JP2003136831A - Ink jet recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that, when a nozzle having a long interval of discharging occurs, an ink is dried and thickened near the meniscus of the nozzle to cause the ink not to be discharged so that the image quality is deteriorated. SOLUTION: The ink jet recorder uses an ink composition of a liquid component containing water, a high melting point organic solvent, and a surface- oxidized self-dispersion pigment in such a manner that the boiling point of the solvent is 120 deg.C or higher, 40 to 70 wt.% of the solvent is blended in the entire weight of the ink and except the pigment. The liquid component has a melting point of 20 deg.C or lower.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an on-demand type ink jet recording apparatus, and more particularly to a line type ink jet recording apparatus for performing stable printing on heated paper at high speed.

[0002]

2. Description of the Related Art Most of the recording liquids for ink jet recording which are widely used are recording liquids containing an aqueous medium and a dye. This is because when a pigment is used, image durability such as light resistance and water resistance is improved, but it is difficult to store the pigment dispersion for a long period of time. Further, since the pigment is insoluble in the aqueous medium and in a solid state, clogging easily occurs in the nozzle holes of the recording head.

In order to solve the above-mentioned drawbacks, many techniques have been reported in which the chemical properties of the dispersant are modified or the surface of the pigment is treated to improve the stability. For example, JP-A-4-85375 reports an ink composition for ink jet using a polymer dispersant as a dispersant, and JP-B-4-23666.
The publication describes a water-based pigment ink for drafting using a pigment which is made hydrophilic by treating a void on the pigment surface with N-alkanolamine and then adsorbing a nonionic surfactant. As described above, the stability has been considerably improved by modifying the chemical characteristics of the dispersant or by subjecting the pigment to the surface treatment. However, when high-speed printing is performed using heated paper, the nozzle holes of the recording head are likely to be clogged.

As a line type ink jet printer, there have been proposed many apparatuses using a continuous ink jet type recording head and an apparatus using an on-demand ink jet type recording head.

Of these, the line type ink jet printer of the on-demand ink jet type has a recording speed lower than that of the continuous ink jet type apparatus, but the printing system is very simple.
It is suitable for providing popular high-speed printers. On the other hand, the on-demand inkjet type line recording head ejects ink particles when recording dot formation is required according to the recording data, unlike the continuous inkjet method in which ink particles are ejected from each nozzle at all times. Therefore, the ink near the nozzle hole dries,
The ejection of recording dots tends to be unstable. Further, not all of the nozzle holes generate ink droplets uniformly, but there are nozzle holes in which the frequency of ink ejection is extremely low depending on the arrangement position, so clogging is likely to occur.

In order to solve such a problem, when the printing operation is continued for a certain period of time, the recording head is retracted to the non-printing area and the ink droplets are forcibly ejected from all the nozzle holes. An inkjet recording device provided with an ejection device has been proposed. Further, in order to reduce the time loss required to move the recording head to a place with an ink receiver, Japanese Patent Laid-Open No. 2000-211159 discloses moving the ink receiver between the head and the recording paper without moving the head. A device is disclosed. In addition, JP-A-11-3
In Japanese Patent No. 34106, between the recording paper and the recording head,
Install the ink receiver at a position displaced from the ink ejection direction,
An apparatus has been disclosed in which an air flow or an electrostatic force is applied to preliminary ejection particles when preliminary ejection is performed, and the adhesion of the preliminary ink particles to a recording sheet is blocked by an ink receiver.

However, in any of the methods, the recording speed is substantially reduced due to the interruption of the recording operation, and the ink amount is wasted by preliminarily ejecting the nozzles that need not be preliminarily ejected. Further, it is difficult to accurately stop and restart the traveling of the recording sheet due to the operation interruption, and there is a problem that the recorded image on the recording sheet is easily disturbed.

In order to lengthen the interval for performing this preliminary ejection, a print signal is sent via a current limiting resistor to a piezoelectric vibrator provided in a pressure generating chamber that communicates with a nozzle hole that does not generate ink drops during a printing operation. A clogging prevention technique has been proposed in which a meniscus in the vicinity of a nozzle hole is vibrated minutely when applied (JP-A-55-123476, JP-A-57-61576, and U.S. Pat. No. 4,350,989).
issue).

According to this clogging prevention technique, it is possible to prevent clogging of the nozzle holes without lowering the printing speed because the printing operation is not required to be interrupted, but the swinging amplitude is changed. In order to do so, it is necessary to adjust the power supply voltage and the resistance value, which complicates the circuit configuration.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to improve the intermittent ejection stability (re-ejection property after ejection suspension time) in an on-demand ink jet type line recording head for high-speed recording on a heated recording medium. An object is to provide a good inkjet recording device.

[0011]

In order to solve the above problems, according to the present invention, a print head is printed on a paper heated to 80 ° C. or more at a recording speed such that the relative speed between the nozzle and the paper is 10 ips or more. An on-demand type ink jet recording apparatus for forming a recording dot by ejecting an ink droplet from a nozzle having water, a high boiling point organic solvent having a boiling point of 120 ° C. or higher, and a surface-oxidized self-dispersion pigment. The high boiling point organic solvent is blended in an amount of 40 to 70% by weight with respect to the total weight of the ink, and a composition comprising a liquid component having a melting point of 20 ° C. or less other than the pigment is used for the ink.

Further, a line type print head is used.

Further, it is characterized by printing on continuous recording paper.

Further, the maximum ejection frequency of ink droplets of the print head is 10 kHz or more.

The viscosity at 25 ° C. is 5 to 20 m.
It is characterized by using an ink composition in the range of Pa · s.

Further, the invention is characterized in that an ink composition containing 1.0 to 10% by weight of the surface-oxidized self-dispersion pigment is used.

The surface-oxidized self-dispersion pigment has one or more functional groups selected from a carbonyl group, a carboxyl group, a hydroxyl group, a sulfone group, a hydroxyl group and a phosphoric acid group on the surface of the pigment. The use of the ink composition according to 1.

The ink meniscus at the nozzle is rocked.

Further, the surface-oxidized self-dispersion pigment is carbon black or pigment yellow 7
4, Pigment Red 122, Pigment Blue 15:
Recording is performed using an ink set selected from No. 4.

[0020]

The printing speed of a printer in the field of the present invention is significantly higher than that of conventional ink jet recording, and the relative speed between the nozzle and the paper (recording medium) is
The feature is that it becomes 10 ips (inch per second) or more. Further, it is intended for a printer in which the maximum ejection frequency of ink droplets is 10 kHz or higher.

The on-demand type ink jet recording head or recording method has various modes such as line type recording, serial type recording and transfer type recording. When the head is fixed and only the paper is moved as in line type recording, the paper moving speed (paper feeding speed) corresponds to the relative speed. Further, in serial type recording, that is, in the case where the head moves vertically in the paper feeding direction to sequentially perform recording and intermittent paper feeding is performed, the head moving speed (carriage speed) corresponds to the relative speed. Also, in the case of a transfer type in which the paper is installed on a rotating drum, etc., and recording is performed on this, or recording is once performed on the drum and then this is transferred to the paper, the moving paper, or the relative distance between the drum surface and the nozzles. It is understood as the speed at which the position changes.

In any case, the printing speed is directly related to the nozzle ejection frequency and the printing resolution. For example, the paper feed speed for line-type recording or the head moving speed (that is, recording speed) V for serial type is represented by V = f × R by the ejection frequency f of ink droplets and the recording resolution R.

The present invention can be effectively used in high speed recording of at least 5 ips or more, particularly preferably 10 ips or more.

In the drying and heating step, even if the ink or the recording medium is heated by contacting with the recording medium, the heating is performed without contacting the recording medium such as irradiating infrared rays or blowing hot air. May be. The temperature suitable for drying is preferably 80 ° C. or higher, and this temperature can improve the settability of the high boiling point organic solvent. The settability in this case is apparently the time until it becomes a dry state. Specifically, it represents the time until ink is not transferred even if a finger or paper is lightly pressed.

Although the upper limit temperature can be changed from the device configuration, if the temperature is too high, when the recording paper stops running, smoke is emitted from the recording paper or discoloration of the recording paper occurs.
It is preferably 180 ° C or lower.

According to the present invention, in line type recording in which the driving is continued without performing the procedure for recovering the reliability of long-term ejection,
Especially effective. In the case of a nozzle having a long ejection interval, ink is dried or thickened near the meniscus of the nozzle. Such a nozzle is required to have a performance of avoiding defective printing because initial ejection is not performed when an electric signal for ejection is given. In this case, by slightly moving the ink so that it is not ejected, the dried ink in the vicinity of the meniscus or the thickened ink is agitated to stably eject the ink. The fine movement method is not particularly limited, but it is preferable to perform pressure control and pressure reduction control so that ink is not ejected. Although the fine movement may be continued during the ejection interval, it may be preferable to perform the fine movement immediately before the ejection because the contact area with the air layer becomes large and the drying of the ink may be promoted.

The ink composition of the present invention contains water, a high-boiling point organic solvent, and a surface-oxidized self-dispersion pigment as essential components, and the boiling point of the high-boiling point organic solvent is 120 ° C. or higher, based on the total weight of the ink. 40% to 70% by weight,
In addition to the pigment, it is composed only of liquid components having a melting point of 20 ° C. or lower. When the content of the high boiling point organic solvent is less than 40% by weight, the effect as a wetting agent is not sufficient, and drying of the vicinity of the meniscus due to evaporation of water, and ink ejection failure due to an increase in viscosity are likely to occur. Furthermore, except for pigments, the melting point is 20 ° C
Even when the ink is not composed of only the following liquid components, ink ejection failure easily occurs. On the other hand, if it exceeds 70% by weight, it takes a long time to dry the ink, and the printing tends to bleed.

The high boiling point organic solvent used in the present invention includes the following. For example, ethylene glycol, propylene glycol, diethylene glycol and dipropylene glycol, triethylene glycol,
Tetraethylene glycol, tripropylene glycol, glycerin, polyethylene glycol having a molecular weight of 400 or less, pentamethylene glycol, polyethylene glycol (made by Wako Pure Chemical Industries, Ltd.), acetylene glycol and acetylene alcohol, etc., methyl glycol, methyldiglycol, methyltriglycol, methyl Ethylene glycol ethers such as polyglycol, butyl glycol, butyldiglycol, butyltriglycol, isobutylglycol (all manufactured by Nippon Emulsifier) and methylpropylene glycol, methylpropylenediglycol, methylpropylenetriglycol, propylpropyleneglycol, propylpropylene. Diglycol,
Examples include propylene glycol-based ethers such as butyl propylene glycol, butyl propylene diglycol, and phenyl propylene glycol (all manufactured by Nippon Emulsifier).

In addition to these, anionic surfactants such as carboxylates, sulfates, sulfonates and phosphates, alkylamine salts, dialkylamine salts, tetraalkylammonium salts, benzalkonium salts, alkylpyriates. There are cationic surfactants such as didium salt and imidazolinium salt, amphoteric surfactants such as carboxybetaine, sulfobetaine aminocarboxylic acid, and phosphoric acid ester salt, ether type, ester type, ether ester type, and nitrogen-containing type. Specifically, polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene polyoxypropylene glycol, glycerin ester, sorbitan ester, sucrose ester, polyoxyethylene ether of glycerin ester, sorbitan ester Polyoxyethylene ethers, polyoxyethylene ethers of sorbitol esters, fatty acid alkanolamides, polyoxyethylene fatty acid amides, amine oxides, acetylenic alcohol,
Nonionic surfactants such as acetylene glycol and formamide can be widely used.

As a pigment which is an essential component for achieving the object of the present invention, a pigment which is easily surface-oxidized, is well dispersed in the above vehicle and is excellent in weather resistance is desirable. Furthermore, pigments having a high safety such as a negative mutagenicity test and no chromosomal abnormality are particularly preferable.

In the present invention, the pigment is not particularly limited, but for example, organic pigments, carbon blacks and inorganic pigments having the following numbers described in the color index can be used. In this case, as red or magenta pigments, Pigment Red 3, 5, 19, 22, 3,
1, 38, 43, 48: 1, 48: 2, 48: 3, 4
8: 4, 48: 5, 49: 1, 53: 1, 57: 1, 5
7: 2, 58: 4, 63: 1, 81, 81: 1, 81:
2, 81: 3, 81: 4, 88, 104, 108, 11
2, 122, 123, 144, 146, 149, 16
6, 168, 169, 170, 177, 178, 17
9, 184, 185, 208, 216, 226, 25
7, Pigment Violet 3, 19, 23,
29, 30, 37, 50, 88, Pigment Or
There is an age 13, 16, 20, 36.

As a blue or cyan pigment, Pigme
nt Blue 1, 15, 15: 1, 15: 2, 1
5: 3, 15: 4, 15: 6, 16, 17-1, 22,
There are 27, 28, 29, 36, 60.

As the green pigment, Pigment Gre
en 7, 26, 36, 50.

As the yellow pigment, Pigment Yel
low 1, 3, 12, 13, 14, 17, 34, 3
5, 37, 55, 74, 81, 83, 93, 94, 9
5, 97, 108, 109, 110, 137, 138,
139, 153, 154, 155, 157, 166, 1
67, 168, 180, 185, 193.

As the black pigment, Pigment Bla is used.
ck 7, 28, 26 and the like can be used according to the purpose.

In the present invention, in particular, Pigment Ye
low 74, PigmentRed 122, Pi
gment Blue 15: 4 is preferable because it is easy to process.

The oxidation treatment of the self-dispersion pigment can be carried out by heating the pigment in an aqueous medium together with an oxidizing agent such as nitric acid, sulfuric acid, potassium persulfate or potassium permanganate, and then washing with water.

Specifically, a dispersion liquid in which a pigment is dispersed in water or a solvent in a high concentration in advance can be used.

For example, Micro Jet CW-1
(Manufactured by Orient Chemical), CAB-O-JET200, C
AB-O-JET300, IJX273, IJX44
4, IJX266, IJX253 (all manufactured by Cabot Specialty Chemicals) and the like.

The suitable amount of the self-dispersion pigment is 1 to 10% by weight. If it is less than 1% by weight, the density is too low to obtain good image quality. If it is more than 10% by weight, the properties such as ink viscosity are adversely affected. It should be noted that two or more kinds of colorants can be appropriately mixed and used for color adjustment or the like.

The viscosity of the ink composition used in the present invention is
Although not particularly limited, the viscosity at 25 ° C. is 5 to 20 m
The range of Pa · s is preferable for maintaining stable ejection characteristics. If the viscosity is less than 5 mPa · s, the shape of the ink droplet and the high-speed ink ejection frequency characteristic are likely to be poor,
If the viscosity exceeds Pa · s, it is difficult to eject ink and it is difficult to stabilize the ink. In addition, it is desirable that the ink composition exhibits Newtonian fluid behavior under the temperature conditions used, but if the shear speed normally used for measurement (about 100 rpm) meets the above conditions, the apparent viscosity will be a little. The presence of dependencies does not matter.

In order to add functionality to the ink composition used in the present invention, a light stabilizer, a surface treatment agent, a surfactant, a viscosity modifier, an antioxidant, an antiaging agent, a crosslinking accelerator, and oxygen. An absorber, a plasticizer, an antiseptic, a rust preventive, an evaporation accelerator, a pH adjuster, a defoaming agent, a moisturizer, a dispersant, a dye and the like can be mixed.

A stirrer, a bead mill and a homogenizer are most suitable for mixing and dispersing the above-mentioned pigment and other components, but various known stirring, pulverizing or dispersing devices can be used without particular limitation.

The ink composition used in the present invention is
It meets several well-known requirements for application in inkjet printers. That is, it has sufficient stability at room temperature, does not corrode the liquid contact member such as the print head and its peripheral members, and does not change the characteristics. Reliable storage before printing and image quality after printing. It is necessary that the composition is such that offset does not occur in the state where printed materials are piled up and that the composition is highly safe considering the environment and human body.

As the recording medium, besides the above-mentioned paper, a plastic film, capsule, gel, metal foil, glass, wood, cloth or the like can be used. A wide variety of media shapes can be used so that non-contact printing is possible.

The present invention will be described more specifically below.
It is not limited to the described example.

FIG. 1 is a schematic view of an ink jet recording apparatus provided with a preheat plate for heating a sheet according to the present invention.

The recording paper 2 is conveyed from the paper supply unit 4 in the paper feeding direction by the guide rollers. The recording paper 2 is heated by the blur heat plate 3 so that the surface temperature of the paper becomes 80 ° C. or higher. Further, the heated recording paper 2 forms an image by the ink droplets ejected from the print head 1, and is then stored in the paper stacker unit 5.

FIG. 2 is a partially enlarged view of an ink jet recording apparatus equipped with a drying blower for heating a sheet according to the present invention.

The recording paper 2 is conveyed in the same manner as in FIG. 1 and heated by the heating blower 6 so that the surface temperature of the paper becomes 80.degree. Further, the heated recording paper 2 forms an image by the ink droplets ejected from the print head 1, and is then stored in the paper stacker unit 5.

FIG. 3 is a partially enlarged view of the ink jet recording apparatus provided with the heat roller for heating the paper according to the present invention.

The recording paper 2 is conveyed in the same manner as in FIG. 1, and is heated by the heated heat roller 7 and the backup rubber roller 8 installed to enhance the heat transfer effect so that the surface temperature of the paper becomes 80 ° C. or more. It Further, the heated recording paper 2 forms an image by the ink droplets ejected from the print head 1, and is then stored in the paper stacker unit 5.

FIG. 4 is a conceptual diagram of a surface oxidation treated pigment, especially a sulfonation treated pigment.

Since the untreated pigment surface is hydrophobic, it is difficult to uniformly disperse it in an aqueous medium. Usually, a pigment is uniformly dispersed and used by adding a dispersant such as a surfactant.

The pigment used in the present invention is subjected to an oxidation treatment (hydrophilicity) by subjecting the pigment to heat treatment in an aqueous medium together with an oxidizing agent such as nitric acid, sulfuric acid, potassium persulfate or potassium permanganate, followed by washing with water. Process). By this treatment, since the pigment surface has a hydrophilic group such as a sulfone group in the figure, it is possible to uniformly disperse the pigment in an aqueous medium without a dispersant.

Next, examples will be described below. [Examples 1 to 5] 35 parts by weight of purified water, 60 parts by weight of glycerin (manufactured by Wako Pure Chemical Industries), and 5 parts by weight of ethylene glycol monoisobutyl ether (manufactured by Wako Pure Chemical Industries) were mixed, and various pigment waters were added thereto. Dispersion (1 ... CAB-O-JET200 manufactured by Cabot Specialty Chemicals, pigment content 19.5% by weight, 2 ... CAB-O-JET300 manufactured by Cabot Specialty Chemicals, pigment content 1
4.0% by weight, 3 ... Cabot Specialty Chemicals IJX444, pigment content 15% by weight, 4 ... Cabot Specialty Chemicals IJX266, pigment content 14.4% by weight, 5 ... Cabot Specialty Chemicals IJX253, pigment content 15 .2% by weight)
Are mixed so that the pigment concentration is constant, and the total composition is 30
0g using a homogenizer (HG30 manufactured by Hitachi Koki),
The mixture was dispersed at a rotation speed of 2000 rpm until a homogeneous mixture was obtained, and further filtered to remove impurities and the like to obtain 5 homogeneous ink compositions. These ink viscosities are measured at temperature 2
Rotational viscometer at 5 ° C (Tokimec EDL model)
It was used.

Using these inks, the head portion of a direct plate making machine (SJ02A manufactured by Hitachi Koki) was extracted,
Fixed and used for printing, maximum ink ejection frequency 6kHz
z, paper feed speed is 10 ips, resolution 600
Printing of (× 600) dpi was performed. In addition, 70 kg paper (NIP paper made by Kobayashi recording paper) is used as a recording medium, and a laser beam printer (LB made by Hitachi Koki) is used as a paper heating means.
The preheater part of 16) was extracted. The preheater surface temperature was set to 95 ± 5 ° C., and heating was performed so that the paper surface temperature was 80 ° C. or higher. Recording was performed after a discharge interval of 10 minutes, and the presence or absence of non-discharge nozzles was confirmed both in the case where fine movement was given and in the case where fine movement was not given. The results are shown in Table 1. [Example 6] 15 parts by weight of purified water, 80 parts by weight of polyethylene glycol 200 (manufactured by Wako Pure Chemical Industries), and ethylene glycol monoisobutyl ether (manufactured by Wako Pure Chemical Industries)
5 parts by weight are mixed, and this is mixed with pigment aqueous dispersion 1 ... CAB-O-JET20 manufactured by Cabot Specialty Chemicals.
0 and a pigment content of 19.5% by weight were added, and an ink composition was obtained by the same procedure as in Example 1. Table 1 shows the results of evaluations made in the same manner as in Example 1 using these inks. [Example 7] 50 parts by weight of purified water, 45 parts by weight of polyethylene glycol 400 (manufactured by Wako Pure Chemical Industries), and ethylene glycol monoisobutyl ether (manufactured by Wako Pure Chemical Industries)
5 parts by weight were mixed, and an aqueous pigment dispersion 5 ... IJX253 manufactured by Cabot Specialty Chemicals and a pigment content of 15.2% by weight were added thereto, and an ink composition was obtained in the same manner as in Example 1. Table 1 shows the results of evaluations made in the same manner as in Example 1 using these inks. Comparative Example 1 35 parts by weight of purified water, 60 parts by weight of glycerin (manufactured by Wako Pure Chemical Industries), and 5 parts by weight of ethylene glycol monoisobutyl ether (manufactured by Wako Pure Chemical Industries) were mixed,
Aqueous Pigment Dispersion 6 ... TM-M2 manufactured by Taisei Kako Co., Ltd., a pigment content of 17.6% by weight, and a nonvolatile content of 7.0% by weight other than the pigment were added, and an ink composition was prepared in the same manner as in Example 1. Got Table 1 shows the results of evaluations made in the same manner as in Example 1 using these inks. [Comparative Example 2] 55 parts by weight of purified water, 35 parts by weight of glycerin (manufactured by Wako Pure Chemical Industries, Ltd.), polyethylene glycol 6000
(Wako Pure Chemical Industries, Ltd.) 5 parts by weight and ethylene glycol monoisobutyl ether (Wako Pure Chemical Industries, Ltd.) 5 parts by weight are mixed, and pigment water dispersion 3 ... Cabot Specialty Chemicals IJX444, pigment content 15 parts by weight %
Was added and an ink composition was obtained in the same procedure as in Example 1. Table 1 shows the results of evaluations made in the same manner as in Example 1 using these inks. [Comparative Example 3] 20 parts by weight of purified water, 40 parts by weight of glycerin (manufactured by Wako Pure Chemical Industries), 35 parts by weight of Acryt 202U (manufactured by Arakawa Chemical Industry), and 5 parts by weight of ethylene glycol monoisobutyl ether (manufactured by Wako Pure Chemical Industries) Parts, and pigment water dispersion 3 ... IJX444 manufactured by Cabot Specialty Chemicals, pigment content 15% by weight is added,
An ink composition was obtained in the same procedure as in Example 1. Table 1 shows the results of evaluations made in the same manner as in Example 1 using these inks.
Described in.

[0058]

[Table 1]

As described above, the ink composition of the present invention contains water, a high boiling organic solvent, and a surface-oxidized self-dispersion pigment as essential components, and the boiling point of the high boiling organic solvent is 120 ° C. or higher. 40% by weight based on the total weight of ink
.About.70% by weight, and is composed only of liquid components having a melting point of 20.degree. If the high boiling point organic solvent is less than 40% by weight, the effect as a wetting agent is not sufficient, and drying near the meniscus accompanying evaporation of water,
Ink ejection is likely to occur due to an increase in viscosity. Furthermore,
Even when the components other than the pigment are not composed of only the liquid component having a melting point of 20 ° C. or less, the non-ejection of the ink is likely to occur. On the other hand, if it exceeds 70% by weight, it takes a long time to dry the ink, and the printing tends to bleed.

[0060]

EFFECT OF THE INVENTION The ink jet recording apparatus of the present invention enables printing with excellent ejection reliability, particularly intermittent ejection performance.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an inkjet recording apparatus including a preheat plate for heating a sheet according to the present invention.

FIG. 2 is a partially enlarged view of an inkjet recording apparatus provided with a drying blower for heating paper according to the present invention.

FIG. 3 is a partially enlarged view of an ink jet recording apparatus including a heat roller for heating a sheet according to the present invention.

FIG. 4 is a conceptual diagram of a surface oxidation treated pigment, particularly a sulfonation treated pigment.

[Explanation of symbols]

Reference numeral 1 is a print head, 2 is a recording sheet, 3 is a preheat plate, 4 is a sheet supply section, 5 is a sheet stacker section, 6 is a heating blower, 7 is a heat roller, and 8 is a backup rubber roller.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kunihiro Tamahashi             Hitachiko, 1060 Takeda, Hitachinaka City, Ibaraki Prefecture             Machine Co., Ltd. F term (reference) 2C056 EA14 EC08 EC13 EC29 FA02                       FA10 FA13 FA14 FB02 FB03                       FB04 FC02                 2H086 BA02 BA52 BA53 BA55 BA60                       BA61                 4J039 AE07 BA04 BC07 BC09 BC10                       BC11 BC13 BE01 BE12 EA44                       EA48 GA24

Claims (9)

[Claims] 1. A recording dot is formed on a paper heated to 80 ° C. or higher by ejecting ink droplets from a nozzle of a print head at a recording speed such that the relative speed between the nozzle and the paper is 10 ips or higher. The on-demand ink jet recording apparatus according to claim 1, which comprises water, a high-boiling point organic solvent having a boiling point of 120 ° C. or higher, and a surface-oxidized self-dispersion pigment, the high-boiling point organic solvent being 40 relative to the total weight of the ink. ˜70% by weight, and a melting point of 20 except for pigments
An ink jet recording apparatus, wherein a composition comprising a liquid component having a temperature of not higher than 0 ° C. is used for ink. 2. The ink jet recording apparatus according to claim 1, wherein a line type print head is used. 3. The ink jet recording apparatus according to claim 2, wherein printing is performed on continuous recording paper. 4. The ink jet recording apparatus according to claim 1, wherein the maximum ejection frequency of the ink droplets of the print head is 10 kHz or higher. 5. The viscosity at 25 ° C. is 5 to 20 mPa ·
The ink jet recording apparatus according to claim 1, wherein the ink composition in the range of s is used. 6. An ink jet recording apparatus according to claim 1, wherein an ink composition containing 1.0 to 10% by weight of the surface-oxidized self-dispersion pigment is used. 7. The surface-oxidized self-dispersion pigment comprises a carbonyl group, a carboxyl group, a hydroxyl group,
The ink jet recording apparatus according to claim 1, wherein the ink composition has one or more functional groups selected from a sulfonic group, a hydroxyl group, and a phosphoric acid group on a pigment surface. 8. The ink jet recording apparatus according to claim 1, wherein the ink meniscus at the nozzle is swung. 9. The surface-oxidized self-dispersion pigment performs recording using an ink set selected from carbon black, pigment yellow 74, pigment red 122, and pigment blue 15: 4. The inkjet recording apparatus according to claim 1, wherein the inkjet recording apparatus comprises: