir for hours. When the temperature has dropped sufficiently, add a polyethylene wax emulsion and stir. After stirring 1
A recording ink was prepared by pressure filtration using a μm membrane filter.

[0021]

[Table 5]

The styrene-maleic acid copolymer emulsion, carbon black and organic ultrafine particles are dispersed for 20 hours using a paint shaker, transferred to a stirring vessel, diethylene glycol is added and the mixture is stirred for another hour. After stirring
Pressure filtration was performed using a 1 μm filter to obtain a recording liquid having an average particle size of 0.15 μm.

[0023]

[Table 6]

Methyl methacrylate emulsion, carbon black, polyvinylpyrrolidone and nonionic dispersant were dispersed for 20 hours using a paint shaker,
Transfer to a stirring container, add diethylene glycol and isopropyl alcohol, and stir for another hour. After stirring, 1μ
The average particle size is 0.0
A recording liquid of 8 μm was obtained.

Furthermore, a recording liquid containing no water-insoluble component was obtained as the ink of Comparative Example with the following composition.

[0026]

[Table 7]

All the components were put in a stirring container and heated to 80 ° C.
Stir for 3 hours. If the temperature drops sufficiently after stirring, 1 μm
The recording ink was prepared by pressure filtration using the membrane filter of No. 1.

Using the inks of the present invention shown in Inks 1 to 5 and the comparative inks, the heads 1 to 3 of the present invention shown in FIGS. 1 to 3 and the recording heads shown in FIGS. 4 and 5 as comparative examples are used. Evaluate clogging. As a comparative example, FIG.
The head shown in (1) is a head which is not subjected to water repellent treatment in the head of FIG. 1 of the present invention. The head shown in FIG. 5 is the same as the head of FIG. 2 of the present invention, which is not subjected to the water repellent treatment.

The following evaluations were made with the above combinations.
First, the nozzle orifices of the heads shown in FIGS. 1 and 3 and FIG. 2 of the present invention and the heads shown in FIGS.
We made a prototype of a head with 48 each. The head of the present invention was subjected to water repellent treatment by each method, and the head of the comparative example was used without water repellent treatment. Using each head, drive frequency 3kHz, ink ejection amount 0.09μg
Adjust the voltage so that PPC paper (PPC paper registered by Xerox Co.), recycled paper (Yamayuri registered by Honshu Paper Co., Ltd.), bond paper (25% cotton paper by Gilbert Bond registered by Mead Co.), fine paper (Oji Paper Co., Ltd.) Solid, alphabetic characters, etc. were printed on a registered trademark OK high-quality paper L), and evaluations of tests 1 to 8 shown below were performed.

(Test 1) Character print sample Visual evaluation of print quality.

The evaluation results are classified as follows.

Bleeding is not observed with the naked eye ... ◎ Bleeding is seen but characters are recognizable ... △ Characters are not recognizable ... Test 2) Macbeth TR-927 type (Kol
Evaluation of the density of a solid printed portion using an optical densitometer (registered trademark of Lomorgan Co.) (aperture size: 4 mm).

The evaluation results are classified as follows.

O. D. Value 1.3 or more ... ◎ O. D. Value 1.1 or more and less than 1.3 ... D. Value less than 1.1 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ × (Test 3) 100% Duty at a pressure of 100 g / cm ^2.
A quick-drying evaluation that rubs the printed part with a cotton cloth and investigates the time until the printing stain does not occur.

The evaluation results are classified as follows.

No stain of printed matter is observed within 15 seconds ... ◎ No stain of printed matter is observed within 30 seconds ... △ Stain of printed matter is observed even after 30 seconds. (Test 4) Evaluation of finger touch is performed by rubbing the printed portion of the character with a finger 5 minutes after completion of printing and visually observing stains on the printed portion.

The evaluation results are classified as follows.

No stain on the printed matter is observed .... ◎ Some stains on the printed matter occur, but characters can be identified. △ Characters cannot be identified due to the stain on the printed matter.・ ・ × (Test 5) After confirming that all the nozzles have ejected ink after filling the head with ink, leave the printer in a high temperature environment of 40 ° C for one month and check the print recoverability. Evaluation. Cleaning was performed with a suction capacity of 5 ml / min.

The evaluation results are classified as follows.

All nozzles can be printed with one cleaning operation ◎ ◎ All nozzles can be printed within 5 times of cleaning operation △: Printing is not possible even if cleaning operation is performed more than 5 times × (Test 6) Head After confirming that all the nozzles have been ejected by filling ink into the printer, leave the printer in a room temperature environment for 3 months, and check the recoverability of printing. Cleaning was performed with a suction capacity of 5 ml / min.

Evaluation results are the same as in Test 5 (Test 7) The printed matter is treated with Xenon Fade Tester XF-
5N in the environment of 70% RH using 15N (Shimadzu)
CR for the color difference of L * a * b before and after leaving after 0 hour light irradiation.
-121 Light resistance evaluation measured with a colorimeter (made by Minolta).

The evaluation results are classified as follows.

ΔE ≦ 10 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ○ ΔE> 10 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ × (Test 8) 24 hours or more after printing Immerse the left printed matter in water for 1 hour, and check the change in the print density before and after maceration.
Water resistance evaluation measured with beth PCM ΙΙ (manufactured by Macbeth).

The evaluation results are classified as follows.

OD value after dipping is 90% or more before dipping ... ◎ OD value after dipping is 50 to 90% before dipping ... △ OD value after dipping is 50% or less before dipping ... × The above evaluation results are shown in Table 8.

[0046]

[Table 8]

As is clear from Table 8, the ink jet recording method of the present invention, in which the ink containing at least a component insoluble in water, is applied to the nozzle orifice of the head for water repellency treatment, the ink jet recording method of the present invention has high printing quality, quick drying, It was found that not only paper compatibility but also water resistance, light resistance, and clogging reliability can be satisfied.

[0048]

By the ink jet recording method of the present invention, an ink containing a water-insoluble component, which has not been used up to now, can be used in the same manner as a conventional water-based ink. As a result, it has been possible to sufficiently satisfy the water resistance and light resistance, which have hitherto been the drawbacks of water-based ink jet printers, and also to realize ink jet recording with high print quality and plain paper compatibility. In addition, since it is basically water-based, safety can be sufficiently satisfied. Further, since the clogging reliability can be obtained by the same cleaning operation as the conventional one, it is possible to realize a high-quality printer at a low price and enhance the versatility of the inkjet.

[Brief description of drawings]

FIG. 1 is a sectional view of a head used in the present invention.

FIG. 2 is a sectional view of a head used in the present invention.

FIG. 3 is a sectional view of a head used in the present invention.

FIG. 4 is a cross-sectional view of a head that has not been subjected to water repellent treatment.

FIG. 5 is a cross-sectional view of a head that has not been subjected to water repellent treatment.

[Explanation of symbols]

 1 Nozzle plate 3 Cavity 6 Water repellent film 7 Piezoelectric element

Claims (4)

[Claims] 1. An inkjet recording method for recording by ejecting ink according to an electric signal, wherein the ink is an ink containing at least a component insoluble in water, and a nozzle of a head for ejecting ink is subjected to a water repellent treatment. An inkjet recording method characterized by the above. 2. The ink jet recording method according to claim 1, wherein the water-insoluble component of the ink is a resin component having a hydrophilic group and a hydrophobic group. 3. The ink jet recording method according to claim 1, wherein the ink is an ink containing a pigment as a colorant. 4. The ink comprises 0.5-15% by weight of a low-volatile solvent such as polyhydric alcohol as a wetting agent, ethanol,
An ink jet recording method comprising an ink containing 0.5 to 10% by weight of a monohydric alcohol selected from 1-propanol and 2-propanol.