JP2002273867A - Method and apparatus for ink-jet printing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet printer which can meet digital image data and can print different images clearly, inexpensively and at high speeds on printing media. SOLUTION: The printer is an ink jet plotter provided with an imaging means for forming images directly onto the printing media on the basis of image data signals, and an image fixing means for obtaining printed matter by fixing images formed by the imaging means, in which the imaging means discharges an oil ink from a recording head by utilizing an electrostatic field. Ink stirring means 70 and 71 for preventing the ink from flocculating and/or sedimenting are set to a channel for the oil ink in a circulation of the ink.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink-jet printing method and a printing apparatus capable of forming a print image directly on a print medium by electrostatic ink-jet recording using oil-based ink and having good print quality and high-speed printing. More specifically, the present invention relates to prevention of aggregation and / or sedimentation of the oil-based ink particles.

[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 apparatus 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 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 non-absorbable medium such as a plastic sheet, 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, bleeding of a 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 area, and it is difficult to form a high-definition image.

In the case of drawing by ink jet, particles in the ink settle or agglomerate to cause clogging of a pipe or clogging of a head, which makes ink ejection unstable and degrades image quality. There is a problem such as stopping. If the particle diameter is large, spontaneous sedimentation may occur when the ink is in a stationary state, so that ejection at a uniform particle concentration becomes impossible, and a normal drawn image cannot be obtained. Further, there is a problem that the discharge is stopped.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to make it possible to print a clear, high-quality image printed matter by an inexpensive and simple method. It is an object of the present invention to provide a digital-compatible inkjet printing method and printing apparatus which does not require a developing process.

[0007]

According to the present invention, an oil-based ink is ejected by utilizing an electrostatic field based on a signal of image data. An image is formed directly on a print medium by an ink jet method, and the image is fixed to form a printed matter. In the ink jet printing method, prevention of aggregation and / or sedimentation of the oil-based ink particles at least during circulation of the ink is performed. It is characterized by performing. According to this configuration, since the oil-based ink is used after being filtered, foreign matter in the ink to the recording head can be prevented, and the ejection state can be stabilized. According to the second aspect of the present invention, in the ink jet printing method according to the first aspect, the oil-based ink is contained 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, It is characterized in that at least colored particles are dispersed. According to a third aspect of the present invention, in the ink jet printing method according to the first or second aspect, at least prevention of the aggregation and / or sedimentation during the circulation of the ink is performed before discharging the ink. I do. Claim 4
According to the invention described in the above, in the printing method according to any one of claims 1 to 3, the prevention of the aggregation and / or the sedimentation is performed at least during the circulation of the ink. Alternatively, it is characterized in that generation of a sediment is prevented. According to a fifth aspect of the present invention, in the printing method according to any one of the first to fourth aspects, the prevention of aggregation and / or sedimentation is achieved by stirring, dispersing, mixing, and jetting at least during circulation of the ink. It is characterized by the effect including any one of the following. According to a sixth aspect of the present invention, in the printing method of the fifth aspect, the stirring, dispersing, mixing, and jetting actions are applied singly, plurally, or multiplely at least during circulation of the ink. . According to a seventh aspect of the present invention, in the printing method according to the fifth or sixth aspect, the stirring, dispersing, mixing, and jetting operations are applied at any time, periodically, or continuously. . According to the eighth aspect of the present invention, any one of the first to seventh aspects is provided.
In the printing method described in the paragraph, the means for preventing aggregation and / or sedimentation is replaceable as a cartridge type. According to the ninth aspect of the present invention, there is provided an image forming means for forming an image directly on a print medium based on a signal of image data, and an image formed by fixing the image formed by the image forming means. An image fixing means for obtaining an ink jet ink, wherein the image forming means is an ink jet drawing apparatus for discharging an oil-based ink from a recording head using an electrostatic field, wherein the flow path of the oil-based ink is at least during circulation of the ink. At least one aggregate and / or
Alternatively, a sedimentation preventing means is provided. According to this configuration, since at least one aggregation and / or sedimentation prevention unit is provided in the flow path of the oil-based ink during the circulation of the ink,
Agglomerates of oil-based ink are eliminated from the ink, and an unstable state of head ejection can be prevented. According to a tenth aspect of the present invention, in the printing apparatus according to the ninth aspect, the aggregation and / or sedimentation prevention means during the circulation of the ink is provided at least immediately before the ink discharge section of the discharge head. And According to the eleventh aspect of the present invention, in the printing apparatus according to the ninth or tenth aspect, the aggregation and / or sedimentation prevention unit includes a coarse aggregate of the oil-based ink and / or Alternatively, it has the ability to prevent the formation of sediment. According to a twelfth aspect of the present invention, in the printing apparatus according to any one of the ninth to eleventh aspects, the aggregation and / or sedimentation prevention means includes agitation, dispersion, mixing, and jetting at least during circulation of the ink. Characterized by being performed by an action including any one of the following. According to a thirteenth aspect of the present invention, in the printing apparatus according to any one of the ninth to twelfth aspects, the stirring, dispersing, mixing, and jetting actions are performed singly, plurally, or multiplely at least during circulation of the ink. It is characterized by applying. According to a fourteenth aspect of the present invention, in the printing apparatus according to any one of the ninth to thirteenth aspects, the stirring, dispersing, mixing, and jetting actions are applied at any time, periodically, or continuously. It is characterized by. According to a fifteenth aspect of the present invention, in the printing apparatus according to any one of the ninth to fourteenth aspects, the aggregation and / or sedimentation prevention means is configured as a cartridge. According to a sixteenth aspect of the present invention, in the printing apparatus according to any one of the ^{ninth to} fifteenth aspects, the oil-based ink has a specific electric resistance of 10 ⁹ Ωcm or more and a dielectric constant of 3.5 or less. It is characterized in that at least colored particles are dispersed in an aqueous solvent. According to a seventeenth aspect of the present invention, in the printing apparatus according to any one of the ninth to sixteenth aspects, dust present on the surface of the print medium before and / or during printing on the print medium. It is characterized by having dust removing means for removing dust. Claim 18
According to the invention described in the above, in the printing apparatus according to any one of claims 9 to 17, when drawing on the printing medium, the facing device is disposed at a position facing the ejection head via the printing medium. The printing is performed by rotating the drum and moving the print medium.
According to a nineteenth aspect of the present invention, in the printing apparatus according to the eighteenth aspect, the ejection head comprises a single-channel head or a multi-channel head, and the image is drawn by moving the head in a direction parallel to the axis of the opposing drum. It is characterized by performing. Claim 20
According to the invention described in the above, in the printing apparatus according to any one of claims 9 to 17, at the time of drawing on the print medium, the print medium is held by at least one pair of cap stun rollers and travels. It is characterized by drawing. According to a twenty-first aspect of the present invention, in the printing apparatus according to the twentieth aspect, the ejection head is a single-channel head or a multi-channel head, and the ejection head is arranged in a direction orthogonal to a traveling direction of the print medium. It is characterized in that drawing is performed by moving. According to the invention described in claim 22, in the printing apparatus according to claim 18 or 20,
The discharge head is a full line head having a length substantially equal to the width of the print medium. According to a twenty-third aspect of the present invention, in the printing apparatus according to any one of the ninth to twenty-second aspects, the inkjet drawing apparatus has an ink supply unit that supplies the oil-based ink to the ejection head. It is characterized by.
According to a twenty-fourth aspect of the present invention, in the printing apparatus according to the twenty-third aspect, there is provided an ink recovery means for recovering the oil-based ink from the ejection head, and the ink is circulated. According to a twenty-fifth aspect of the present invention, in the printing apparatus according to any one of the ninth to twenty-fourth aspects, the inkjet drawing apparatus agitates the oil-based ink in an ink tank that stores the oil-based ink. It is characterized by having stirring means. According to a twenty-sixth aspect of the present invention, in the printing apparatus according to any one of the ninth to twenty-fifth aspects, the inkjet drawing apparatus may control a temperature of the oil-based ink in an ink tank storing the oil-based ink. It is characterized by having an ink temperature management means for managing. And claim 2
According to a seventh aspect of the present invention, in the printing apparatus according to any one of the ninth to twenty-sixth aspects, the inkjet drawing apparatus has an ink density control unit that controls the density of the oil-based ink. According to a twenty-eighth aspect of the invention, in the printing apparatus according to any one of the ninth to twenty-seventh aspects, the printing apparatus further comprises a cleaning unit for cleaning the ejection head.

[0008]

Embodiments of the present invention will be described below in detail. The present invention is characterized by preventing aggregation and sedimentation of oil-based ink particles when forming an image by an ink-jet method in which oil-based ink is discharged onto a print medium supplied to a printing apparatus 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 a discharge position to form an aggregate of the colored particles at the discharge position. An object is ejected from the ejection position. In this way, the colored particles are ejected as highly concentrated aggregates, 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 tip of the ejection electrode or the electric field forming condition. Therefore, if a small ejection electrode and appropriate electric field forming conditions are used, a small ink droplet can be obtained without reducing the ejection nozzle diameter or 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 clear and high-quality images.

First, an ink ejection drawing apparatus according to the present invention will be described in detail with reference to FIG. FIG. 1 is a schematic configuration example of an ink discharge drawing apparatus including a control unit, an ink supply unit, and a head separation / contact mechanism of the drawing apparatus.

As shown in FIG. 1, the ink ejection and drawing apparatus 3 used in the present ink jet printing method includes an ejection head 22 and an ink supply unit 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 as described later with reference to FIG.
In this case, the ink supply unit also has a collection and circulation function. The stirring means 27 is an agglomeration and / or sedimentation prevention means for preventing the aggregation and / or sedimentation of the ink by an agitation action or the like. You. As the stirring means 27 for preventing coagulation and / or sedimentation, a rotating blade, an ultrasonic vibrator, and a circulation pump can be used, and these are used or in combination. The details will be described later. The ink temperature management unit 28 is arranged so that a high-quality image can be stably formed without changing the physical properties of the ink due to a change in ambient temperature and without changing the dot diameter. As the ink temperature management means, a heater in the ink tank,
A known method such as arranging a heating element or a cooling element such as a Peltier element together with a stirring means so as to keep the temperature distribution in the tank constant, and controlling with a temperature sensor, for example, a thermostat, 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. By arranging a filtering means such as a filter immediately before the discharge head 22, it is possible to supply a cleaner ink that does not include paper fibers or dust to the discharge head 22.

FIG. 2 is a configuration diagram of an ink supply device 24 having an ink recovery function. As shown in the figure, the ink supply device 24 has a valve 61, a pump 26 for supplying ink to the ejection head 22, and an ink concentration control unit 29, and also has a circulating recovery device for circulating and recovering ink from the head. Pump 26 'and a valve 61'. FIG. 2 further includes an aggregation / settling prevention means for preventing aggregation and settling of the oil-based ink particles. As described above, various types of aggregation / settling prevention means are conceivable. Here, the stirring motor 70 and the stirring blade 71 are illustrated. As a result, it is possible to supply the recording and discharging head 22 with fine ink of oily ink particles that are not aggregated and settled.

Further, the present ink discharge drawing apparatus 3 has an ink density control means 29 for performing high quality drawing. The ink concentration is measured by optical detection, physical property measurement such as conductivity measurement, viscosity measurement, or management based on the number of drawn images. When performing management by physical property measurement, in the ink tank or in the ink flow path, provide an optical detector, a conductivity measuring device, a viscosity measuring device alone or in combination thereof,
When the management is performed by the output signal and by the number of drawn sheets, the supply of the liquid from the replenishment concentrated ink tank or the diluted ink carrier tank (not shown) to the ink tank is controlled by the number of printed sheets and the frequency.

Reference numeral 21 denotes an image data calculation control unit. The image data calculation control unit 21 calculates the input image data, and calculates the timing from the encoder 30 mounted on the head separation / contact device 31, the opposed drum or the capstan roller. The pulse is fetched, and the head is driven according to the timing pulse. Further, when drawing is performed by the ink discharge drawing device 3, the opposing drum 4 is driven using a high-precision driving unit. Specifically, for example, there is a method of driving the drawing drum by reducing the output from a high-precision motor using a high-precision gear or a steel belt. By using such means alone or in combination of two or more, higher-quality drawing can be performed. As described above, the image data arithmetic control unit 21 receives the image data from the image scanner, the magnetic disk device, the image data transmission device, and the like, performs color separation, and has an appropriate number of pixels and a suitable number of pixels for the separated data. Divided into tones,
In order to sort the oil-based ink image into halftone dots using the ejection head 22 of the ink ejection drawing device 3, the dot area ratio is also calculated.

The image data calculation control unit 21 controls the movement of the ink jet discharge head 22 and the discharge timing of the oil-based ink, and also controls the print medium operation timing as needed. That is, the image data from the magnetic disk device or the like is given to the image data calculation control unit 21, and the image data calculation control unit 21 determines the discharge position of the oil-based ink and the halftone dot area ratio at that position in accordance with the input image data. Perform the operation. These operation 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 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. . As the ejection head 22, a single-channel head, a multi-channel head, or a full-line head can be used. When a single-channel head or a multi-channel head is used as the discharge head, the arrangement direction of the discharge unit is set substantially parallel to the running direction of the print medium, and the main unit is moved by moving the discharge head in a direction parallel to the axis of the opposed drum. Printing is performed by performing sub-scanning by rotating the opposed drum. 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 substantially perpendicular to the running direction of the printing medium, and the printing medium is rotated by rotation of the opposing drum. Pass through the drawing section to form an oil-based ink image, thereby completing a printed matter.

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

The separation / contact means 31 operates so as to separate the recording head from the drawing drum 4 by at least 500 μm except during drawing. The detachment operation may be a slide 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 way, the head can be protected from physical damage or contamination, and a longer life can be achieved.

Next, the ejection head 22 will be described with reference to FIGS.
It will be described using. 3 to 9 are for explaining the ejection head 22 provided in the ink ejection drawing apparatus of FIG. However, the contents of the present invention are not limited to the following examples.

FIGS. 3 and 4 show an example of a head provided in the ink discharge drawing apparatus. The ejection head 22
It 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 2 in the slit.
2b is disposed, and the slit 23 is filled with the ink 23 supplied from the ink supply device. As the insulating base material, for example, plastic, glass, ceramics and the like can be applied. The ejection electrode 22b is
A conductive material such as aluminum, nickel, chromium, gold, or platinum is vacuum-deposited, sputtered, or electroless-plated on the lower unit 222 made of an insulating base material, and a photoresist is applied thereon, and a predetermined electrode is formed. A known method such as exposing a photoresist through a pattern mask and developing it to form a photoresist pattern of the discharge electrode 22b, followed by etching or mechanical removal, or a combination thereof Formed by

In the ejection head 22, a voltage is applied to the ejection electrode 22b in accordance with a digital signal of image pattern information. As shown in FIG. 3, a drawing drum serving as a counter electrode is provided so as to face the discharge electrode 22b.
A print medium is provided on the drawing drum. By applying a voltage, a circuit is formed between the discharge electrode 22b and the drawing drum serving as the counter electrode, and the oil-based ink 23 is discharged from the discharge slit 22a of the discharge head 22 and provided on the drawing drum serving as the counter electrode. An image is formed on the printed printing medium.

The width of the discharge electrode 22b is set so that a high quality image can be formed.
The tip is preferably as thin as possible to do
No. Specific numerical values depend on conditions such as applied voltage and ink physical properties.
Therefore, although different, usually in the range of the tip width of 5 to 100 μm
Used.

For example, a 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 for 0.1 millisecond between the electrodes.

FIGS. 5 and 6 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, and this discharge head 22 has a first insulating base material 33 having a gradually decreasing shape.
have. A second insulating substrate 34 is provided on the first insulating substrate 33 so as to be spaced apart and opposed to the first insulating substrate 33, and a slope portion 35 is formed at the tip of the second insulating substrate 34.
The first and second insulating bases are formed of, for example, plastic, glass, ceramic, or the like. A plurality of discharge electrodes 22b are provided on an upper surface portion 36 of the second insulating base material 34, which forms an acute angle with the slope portion 35, as an electrostatic field forming means for forming an electrostatic field in the discharge portion. The tips of the plurality of ejection electrodes 22b are extended to near the tips of the upper surface portion 36, and the tips are formed of the first insulating substrate 3
3 and forms a discharge section. 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 discharge unit. An ink recovery path 38 is formed. The discharge electrode 22b
Is formed on the second insulating base material 34 by using a conductive material such as aluminum, nickel, chromium, gold, and platinum 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 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 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 discharge 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 ink, and ink leakage may occur. 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. 6 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 a certain amount of ink near the tip of the ejection electrode is guided from an opening on the ejection electrode 22b side by a capillary force according to the opening diameter. Ink collection path 38
It has the function of discharging to For this reason, 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 and the depth is 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. 7 and 8 show another example of the ejection head used to carry out the present invention. FIG. 7 is a schematic diagram showing only a part of the head for explanation. As shown in FIG. 7, the recording / discharging 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 section. In addition, the regulating plate 42 from the head,
The head main body will be described in detail with reference to FIG. The head main body 41 has a plurality of ink grooves 43 for circulating ink perpendicular to the edge of the head main body. The shape of the ink groove 43 may be set in a range in which capillary force acts so that a uniform ink flow can be formed, and particularly preferably, the width is 10 to 200 μm and the depth is 10 to 300 μm. The ejection electrode 22b is provided inside the ink groove 43. This discharge electrode 22b
Using a conductive material such as aluminum, nickel, chromium, gold, or platinum on a head body 40 made of an insulating material, the entire surface of the ink groove 43 is formed by a known method similar to that of the above-described apparatus embodiment. Or may be formed only partially. The discharge electrodes are electrically isolated. Two adjacent ink grooves form one cell, and a discharge part 45,
45 'is provided. 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 formed 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 separated by a partition wall 46, and the tip 47 thereof is connected to the discharge unit 4
It is chamfered so as to be retracted more than 5, 45 '. Ink is supplied to the head from an I direction through an ink groove by an ink supply unit of an ink supply device (not shown) to supply ink to a discharge unit. Excess ink is collected in the O direction by an ink collecting means (not shown).
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 unit and has a print medium abutted on the surface thereof. The ink is ejected from the section to form an image on the print medium.

Another embodiment of the discharge head will be described with reference to FIG. As shown in FIG.
2 has a pair of substantially rectangular plate-shaped support members 50 and 50 '. These support members 50 and 50 'are formed of a plate-like plastic, glass, ceramic, or the like having a thickness of 1 to 10 mm having an insulating property. A plurality of elongated rectangular grooves 51, 51 'are formed. Each groove 51, 51 '
Is preferably in the range of 10 to 200 μm in width and 10 to 300 μm in depth, and the ejection electrode 22 b is formed on the whole or a part thereof. In this manner, 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 provided between the grooves 51.
Is inevitably provided. The support members 50, 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 the outer peripheral surface for flowing ink. The grooves 51, 51 ′ formed in the support members 50, 50 ′ are connected in a one-to-one correspondence via a rectangular part 54 of the discharge head 22. It is retracted from the upper end 53 of the head 22 by a predetermined distance (50 to 500 μm). That is, on both sides of each rectangular portion 54, the upper end 55 of each partition 52 of each support member 50, 50 ′ is provided so as to protrude from the rectangular portion 54. A guide projection 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, the ink is supplied to each rectangular portion 54 via each groove 51 formed on the outer peripheral surface of one support member 50, and the support member on the opposite side is supplied. It is discharged through each groove 51 'formed in 50'. In this case, the ejection head 22 is inclined at a predetermined angle to enable smooth ink distribution. In other words, the ejection head 22 is inclined such that the ink supply side (support member 50) is located above and the ink discharge side (support member 50 ') is located 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 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) in which a print medium is in contact with the surface. 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 ', 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 ejection head 22 described above with reference to FIGS. 3 to 9 can 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. Also, 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 contamination 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 an ink solvent, and these methods can be used alone or in combination.

Hereinafter, prevention of aggregation and / or settling of ink will be described. If the ink flows in the ink tank and the ink particles agglomerate and / or settle, clogging of the pipe and clogging of the head will occur, and ink ejection will become unstable. Therefore, the ink particles are made uniform by preventing these aggregates and sediments from aggregating and / or sedimenting. Agglomeration and / or sedimentation prevention can be achieved by an action including any one of stirring, dispersion, mixing, and jetting. Also,
Each action can be applied singly or in multiples or multiples according to the volume and type of the ink, and can be applied as needed, periodically or continuously. By arranging the coagulation and / or sedimentation prevention means upstream of the ink discharge unit, uniform ink particles can be supplied to the ink discharge unit. It is more effective to provide a pipeline stirrer such as an in-line mixer immediately before the ink discharge unit. Also,
When the ink flow is resumed after the suspension, the coagulation and / or sedimentation prevention means is activated before the ink flow is restarted to make the ink particles uniform so that the aggregates and sediments are not supplied to the ink ejection section. Is effective. It is to be noted that the aggregation and / or settling prevention means is replaceably attached to the ink flow path as a cartridge type, so that the aggregation and / or settling prevention means having different functions can be adaptively selected according to the capacity and type of the ink. And maintainability is improved.

As a specific example of the coagulation and / or sedimentation prevention means, the stirring blade has a disk shape or a fan shape and exhibits a stirring action, and the peripheral speed of the stirring blade is 1 to 3.
It is composed of a stirrer in the range of 000 rpm, a specially shaped turbine that rotates at high speed, and a stator with radial baffles. By utilizing the fact that ink is ejected by the pressure difference generated between the bottom and top of the turbine due to the high speed rotation of the turbine. A homomixer that stirs aggregates, a pipeline mixer that stirs aggregates by rotating stirring blades arranged in the ink flow path, a magnet mixer (magnetic stirrer, star head stirrer manufactured by Tokai Riki Co., Ltd., etc.) ), A super-vibration stirrer that stirs and disperses aggregates and the like by ultrasonic vibration. It has a structure in which two disks with a honeycomb-type wall are arranged on top of each other. Stirrer (Tokai Riki Co., Ltd.) that agitates ink by sucking ink from above and blowing out from the side beyond the honeycomb wall
Manufactured). Further, as those exhibiting a dispersing action, a homogenizer (manufactured by Nippon Seiki Seisakusho, etc.) that disperses aggregates and the like by rotation of a stirring blade, and an ultrasonic homogenizer (Japan Co., Ltd.) that disperses aggregates and the like by ultrasonic vibration Ultrasonic filter (manufactured by Ginsen Co., Ltd.) that vibrates the filter surface at high speed to disperse aggregates, high-speed disperser (Keddy Mill), ultrasonic cleaner (Nippon Seiki Seisakusho) Manufactured by Nippon Techno Co., Ltd.). In addition, a mixing pump (manufactured by Nippon Ball Valve Co., Ltd.) that enables uniform mixing by a two-liquid mixing function, and a plurality of stirring blades attached to a rotating shaft in a vessel are used as a device exhibiting a mixing action. And an in-line mixer (Dynamic Mixer manufactured by Nippon Ball Valve Co., Ltd.) for mixing. In addition, as having a jet effect, (underwater)
And a pump (manufactured by Lacey Co., Ltd.). It is preferable that each of the above means is arbitrarily reduced in size and partially improved for the present invention.

Next, FIGS. 15 to 20 show examples of the configuration of various printing apparatuses according to the present invention equipped with the ink ejection drawing apparatus 3 provided with such aggregation / settling prevention means. However, the present invention is not limited to the following configuration examples.

FIGS. 15 to 20 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 rotation of an opposite drum. FIG.
FIG. 18 is a diagram illustrating a schematic configuration example of a Web-type printing apparatus in which a roll-shaped print medium is stretched by an opposing drum, a print medium supply roll, and a print medium take-up roll or a guide roll. FIG. 15 shows a single-sided single-color printing apparatus, and FIG. 16 shows a single-sided four-color printing Web apparatus. FIGS. 17 and 18 are schematic diagrams showing examples of a two-sided four-color printing apparatus. FIG. 19 is a diagram illustrating 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 opposing drum, and FIG. It is a figure showing the example of composition. On the other hand, FIGS. 21 and 22 are diagrams showing an example of a schematic configuration of a printing apparatus which performs drawing by sandwiching and running a print medium with a cap stun roller according to the present invention, and FIG. FIG. 22 is a diagram illustrating a schematic configuration example of a printing apparatus using a print medium, and FIG.

First, the printing process according to the present invention will be described with reference to FIG. Inkjet printing device (hereinafter also referred to as “printing device”) shown in FIG.
Is a supply roll 1 for a roll-shaped printing medium, a dust / paper dust removing device 2, an ink ejection / drawing device 3, an opposing (drawing) drum 4 disposed at a position facing the ink ejection / drawing device 3 via the printing medium, It comprises a fixing device 5 and a print medium take-up roll 6. After the dust and the like on the print medium sent from the supply roll are removed by the dust / paper dust removing device 2, the ink is discharged from the discharge head 22 of the ink discharge drawing device 3 to the print medium on the drawing drum 4 on the print medium. The ink is ejected imagewise to record a print image. 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. A metal layer provided on the surface by vapor deposition, plating or the like is used. As a result, an effective electric field can be formed between the ink jetting device 3 and the ejection unit. Further, a heating means is provided on the drawing drum 4,
Increasing the drum temperature is also effective in 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 can be performed. In order to stabilize the drum temperature, 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, it is desirable to use either air suction or air blowing, or a combination thereof.

The print medium M sent out from the print medium supply roll 1 is given tension by the drive of the print medium take-up roll 6 and contacts the drawing (opposite) drum 4. Thus, it is possible to prevent the print medium web from vibrating and coming into contact with the ink discharge drawing apparatus 3 during drawing to be damaged. In addition, means for adhering the print medium M to the drawing (opposite) drum 4 only around the drawing position of the ink discharge drawing device 3 is provided, and this is acted upon at least when drawing is performed. Contact with the device 3 can also be prevented. Specifically, for example, a guide, an electrostatic chuck, or the like in which a pressing roller is disposed upstream and downstream of the drawing position of the drawing drum 4 is effective.

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, an infrared lamp, a halogen lamp, a xenon flash lamp irradiation, 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. 16 to 18 show an example of the structure of a single-sided and two-sided four-color printing apparatus. Although the configuration example of the four-color printing apparatus has been described here,
The number of colors is not limited to this, and the number of colors is arbitrarily determined as needed.

FIGS. 19 and 20 show another example of the construction according to the present invention, which is an explanatory view of a printing apparatus having an automatic discharge device 7 and using the printing medium M wound around the opposing drum 4. FIG. 20 shows an example of an apparatus configuration using a sheet-shaped print medium having the automatic feeding device 9. Here, a description will be given using an example of an apparatus configuration using the roll-shaped print medium M in FIG.

First, the print medium M pulled out by the print medium supply roll 1 and cut to an arbitrary size by the cutter 8 is mounted on the opposing drum 4. At this time, the printing medium is tightly fixed on the drum by a mechanical method using a known sheet head / butt holding device, an air suction device, or the like, or the like. It is possible to prevent the ejection drawing device 3 from being damaged by contacting the same. In addition, means for adhering the print medium M to the drum 4 only around the drawing position of the ink discharge drawing apparatus 3 is provided, and at least when drawing is performed, the print medium M comes into contact with the ink jet recording apparatus 3. This can be prevented. Specifically, for example, there is a method of arranging a pressing roller upstream and downstream of the drawing position of the opposing drum 4. Further, when the drawing is not performed, it is desirable to keep the head away from the print medium M, so that it is possible to effectively prevent the ink discharge drawing device 3 from causing troubles such as contact damage.

As the discharge head 22 (FIG. 1), a single-channel head, a multi-channel head, or a full-line head can be used.
The main scanning is performed by the rotation of. 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 a direction parallel to the axis of the opposed drum 4. Further, in the case of a single channel head or a multi-channel head, the ejection head 22 is continuously or sequentially moved in the direction parallel to the axis of the opposing drum by the image data arithmetic control unit 21. The oil-based ink is discharged onto the print medium M mounted on the drum 4 at the discharge position and the dot area ratio obtained by the calculation. As a result, a halftone image corresponding to the density of the print document is drawn on the print medium M with the oil-based ink. This operation continues until a predetermined oil-based ink image is formed on the print medium M. 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 the print medium M, and a print is completed. 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 M 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. .

On the other hand, FIGS. 21 and 22 are diagrams showing a schematic configuration example of a printing apparatus for performing drawing by nipping and running the printing medium M by the cap stun roller according to the present invention. FIG. 22 is a diagram illustrating a schematic configuration example of a printing apparatus using a roll-shaped printing medium M, 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 M shown in FIG. The print medium M is a pair of capstan rollers 10
The image data is drawn by the ink discharge drawing device 3 using data divided and calculated into an appropriate number of pixels and a proper number of gradations by the image data calculation control unit (21 in FIG. 1). It is preferable that a grounding means 11 is provided at a portion where drawing is performed by the ink discharge drawing device 3 so as to be a counter electrode of a discharge head electrode in electrostatic field discharge, thereby facilitating drawing.

In FIG. 21, the sheet cutter 8 is provided upstream of the automatic discharge device 7 for cutting the roll-shaped print medium M. However, the sheet cutter 8 can be arranged at any desired position.

Next, referring to FIG. 21, the process of producing a printed matter by the printing apparatus of the present invention will be described in further detail below.

First, the print medium M is transported using the cap stun roller 10. At this time, if necessary, by providing a printing medium guide means (not shown), it is possible to prevent the head / tail of the printing medium M from fluttering and coming into contact with the ink ejection drawing device 3 and being damaged. Further, means for preventing the print medium M from sagging only around the drawing position of the ink discharge drawing apparatus 3 is provided. Can also be prevented. Specifically, for example, there is a method of disposing a pressing roller upstream and downstream of the drawing position. In addition, if you do not want to draw,
It is desirable to keep the head away from the print medium M, which can effectively prevent problems such as contact damage in the ink ejection drawing device 3 from occurring.

Image data from a magnetic disk drive or the like
The image data calculation control unit 21 is provided to the image data calculation control unit 21 in FIG. 1 and 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 operation data are temporarily stored in the buffer.
The image data calculation control unit 21 moves the ejection head 22,
The ejection timing control of the oil-based ink and the operation timing control of the capstan roller 10 are performed, and the ejection head 22 is moved closer to the position where the ejection head 22 is brought close to the print medium M by the head separation / contact device 31 (FIG. 1) as necessary. Discharge head 2
The distance between the printing medium 2 and the surface of the print medium M is maintained at a predetermined distance during drawing by mechanical distance control such as an abutment roller or control of a head separation / contact 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 print medium or the dot diameter does not change particularly 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 discharge units, the arrangement direction of the discharge units is set substantially parallel to the running direction of the print medium M. Further, in the case of a single-channel head or a multi-channel head, the ejection head 22 is moved in a direction perpendicular to the traveling direction of the print medium M by the image data arithmetic control unit 21 so that the ejection position and the halftone dot area obtained by the above calculation are obtained. Discharges oil-based ink at a rate. As a result, a halftone image corresponding to the density of the print document is drawn on the print medium M with the oil-based ink. This operation continues until a predetermined oil-based ink image is formed on the print medium M. 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 substantially perpendicular to the traveling direction of the print medium M,
When the print medium M passes through the drawing unit, the print medium M
An oil-based ink image is formed thereon. The printed print medium M is fixed by the fixing device 5 and discharged by the automatic discharge device.

Here, a configuration example 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, the printing medium M used in the present invention will be described. Examples of the printing medium include high quality paper, finely coated paper, and coated paper that are commonly used printing papers. In addition, 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 a metal is vapor-deposited or a metal foil 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.), silicone oil, etc. 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. These non-aqueous solvents are used alone or as a mixture with other solvents as a washing solution.

The reason why the electric resistance of the non-aqueous solvent used is in the above 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 light or bleeds. The reason for setting the dielectric constant to the above range is that when the dielectric constant is high, the electric field is relaxed due to the polarization of the solvent, whereby the ejection of the ink tends to be deteriorated.

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 the fixing property. 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 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. 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 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 printing medium is improved, and the anti-scratch property is improved. On the other hand, 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 copolymers), vinylidene chloride copolymers, vinyl alkanoate polymers and copolymers, allyl alkanoate polymers and copolymers, and polymers and copolymers 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-methacrylate copolymer, cyclized rubber-acrylate copolymer, copolymer containing a nitrogen-free heterocycle (for example, furan as a heterocycle, 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. When the content is small, the density of the printed image becomes insufficient, or the affinity between the ink and the print medium surface becomes difficult to obtain, so that a problem such 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 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 directly pulverized with a conventionally known pulverizer to obtain fine particles, and a dispersed polymer is used in combination. (For example, ball mill
A dispersing method using a paint shaker, a caddy mill, a dyno mill, etc.), a colorant material serving as a colored particle component, and a dispersing aid polymer (or a coating polymer) are kneaded in advance to form a kneaded product, which is 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 books such as Asakura Shoten (1971) and Yuji Harasaki "Basic Science of Coating" 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 superfine polymer supervised by Soichi Muroi, Chapter 2, CMC Publishing (1991), Koichi Nakamura, edited by Koichi Nakamura 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).

[0072]

Embedded image

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, heptyl, octyl, nonyl, decyl, dodecyl, tridecyl,
Tetradecyl group, hexadecyl group, octadecyl group, eicosanyl group, docosanyl group, 2-chloroethyl group,
A bromoethyl group, a 2-cyanoethyl group, a 2-methoxycarbonylethyl group, a 2-methoxyethyl group, a 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, 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 resin (P) particles are produced as a dispersion (latex) or the like, the dispersion polymer is preferably added in advance during the polymerization.

The amount of the dispersing polymer to be added depends on 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 or negatively chargeable particles.

In order to impart an electric detecting property to these particles, it can be achieved by appropriately using a technique of a wet type electrophotographic developer. Specifically, the aforementioned "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 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 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 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.

[0087]

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 ink resin particles (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 the mixture was reacted for 3 hours. Twenty minutes after the initiator was added, 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.).

[0089]

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 , 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 Preparation 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 liters of the oil ink (IK-1) prepared as described above was filled in the ink tank in the ink discharge drawing device 3 of the drawing device of the printing device shown in FIG.
Here, 900d of the type shown in FIG.
pi, a full line head was used, and a piezoelectric pump was used for ink supply. A throwing heater and a stirring blade 71 (Ramon stirrer (model number ST02) manufactured by Tokai Riki Co., Ltd.) are provided in the ink tank 25 as ink temperature management means, the ink temperature is set at 30 ° C., and the stirring blade 71 is set at 30 rpm. The temperature was controlled with a thermostat while rotating.
The stirring blade 71 was used by being driven by a stirring motor 70 (a simple stirrer (model number K-1R) manufactured by Tokai Riki Co., Ltd.) as means for preventing aggregation and / or sedimentation 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 arranged with the ink flow path interposed therebetween. The concentration was adjusted by doubling the concentration). A roll-shaped fine coated paper as a print medium was provided on a counter drum and transported. After removing dust on the print medium surface by suction of air pump,
Move the ejection head close to the printing medium to the drawing position, transmit the image data to be printed to the image data calculation control unit, and eject the oil-based ink from the full-line multi-channel head while transporting the printing medium by rotating the opposing drum to image. Was formed. At this time, the tip width of the discharge electrode of the ink jet head was 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. A voltage of 2.5 KV is constantly applied as a bias voltage, and when performing ejection, a pulse voltage of 500 V is further superimposed, and the pulse voltage is reduced from 0.2 milliseconds to 0.05.
Drawing was performed while changing the dot area by changing the area in 256 steps within the range of milliseconds. No foreign matter such as ink agglomerates or dust, or drawing failure due to dust is seen at all.
Further, no image deterioration due to a change in dot diameter or the like was observed even when the outside air temperature changed or the printing time 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 printing, the ink discharge drawing device was retracted by 50 mm from a position close to the drawing drum to protect the ink jet head.

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

Embodiment 2 Using the printing apparatus shown in FIG. 16 and FIG. 17, means for preventing aggregation and / or settling of the ink jet drawing apparatus 24 shown in FIG.
12, in which four 150 dpi 64-channel multi-channel heads of the type shown in FIG. 5 are used in the apparatus shown in FIG. The heads were arranged so as to be arranged in the direction. A micro gear pump (manufactured by Chuo Rika Kogyo Co., Ltd.) is used for ink circulation, and ink reservoirs are 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.
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, as a circulation pump, a submersible pump (Lacey pump manufactured by Lacey Corporation (model number P-1)) shown in FIG.
12)) was also used as a means for preventing aggregation and / or sedimentation for preventing precipitation and aggregation. Then, an electric 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 a direction parallel to the drum axis, the main scanning is performed, and the drawing drum is moved. By performing sub-scanning while rotating and drawing images, ink was ejected onto the roll-shaped finely coated paper to form an image. A black ink IK-1 and a cyan ink IK prepared in the same manner as the IK-1 ink except that nigrosine used as a coloring agent of the IK-1 ink was replaced with phthalocyanine blue as the oil-based ink.
-2 and CI Pigment Red 57: 1 instead of Nigrosine used as a colorant for the IK-1 ink.
Magenta ink IK-3 produced similarly to K-1 ink
And Nigrosine used as a colorant for IK-1 ink
IK-1 except that I Pigment Yellow 14 was used.
Four inks, each of which was a yellow ink IK-4, prepared in the same manner as the ink, were used to fill four heads. No foreign matter such as ink agglomerates or dust, no defective drawing due to dust, etc., was observed, and no image deterioration due to a change in the dot diameter was observed even when the outside air temperature was changed or the number of printed sheets was increased. Good single-sided and double-sided full-color printing was possible with either type of head shown in FIG. After the printing, the isoper G was circulated through the head, and a nonwoven cloth containing the isoper 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. 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. 7 instead of the ink jet head of the type shown in FIG. 5, and in any case, the stirring was always performed stably by using the stirring means. High-quality drawing was possible.

Example 3 Using the printing apparatus shown in FIG. 19, 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 the four sets of ink jet drawing apparatuses, and four 100 dpi 256-channel multi-channel heads of the type shown in FIG. 9 are used. The main scanning is performed by the rotation of the opposing drum, and the head is sequentially moved every one rotation in the direction parallel to the axis of the drum, thereby 900 dp on the coated paper.
The image of i was drawn. No foreign matter such as ink agglomerates or dust was mixed in, and no drawing failure due to dust was observed at all, and a clear, high-quality full-color printed matter was obtained.

Example 4 Using the printing apparatus shown in FIG. 21 and FIG.
Full color printing was performed. The oil-based ink was used in Example 3.
The same four color inks were used. Here, a 600 dpi, 64 channel multi-channel head of the type shown in FIG. 5 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 and control unit, and 6
By moving the four-channel multi-channel head in a direction perpendicular to the direction of transport of the print medium and rotating the cap stun roller to transport the print medium,
An image of 0 dpi was formed on ink jet paper.
Further, in place of the stirring blade 71 of the first embodiment, a coagulation and / or settling prevention means shown in FIG. 13 was used. That is, a stirrer 81 (star head stirrer (size 58) manufactured by Tokai Riki Co., Ltd.) is put into the ink tank 25, and a stirrer 82 (magnetic manufactured by Tokai Riki Co., Ltd.) provided outside the ink tank 25 is placed. The ink was stirred with a stirrer (model number HS-50E). Otherwise, the same operation as in Example 1 was performed.
No foreign matter such as ink agglomerates or dust was mixed in, and drawing defects due to dust were not seen at all, and good four-color full color printing was possible.

Example 5 Instead of the stirring blade 71 of Example 1, an agglomeration and / or settling prevention means shown in FIG. 14 was used. That is, an ultrasonic bath 83 (Ultrasonic cleaner (Model No. USK-2) manufactured by Tokai Riki Co., Ltd.) was used as the ink tank 25, and the ink was dispersed by ultrasonic vibration.

Example 6 Instead of the stirring blade 71 of Example 1, a coagulation and / or sedimentation prevention means shown in FIG. 15 was used. That is, the vibrator 84 (φ5) is put into the ink tank 25 and the oscillator 85
(Ultrasonic disperser manufactured by Tokai Riki Co., Ltd. (Model UH-50))
By vibrating the vibrator 84, the ink was dispersed.

Example 7 Instead of the stirring blade 71 of Example 1, a re-stirring means shown in FIG. 16 was used. That is, a multistage vibrating blade (single shaft type) 86 is put into the ink tank 25, and a low frequency is transmitted to the vibrating blade 86 from the vibrator 87 (super vibration α-stirrer manufactured by Nippon Techno Co., Ltd.). The ink was stirred by the frequency vibration.
In the seventh embodiment, the stirring is not performed by the rotation of the stirring blade as in the first embodiment, but the stirring is performed by the vibration of the stirring blade. Therefore, there is no possibility that air is mixed into the ink. In addition, since the blades do not rotate, they can be installed at the outermost end of the ink tank, and the degree of freedom of installation is large.

On the other hand, in each of the first to seventh embodiments, when the drawing is performed without using the stirring / dispersing means, the ejection becomes unstable in several hours to several days in any of the embodiments, and the image becomes unstable. After the non-ejection state continued, in the worst case, the ejection opening of the head was completely blocked by the solid aggregates of the majority of the ink particles, and rendering was impossible.

The means for preventing coagulation and sedimentation or for preventing coagulation and / or sedimentation shown in the above-described embodiments may be of a large size for production lines. It is preferable that the size be appropriately reduced in accordance with the capacity of the printing apparatus, and that the printing apparatus be improved so as to be applicable to the printing apparatus according to the present invention.

[0104]

According to the present invention, an image is formed directly on a print medium by an ink-jet method in which an oil-based ink is ejected by utilizing an electrostatic field based on a signal of image data, and the image is fixed by fixing the image. In the ink-jet printing method for preparing the ink, an oil-based ink aggregation / sedimentation prevention means such as an ink stirring means is provided. Even when printing is performed on ordinary printing paper or a non-absorbable medium such as a plastic sheet without using the image, the image does not bleed and fine droplets can be ejected. It becomes small and thin, and it is possible to print high-quality image information such as a photographic image at low cost and at high speed.

[Brief description of the drawings]

FIG. 1 is a schematic configuration example of a drawing apparatus including a control unit, an ink supply unit, and a head separation / contact mechanism of a drawing apparatus of an inkjet printing apparatus according to the present invention.

FIG. 2 is a configuration diagram of an apparatus in which an ink circulation function is added to the ink supply apparatus of FIG.

FIG. 3 is a perspective view showing one specific example of the ejection head of FIG.

FIG. 4 is a diagram illustrating an enlarged cross section of the ink discharge drawing apparatus of FIG. 3;

FIG. 5 is a diagram schematically illustrating a cross section near an ink discharge unit of another example of a discharge head.

FIG. 6 is a schematic front view showing the vicinity of an ink ejection portion of another example of an ejection head.

FIG. 7 is a schematic view showing only a part of a discharge head of another example.

FIG. 8 is a schematic view of the recording head of FIG. 7 from which restriction plates 42 and 42 'have been removed.

FIG. 9 is a schematic view showing a part of an ejection head according to another embodiment having a pair of substantially rectangular plate-shaped support members.

FIG. 10 is a configuration diagram of an apparatus in which a part of the apparatus shown in FIG. 2 is replaced.

FIG. 11 is a schematic sectional view showing a coagulation and / or sedimentation prevention means.

FIG. 12 is a schematic sectional view showing another agglomeration and / or settling prevention means.

FIG. 13 is a schematic sectional view showing another means for preventing aggregation and / or settling.

FIG. 14 is a schematic sectional view showing another means for preventing aggregation and / or sedimentation.

FIG. 15 is an overall configuration diagram schematically illustrating a Web-type apparatus that performs single-sided single-color printing, which is an example of the inkjet printing apparatus of the present invention.

FIG. 16 is an overall configuration diagram schematically showing a Web-type apparatus that performs four-sided four-color printing, which is another example of the inkjet printing apparatus of the present invention.

FIG. 17 is an overall configuration diagram schematically showing a two-sided four-color printing apparatus as another example of the inkjet printing apparatus of the present invention.

FIG. 18 is an overall configuration diagram schematically showing a two-sided four-color printing apparatus as another example of the inkjet printing apparatus of the present invention.

FIG. 19 is an overall configuration diagram schematically showing a single-sided four-color printing apparatus that cuts a roll-shaped printing medium and winds and prints it on an opposing drum, which is another example of the inkjet printing apparatus of the present invention.

FIG. 20 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. 21 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 as another example of the inkjet printing apparatus of the present invention.

FIG. 22 is an overall configuration diagram schematically illustrating a printing apparatus that performs drawing by sandwiching 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.

[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 Capstan roller 11 Grounding means 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 31 Head separation Apparatus 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 passage 38 Ink Recovery path 39 Backing 40 Groove 41 Head Main body 42, 42 ′ Meniscus regulating plate 43 Ink groove 44 Partition wall 45, 45 ′ Ejection section 46 Partition wall 47 Partition tip 50, 50 ′ Support member 51, 51 groove 52 Partition 53 Upper end 54 Rectangular portion 55 Upper end 56 of partition 70 Stirring Motor 71 Stirring Blade 72 Pump 81 Stirrer 82 Stirrer 83 Ultrasonic Bath 84 Ultrasonic Vibrator 85 Ultrasonic Oscillator 86 Vibrating Blade 87 Vibrator M Vibration Medium

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Mutsumi Naniwa 4000 Kawarijiri, Yoshida-cho, Haibara-gun, Shizuoka Prefecture F-term within Fujisha Shin Film Co., Ltd. 2C056 EA14 EC19 EC46 FA07 FC01 KB16 KC02 2C057 AF72 BD07 2H086 BA02 BA54 BA60

Claims (28)

[Claims] 1. An ink-jet printing method in which an image is formed directly on a printing medium by an ink-jet method in which an oil-based ink is ejected by utilizing an electrostatic field based on a signal of image data, and the image is fixed to form a printed matter. A printing method, wherein the aggregation and / or settling of the oil-based ink particles is prevented at least during circulation of the ink. 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. The printing method according to claim 1, wherein the prevention of the aggregation and / or the sedimentation at least during the circulation of the ink is performed before the ink is ejected. 4. The method according to claim 1, wherein the prevention of agglomeration and / or sedimentation is to prevent the formation of coarse aggregates and / or sediments of the oil-based ink at least during circulation of the ink. The printing method according to any one of claims 1 to 3. 5. The method according to claim 1, wherein the aggregation and / or sedimentation is prevented by an action including at least one of agitation, dispersion, mixing, and jet flow during circulation of the ink. 3. The printing method according to claim 1. 6. The printing method according to claim 5, wherein the stirring, dispersing, mixing, and jetting actions are applied singly, plurally or in multiples at least during circulation of the ink. 7. The printing method according to claim 5, wherein the stirring, dispersing, mixing, and jetting actions are applied as needed, periodically, or continuously. 8. The printing method according to claim 1, wherein said aggregation and / or settling prevention means is replaceable as a cartridge type. 9. 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 a printing apparatus, wherein the image forming means is an ink jet drawing apparatus for discharging oil-based ink from a recording head by utilizing an electrostatic field, at least one aggregation and / or settling prevention in a flow path of the oil-based ink at least during circulation of ink. A printing device comprising: means for printing. 10. A printing apparatus according to claim 9, wherein said means for preventing aggregation and / or settling during the circulation of ink is provided at least immediately before an ink discharge section of said discharge head. 11. The coagulation and / or settling prevention means,
The printing apparatus according to claim 9, wherein the printing apparatus has at least an ability to prevent the formation of coarse aggregates and / or precipitates of the oil-based ink during circulation of the ink. 12. The method according to claim 9, wherein the means for preventing aggregation and / or settling is performed by an action including at least one of agitation, dispersion, mixing, and jet flow during circulation of the ink. The printing device according to any one of claims 11 to 13. 13. The method according to claim 9, wherein the stirring, dispersing, mixing, and jetting actions are applied singly, plurally or multiplexed at least during circulation of the ink.
A printing device according to any one of the preceding claims. 14. The printing apparatus according to claim 9, wherein the stirring, dispersing, mixing, and jetting actions are applied at any time, periodically, or continuously. 15. The printing apparatus according to claim 9, wherein said aggregation and / or settling prevention means is configured as a cartridge. 16. The oil-based ink has a specific electric resistance value of 1.
In a non-aqueous solvent having a dielectric constant of not less than 0 ⁹ Ωcm and not more than 3.5,
16. The printing apparatus according to claim 9, wherein at least colored particles are dispersed. 17. The printing apparatus according to claim 9, 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. The printing device according to the above. The printing device according to claim 3. 18. 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. Claims 9-1
The printing device according to any one of claims 7 to 10. 19. The printing apparatus according to claim 18, wherein the discharge head is a single-channel head or a multi-channel head, and performs drawing by moving the head in a direction parallel to the axis of the opposing drum. 20. The image forming apparatus according to claim 9, 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. 21. The image forming apparatus according to claim 2, 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 orthogonal to a running direction of the print medium.
0 printing apparatus. 22. The printing apparatus according to claim 18, wherein said discharge head is a full line head having a length substantially equal to a width of said print medium. 23. The ink-jet drawing apparatus according to claim 9, further comprising 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. 24. The printing apparatus according to claim 23, further comprising an ink collecting means for collecting the oil-based ink from the discharge head, and performing ink circulation. 25. The ink-jet drawing apparatus according to claim 9, further comprising a stirring means for stirring the oil-based ink in an ink tank storing the oil-based ink.
25. The printing device according to any one of claims 24 to 24. 26. The ink-jet drawing apparatus according to claim 9, 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. 27. The printing apparatus according to claim 9, wherein said ink jet drawing apparatus has an ink density control means for controlling the density of said oil-based ink. 28. The image forming apparatus according to claim 9, further comprising cleaning means for cleaning said discharge head.
The printing device according to any one of claims 7 to 10.