JP2001171103A - Ink jet printing method and printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet printing method and printer which can deal with digital image data and can print various images onto a print medium clearly and inexpensively at high speed. SOLUTION: In the ink jet printing method for forming an image directly onto a print medium based on an image data signal, a print image is formed by a system for ejecting oil ink utilizing an electrostatic field being formed by applying a voltage, corresponding to a digital image signal, onto an electrode provided in an ink head.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing method for forming a printed image directly on a printing medium, and more particularly, to a method for printing images at a high print speed by electrostatic ink jet recording using oil-based ink. It relates to a possible ink jet printing method and a printing device.

[0002]

2. Description of the Related Art As a printing method for forming a print image on a print medium based on an image data signal, there are an electrophotographic system, a sublimation type and a fusion type thermal transfer system, an ink jet system, and the like. The electrophotographic method requires a process of forming an electrostatic latent image on a photosensitive drum by charging and exposure, and the system becomes complicated and becomes an expensive apparatus. In the thermal transfer system, the apparatus is inexpensive, but the use of an ink ribbon causes a high running cost and waste materials are generated. On the other hand, the ink jet system is an inexpensive device and discharges ink only to a required image portion to perform printing directly on a print medium. Therefore, the colorant can be used efficiently and the running cost is low.

As a method of applying the ink jet technology to a printing system, for example, Japanese Patent Application Laid-Open No. Hei 10-286939 discloses a method in which an ink jet printing device is attached to a rotary printing press and variable numbers and marks are added on the same printing paper. A method for printing with an inkjet system is disclosed. However, it is more preferable to be able to print advanced image information such as a photographic image. However, with the conventional ink technology in which a water-based or organic solvent-based ink containing a dye or pigment as a colorant is ejected by using pressure, droplets containing a large amount of solvent are ejected, so printing without using expensive special paper is required. There is a drawback that the image blurs. Therefore, when printing is performed on ordinary printing paper or a plastic sheet that is a non-absorbable medium, a high-quality printed image cannot be obtained.

[0004] As one of the ink-jet technologies,
There is a method in which an ink in a solid state is heated and melted at room temperature to eject a liquid ink to form an image. When this ink is used, the bleeding of the printed image is reduced, but since the ink viscosity at the time of ejection is high, it is difficult to eject fine droplets,
The obtained individual dot images have a large area and a large thickness, and it is difficult to form a high-definition image.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to print a clear, high-quality image by using an inexpensive apparatus and a simple method. It is an object of the present invention to provide an inkjet printing method that enables the method.

[0006]

[MEANS FOR SOLVING THE PROBLEMS] To achieve the above object
Next, the invention will be described with reference to the accompanying drawings.
According to the statement, based on the signal of the image data,
Printed matter by directly forming an image and fixing the image
In the printing method to create
Ink is formed by ink jetting
It is characterized by nau. The invention according to claim 2
According to the above, the oil-based ink has a specific electric resistance value of 10 ⁹Ω
cm in a non-aqueous solvent with a dielectric constant of 3.5 or less
Both are characterized by the dispersion of colored particles
You. Further, according to the invention of the printing apparatus of the third aspect, the image
Form an image directly on a print medium based on an image data signal
Image forming means, and an image formed by the image forming means.
Image fixing means for fixing and obtaining a printed matter;
Wherein the image forming means uses an electrostatic field to
Ink jet drawing that discharges the fusible ink from the discharge head
It is characterized by being an image device. Claim 4
According to the described invention, the oil-based ink has a specific electric resistance.
Value 10⁹In a non-aqueous solvent of Ωcm or more and dielectric constant of 3.5 or less
In particular, it is noted that at least colored particles are dispersed.
It is a sign. And according to the invention of claim 5,
Before and / or during printing on the print medium,
It is necessary to have a dust removing means for removing dust present on the medium surface.
It is characterized by. Further, according to the invention described in claim 6,
For example, when drawing on the print medium,
And a facing nozzle disposed at a position facing the ejection head.
By moving the print medium by rotating the ram,
In addition, drawing is performed. Claims
According to the invention as set forth in claim 7, the ejection head is a single channel.
Consisting of a channel head or multi-channel head,
Drawing by moving the head in the axial direction of the opposing drum
It is characterized by performing. Furthermore, claim 8
According to the invention, at the time of drawing on the print medium, at least
Also sandwiches the print medium between a pair of capstan rollers.
The feature is that drawing is performed by holding and running
And According to the ninth aspect of the present invention,
The ejection head is a single channel head or multi
Channel head, and the running direction of the printing medium
Drawing by moving the ejection head in a direction orthogonal to
It is characterized by performing painting. Claim 10
According to the invention described above, the discharge head is provided with the print medium.
Consists of a full line head having a length approximately equal to the width
It is characterized by. Further, according to the invention described in claim 11,
For example, the inkjet drawing apparatus may
Having ink supply means for supplying the oil-based ink
It is characterized by. According to the twelfth aspect of the present invention,
If the oil-based ink is collected from the ejection head,
It has ink collecting means and performs ink environment.
ing. Further, according to the invention of claim 13,
An inkjet drawing device for storing the oil-based ink
Stirring means for stirring the oil-based ink in the ink tank;
It is characterized by having. And Claim 14
According to the invention, the inkjet drawing apparatus,
The oil-based ink in an ink tank storing oil-based ink
It has an ink temperature management means for managing the temperature of the ink.
It is a sign. According to the invention of claim 15,
The inkjet drawing apparatus is configured to control the concentration of the oil-based ink.
Characterized by having ink density control means for controlling
ing. According to the invention of claim 16,
Has cleaning means for cleaning the ejection head
It is characterized by that.

[0007]

Embodiments of the present invention will be described below in detail. The present invention is characterized in that an image is formed on a print medium supplied to a printing apparatus by an inkjet method in which oil-based ink is discharged by an electrostatic field.

The ink-jet method according to the present invention uses a PC
T publication WO93 / 11866, and in this ink jet method, an insulating solvent contains
An ink having a high resistance in which at least colored particles are dispersed is used, and a strong electric field is applied to the ink at the ejection position to form an aggregate of the colored particles at the ejection position. An object is discharged from the discharge position. Thus, the colored particles are ejected as agglomerates with a high concentration, and the ink droplets contain only a small amount of solvent. As a result, there is no bleeding on printing paper or a printing plastic film used as a recording medium,
A clear image is formed at a high density. In the present inkjet method, the size of the ejected ink droplet is determined by the size of the ejection electrode and the conditions for applying the electric field. Therefore, if a small ejection electrode and appropriate electric field application conditions are used, a small ink droplet can be obtained without reducing the diameter of the ejection nozzle or the slit width. Therefore, fine images can be controlled without the problem of ink clogging of the head, and the present invention is an inkjet printing method capable of printing a clear and high-quality image printed matter.

An example of the configuration of a printing apparatus used for carrying out the ink jet printing method of the present invention will be described below. However, the present invention is not limited to the following configuration examples.

FIGS. 1 to 4 and FIGS. 5 to 8 are schematic diagrams showing examples of the configuration of a printing apparatus according to the present invention which performs drawing by moving a print medium by rotating an opposing drum. FIG. 1 to FIG. 4 are views showing a schematic configuration example of a Web-type printing apparatus in which a roll-shaped print medium is stretched by an opposed drum, a print medium supply roll, and a print medium take-up roll or a guide roll. FIG. 1 shows a single-sided single-color printing apparatus, and FIG. 2 shows a single-sided four-color printing Web apparatus. FIGS. 3 and 4 are schematic diagrams showing examples of a two-sided four-color printing apparatus. FIG. 5 is a diagram showing an example of a schematic configuration of a single-sided four-color printing apparatus that cuts a roll-shaped printing medium and performs winding printing on an opposite drum, and FIG. 6 is a schematic view of a printing apparatus using a sheet-shaped recording medium. It is a figure showing the example of composition. FIGS. 7 and 8 are schematic diagrams showing an example of a schematic configuration of a printing apparatus that performs drawing by sandwiching and running a print medium with a cap stun roller according to the present invention. FIG. FIG. 8 is a view showing a schematic configuration example of a printing apparatus using a print medium, and FIG. FIG. 9 is a schematic configuration example of a drawing apparatus including a control unit, an ink supply unit, and a head separation mechanism of the drawing apparatus. 10 to FIG.
Is for describing an ink jet recording apparatus provided in the drawing apparatus of FIG.

First, a printing process according to the present invention will be described with reference to an overall configuration diagram of an apparatus for performing one-sided one-color printing on a roll-shaped printing medium shown in FIG. An inkjet printing apparatus (hereinafter also referred to as “printing apparatus”) shown in FIG. 1 includes a supply roll 1 for a roll-shaped printing medium, a dust / paper dust removing apparatus 2,
The image forming apparatus includes a drawing device 3, a facing (drawing) drum 4, a fixing device 5, and a print medium take-up roll 6, which are arranged at positions facing the drawing device 3 via a print medium. After the dust and the like on the printing medium sent from the supply roll are removed by the dust / paper dust removing device 2, the ink is discharged from the ink discharge unit (described later) of the drawing device 3 to the printing medium on the drawing drum 4 on the printing medium. The ink is ejected in an imagewise direction, and a printed image is recorded.
After fixing the image on the print medium using the fixing device 5, the printed print medium is taken up by the print medium take-up roll 6.

The opposing (drawing) drum 4 is a metal roll or a roll having a conductive rubber layer on the surface thereof, or an insulating drum of plastic, glass, ceramic or the like, for use as a counter electrode with respect to the discharge electrode of the ink discharge section. For example, a metal layer provided on the surface by vapor deposition, plating, or the like is used. Thereby, an effective electric field can be formed between the discharge unit of the drawing apparatus 3. Providing a heating means on the drawing drum 4 to increase the drum temperature is also effective for improving the drawing quality. Bleeding is further suppressed in order to promote quick fixing of the ejected ink droplets on the print medium. Further, by keeping the drum temperature constant, the physical property values of the ink droplets ejected on the print medium are controlled, and stable and uniform dot formation becomes possible. In order to stabilize the temperature of the drum, it is more preferable to have a cooling unit.

As a means for removing dust, paper dust and the like, there can be used a contact method using a brush or a roller, in addition to a known non-contact method such as suction removal, blow-off removal and electrostatic removal. In the present invention, either air suction or air blowing or a combination thereof is used.

Further, the drawing device 3 has an ink jet recording device 20 as shown in FIG. In the inkjet recording apparatus 20, the oil-based ink is ejected onto the print medium by an electrostatic field formed between the ejection head 22 and the opposing drum 4 in accordance with the image data sent from the image data operation control unit 21. To form a drawing image.

An image data arithmetic control unit 21 receives image data from an image scanner, a magnetic disk device, an image data transmission device, etc., performs color separation, and has an appropriate number of pixels and gradation for the separated data. Divide into numbers and distribute to each head. Further, the inkjet recording device 2
In order to convert the oil-based ink image into a halftone dot using the inkjet discharge head 22 (see FIG. 10 described later) of 0, the halftone dot area ratio is also calculated.

As will be described later, the image data calculation control unit 21 controls the movement of the ink jet head 22, the ejection timing of the oil-based ink, and also controls the print medium operation timing as needed.

Referring to FIGS. 1 and 9, the printing plate process by the printing apparatus will be described in detail below.

The print medium sent out from the print medium supply roll is given tension by driving the print medium take-up roll, and abuts on the drawing (opposite) drum. Thus, it is possible to prevent the print medium web from vibrating and contacting the ink jet recording apparatus at the time of drawing to damage the print medium web. In addition, means for adhering the printing medium to the drawing (opposite) drum only around the drawing position of the ink jet recording apparatus is provided, and this is acted upon at least when drawing is performed, so that the printing medium contacts the ink jet recording apparatus. It can also be prevented. Specifically, for example, there is a method of arranging a pressing roller upstream and downstream of the drawing position of the drawing drum. Specifically, a pressing roller, a guide, electrostatic attraction, or the like is effective.

Image data from a magnetic disk device or the like
The image data arithmetic control unit 21 calculates the discharge position of the oil-based ink and the halftone dot area ratio at that position in accordance with the input image data. These calculation data are temporarily stored in the buffer. The image data calculation control unit 21 causes the ejection head 22 to move closer to a position close to the print medium that comes into contact with the drawing drum by the head separation / contact device 31. The distance between the discharge head 22 and the surface of the drawing drum is controlled by mechanical distance control such as a contact roller,
Alternatively, the head is kept at a predetermined distance during writing by controlling the head separation / contact device based on a signal from the optical distance detector. As the ejection head 22, a single-channel head, a multi-channel head, or a full-line head can be used. If a single-channel head or multi-channel head is used as the ejection head,
The arrangement direction of the ejection units is set in parallel or substantially parallel to the running direction of the print medium, and the main scanning is performed by moving the ejection head in the axial direction of the opposing drum, and the sub scanning is performed by rotating the opposing drum to perform printing. The movement control of the opposing drum and the discharge head described above is performed by the image data calculation control unit 21, and the discharge head discharges the oil-based ink onto the print medium at the discharge position and the dot area ratio obtained by the above calculation. As a result, a halftone image corresponding to the density of the print document is drawn on the print medium with the oil-based ink. This operation continues until a predetermined ink image is formed on the print medium. On the other hand, when the ejection head 22 is a full line head having substantially the same length as the width of the drum, the arrangement direction of the ejection units is set to be perpendicular or substantially perpendicular to the running direction of the print medium, and When the print medium passes through the drawing section, an oil-based ink image is formed, and a print is completed.

After the printing is completed, if necessary, the ejection head 22 is retracted away from a position close to the drawing drum to protect the ejection head 22. At this time, only the ejection head 22 may be separated and connected, but the ejection head 22 and the ink supply unit 24 may be separated and connected together.

This separation / contact means operates so as to separate the recording head from the drawing drum by at least 500 μm except during drawing. The detachment operation may be a sliding type, or the head may be fixed by an arm fixed to a certain axis, and the arm may be moved around the axis to move like a pendulum. By retracting the head during non-drawing in this manner, the head can be protected from physical damage or contamination, and a long life can be achieved.

Further, the formed oil-based ink image is reinforced by the fixing device 5. As a means of fixing ink,
Known means such as heat fixing, solvent fixing, and flash exposure fixing can be used. In the heat fixing, infrared or halogen lamp or xenon flash lamp irradiation, hot air fixing using a heater, and heat roll fixing are generally used. Also, when using laminated paper, a rapid rise in temperature causes the water inside the paper to evaporate rapidly, causing development called blisters, which cause irregularities on the paper surface. It is preferable to change the power supply and / or the distance from the fixing device to the recording medium so as to gradually increase the temperature in order to prevent blisters.

In solvent fixing, a solvent capable of dissolving the resin component in the ink, such as methanol or ethyl acetate, is sprayed or exposed to vapor, and excess solvent vapor is recovered. Also, flash fixing using a xenon lamp or the like is known as a fixing method of electrophotographic toner, and has an advantage that fixing can be performed in a short time. In addition, at least in the process from the formation of the oil-based ink image by the ejection head 22 to the fixing by the fixing device 5, it is desirable that nothing is kept in contact with the image on the print medium.

FIGS. 2 to 4 show examples of the configuration of the single-sided and double-sided four-color printing apparatus. The operation principle and the like can be easily inferred from the above description of the single-sided single-color printing apparatus, and therefore the description thereof will be omitted. Although the configuration example of the four-color printing apparatus has been described here, the present invention is not limited to this, and the number of colors is arbitrarily determined as needed.

FIGS. 5 and 6 show another configuration example according to the present invention, and are explanatory views of a printing apparatus having an automatic discharge device 7 and using a printing medium wound around an opposite drum. FIG.
Is a device configuration example using a sheet-shaped print medium having an automatic feeding device 9. Here, a description will be given using an example of an apparatus configuration using a roll-shaped print medium in FIG.

First, the print medium supply roll 1 is
And the print medium cut into an arbitrary size by the cutter 8 is mounted. At this time, a known seat head /
The printing medium is tightly fixed on the drum by a mechanical method such as a tail holding device, an air suction device, or an electrostatic method, so that the paper flutters and comes into contact with the ink discharge drawing device 3 at the time of drawing and is damaged. Can be prevented. In addition, means for adhering the print medium to the drum only around the drawing position of the ink discharge drawing apparatus is provided, and at least at the time of drawing, the print medium is operated to prevent the print medium from contacting the ink jet recording apparatus. Can also. Specifically, for example, there is a method of arranging a pressing roller upstream and downstream of the drawing position of the opposing drum. Further, when no drawing is performed, it is desirable to keep the head away from the print medium, and thereby it is possible to effectively prevent the occurrence of problems such as contact damage in the ink discharge drawing device.

As the ejection head 22, a single-channel head, a multi-channel head, or a full-line head can be used. In the case of a multi-channel head or a full line head having a plurality of discharge units, the arrangement direction of the discharge units is set in the axial direction of the opposed drum 4. Further, in the case of a single-channel head or a multi-channel head, the head 22 is continuously or sequentially moved in the axial direction of the opposing drum by the image data arithmetic control unit 21 and is obtained by the arithmetic operation of the image data arithmetic control unit 21. The oil-based ink is discharged onto the print medium mounted on the drum 11 at the specified discharge position and the dot area ratio. As a result, a halftone image corresponding to the density of the print document is drawn on the print medium with the oil-based ink. This operation continues until an oil-based ink image is formed on the print medium. On the other hand, the ejection head 22
Is a full line head having a length substantially equal to the width of the drum, an oil-based ink image is formed on a print medium by one rotation of the drum, and a print is completed.
By performing main scanning by rotating the drum in this manner,
It is possible to improve the positional accuracy in the main scanning direction and perform high-speed drawing. The printed print medium is fixed by the fixing device 5 and discharged by the automatic discharge device 7.

Here, an example of the configuration of a single-sided four-color printing machine has been described, but the present invention is not limited to this, and the number of colors and single-sided / double-sided printing can be arbitrarily determined as necessary. .

FIGS. 7 and 8 are schematic diagrams each showing an example of a schematic configuration of a printing apparatus which performs drawing by nipping and running a print medium with a cap stun roller according to the present invention. FIG. FIG. 8 is a diagram showing a schematic configuration example of a printing apparatus using a sheet-shaped printing medium, and FIG.

Here, a description will be given with reference to an overall configuration diagram of an apparatus for performing single-sided four-color printing on a roll-shaped print medium shown in FIG. The print medium M is conveyed while being nipped by the two pairs of capstan rollers 10, and the ink jet recording apparatus uses the data divided and processed by the image data calculation control unit (21 in FIG. 9) into an appropriate number of pixels and gradations. 3 is drawn. It is preferable that a grounding means 11 is provided at a portion where drawing is performed by the inkjet recording device 3 so as to be a counter electrode of the discharge head electrode in electrostatic field discharge, thereby facilitating drawing.

In FIG. 7, a sheet cutter 8 is provided upstream of the automatic discharge device 7 for cutting the roll-shaped print medium.

Next, referring to FIG. 7, the process of producing a printed matter by the printing apparatus of the present invention will be described in more detail below.

First, the print medium is transported using the cap stun roller 10. At this time, by providing a print medium guide unit (not shown) as necessary, it is possible to prevent the head / tail of the print medium from fluttering and coming into contact with the ink ejection drawing device 3 and being damaged. In addition, means for preventing the print medium from sagging only around the drawing position of the ink discharge drawing apparatus is provided, and at least when drawing is performed, it is operated to prevent the print medium from contacting the ink discharge drawing apparatus. Can also. Specifically, for example, there is a method of arranging a pressing roller upstream and downstream of the drawing position. Further, when no drawing is performed, it is desirable to keep the head away from the print medium, and thereby it is possible to effectively prevent the occurrence of problems such as contact damage in the ink discharge drawing device.

Image data from a magnetic disk device or the like
The image data calculation control unit 21 shown in FIG. 9 calculates the ejection position of the oil-based ink and the dot area ratio at that position in accordance with the input image data. These calculation data are temporarily stored in the buffer.
The image data calculation control unit 21
2, the ejection timing control of the oil-based ink and the operation timing control of the capstan roller are performed, and the ejection head 22 is moved closer to the position close to the print medium by the head distance device 31 as necessary. The distance between the ejection head 22 and the surface of the print medium is maintained at a predetermined distance during drawing by mechanical distance control such as an abutment roller, or control of a head separation device by a signal from an optical distance detector. . By this distance control, good printing can be performed without the dot diameter becoming non-uniform due to the floating of the printing medium or the dot diameter not changing even when vibration is applied to the printing apparatus.

As the ejection head 22, a single-channel head, a multi-channel head, or a full-line head can be used, and the sub-scan is performed by transporting the print medium. In the case of a multi-channel head having a plurality of ejection sections, the arrangement direction of the ejection sections is set parallel or substantially parallel to the running direction of the print medium. Further, in the case of a single-channel head or a multi-channel head, the head 22 is moved in a direction perpendicular to the running direction of the print medium by the image data calculation control unit 21, and the ejection position and the dot area ratio obtained by the above calculation are calculated. Discharges oil-based ink. As a result, a halftone image corresponding to the density of the print document is drawn on the print medium with the oil-based ink. This operation continues until an oil-based ink image is formed on the print medium. On the other hand, when the ejection head 22 is a full line head having a length substantially equal to the width of the drum, the arrangement direction of the ejection units is set at a right angle or a substantially right angle with the traveling direction of the print medium,
The oil-based ink image is formed on the print medium as the print medium passes through the drawing unit. The printed print medium is fixed by the fixing device 5 and discharged by the automatic discharge device.

Here, an example of the configuration of the single-sided four-color printing machine has been described, but the present invention is not limited to this, and the number of colors and single-sided / double-sided printing are arbitrarily determined as needed.

Next, FIG.
This will be described in detail with reference to FIG.

As shown in FIG. 9, the drawing apparatus used in the present ink jet printing method includes an ink jet recording device 22 and an ink supply section 24. Ink supply unit 2
4 further includes an ink tank 25, an ink supply device 26,
The ink tank includes an ink concentration control unit 29 and an agitating unit 27 and an ink temperature management unit 28 in the ink tank. The ink may be circulated in the head, and in this case, the ink supply unit also has a recovery circulation function. The stirring means 27 suppresses precipitation and aggregation of the solid components of the ink. As the stirring means, a rotary blade, an ultrasonic vibrator, and a circulation pump can be used, and these are used or in combination. The ink temperature management means 28 is arranged such that a high-quality image can be stably formed without a change in the physical properties of the ink due to a change in the surrounding temperature and a change in the dot diameter. As the ink temperature management means, a heating element or a cooling element such as a heater or a Peltier element is arranged in an ink tank together with a stirring means so as to keep the temperature distribution in the tank constant, and controlled by a temperature sensor such as a thermostat. A publicly known method such as the above method can be used. The temperature of the ink in the ink tank is desirably from 15 ° C to 60 ° C, more preferably from 20 ° C to 50 ° C. Further, the stirring means for keeping the temperature distribution in the tank constant may be shared with the stirring means for suppressing the precipitation and aggregation of the solid components of the ink. The drawing printing apparatus further includes an ink density control unit 29 for performing high-quality drawing. The ink density is measured by optical detection, physical property measurement such as conductivity measurement, viscosity measurement, or the like, or management based on the number of drawn images. When managing by physical property measurement, an optical detector, conductivity meter, and viscosity meter are provided alone or in combination in the ink tank or ink flow path, and drawing is performed by the output signal of the optical detector, conductivity meter, and viscosity meter. When performing management based on the number of prints, the supply of liquid from a replenishment concentrated ink tank or a dilution ink carrier tank (not shown) to the ink tank is controlled based on the number of prints and the frequency.

As described above, the image data calculation control section 21 calculates the input image data, and controls the head separation / contact device 31,
The timing pulse from the encoder 30 installed on the opposing drum or the capstan roller is taken in, and the head is driven according to the timing pulse. When drawing is performed by the ink jet recording apparatus, the drawing drum is driven by a high-precision driving unit. Specifically, for example, the output from a high-precision motor is converted to a high-precision gear,
Alternatively, there is a method of driving the drawing drum at a reduced speed by a steel belt or the like. By using such means alone or in combination of two or more, higher-quality drawing can be performed.

Next, the ejection head will be described with reference to FIGS. However, the contents of the present invention are not limited to the following examples.

FIGS. 10 and 11 show an example of a head provided in an ink jet recording apparatus. Head 22
Has a slit sandwiched between an upper unit 221 and a lower unit 222 made of an insulating base material, the tip of which is a discharge slit 22a, and a discharge electrode 22b is arranged in the slit. Is supplied to the inside of the slit.
Examples of the insulating substrate include plastic, glass,
Ceramics and the like can be applied. Also, the ejection electrode 22b
Is vacuum-evaporated, sputtered, or electrolessly plated with a conductive material such as aluminum, nickel, chromium, gold, and platinum on the lower unit 222 made of an insulating base material.
A method of applying a photoresist thereon, exposing the photoresist through a mask of a predetermined electrode pattern, developing the photoresist pattern of the discharge electrode 22b, and etching the photoresist pattern, or a machine. It is formed by a publicly known method such as a method of removing it or a method of combining them.

In the head 22, a voltage is applied to the ejection electrode 22b according to a digital signal of image pattern information. As shown in FIG. 10, a drawing drum serving as a counter electrode is provided so as to face the discharge electrode 22b, and a printing medium is provided on the drawing drum. By applying a voltage, a circuit was formed between the discharge electrode 22b and the drawing drum serving as the counter electrode, and the oil-based ink 23 was discharged from the discharge slit 22a of the head 22 and provided on the drawing drum serving as the counter electrode. An image is formed on the print medium.

It is preferable that the width of the discharge electrode 22b is as narrow as possible at the tip in order to form a high quality image. Specific numerical values differ depending on the electrode spacing and applied voltage, but are usually used in the range of the tip width of 5 to 100 μm.

For example, the discharge electrode 22b having a tip of 20 μm width
With the distance between the discharge electrode 22b and the plate cylinder 11 serving as the counter electrode being 1.0 mm, a voltage of 3 KV is applied between the electrodes for 0.1 millisecond to form dots of 40 μm on the print medium 9. be able to.

FIGS. 12 and 13 are a schematic sectional view and a schematic front view, respectively, showing the vicinity of the ink discharge portion of another example of the discharge head. In the figure, reference numeral 22 denotes a discharge head.
The ejection head 22 has a first insulating substrate 33 having a gradually decreasing shape. The first insulating substrate 33 has a second
The insulating base material 34 is provided so as to be spaced apart and opposed, and a slope portion 35 is formed at the tip end of the second insulating base material 34. The first and second insulating substrates are made of, for example, plastic, glass, ceramics, or the like. Upper surface 3 forming an acute angle with slope 35 of second insulating substrate 34
6 is provided with a plurality of ejection electrodes 22b as electrostatic field forming means for forming an electrostatic field in the ejection section. The tips of the plurality of ejection electrodes 22b extend to near the tips of the upper surface portion 36, and the tips protrude forward of the first insulating base material 33 to form ejection portions.
The ink inflow path 3 is provided between the first and second insulating bases 33 and 34 as a means for supplying the ink 23 to the discharge section.
7 is formed, and an ink recovery path 38 is formed below the second insulating base material 34. The ejection electrode 22
b is formed by using a conductive material such as aluminum, nickel, chromium, gold, or platinum on the second insulating base material 34 by a known method as described above. Individual electrode 22b
Are electrically insulated from each other. The amount by which the tip of the discharge electrode 22b projects from the tip of the insulating substrate 33 is preferably 2 mm or less. The reason why the amount of protrusion is limited to the above range is that if the amount of protrusion is too large, the ink meniscus does not reach the tip of the discharge portion, making it difficult to discharge or lowering the recording frequency. Also,
The space between the first and second insulating substrates 33 and 34 is preferably in the range of 0.1 to 3 mm. The reason for limiting this space to the above range is that if the space is too narrow, it becomes difficult to supply ink and it becomes difficult to discharge, or the recording frequency is lowered, and if the space is too wide, the meniscus is not stable. This is because the ejection becomes unstable.
The ejection electrode 22b is connected to the image data calculation control unit 21, and when recording is performed, a voltage is applied to the ejection electrode based on image information to eject ink on the ejection electrode, and the ejection electrode 22b is arranged to face the ejection unit. Is drawn on a print medium (not shown). The direction opposite to the ink droplet ejection direction of the ink inflow path 37 is connected to an ink feeding unit of an ink supply device (not shown). A backing 39 is provided on the surface of the second insulating substrate 34 opposite to the surface on which the ejection electrodes are formed, facing away from each other, and an ink recovery path 38 is provided between the two. The space of the ink recovery path 38 is desirably 0.1 mm or more. The reason for limiting this space to the above range is that if the space is too narrow, it becomes difficult to collect the ink, which may cause ink leakage. The ink recovery path 38 is connected to an ink recovery means of an ink supply device (not shown). When a uniform ink flow on the ejection section is required, a groove 40 may be provided between the ejection section and the ink recovery path. FIG. 13 is a schematic front view of the vicinity of the ink ejection portion of the ejection head, and a plurality of grooves are formed on the slope of the second insulating base 34 from near the boundary with the ejection electrode 22 b toward the ink recovery path 38. 40 are provided. A plurality of the grooves 40 are arranged in the arrangement direction of the ejection electrodes 22b, and guide the ink from the openings on the ejection electrode 22b side to the respective grooves 40 by capillary force, and discharge the guided ink to the ink recovery path 38. Having. Also, groove 4
0 sucks a certain amount of ink near the tip of the discharge electrode by capillary force according to the opening diameter. Therefore, it has a function of forming an ink flow having a constant liquid thickness near the tip of the discharge electrode. The shape of the groove 40 may be any range as long as the capillary force acts, and particularly preferably, the width is 10 to 200 μm.
m and depth are in the range of 10 to 300 μm. The groove 40
Are provided in a required number so that a uniform ink flow can be formed over the entire surface of the head.

The width of the discharge electrode 22b is preferably as narrow as possible at the end in order to perform high-quality image formation, for example, printing. Specific numerical values vary depending on the electrode spacing, applied voltage, and the like, but are usually used in the range of the tip width of 5 to 100 μm.

FIGS. 14 and 15 show another example of the ejection head used to carry out the present invention. FIG.
Is a schematic diagram showing only a part of the head for explanation. As shown in FIG. 14, the recording head 22 includes a head main body 41 made of an insulating material such as plastic, ceramic, and glass, and meniscus regulating plates 42 and 42 '. In the drawing, reference numeral 22b denotes an ejection electrode for applying a voltage to form an electrostatic field in the ejection portion. Further, the head main body will be described in detail with reference to FIG. 15 in which the regulating plates 42 and 42 'have been removed from the head. The head body 41 is provided with a plurality of ink grooves 43 for circulating ink perpendicular to the edge of the head body. The shape of the ink groove 43 may be set in a range where the capillary force acts so that a uniform ink flow can be formed, and particularly preferably, the width is 10 to 200 μm.
m, the depth is 10 to 300 μm. The ejection electrode 22b is provided inside the ink groove 43. The discharge electrode 22b is formed on a head body 40 made of an insulating material by using a conductive material such as aluminum, nickel, chromium, gold, or platinum by a known method similar to that of the above-described apparatus embodiment. It may be arranged on the entire surface in the groove 43 or may be formed only on a part thereof. The discharge electrodes are electrically isolated. Two adjacent ink grooves form one cell, and ejection parts 45 and 45 'are provided at the end of the partition wall 44 at the center. In the ejection portions 45 and 45 ', the partition walls are thinner than the other partition portions 44 and are sharpened. Such a head body is manufactured by a known method such as machining, etching, or molding of an insulating material block. The thickness of the partition wall at the discharge portion is preferably 5 to 100 μm, and the radius of curvature of the sharpened tip is preferably 5 to 50 μm. The tip of the discharge section may be slightly chamfered, such as 45 '. Although only two cells are shown in the figure,
The cells are partitioned by a partition wall 46, and a tip end portion 47 is chamfered so as to be retracted from the discharge portions 45 and 45 '. Ink is supplied to the head from an I direction through an ink groove by an ink feeding means of an ink supply device (not shown) to supply ink to a discharge unit. Further, surplus ink is collected in the O direction by an ink collecting means (not shown), and as a result, fresh ink is always supplied to the ejection unit. In this state, a voltage is applied to the discharge electrode according to image information to a drawing drum (opposite drum) (not shown), which is provided so as to face the discharge section and has a print medium in contact with the surface thereof. The ink is ejected from the section to form an image on the print medium.

Another embodiment of the ejection head will be described with reference to FIG. As shown in FIG. 16, the ejection head 22 has a pair of substantially rectangular plate-shaped support members 50 and 50 '. These support members 50, 50 'are made of a plate-like plastic, glass, ceramic or the like having a thickness of 1 to 10 mm having an insulating property, and one surface of each is parallel to each other according to the recording resolution. A plurality of elongated rectangular grooves 51, 51 '(not shown) are formed. Each groove 51, 51 'has a width of 10 to 200 μm and a depth of 10 to 3
The discharge electrode 22b is preferably formed in a range of 00 μm, and the whole or a part thereof is formed with the discharge electrode 22b. Thus, the plurality of grooves 51, 5 are provided on one surface of the support members 50, 50 '.
By forming 1 ', a plurality of rectangular partitions 52 are inevitably provided between the grooves 51. Each support member 5
0, 50 'are combined so that the surfaces on which the grooves 51, 51' are not formed face each other. That is, the ejection head 22
Has a plurality of grooves on its outer peripheral surface for flowing ink. Grooves 5 formed in each support member 50, 50 '
1, 51 'are connected in a one-to-one correspondence via the upper end 53 of the ejection head 22, and a rectangular portion 54 in which each groove is connected.
Is a predetermined distance (50 to 5) from the upper end 53 of the ejection head 22.
(00 μm). That is, each rectangular portion 54
The upper ends 55 of the partition walls 52 of the support members 50 and 50 ′ are provided on both sides of the support members 50 and 50 ′ so as to protrude from the rectangular portions 54. A guide protrusion 56 made of an insulating material as described above is provided so as to protrude from each rectangular portion 54 to form a discharge portion. When the ink is circulated through the ejection head 22 configured as described above, one of the support members 50 is used.
Of each rectangular portion 54 via each groove 51 formed on the outer peripheral surface of the
And the ink is discharged through the grooves 51 'formed in the support member 50' on the opposite side. In this case, the ejection head 22 is inclined at a predetermined angle to enable smooth ink distribution. In other words, the ink supply side (support member 50) is located upward, and the ink discharge side (support member 5).
The ejection head 22 is inclined such that 0 ′) is located below. As described above, when the ink is circulated through the ejection head 22, the ink passing through each rectangular portion 54 becomes
6, the ink meniscus is formed near the rectangular portion 54 and the protrusion 56. Then, in a state in which an independent ink meniscus is formed in each rectangular portion 54, the ink meniscus is provided so as to face the discharge unit, and the discharge electrode 22b is applied to a drawing drum (not shown) having a surface in contact with a print medium. By applying a voltage based on the image information, the ink is ejected from the ejection unit and an image is formed on the print medium. By providing a cover for covering the groove on the outer peripheral surface of each support member 50, 50 ', each support member 5
A pipe-shaped ink flow path may be formed along the outer peripheral surface of 0, 50 ', and ink may be forcibly circulated through the ink flow path. In this case, it is not necessary to tilt the ejection head 22.

The head 22 described above with reference to FIGS. 10 to 16 may include a maintenance device such as a head cleaning means as required. For example, if the hibernation state continues or if a problem occurs in image quality, the tip of the ejection head is wiped with a flexible brush, brush, cloth, or the like, circulates only the ink solvent, supplies only the ink solvent, Alternatively, a single means such as suctioning the discharge part while circulating,
Alternatively, a good drawing state can be maintained by performing the combination. To prevent ink sticking, put the ejection head in a cover filled with ink solvent vapor,
It is also effective to cool the head and suppress evaporation of the ink solvent. If the stain is further severe, the ink is forcibly sucked from the ejection portion, or the jet of air, ink, or ink solvent is forcibly injected from the ink flow path,
Alternatively, it is also effective to apply ultrasonic waves while the head is immersed in the ink solvent, and these methods can be used alone or in combination.

Next, the printing medium used in the present invention will be described. Examples of the print medium include high quality paper, finely coated paper, and coated paper that are commonly used printing papers.
Further, for example, a polyolefin laminated paper having a resin film layer on the surface, and a plastic film such as a polyester film, a polystyrene film, a vinyl chloride film, a polyolefin film, and the like can also be used. Further, a plastic film or processed paper on which metal is deposited on the surface or a metal layer is laminated can be used. Of course, a special paper and a special film for inkjet can also be used.

Hereinafter, the oil-based ink used in the present invention will be described.

The oil-based ink used in the present invention is obtained by dispersing at least colored particles in a non-aqueous solvent having a specific electric resistance of 10 ⁹ Ωcm or more and a dielectric constant of 3.5 or less.

The specific electric resistance used in the present invention is 10 ⁹ Ωcm.
As the non-aqueous solvent having a dielectric constant of 3.5 or less, preferably a linear or branched aliphatic hydrocarbon, alicyclic hydrocarbon, or aromatic hydrocarbon, and a halogen-substituted product of these hydrocarbons are used. is there. For example, hexane, heptane, octane, isooctane, decane, isodecane, decalin,
Nonane, dodecane, isododecane, cyclohexane, cyclooctane, cyclodecane, benzene, toluene, xylene, mesitylene, isoper C, isoper E, isoper G, isoper H, isoper L (Isoper; trade name of Exxon), Shellsol 70, shell Sol 71 (Shellsol; trade name of Shell Oil Co.), Amsco OMS, Amsco 460 solvent (Amsco; trade name of Spirits Co., Ltd.), silicone oil and the like are used alone or in combination. The upper limit of the specific electric resistance of such a non-aqueous solvent is about 10 ¹⁶ Ωcm, and the lower limit of the dielectric constant is about 1.9.

The reason why the electric resistance of the non-aqueous solvent used is in the above range is that if the electric resistance is low, the electric resistance of the ink is not appropriate and the ejection of the ink by the electric field is deteriorated. The reason for the range is that when the dielectric constant is increased, the electric field is relaxed by the polarization of the solvent, whereby the color of the dot formed thereby becomes lighter or bleeds.

The colored particles dispersed in the non-aqueous solvent may be dispersed in the non-aqueous solvent as the coloring material itself as dispersed particles, or may be contained in the dispersed resin particles for improving fixability. May be. When it is contained, pigments and the like are generally coated with the resin material of the dispersed resin particles to obtain resin-coated particles, and dyes and the like are generally obtained by coloring the dispersed resin particles into colored particles. is there.

As the coloring material, any pigments and dyes conventionally used in oil-based ink compositions or liquid developers for electrostatography can be used.

As the pigment, those generally used in the technical field of printing can be used irrespective of inorganic pigments and organic pigments. Specifically, for example, carbon black, cadmium red, molybdenum red, chrome yellow, cadmium yellow, titanium yellow, chromium oxide, viridian, cobalt green, ultramarine blue, Prussian blue, cobalt blue, azo pigment, phthalocyanine pigment , Quinacridone-based pigments, isoindolinone-based pigments, dioxazine-based pigments, threne-based pigments, perylene-based pigments, perinone-based pigments, thioindigo-based pigments, quinophthalone-based pigments, metal complex pigments, and other known pigments. It can be used without.

As dyes, azo dyes, metal complex dyes,
Naphthol dye, anthraquinone dye, indigo dye,
Oil-soluble dyes such as carbonium dyes, quinone imine dyes, xanthene dyes, aniline dyes, quinoline dyes, nitro dyes, nitroso dyes, benzoquinone dyes, naphthoquinone dyes, phthalocyanine dyes and metal phthalocyanine dyes are preferred.

These pigments and dyes may be used alone or in combination as appropriate, but may be contained in the range of 0.5 to 5% by weight based on the whole ink. desirable.

The oil-based ink used in the present invention preferably contains, in addition to the above-mentioned colored particles, dispersed resin particles for improving the fixability of an image after printing.

The resin particles dispersed in the non-aqueous solvent may be hydrophobic resin particles which are solid at a temperature of 35 ° C. or lower and have a good affinity for the non-aqueous solvent. Glass transition point is -5 ° C to 110 ° C or softening point 33 ° C
The resin (P) having a glass transition point of 10 to 100 ° C or a softening point of 38 to 1 ° C is more preferable.
20 ° C., more preferably 15 ° C.
80 ° C or a softening point of 38 ° C to 100 ° C.

By using such a resin having a glass transition point or a softening point, the affinity between the surface of the printing medium and the resin particles increases, and the bonding between the resin particles on the printing medium becomes stronger. The adhesion between the image area and the surface of the print medium is improved, and the anti-scratch property is improved. On the other hand, regardless of whether the glass transition point or the softening point is low or high, the affinity between the printing medium surface and the resin particles is reduced, or the bonding between the resin particles is weakened.

The weight average molecular weight Mw of the resin (P) is 1 ×
10 ³ to 1 × 10 ⁶ , preferably 5 × 10 ³ to 8 ×
10 ⁵ , more preferably 1 × 10 ^{4 to} 5 × 10 ⁵ .

As such a resin (P), specifically,
Olefin polymers and copolymers (eg, polyethylene,
Polypropylene, polyisobutylene, ethylene-vinyl acetate copolymer, ethylene-acrylate copolymer, ethylene-methacrylate copolymer, ethylene-methacrylic acid copolymer, etc.), vinyl chloride polymer and copolymer (for example, polychlorinated Vinyl, vinyl chloride-vinyl acetate copolymer, etc.), vinylidene chloride copolymer, vinyl alkanoate polymer and copolymer, allyl alkanoate polymer and copolymer, polymer and copolymer of styrene and its derivatives (For example, butadiene-styrene copolymer, isoprene-
Styrene copolymer, styrene-methacrylate copolymer, styrene-acrylate copolymer, etc.), acrylonitrile copolymer, methacrylonitrile copolymer, alkyl vinyl ether copolymer, acrylic ester polymer and copolymer, methacryl Acid ester polymer and copolymer, itaconic acid diester polymer and copolymer, maleic anhydride copolymer, acrylamide copolymer, methacrylamide copolymer, phenol resin, alkyd resin, polycarbonate resin, ketone resin, polyester resin,
Silicon resin, amide resin, hydroxyl and carboxyl group modified polyester resin, butyral resin, polyvinyl acetal resin, urethane resin, rosin resin, hydrogenated rosin resin, petroleum resin, hydrogenated petroleum resin, maleic acid resin, terpene resin, hydrogenated Terpene resin, coumarone-indene resin, cyclized rubber-methacrylic acid ester copolymer, cyclized rubber-acrylic acid ester copolymer, copolymer containing a nitrogen-free heterocycle (for example, furan Ring, tetrahydrofuran ring, thiophene ring, dioxane ring, dioxofuran ring, lactone ring,
Benzofuran ring, benzothiophene ring, 1,3-dioxetane ring, etc.), epoxy resin and the like.

The total content of the dispersed colored particles and resin particles in the oil-based ink of the present invention is preferably 0.5 to 20% by weight of the whole ink. If the content is low, the density of the printed image becomes insufficient, or the affinity between the ink and the printing medium surface becomes difficult to obtain, so that a problem such as that a strong image cannot be obtained tends to occur. When the number of inks increases, it becomes difficult to obtain a uniform dispersion liquid, ink tends to be clogged in the discharge head, and it is difficult to obtain stable ink discharge.

The colored particles dispersed in the non-aqueous solvent of the present invention, further including resin particles and the like, preferably have an average particle diameter of 0.05 μm to 5 μm. More preferably 0.1 μm to 1.5 μm, even more preferably 0.4 μm
The range is from μm to 1.0 μm. This particle size is CAPA-
500 (trade name, manufactured by Horiba, Ltd.).

The non-aqueous dispersion colored particles used in the present invention can be produced by a conventionally known mechanical pulverization method or polymerization granulation method. As a mechanical pulverization method, if necessary, a colorant and a resin are mixed, melted, kneaded, and then directly pulverized with a conventionally known pulverizer to obtain fine particles, and a dispersed polymer is used in combination. (For example, ball mill
A method of dispersing with a paint shaker, a caddy mill, a dyno mill, etc.), a colorant material to be a colored particle component, and a dispersing auxiliary polymer (or a coating polymer) are kneaded in advance to form a kneaded material, and then pulverized, and then the coexistence of the dispersed polymer And dispersion. Specifically, a method for producing a paint or a liquid developer for electrostatography can be used. For example, these methods are described in Kenji Ueki, “Flow and paint dispersion of paint”, Kyoritsu Shuppan (1971), “Solomon , Science of Paints, "Paint and Surface CoatingTheory and Practi
ce ”, Yuji Harasaki“ Coating Engineering ”Asakura Shoten (197
1 year) and Yuji Harazaki, "Basic Science of Coatings", Maki Shoten (1977).

There is also a method of producing colored particles by coloring resin particles granulated by a polymerization granulation method by dyeing.
As the polymerization granulation method, a conventionally known non-aqueous dispersion polymerization method can be mentioned, and specifically, the latest technology of ultrafine polymer supervised by Soichi Muroi, Chapter 2, CMC Publishing (1991), edited by Koichi Nakamura, ed. Recent Electrophotographic Development System and Development and Practical Use of Toner Materials ", Chapter 3, (Nippon Kagaku Kagaku Co., Ltd. 1985), KEJ Barrett," Dispersion Polymerization
in Organic Media "and written books such as John Wiley (1975).

Usually, a dispersion polymer is used in combination to stabilize the dispersion of the dispersed particles in a non-aqueous solvent. The dispersed polymer contains a repeating unit soluble in a non-aqueous solvent as a main component, and has an average molecular weight of 1 × 10 in weight average molecular weight Mw.
^It is preferably ³ to 1 × 10 ⁶ , more preferably 5 × 10 ³
５5 × 10 ⁵ .

Preferred examples of the soluble repeating unit of the dispersion polymer used in the present invention include a polymerization component represented by the following general formula (1).

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In the general formula (I), X ₁ is —COO
Represents-, -OCO- or -O-.

R represents an alkyl or alkenyl group having 10 to 32 carbon atoms, preferably an alkyl or alkenyl group having 10 to 22 carbon atoms, which may be linear or branched, and unsubstituted. Those are preferable, but may have a substituent.

Specifically, decyl, dodecyl, tridecyl, tetradecyl, hexadecyl, octadecyl, eicosanyl, docosanyl, decenyl,
A dodecenyl group, a tridecenyl group, a hexadecenyl group, an octadecenyl group, a linolel group and the like.

A ₁ and a ₂ may be the same or different from each other, and are preferably a hydrogen atom, a halogen atom (eg, a chlorine atom, a bromine atom, etc.), a cyano group, and a carbon number of 1 to 3.
Alkyl group (e.g., methyl group, ethyl group, propyl group, etc.), - COO-Z ₁ or -CH ₂ COO-Z ₁ [Z
₁ represents an optionally substituted hydrocarbon group having 22 or less carbon atoms (eg, an alkyl group, an alkenyl group, an aralkyl group, an alicyclic group, an aryl group, etc.).

Z ₁ specifically represents a hydrocarbon group,
Preferred hydrocarbon groups include alkyl groups having 1 to 22 carbon atoms which may be substituted (for example, methyl group, ethyl group,
Propyl, butyl, heptyl, hexyl, octyl, nonyl, decyl, dodecyl, tridecyl, tetradecyl, hexadecyl, octadecyl, eicosanyl, docosanyl, 2-chloroethyl, 2-bromoethyl Group, 2-cyanoethyl group, 2-methoxycarbonylethyl group, 2-methoxyethyl group, 3
-Bromopropyl group, etc.), and an optionally substituted alkenyl group having 4 to 18 carbon atoms (for example, 2-methyl-1-propenyl group, 2-butenyl group, 2-pentenyl group, 3-methyl-2-pentenyl group) , A 1-pentenyl group, a 1-hexenyl group, a 2-hexenyl group, a 4-methyl-2-hexenyl group, a decenyl group, a dodecenyl group, a tridecenyl group, a hexadecenyl group, an octadecenyl group, a linolenyl group, and the like; Optionally substituted aralkyl groups (for example, benzyl group, phenethyl group, 3-phenylpropyl group, naphthylmethyl group, 2-naphthylethyl group,
Chlorobenzyl group, bromobenzyl group, methylbenzyl group, ethylbenzyl group, methoxybenzyl group, dimethylbenzyl group, dimethoxybenzyl group, etc.), having 5 to 8 carbon atoms
Which may be substituted (e.g., cyclohexyl group, 2-cyclohexylethyl group, 2-cyclopentylethyl group, etc.) and an optionally substituted aromatic group having 6 to 12 carbon atoms (e.g., phenyl group , Naphthyl, tolyl, xylyl, propylphenyl, butylphenyl, octylphenyl, dodecylphenyl, methoxyphenyl, ethoxyphenyl, butoxyphenyl, decyloxyphenyl, chlorophenyl, dichlorophenyl, bromo Phenyl group, cyanophenyl group, acetylphenyl group, methoxycarbonylphenyl group, ethoxycarbonylphenyl group, butoxycarbonylphenyl group, acetamidophenyl group, propioamidophenyl group, dodecyloylamidophenyl group, etc.).

In the dispersion polymer, another repeating unit may be contained as a copolymer component together with the repeating unit represented by the general formula (I). Other copolymer components include:
Any compound may be used as long as it is composed of a monomer copolymerizable with a monomer corresponding to the repeating unit of the general formula (I).

The proportion of the polymer component represented by the general formula (I) in the dispersion polymer is preferably at least 50% by weight, more preferably at least 60% by weight.

Specific examples of these dispersion polymers include:
Examples include the dispersion stabilizing resin (Q-1) used in Examples, and a commercially available product (Solprene 1205, manufactured by Asahi Kasei Corporation) can also be used.

When the above-mentioned resin (P) particles are produced as an emulsion (latex) or the like, it is preferable that the dispersion polymer is added in advance during polymerization.

The addition amount of the dispersing polymer is determined by the resin for particles (P).
About 1 to 50% by weight.

The dispersed resin particles and colored particles (or coloring material particles) in the oil-based ink of the present invention are preferably positively charged or negatively charged electro-detectable particles.

In order to impart an electric detecting property to these particles, it can be achieved by appropriately utilizing a technique of a wet type electrophotographic developer. Specifically, the above-mentioned “Recent development and practical use of electrophotographic development systems and toner materials”, pp. 139-148,
The Society of Electrophotography, "Basics and Application of Electrophotographic Technology," 497-
505 (Corona Co., 1988), Yuji Harasaki "Electrophotography" 16 (No. 2), page 44 (1977), and the like, using an electric test material and other additives.

Specifically, for example, British Patent No. 8934
No. 29, No. 934038, No. 11222397,
U.S. Patent Nos. 3,900,412 and 4,606,899,
JP-A-60-179751, JP-A-60-185963
And JP-A-2-13965.

The charge control agent described above is preferably used in an amount of 0.001 to 1.0 part by weight based on 1000 parts by weight of the dispersion medium as the carrier liquid. If desired, various additives may be added. The upper limit of the total amount of these additives is regulated by the electrical resistance of the oil-based ink. That is, if the electric resistance of the ink from which the dispersed particles are removed is lower than 10 ⁹ Ωcm, it becomes difficult to obtain a high-quality continuous tone image. Therefore, it is necessary to control the amount of each additive within this limit. It is.

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EXAMPLES The present invention will be described in detail with reference to examples below, but the contents of the present invention are not limited to these examples. First, a production example of the resin particles for ink (PL-1) will be described.

Production Example 1 Production of Resin Particles (PL-1) A mixed solution of 10 g of a dispersion stabilizing resin (Q-1) having the following structure, 100 g of vinyl acetate and 384 g of Isopar H was heated to 70 ° C. while stirring under a nitrogen stream. Warmed. 0.8 g of 2,2'-azobis (isovaleronitrile) (abbreviated AIVN) was added as a polymerization initiator and reacted for 3 hours. Twenty minutes after addition of the initiator, cloudiness occurred and the reaction temperature rose to 88 ° C. Further, 0.5 g of this initiator was added, and after reacting for 2 hours, the temperature was raised to 100 ° C., and the mixture was stirred for 2 hours to distill off unreacted vinyl acetate. After cooling, the mixture was passed through a 200-mesh nylon cloth, and the resulting white dispersion was a latex having a degree of polymerization of 90% and an average particle size of 0.23 μm and having good monodispersity. The particle size was measured with CAPA-500 (manufactured by Horiba, Ltd.).

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A part of the white dispersion was centrifuged (rotation speed: 1 × 10 ⁴ rpm, rotation time: 60 minutes), and the precipitated resin particles were collected and dried. The weight average molecular weight (Mw: GPC value in terms of polystyrene) of the resin particles is 2
× 10 ⁵ , and the glass transition point (Tg) was 38 ° C.

Example 1 First, an oil-based ink was prepared. <Oil-based ink (IK-1)> dodecyl methacrylate /
Acrylic acid copolymer (copolymerization ratio; 95/5 weight ratio)
0 g, Nigrosine 10 g and Shersol 71 30 g
Was placed in a paint shaker (manufactured by Toyo Seiki Co., Ltd.) together with the glass beads, and dispersed for 4 hours to obtain a fine dispersion of nigrosine.

Preparation of Resin Particles for Ink 30 g of resin particles (PL-1) of Example 1 (as solid content), 20 g of the above nigrosine dispersion, FOC-1400 (Nissan Chemical Co., Ltd.)
G), and octadecene-half-maleic acid octadecylamide copolymer 0.08
g was diluted to 1 liter of Isopar G to prepare a black oil-based ink.

Next, the ink tank was filled with the oil-based ink IK-12L prepared as described above in the ink jet recording apparatus of the drawing apparatus of the printing apparatus shown in FIG. Here, 900 dpi of the type shown in FIG.
A full line head was used. A throwing heater and a stirring blade were provided in the ink tank as ink temperature management means, the ink temperature was set to 30 ° C., and the temperature was controlled by a thermostat while rotating the stirring blade at 30 rpm. Here, the stirring blade was also used as a stirring means for preventing sedimentation and aggregation. Further, the ink flow path is partially transparent, and L
An ED light-emitting element and a light-detecting element are arranged, and density control is performed by inputting an ink diluent (Isoper G) or a concentrated ink (the solid content of the IK-1 ink is adjusted to be doubled) according to the output signal. Was. A rolled fine coated paper as a print medium was provided on a counter drum and transported.
After removing dust from the surface of the print medium by suction of the air pump, move the discharge head close to the print medium to the drawing position, transmit the image data to be printed to the image data calculation control unit, and transport the print medium by rotating the opposing drum An oil-based ink was ejected from the full-line multi-channel head while forming the image to form an image. At this time, the tip width of the discharge electrode of the ink jet head was set to 10 μm, and the distance between the head and the print medium was kept at 1 mm by the output from the optical gap detector. When discharging, the bias voltage is 2.5 KV.
Voltage is always applied, and 500 V
Is further superimposed, and the pulse voltage is 0.2
Drawing was performed while changing the area of the dot by changing the dot area in 256 steps from millisecond to 0.05 millisecond. No drawing failure due to dust or the like was observed at all, and no image deterioration due to a change in dot diameter or the like was observed even when the outside air temperature was changed or the printing time was increased, and good printing was possible.

Further, the image was strengthened by heating using a xenon flash fixing device (light emission intensity 200 J / pulse, manufactured by Ushio Inc.). After the printing plate was completed, the ink jet recording apparatus was retracted 50 mm from a position close to the drawing drum in order to protect the ink jet head.

The obtained printed matter was an extremely clear image without any skipping or blurring in the printed image. After printing, 1
After supplying Isopar G to the head for 0 minute and cleaning by dripping Isopar G from the opening of the head, storing the head in a cover filled with vapor of Isopar G, for 3 months, Without the need for maintenance
Good printed matter was produced.

Example 2 Using the printing apparatus shown in FIGS. 2 and 3, a circulating pump was used as the stirring means (27 in FIG. 9), and FIGS.
The four 150-dpi 64-channel multi-channel heads of the type shown in FIG. 4 were used, and the heads were arranged so that the ejection units for 64 channels were arranged in the direction perpendicular to the axial direction of the drum. As oil-based inks, black ink IK-1 and IK-1
The cyan ink IK-2 produced in the same manner as the IK-1 ink except that the nigrosine used as the coloring material of the K-1 ink was replaced by phthalocyanine blue, and the nigrosine used as the coloring material of the IK-1 ink were CI Pigment Red, except that IK-1 ink was prepared in the same manner as IK-1 ink, and IK-1 ink, except that nigrosine used as a colorant of IK-1 ink was replaced by CI Pigment Yellow. Four inks of yellow ink IK-4 produced in the same manner were used to fill four heads. Here, a pump is used, and an ink reservoir is provided between the pump and the ink inflow path of the discharge head, and between the ink recovery path of the discharge head and the ink tank, respectively.
The ink was circulated by the hydrostatic pressure difference, and a heater and the above-mentioned pump were used as ink temperature management means, the ink temperature was set to 35 ° C., and the temperature was controlled by a thermostat. Here, the circulation pump was also used as a stirring means for preventing precipitation and aggregation. In addition, a conductivity measuring device was arranged in the ink flow path, and the density was controlled by diluting the ink or feeding the concentrated ink based on the output signal. After removing dust on the print medium surface with a nylon rotating brush,
The image data to be printed is transmitted to the image data arithmetic and control unit, the head is moved in the axial direction of the drum to perform main scanning, and the sub-scanning is performed by rotating the drawing drum to draw the image. To form an image. No defective drawing due to dust is observed at all, and no image deterioration due to a change in dot diameter or the like is observed even when the outside air temperature changes or the number of printed sheets increases, and the head of either type shown in FIGS. 12 and 14 is used. If you have
Good single-sided and double-sided full-color printing was possible. After printing, the head was cleaned by circulating Isopar G, and then a non-woven cloth containing Isopar G was brought into contact with the tip of the head to perform cleaning. As a result, no maintenance work was required for three months. And a good printed matter was produced.

Example 3 Using the printing apparatus shown in FIG. 5, full-color printing of four colors on one side was performed. As the oil-based ink, the four color inks described in the second embodiment are used for each of four sets of ink jet drawing apparatuses, and four 100 dpi 256-channel multi-channel heads of the type shown in FIG. 16 are used. It is arranged in parallel with the axis, performs main scanning by rotating the opposing drum, and draws a 900 dpi image on coated paper by moving the head sequentially in each rotation in the axial direction of the drum, clear, high-quality full-color printed matter I got

Example 4 Using the printing apparatus shown in FIGS. 7 and 8, full-color printing of four colors on both sides was performed. As the oil-based ink, the same four-color inks as in Example 3 were used. Here, a 600 dpi, 64 channel multi-channel head of the type shown in FIG. 12 was used as the ejection head, and the ejection section was arranged at an angle of about 60 degrees with the running direction of the print medium. The image data to be printed is transmitted to the image data arithmetic control unit,
While moving the channel multi-channel head in a direction perpendicular to the print medium, the print medium was conveyed by rotating the cap stun roller, thereby forming an image of 700 dpi on the ink jet exclusive paper. Otherwise, the same operation as in Example 1 was performed, and good printing of four full colors was possible.

[0098]

According to the present invention, there is provided a printing method in which an image is formed directly on a print medium based on a signal of image data, and the image is fixed to form a printed matter. Since the image is formed by an ink jet method of discharging ink, no bleeding occurs in the image even when printing on a normal printing paper or a plastic sheet which is a non-absorbable medium without using expensive special paper, Then, since it becomes possible to eject fine droplets, the resulting dot images have a small area and a small area, making it possible to print sophisticated image information such as photographic images at low cost and at high speed. Becomes

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram schematically illustrating a Web-type apparatus that performs single-sided, single-color printing, which is an example of an inkjet printing apparatus according to the present invention.

FIG. 2 is an overall configuration diagram schematically illustrating a Web-type apparatus that performs four-color printing on one side, which is another example of the inkjet printing apparatus of the present invention.

FIG. 3 is an overall configuration diagram schematically showing a two-sided four-color printing apparatus which is another example of the inkjet printing apparatus of the present invention.

FIG. 4 is an overall configuration diagram schematically showing a two-sided four-color printing apparatus which is another example of the inkjet printing apparatus of the present invention.

FIG. 5 is an overall configuration diagram schematically showing a single-sided four-color printing device that cuts a roll-shaped printing medium and winds the image on an opposed drum, which is another example of the inkjet printing device of the present invention. It is.

FIG. 6 is an overall configuration diagram schematically illustrating a printing apparatus using a sheet-shaped recording medium, which is another example of the inkjet printing apparatus of the present invention.

FIG. 7 is an overall configuration diagram schematically illustrating a printing apparatus that performs drawing by nipping and running a roll-shaped printing medium with a cap stun roller, which is another example of the inkjet printing apparatus of the present invention.

FIG. 8 is an overall configuration diagram schematically showing a printing apparatus that performs drawing by nipping and running a sheet-shaped recording medium with a cap stun roller, which is another example of the inkjet printing apparatus of the present invention.

FIG. 9 is a schematic configuration example of a drawing apparatus including a control unit, an ink supply unit, and a head separation / attachment mechanism of the drawing apparatus of the inkjet printing apparatus of the present invention.

FIG. 10 is a diagram illustrating an ink jet recording apparatus included in the drawing apparatus of FIG.

11 is a diagram for explaining an enlarged cross section of the ink jet recording apparatus of FIG.

FIG. 12 is a diagram schematically illustrating a cross section near an ink discharge unit of another example of a discharge head.

FIG. 13 is a schematic front view showing the vicinity of an ink ejection section of another example of an ejection head.

FIG. 14 is a schematic view showing only a part of a discharge head of another example.

FIG. 15 shows a state in which the recording head shown in FIG.
FIG.

FIG. 16 is a schematic diagram showing only a part of an ejection head using four 100 dpi 256-channel multi-channel heads.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 print medium supply roll 2 dust removal device 3 ink discharge drawing device 4 facing (drawing) drum 5 fixing device 6 print medium take-up roll 7 automatic discharge device 8 cutter 9 automatic supply device 10 cap stun roller 11 grounding means 20 inkjet recording device DESCRIPTION OF SYMBOLS 21 Image data calculation control part 22 Discharge head 221 Upper unit 222 Lower unit 22a Discharge slit 22b Discharge electrode 23 Oil-based ink 24 Ink supply part 25 Ink tank 26 Ink supply device 27 Stirrer 28 Ink temperature management means 29 Ink temperature control means 30 Encoder 31 Head Separating Device 32 Head Sub-Scanning Means 33 First Insulating Base 34 Second Insulating Base 35 Slope of Second Insulating Base 36 Upper Surface of Second Insulating Base 37 Ink Flow path 38 Ink recovery path 39 King 40 Groove 41 Head main body 42, 42 'Meniscus regulating plate 43 Ink groove 44 Partition wall 45, 45' Ejection part 46 Partition wall 47 Partition end part 48, 50 'Support member 49, 51 Groove 50 Partition wall 51 Upper end part 52 Rectangular part 53 Partition wall Upper end 54 Guide protrusion M Print medium

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Sadao Osawa 4,000 Kawajiri, Yoshida-cho, Haibara-gun, Shizuoka Prefecture Inside Fujisha Shin Film Co., Ltd. Incorporated F term (reference) 2C056 EA05 EC19 EC29 EC44 EC46 FA07 FA10 FA13 FA14 FB02 FC02 HA46 HA47 JB16 JC18 KB16 2C057 AF27 AG22 AH20 AJ02 AM14 AN01 AN05 AN06 BD05

Claims (16)

[Claims] 1. A printing method in which an image is formed directly on a print medium based on a signal of image data and a printed matter is created by fixing the image. Forming an image by using the above method. 2. The method according to claim 1, wherein the oil-based ink has a specific electric resistance value of 10.
^2. The ink jet printing method according to claim 1, wherein at least the colored particles are dispersed in a non-aqueous solvent having a resistivity of not less than ⁹ Ωcm and not more than 3.5. 3. A printing apparatus comprising: an image forming unit for forming an image directly on a print medium based on a signal of image data; and an image fixing unit for fixing an image formed by the image forming unit to obtain a printed matter. In the apparatus, the image forming unit is an ink jet drawing apparatus that discharges oil-based ink from a discharge head using an electrostatic field. 4. The oil-based ink has a specific electric resistance of 10
4. The printing apparatus according to claim 3, wherein at least colored particles are dispersed in a non-aqueous solvent having a resistivity of not less than ⁹ Ωcm and not more than 3.5. 5. The printing apparatus according to claim 3, further comprising dust removing means for removing dust existing on the surface of the print medium before and / or during printing on the print medium. 6. When drawing on the print medium, drawing is performed by rotating an opposing drum disposed at a position facing the discharge head via the print medium to move the print medium. The printing apparatus according to any one of claims 3 to 5, wherein the printing apparatus is a printing apparatus. 7. The printing apparatus according to claim 6, wherein the discharge head is a single-channel head or a multi-channel head, and performs drawing by moving the head in the axial direction of a counter drum. 8. The image forming apparatus according to claim 3, wherein at the time of drawing on said print medium, drawing is performed by nipping and running said print medium by at least a pair of cap stun rollers. The printing device according to the above. 9. The image forming apparatus according to claim 8, wherein the ejection head is a single-channel head or a multi-channel head, and the drawing is performed by moving the ejection head in a direction orthogonal to a running direction of the print medium. Printing equipment. 10. The printing apparatus according to claim 6, wherein the ejection head is a full line head having a length substantially equal to a width of the print medium. 11. The ink-jet drawing apparatus according to claim 3, further comprising an ink supply unit for supplying the oil-based ink to the ejection head.
A printing device according to any one of the preceding claims. 12. The printing apparatus according to claim 11, further comprising an ink recovery unit configured to recover the oil-based ink from the discharge head, and circulating the ink. 13. The ink jet drawing apparatus according to claim 3, further comprising a stirring unit for stirring the oil-based ink in an ink tank storing the oil-based ink.
13. The printing apparatus according to any one of claims 12 to 12. 14. The ink-jet drawing apparatus according to claim 3, further comprising an ink temperature management unit for managing a temperature of the oil-based ink in an ink tank storing the oil-based ink. The printing device according to the above. 15. The printing apparatus according to claim 3, wherein the inkjet drawing apparatus has an ink density control unit that controls the density of the oil-based ink. 16. The apparatus according to claim 3, further comprising a cleaning unit for cleaning said discharge head.
7. The printing device according to any one of 6.