JP2001199070A - Ink jet printing method and printer - Google Patents

Abstract

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

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. Since the inkjet system uses an aqueous or organic solvent-based ink containing a dye or pigment as a colorant, the ejected droplets contain a large amount of solvent and cause bleeding. Therefore, although it is suitable for an application in which a mark or the like is additionally printed on a part of the printing paper, bleeding is unlikely to occur when printing advanced image information such as a photographic image on the entire printing paper. Special paper having water absorption is required. Therefore, it is not suitable for printing on ordinary printing paper or a plastic sheet which is a non-absorbable medium.

[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] In addition, ink jet technology is inherently prone to local concentration of ink due to evaporation or volatilization of the solvent, which causes clogging at individual thin nozzles corresponding to the resolution. In particular, in the method using the pressure of steam for forming an ink jet, insoluble substances are attached due to thermal or chemical reaction with the ink, and in the method using the pressure by the piezoelectric element, complicated methods such as an ink flow path are used. The structure further facilitates clogging. In addition, dozens of
Line scanning heads that require thousands of nozzles, even more than serial scanning heads that use hundreds or more of tens of nozzles, cause clogging to occur at a much higher probability and reliability. Is a big problem.

Further, there is a problem that the conventional inkjet technology is not suitable for improving the resolution. In other words, in the method using the pressure of steam, it is difficult to generate expulsion ink particles having a diameter of 20 μm or less, and since the ink particles cause bleeding on the recording medium, it is necessary to generate recording dots having a diameter of 50 μm or less. Will be difficult. Further, in the method using the pressure generated by the piezoelectric element, the head has a complicated structure, so that it is difficult to produce a high-resolution head even with a problem in processing technology.

In order to overcome these drawbacks, a technique has been devised in which a voltage is applied to a thin-film electrode array, and an ink or a colorant component in the ink is caused to fly from an ink liquid surface using electrostatic force. Specifically, a method of flying ink using electrostatic attraction (JP-A-49-62024, JP-A-56-4467, etc.), and a method of coloring a colorant using an ink containing charged colorant particles. Method of flying with increased concentration (WO9
3/11866: PCT / AU92 / 00665) and the like.

In these systems, the head configuration is a slit-shaped nozzle configuration that does not require a nozzle for each individual dot, or a nozzleless configuration that does not require a partition of an ink flow path for each individual dot. This is effective for preventing and recovering from clogging, which has been a major obstacle in realizing a line scanning head. In particular, the latter can stably generate and compensate for ink droplets having a very small diameter, and is suitable for high resolution because there is no bleeding because the colorant particles in the ink mainly fly. In the conventional technology using a method of flying a colorant with such an electrostatic force,
As described above, a head having an electrode array in which electrodes are arranged is used, and ink is caused to fly by applying a high voltage of several hundred V to several KV to each electrode of the electrode array.

[0009]

However, when a multi-nozzle head having a plurality of ink ejection ports, such as a line scanning recording head, is constructed by using such an electrode array, if the voltage applied to the electrodes is high, the adjacent nozzles will become adjacent. Electric field interference between the electrodes becomes a problem. In general, the voltage signal for normal flight is created by controlling the output voltage from the high-voltage power supply on and off with a driving driver. When the applied voltage is high, a driver with a high withstand voltage must be used. Yes,
It will be expensive. To prevent these problems, the distance between the recording head and the recording medium may be reduced to reduce the applied voltage. In that case, the thickness of the recording medium,
The effect of paper dust and dust tends to occur, making it difficult to draw stably.

The present invention has been made by paying attention to the above circumstances, and is capable of printing a clear and high-quality image printed matter, and also has an ink jet printing method using a head which can be driven stably and easily formed into a line head. It is an object to provide a method and an apparatus.

[0011]

According to a first aspect of the present invention, there is provided a printing method comprising: forming an image directly on a print medium based on a signal of image data; and fixing the image. In a printing method for producing a printed matter, an oil-based ink is supplied to a discharge head arranged to face the print medium, and an electrostatic field is formed on the discharge head, and the insulating ink is irradiated with light. And applying a modulation voltage, which is voltage-modulated based on the signal, to the discharge head to cause the oil-based ink to fly from the discharge head to form an image directly on the print medium.

According to a second aspect of the present invention, in the printing method, the oil-based ink has a specific electric resistance of 10 ⁹ Ωcm or more and a dielectric constant of 3.
It is characterized in that at least colored particles are dispersed in 5 or less non-aqueous solvents.

According to a third aspect of the present invention, the printing method includes a wavelength at which the light is absorbed by the oil-based ink.

According to a fourth aspect of the present invention, there is provided a printing apparatus, comprising: an image forming means for forming an image directly on a print medium based on a signal of image data; and an image for obtaining a printed matter by fixing the image formed by the image forming means. And a fixing unit, wherein the discharge head is disposed to face the print medium, the oil-based ink is ejected to the print medium, and a bias voltage is applied to form an electrostatic field in the discharge head.
A voltage application unit that applies a modulation voltage that is voltage-modulated based on the image data signal; and a light irradiation unit that irradiates the oil-based ink with light. By forming an electrostatic field on the ejection head and irradiating the oil-based ink with the light by the light irradiating unit, further applying the modulation voltage to the ejection head by the voltage applying unit, thereby obtaining the oil-based ink. Is ejected from the discharge head onto the print medium to form an image directly on the print medium.

According to a fifth aspect of the present invention, in the printing apparatus, the oil-based ink has a specific electric resistance of at least 10 ⁹ Ωcm and a dielectric constant of 3.
It is characterized in that at least colored particles are dispersed in 5 or less non-aqueous solvents.

According to a sixth aspect of the present invention, in the printing apparatus, the light irradiating unit irradiates light having a wavelength that is absorbed by the oil-based ink.

According to a seventh aspect of the present invention, there is provided the printing apparatus, 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.

In the printing apparatus according to the present invention, at the time of drawing on the print medium, the print medium is moved by rotating an opposing drum disposed at a position facing the discharge head via the print medium. In this case, drawing is performed.

A printing apparatus according to a ninth aspect is characterized in that 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 the opposing drum.

According to a tenth aspect of the present invention, at the time of drawing on the print medium, drawing is performed by nipping and running the print medium by at least a pair of capstan rollers.

[0021] In the printing apparatus according to the eleventh aspect, the discharge head is a single-channel head or a multi-channel head, and performs drawing by moving the discharge head in a direction orthogonal to a running direction of the print medium. It is characterized by the following.

According to a twelfth aspect of the present invention, in the printing apparatus, the discharge head is a full line head having a length substantially equal to a width of the print medium.

A printing apparatus according to a thirteenth aspect is characterized in that the ink jet drawing apparatus has an ink supply means for supplying the oil-based ink to the discharge head.

According to a fourteenth aspect of the present invention, there is provided a printing apparatus having an ink recovery means for recovering the oil-based ink from the discharge head, and performing ink circulation.

A printing apparatus according to a fifteenth aspect is characterized in that the ink jet drawing apparatus has stirring means for stirring the oily ink in an ink tank storing the oily ink.

A printing apparatus according to a sixteenth aspect is characterized in that the ink jet drawing apparatus has an ink temperature management means for managing the temperature of the oily ink in an ink tank storing the oily ink.

[0027] A printing apparatus according to a seventeenth aspect is characterized in that the ink jet drawing apparatus has an ink density control means for controlling the density of the oil-based ink.

[0028] The printing apparatus according to the eighteenth aspect is characterized in that it has a cleaning means for cleaning the discharge head.

[0029]

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. Further, in the present inkjet method, the size of the ejected ink droplet is determined by the size of the tip of the ejection electrode or the electric field application condition. 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 provides an inkjet printing method capable of printing a clear and high-quality image print.

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.

FIG. 1 to FIG. 6 are views showing a schematic configuration example of a printing apparatus for performing drawing by moving a print medium by rotation of an opposite drum according to the present invention. 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.
FIG. 2 shows a Web-type apparatus for printing one-sided single color, and FIG. 2 shows a Web-type apparatus for printing one-sided four-color. FIGS. 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. FIGS. 10 to 16 illustrate an ink jet recording apparatus provided in the drawing apparatus of FIG.

First, the printing process according to the present invention will be described with reference to the 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, 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 and paper dust, 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, it is desirable to use either air suction or air blowing, or a combination thereof.

Further, the drawing apparatus 3 has an ink jet recording apparatus 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.

The 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 and the ejection timing of the oil-based ink, and also controls the print medium operation timing as needed.

The printing process by the printing apparatus will be described in detail below with reference to FIGS.

The print medium sent from the print medium supply roll is given tension by driving the print medium take-up roll, and comes into contact with 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, a pressing roller is arranged upstream and downstream of the drawing position of the drawing drum,
It is effective to use a guide and electrostatic attraction.

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 moves the ejection head 22 by the head separation / contact device 31 to a position close to a print medium that is in contact with the drawing drum. 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 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 and solvent fixing can be used. In the heat fixing, irradiation with an infrared lamp, a halogen lamp or a xenon flash lamp, hot air fixing using a heater, and heat roll fixing are generally used. Flash fixing using a xenon lamp or the like is known as a method for fixing electrophotographic toner, and has an advantage that fixing can be performed in a short time. 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. 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 a 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 is 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 example of the configuration 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, and the main scanning is performed by the rotation of the opposing drum 4. 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 a predetermined 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, one rotation of the drum forms an oil-based ink image on a print medium to produce a printed matter. By performing the main scanning by rotating the drum in this manner, the positional accuracy in the main scanning direction can be improved, and high-speed drawing can be performed. 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. However, 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 diagrams showing an example of a schematic configuration of a printing apparatus for performing drawing by nipping and running a printing 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 one-sided four-color printing on a roll-shaped print medium shown in FIG. The print medium M is nipped and conveyed by two pairs of capstan rollers 10, and is subjected to ink ejection drawing using data divided and processed into an appropriate number of pixels and an appropriate number of gradations by an image data calculation control unit (21 in FIG. 9). The image is drawn by the device 3.
In a part where drawing is performed by the ink discharge drawing device 3,
In electrostatic field discharge, it is preferable to provide a grounding means 11 to be a counter electrode of the discharge head electrode, thereby facilitating drawing.

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

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 is
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 timing of controlling the ejection of the oil-based ink, and the timing of the operation of the capstan roller are controlled, and the ejection head 22 is moved closer to the print medium by the head separation 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 a predetermined 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 to be perpendicular or substantially perpendicular to the traveling direction of the printing medium, and the printing medium is To form an oil-based ink image on the print medium. 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 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 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 a discharge head 22 to which light L is irradiated and an ink supply unit 24. The ink supply unit 24 further includes an ink tank 25 and an ink supply device 2.
6. It has an ink density control means 29, and includes an agitation means 27 and an ink temperature management means 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 stirring means,
A rotary wing, 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 unit 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 photoresist is applied thereon, the photoresist is exposed through a mask having a predetermined electrode pattern, and the photoresist is exposed and developed to form a photoresist pattern of the discharge electrode 22b. Then, the photoresist pattern is etched or removed mechanically. It is formed by a known method such as a method or a method combining them.

In the head 22, a voltage is applied to the ejection electrode 22b in accordance with the digital signal of the pattern information of the image, and light is irradiated as indicated by L in the figure. 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 is formed between the ejection electrode 22 b and the drawing drum serving as the counter electrode, and the ejection slit 22 of the head 22 is formed.
The oil-based ink 23 is ejected from a, and an image is formed on a print medium provided on a drawing drum serving as a counter electrode. Here, the light irradiation is performed by light including a wavelength that is absorbed by the ink from a light irradiation unit (not shown). As the light irradiation unit, an electrophotographic device, an exposure apparatus used in the technical field of plate making can be used, For example, a known light source such as a laser, an LED, a plasma light emitting array, a halogen lamp, a xenon lamp, and a fluorescent lamp can be used. The wavelength of the light irradiation means is selected in consideration of the absorption of the ink used.

The width of the discharge electrode 22b is preferably as narrow as possible in order to form a high quality image. Specific numerical values vary depending on conditions such as applied voltage and ink physical properties, but are usually used in a range of a tip width of 5 to 100 μm.

For example, the discharge electrode 22b having a tip of 20 μm width
And the drawing drum 4 serving as the counter electrode and the discharge electrode 22b
Is set to 1.0 mm, a dot of 40 μm can be formed on the print medium 9 by applying a voltage of 3 KV between the electrodes for 0.1 millisecond.

FIGS. 12 and 13 are a schematic sectional view and a schematic front view, respectively, showing the vicinity of the ink ejection portion of another example of the ejection 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, a plurality of ejection electrodes 22b to which light is applied as indicated by L in the figure as electrostatic field forming means for forming an electrostatic field in the ejection section.
Is provided. 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. An ink inflow path 37 is formed between the first and second insulating bases 33 and 34 as a means for supplying the ink 23 to the ejection section.
An ink recovery path 38 is formed below the insulating base material 34. The ejection electrode 22b is formed on the second insulating base material 34 using a conductive material such as aluminum, nickel, chromium, gold, and platinum by a known method as described above. The individual electrodes 22b are configured to be 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. The space between the first and second insulating bases 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 modulation voltage modulated based on image information is applied to the ejection electrode in a state where light is applied to the ejection electrode 22b. The upper ink is ejected, and drawing is performed on a print medium (not shown) that is arranged to face the ejection unit. 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.
Shows a schematic front view of the vicinity of the ink ejection section of the ejection head.
A plurality of grooves 40 are provided from near the boundary with b to the ink recovery path 38. A plurality of the grooves 40 are arranged in the arrangement direction of the ejection electrodes 22b, and a certain amount of ink near the tip of the ejection electrode is guided from the opening on the ejection electrode 22b side by a capillary force according to the opening diameter. A function of discharging the discharged ink to the ink recovery path 38. 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.
The depth is in the range of 10 to 300 μm.
The necessary number of grooves 40 are provided 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 in order to form a high quality image. The specific numerical value varies depending on the applied voltage, the physical properties of the ink, and the like, but is 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 drawing drum (opposite drum) (not shown), which is provided so as to face the discharge unit and whose surface is in contact with the print medium, is irradiated with light, and the discharge electrode responds to image information. By applying the modulated voltage, the ink is ejected from the ejection unit and an image is formed on a 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 'are formed. Each groove 51, 5
1 'is preferably in the range of 10 to 200 μm in width and 10 to 300 μm in depth, and the discharge electrode 22b is formed entirely or partially inside. As described above, by forming the plurality of grooves 51, 51 'on one surface of the support members 50, 50', a plurality of rectangular partition walls 52 are inevitably provided between the grooves 51. Each support member 50, 50 '
Are combined so that the surfaces on which the grooves 51 and 51 'are not formed face each other. That is, the ejection head 22 has a plurality of grooves on the outer peripheral surface for flowing ink.
Grooves 51, 51 'formed in each support member 50, 50'
Are connected in a one-to-one correspondence via a rectangular portion 54 of the ejection head 22, and the rectangular portion 54 to which each groove is connected is a predetermined distance (50 to 500 μm) from the upper end 53 of the ejection head 22.
m) has receded. That is, on both sides of each rectangular portion 54, the upper end 55 of each partition 52 of each support member 50, 50 '.
Are provided so as to protrude from the rectangular portion 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. Discharge head 22 configured as described above
When the ink is circulated to each of the rectangular portions 54 via the respective grooves 51 formed on the outer peripheral surface of one of the support members 50, the ink is supplied to the respective rectangular portions 54, and the respective grooves 51 'formed on the opposite support member 50'. Drain through. In this case, the ejection head 22 is inclined at a predetermined angle to enable smooth ink distribution. That is, the ink supply side (support member 50)
Is positioned above, and the ejection head 22 is inclined such that the ink discharge side (support member 50 ') is positioned below. As described above, when the ink is circulated through the ejection head 22, the ink passing through each rectangular portion 54 gets wet along each protrusion 56, and an ink meniscus is formed near the rectangular portion 54 and the protrusion 56. Then, in a state where independent ink meniscuses are formed in the respective rectangular portions 54, light is applied to a drawing drum (not shown) which is provided so as to face the ejection unit and which abuts the print medium on the surface thereof. In this state, by applying a voltage modulated based on image information to the ejection electrode 22b, ink is ejected from the ejection unit and an image is formed on a print medium. By providing a cover for covering the groove on the outer peripheral surface of each support member 50, 50 ', a pipe-shaped ink flow path is formed along the outer peripheral surface of each support member 50, 50'. May be used to force the ink to circulate. 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, if necessary. 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.

The oil-based ink used in the present invention will be described below.

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 within the above-mentioned range is that, when the electric resistance is low, the concentration of the colored particles and the like becomes difficult to occur, and the color of the formed dot becomes pale or bleeds. The reason why the dielectric constant is set to the above range is that when the dielectric constant is increased, the electric field is relaxed due to the polarization of the solvent, whereby the ejection of the ink tends to be deteriorated.

The coloring 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 electrophotography 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 the dye, 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 colored particles, dispersed resin particles for improving the fixability of an image after printing.

The resin particles dispersed in the above 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 softening point, the affinity between the surface of the printing medium and the resin particles is increased, and the bonding between the resin particles on the printing medium is increased. 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 .

Specific examples of such a resin (P) include:
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 is difficult to obtain a uniform dispersion liquid, the flow of ink in the discharge head tends to be uneven, and it is difficult to obtain stable ink discharge.

The average particle diameter of these particles, including the colored particles dispersed in the non-aqueous solvent of the present invention and further the resin particles, is preferably 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 are described in Kenji Ueki, “Flow of paint and pigment dispersion”, Kyoritsu Shuppan (1971), Solomon “ Paint Science "
Hirokawa Shoten (1969), Yuji Harasaki "Coating Engineering"
It is described in such books as Asakura Shoten (1971) and Yuji Harasaki "Basic Science of Coating" Maki Shoten (1977).

There is also a method in which resin particles granulated by polymerization granulation are colored by dyeing to produce colored particles.
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).

[0093]

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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 linolenyl group and the like.

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

Among the hydrocarbon groups represented by Z ₁ , preferred hydrocarbon groups include alkyl groups having 1 to 22 carbon atoms which may be substituted (for example, methyl group, ethyl group, propyl group, butyl group, Hexyl group, heptyl group, octyl group, nonyl group, decyl group, dodecyl group, tridecyl group,
Tetradecyl group, hexadecyl group, octadecyl group, eicosanyl group, docosanyl group, 2-chloroethyl group, 2
-Bromoethyl group, 2-cyanoethyl group, 2-methoxycarbonylethyl group, 2-methoxyethyl group, 3-bromopropyl group and the like, 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, 1-pentenyl group, 1-hexenyl group, 2-hexenyl group, 4-methyl-2-hexenyl group, decenyl group, dodecenyl group, tridecenyl group, hexadecenyl group, octadecenyl group, linolenyl group, etc.),
An aralkyl group having 7 to 12 carbon atoms which may be substituted (for example, benzyl group, phenethyl group, 3-phenylpropyl group, naphthylmethyl group, 2-naphthylethyl group, chlorobenzyl group, bromobenzyl group, methylbenzyl group, An ethylbenzyl group, a methoxybenzyl group, a dimethylbenzyl group, a dimethoxybenzyl group, etc., an alicyclic group having 5 to 8 carbon atoms which may be substituted (for example, cyclohexyl group,
-Cyclohexylethyl group, 2-cyclopentylethyl group, etc.) and an optionally substituted aromatic group having 6 to 12 carbon atoms (for example, phenyl group, naphthyl group, tolyl group, xylyl group, propylphenyl group, butylphenyl group) Octylphenyl, dodecylphenyl, methoxyphenyl, ethoxyphenyl, butoxyphenyl, decyloxyphenyl, chlorophenyl, dichlorophenyl, bromophenyl, cyanophenyl, acetylphenyl, methoxycarbonylphenyl, ethoxy Carbonylphenyl group, butoxycarbonylphenyl group, acetamidophenyl group, propionamidophenyl 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 a dispersion (latex) or the like, the dispersion polymer is preferably 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 colored particles (or coloring material particles) and the dispersed resin particles in the oil-based ink of the present invention are preferably positively charged or negatively charged electroconductive 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 Publishing Co., 1988), Yuji Harazaki "Electrophotography" 16 (No. 2), page 44 (1977), etc., by using a charge detecting material such as a charge control agent and other additives. Done.

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 as described above is preferably used in an amount of 0.001 to 1.0 part by weight with respect to 1000 parts by weight of 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 specific electric resistance of the ink from which the dispersed particles have been removed is lower than 10 ⁹ Ωcm, it becomes difficult to obtain a high-quality continuous tone image. desirable.

In the present invention, a low signal voltage (modulation voltage)
The mechanism that can draw high-resolution dots without bleeding is as follows: colored particles irradiated with light are charged by carrier injection from electrodes under an electric field, or are electrophoresed on the liquid surface by strengthening the charge. It is presumed that ejection occurs after concentration, but details are unknown. However, the present invention is not limited by the above estimation mechanism.

[0109]

The present invention will be described in detail with reference to the following examples, but the present invention is 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.).

[0111]

Embedded image

A part of the white dispersion was centrifuged (rotation speed: 1 × 10 ⁴ rpm, rotation time: 60 minutes), and the sedimented 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 (as solid content) of resin particles (PL-1) of Example 1, 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, 2 L of the oil-based ink (IK-1) prepared as described above was filled in an ink tank of the ink jet recording apparatus of the drawing apparatus of the printing apparatus shown in FIG. Here, 900 dp of the type shown in FIG.
i, full line head was used. A throwing heater and a stirring blade are provided in the ink tank as ink temperature management means, the ink temperature is set at 30 ° C., and the stirring blade is set at 30 rpm.
The temperature was controlled with a thermostat while rotating at. 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 an LED light emitting element and a light detecting element are disposed with the ink flow path interposed therebetween. The density was adjusted by a factor of 2). 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 ejection electrode of the ink jet head is 10 μm, and the distance between the head and the print medium is 1 according to the output from the optical gap detection device.
mm. A voltage of 2.5 KV is constantly applied as a bias voltage, and a 100 W white light source (Cold Light HLS) is used.
2100R (manufactured by HOYA) was applied to each ejection electrode via an optical fiber. A pulse voltage (modulation voltage: 37) voltage-modulated based on image information
5V) is 25 in the range of 0.2 ms to 0.05 ms.
Drawing was performed while changing the area of the dot by changing it in six stages. As a result, no drawing failure due to dust was observed at all, and no image deterioration due to a change in dot diameter or the like was observed even due to a change in outside air temperature or an increase in printing time, and good printing was possible.

Further, the image was strengthened by heating with a xenon flash fixing device (light emission intensity: 200 J / pulse, manufactured by Ushio Inc.). After printing, 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 as stirring means (27 in FIG. 9), and four 150 dpi 64-channel multi-channel heads of the type shown in FIG. The heads were arranged such that the ejection units for 64 channels were arranged in a direction perpendicular to the axial direction of the drum. As oil-based inks, black ink IK-1 and cyan ink IK-2 produced in the same manner as IK-1 ink except that nigrosine used as a coloring material of IK-1 ink was replaced with phthalocyanine blue, and IK- A magenta ink IK-3 prepared in the same manner as the IK-1 ink except that the nigrosine used as the coloring material of one ink was replaced with CI Pigment Red 57: 1, and nigrosine used as the coloring material of the IK-1 ink were used. Except for replacing with CI Pigment Yellow 14, inks of four colors of yellow ink IK-4 produced in the same manner as IK-1 ink were used to fill four heads respectively. Here, a pump is used, and ink reservoirs are respectively 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. As a means, use a heater and the above-mentioned pump,
The ink temperature was set at 35 ° C. and controlled with 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 the dust on the print medium surface with a rotating brush made of nylon, the image data to be printed is transmitted to the image data calculation control unit, the head is moved in the axial direction of the drum, the main scanning is performed, and the drawing drum is rotated. By performing sub-scanning while drawing, ink was ejected onto the rolled fine coated paper to form an image. At the time of ejection, a voltage of 2.5 KV is constantly applied as a bias voltage, and the output light of a 100 W white light source (Cold Light HLS2100R; manufactured by HOYA) is applied to 64.
Irradiation was performed on each discharge electrode via the optical fiber. Then, by changing the pulse voltage (modulation voltage: 375 V) voltage-modulated based on the image information in 256 steps in the range of 0.2 to 0.05 ms, drawing is performed while changing the dot area. went. As a result, 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 changed or the number of printed sheets increased, and any of the types shown in FIGS. Even when the head was used, good single-sided and double-sided full-color printing was possible. Further, after the printing, the circulation of the isopar G to the head is performed.
When the cleaning was performed by contacting the non-woven cloth containing with the tip of the head, no maintenance work was required for three months.
Good printed matter was produced. Further, the same operation was performed using a 150 dpi 64-channel multi-channel head of the type shown in FIG. 14 instead of the ink jet head of the type shown in FIG. 12, and good results were obtained as described above.

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
At the time of ejection, a voltage of 2.5 KV is always applied as a bias voltage, and a 100 W white light source (Cold Light HLS) is applied.
2100R (manufactured by HOYA) was applied to each discharge electrode via 256 optical fibers. And
Drawing was performed while changing the dot area by changing the pulse voltage (modulation voltage: 375 V) voltage-modulated based on the image information in 256 steps in the range of 0.2 to 0.05 ms. .

Example 4 Using the printing apparatus shown in FIGS. 7 and 8, full-color printing of four colors on one side 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. At the time of ejection, a voltage of 2.5 KV is constantly applied as a bias voltage, and a 100 W white light source (Cold Light HLS2100R; HOY
(A company) was irradiated onto each ejection electrode via 64 optical fibers. Then, a pulse voltage (modulation voltage: 375) voltage-modulated based on the image information
V) in the range of 0.2 ms to 0.05 ms for 256
The drawing was performed while changing the area of the dot by changing it in stages. Otherwise, the same operation as in Example 1 was performed, and good printing of four full colors was possible.

[0121]

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 inkjet method of discharging ink, the image does not bleed even when printed on a normal printing paper or a plastic sheet which is a non-absorbable medium without using expensive special paper,
Discharge of minute droplets becomes possible. Therefore, the obtained individual dot images have a small area and a small area, and it is possible to print high-quality image information such as a photographic image at low cost and at high speed. Further, by irradiating the head with light, the voltage applied to the head can be reduced, so that stable driving of the head and the formation of a line head can be easily achieved.

[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 apparatus that cuts a roll-shaped printing medium and winds it around an opposing drum, which is another example of the inkjet printing apparatus of the present invention.

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]

 DESCRIPTION OF SYMBOLS 1 Print medium supply roll 2 Dust removal device 3 Ink discharge drawing device 4 Opposing (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 Ink jet recording device Reference Signs List 21 Image data calculation control unit 22 Discharge head 221 Upper unit 222 Lower unit 22a Discharge slit 22b Discharge electrode 23 Oil-based ink 24 Ink supply unit 25 Ink tank 26 Ink supply device 27 Stirring unit 28 Ink temperature management unit 29 Ink temperature control unit 30 Encoder DESCRIPTION OF SYMBOLS 31 Head separation / attachment device 32 Head sub-scanning means 33 First insulating base material 34 Second insulating base material 35 Slope portion of second insulating base material 36 Upper surface portion of second insulating base material 37 Ink Inflow path 38 Ink recovery path 39 Locking 40 Groove 41 Head body 42, 42 ′ Meniscus regulating plate 43 Ink groove 44 Partition wall 45, 45 ′ Ejecting section 46 Partition wall 47 Partition tip 48, 50 ′ Support member 49, 51 Groove 50 Partition wall 51 Upper end section 52 Rectangular section 53 Partition wall Upper end 54 Guide protrusion M Print medium

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) B41M 5/00 B41J 3/04 102R 102Z (72) Inventor Eiichi Kato 4000 Kawajiri, Yoshida-cho, Harihara-gun, Shizuoka Prefecture Fujifilm Shin Film Incorporated F term (reference) 2C056 EA01 EA16 EA27 EA28 EC19 EC23 EC29 EC43 EC46 FA07 FA13 FA14 FC01 HA44 KB16 2C057 BD05 BD11 BD17 2H086 BA03 BA54 BA55 BA60

Claims (18)

[Claims] 1. A printing method for forming a print directly by forming an image on a print medium based on a signal of image data and fixing the image, wherein an oil-based ink is disposed to face the print medium. To form a static electric field on the ejection head and irradiate the insulating ink with light, and apply a modulation voltage, which is voltage-modulated based on the image data signal, to the ejection head to apply the oily property. An ink jet printing method, wherein an image is formed directly on the print medium by causing ink to fly from the discharge head. 2. The method according to claim 1, wherein the oil-based ink has a specific electric resistance value of 10.
^In a non-aqueous solvent having a resistivity of ⁹ Ωcm or more and a dielectric constant of 3.5 or less,
2. The ink jet printing method according to claim 1, wherein at least colored particles are dispersed. 3. The ink jet printing method according to claim 1, wherein the light includes a wavelength that is absorbed by the oil-based ink. 4. 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 material. In the apparatus, an ejection head disposed to face the print medium and flying oil-based ink onto the print medium, and applying a bias voltage to form an electrostatic field in the ejection head, based on a signal of the image data An ink jet drawing apparatus comprising: a voltage application unit for applying a voltage-modulated voltage; and a light irradiation unit for irradiating the oil-based ink with light, wherein the voltage application unit forms an electrostatic field in the ejection head. While the light irradiating unit irradiates the oil-based ink with the light, and further modulates the discharge head by the voltage applying unit. By applying a printing apparatus, and forming an image directly to the oil-based ink onto the print medium by ejecting the print medium from the ejection head. 5. The oil-based ink has a specific electric resistance of 10
5. The printing apparatus according to claim 4, wherein at least the coloring particles are dispersed in a non-aqueous solvent having a resistivity of not less than ⁹ Ωcm and not more than 3.5. 6. The printing apparatus according to claim 4, wherein the light irradiating unit irradiates light including a wavelength absorbed by the oil-based ink. 7. The printing apparatus according to claim 4, further comprising dust removing means for removing dust existing on the surface of the printing medium before and / or during printing on the printing medium. The printing device according to the above. 8. 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 and moving the print medium. The printing apparatus according to any one of claims 4 to 7, wherein the printing apparatus is a printing apparatus. 9. The printing apparatus according to claim 8, 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. 10. The image forming apparatus according to claim 4, 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. 11. The image forming apparatus according to claim 1, wherein the discharge head comprises a single-channel head or a multi-channel head, and performs drawing by moving the discharge head in a direction perpendicular to a running direction of the print medium.
0 printing apparatus. 12. The printing apparatus according to claim 8, wherein the discharge head is a full line head having a length substantially equal to a width of the print medium. 13. The ink jet drawing apparatus according to claim 4, wherein the ink jet drawing apparatus has an ink supply unit for supplying the oil-based ink to the discharge head.
A printing device according to any one of the preceding claims. 14. The printing apparatus according to claim 13, further comprising an ink recovery means for recovering said oil-based ink from said discharge head, and performing ink circulation. 15. The ink-jet drawing apparatus according to claim 4, further comprising a stirring means for stirring the oil-based ink in an ink tank storing the oil-based ink.
15. The printing apparatus according to any one of claims 14 to 14. 16. The ink-jet drawing apparatus according to claim 4, wherein said ink-jet drawing apparatus has an ink temperature management means for managing a temperature of said oil-based ink in an ink tank storing said oil-based ink. The printing device according to the above. 17. The printing apparatus according to claim 4, wherein said ink jet drawing apparatus has an ink density control means for controlling the density of said oil-based ink. 18. The apparatus according to claim 4, further comprising cleaning means for cleaning said discharge head.
The printing device according to any one of claims 7 to 10.