JPH1128810A - Ink jet recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high quality image by eliminating waving of a paper, blurring or striking through of ink, and the like. SOLUTION: The ink jet recorder comprises an ink jet unit 100, and an image fixing unit 200. The ink jet unit 100 jets an ink 108 containing a polysaccharide polymer according to an image signal to form an image on a recording medium 1. The image fixing unit 200 imparts a solidifying liquid 204 containing a metal salt to the image formed on the recording medium 1. Since the metal salt dissolved into the water of the solidifying liquid is diffuses into the polysaccharide polymer dissolved into the water of the ink and captures the solvent, i.e., the water, instantaneously, the ink formed on the recording medium 1 is solidified instantaneously to produce a final output image.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus used for a printer, a facsimile, a copying machine, etc., and more particularly to an ink jet recording apparatus capable of recording a high quality image.

[0002]

2. Description of the Related Art An ink jet recording apparatus is widely used as an image forming apparatus which requires a small number of processes, is low in cost, can be reduced in power consumption, and can be miniaturized.

However, in an ink jet recording apparatus, when recording on plain paper, when printing a color image with a large amount of ink, or when printing at an increased printing speed, the paper may be wavy, bleeding, or strike-through. Problem may occur. This is because the liquid permeates along the fibers of the paper and the paper contains too much water. Further, there is a problem that the fixing power of the recorded image to the paper is weak and the water resistance is poor.

Therefore, various methods have been proposed to solve the above-mentioned problems by heating the back surface of the ink-attached portion on the recording medium with a heater or the like, and printing while evaporating water. Japanese Patent Application Laid-Open No. 1-63185 discloses a proposal in which a recording medium is pre-treated with a liquid for insolubilizing a dye in the ink, and the ink is insolubilized by overprinting the recording medium to improve the water resistance. I have. further,
Japanese Patent Application Laid-Open No. 57-1078 discloses a method in which the ink is ejected in the form of a plurality of particles by the energy of discharge, so that the ink is dried faster than when one droplet of the same volume is printed.
No. 47 is described. In addition, since a larger discharge force can be obtained as compared with a conventional piezoelectric type or thermal pressure type discharge liquid, a liquid having a high viscosity can be used. If a liquid having a high viscosity is used, problems such as bleeding and strikethrough can be solved.

[0005]

As described above, various proposals have hitherto been made, but none of them is sufficient. The method of evaporating water with a heater greatly increases the total energy required for recording, and the problem of poor water resistance still remains. Also, the method of pre-treating the recording medium with a liquid that insolubilizes the dye in the ink does not perform any treatment of the water in the ink, so when printing a color image with a large amount of ink, or by increasing the printing speed. In the case of printing, paper is wavy due to excessive moisture. Furthermore, in the method using ink having high viscosity, the flow rate of ink is low in the conventional ink supply method using capillary force and atmospheric pressure because the fluidity of the ink is poor. Can not solve the inferior problem.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an ink jet recording apparatus capable of obtaining a high-quality image without causing paper undulation, ink bleeding, strike-through, or the like.

[0007]

An object of the present invention is to provide an ink ejecting apparatus for ejecting ink to a recording medium based on image information, and an image for applying a solidifying liquid for solidifying the ink to the ink ejected to the recording medium. This is achieved by an ink jet recording apparatus having a fixing device.

The ink contains at least a polysaccharide polymer, a coloring agent and water, and the solidified liquid contains at least a metal salt and water. When the solidified liquid is applied to the ink, the metal salt dissolved in the water in the solidified liquid diffuses into the polysaccharide polymer dissolved in the water in the ink, and instantaneously embraces water as a solvent. This instantly solidifies the ink.

Examples of the polysaccharide polymer include algin, alginic acid, a monovalent metal salt of alginic acid, carrageenan, and pectin, or a combination thereof. The amount of the polysaccharide polymer in the ink is an amount capable of sufficiently hydrating the ink and water, which is a component of the solidification liquid, and an amount sufficient to fix the colorant to the recording medium 1. Importantly, it is at least 1% by weight, preferably at least 3% by weight. There is water that is not hydrated below 1% by weight and that water penetrates into the paper. The upper limit is 20% by weight, and above this, the ink containing the polysaccharide polymer becomes too hard, and the transportability with the ink applying roll deteriorates.

The polysaccharide polymer has a molecular weight of 10,000 or more, preferably 50,000 or more, and 1,000,000.
The following are appropriate: When the molecular weight is low, the film-forming ability is insufficient, and the fixing strength of the image constituent composed of the ink and the solidified liquid to the recording medium 1 is low. If it is 1,000,000 or more, the ink containing the polysaccharide polymer becomes too hard, and the transportability with the ink applying roll becomes poor.

When the concentration and the molecular weight are within the above-mentioned preferred ranges, the viscosity of the ink becomes considerably high, so that the ink cannot be ejected by the ordinary ink-jet method, and it is difficult to transport the ink.

The pH of the aqueous solution of the metal salt varies depending on the type of the polysaccharide polymer, but may be in the range of pH 6 to 9, and preferably in the range of pH 6.5 to 8.5. is there. This is because it is not preferable from the viewpoint of the durability of the paper that the liquid having a high acidity or alkalinity comes into contact with the recording medium paper.

[0013]

FIG. 1 is a schematic diagram of an ink jet recording apparatus according to the present invention. As shown in FIG. 1, the recording medium 1 is first conveyed by a feed roll 2 in a direction indicated by an arrow A to an ink ejection device 100 and then to an image fixing device 200.

The ink ejection device 100 ejects an ink containing a polysaccharide polymer in accordance with an image signal to form an image on the recording medium 1. The image fixing device 200 applies a solidifying liquid containing a metal salt to an image formed on the recording medium 1. Then, the metal salt dissolved in the water in the solidified liquid diffuses into the polysaccharide polymer dissolved in the water in the ink, and instantaneously embraces water as a solvent. As a result, the ink solidifies instantaneously, and a final output image is obtained.

FIG. 2 is a detailed view of the ink discharge device 100 and the image fixing device 200.

The ink ejection device 100 includes an ink 108
Roll 101 made of a conductor such as metal
And a high-voltage power supply 109 for applying a high voltage to the ink 108
And an ink thickness regulating blade 106 for regulating the amount of ink on the ink applying roll 101, a nozzle 103, and an electrode 102 concentrically mounted outside the nozzle 103. First, when the ink applying roll 101 rotates in the direction of arrow B, the ink 108 adheres to the roll surface,
Conveyed. An ink thickness regulating blade 106 disposed close to the ink applying roll 101 regulates the thickness of the ink on the roll surface and forms a uniform ink thin film 110.
When the ink applying roll 101 rotates, the ink thin film 11
0 is conveyed to the nozzle 103. The nozzle 103 is formed by making a hole in the insulating plate 104, and is manufactured with an inclination so that the ink opening 111 side becomes narrower. Thereby, the ink ejection direction is controlled so as to be perpendicular to the recording medium 1. The insulating plate 104 includes an insulating plate 105
Is attached to the ink tank 107 via the.

The ejection of ink from the nozzle 103 is performed as follows. When the conductivity of the ink thin film 110 is larger than the conductivity of the surface of the ink applying roll 101, when a pulse signal is input to the high-voltage power supply 109 in accordance with the image signal,
Discharge occurs between the electrode 102 and the ink thin film 110, generating heat and partially vaporizing the ink, causing the nozzle 1
03 is pressurized, the torn ink is discharged from the nozzle opening 111 toward the recording medium 1, and an image is formed on the recording medium 1. Conversely, ink application roll 1
When the electric conductivity of the surface of the recording medium 1 is larger than the electric conductivity of the ink thin film 110, a discharge occurs between the electrode 102 and the ink applying roll 101, and an image is formed on the recording medium 1 by the discharged ink. . When the ink applying roll 101 further rotates, the unused portion of the ink thin film 110 is collected in the ink tank 107.

The optimum voltage value applied to the electrode 102 depends on the distance between the electrode 102 and the ink applying roll 101, but is generally in the range of several hundred V to several kV. Here, the magnitude relationship between the conductivity of the surface of the ink applying roll 101 and the conductivity of the ink thin film 110 may be set to a relationship that facilitates ejection depending on physical properties such as viscosity and conductivity of the ink used.
The voltage applied from the high-voltage power supply 109 is a DC voltage in the case of FIG. 2, and the electrode 102 side is positive. However, the electrode 102 side may be negative, or only the AC voltage or the DC voltage is superimposed on the AC voltage. Can also.

If the viscosity of the ink 108 to be used is about several mPa · s as in an ordinary ink jet system, the ink can be supplied to the nozzles only by capillary force. However, when the ink viscosity is several tens mPa · s or higher, the supply of the ink cannot be performed in time with only the capillary force, and the stable ink cannot be discharged. However, in this method, since the adhesive force between the roll and the ink is used, it is possible to stably supply the ink having a high viscosity as described above. When the ink has a thixotropic property, the rotation of the ink applying roll 101 acts on the ink 108 as a shearing force, and as a result, the viscosity of the ink decreases, so that a liquid having a medium viscosity can be used. When it is desired to increase the printing frequency, the printing frequency can be easily increased by increasing the rotation speed of the ink applying roll 101.

In the case of using the pressure caused by the vibration of the piezoelectric element and the expansion of the ink due to the heat applied by the heating element used in the ordinary ink jet system, the ink having a high viscosity results in an insufficient ejection force. In the present invention, since a large discharge energy is instantaneously applied, ink having a relatively high viscosity of several tens mPa · s or more can be used.

FIG. 3 shows the ink ejection device 10 shown in FIG.
0 is an XY cross-sectional view. The point to be noted in this figure is that the ink applying roll 101 and the ink tank 107 are common to each nozzle 103. Although not shown, the ink thickness regulating blade 106 also
03 is common. This makes it possible to reduce the size of the device. When printing, a plurality of nozzles can be combined into one unit to scan in a carriage type, or nozzles for the width of the recording medium can be prepared and used with the entire ink ejection device fixed. it can.

Next, returning to FIG.
Will be described. The image fixing means 200 includes a solidifying liquid application roll 201 which rotates in the direction of arrow C to supply the solidifying liquid 204 to the recording medium 1, a blade 203 for regulating the amount of the solidifying liquid 204, and a solidifying liquid in the direction of arrow D. Coating roll 20
1 has a pressure roll 202 that applies pressure to the recording medium 1 while rotating at the same speed as that of the recording medium 1. Since pressure is applied to the recording medium 1 by the solidifying liquid application roll 201 and the pressure roll 202, the gloss of the output image becomes uniform. The amount of the solidifying liquid applied to the recording medium 1 may be the minimum amount necessary for solidifying the ink. Further, the configuration of the image fixing device 200 is not limited to the solidifying liquid application roll described above, a method of supplying a solidifying liquid from a slit, a method of spraying a mist, or only an image portion using an inkjet method,
Alternatively, a method of supplying the image to the image portion and its vicinity can also be used.

When the recording medium 1 on which an image has been formed by the ink discharge device 100 reaches the image fixing device 200, the solidifying liquid 204 is applied onto the recording medium 1 by the rotation of the solidifying liquid application roll 201 in contact with the recording medium 1. As a result, the ink solidifies instantaneously and at the same time is given water resistance. This is because, as described above, the metal salt dissolved in the water in the solidified liquid diffuses into the polysaccharide polymer dissolved in the water in the ink and instantaneously embraces water as a solvent.

Examples of polysaccharide polymers include agar (agarose), carrageenan, sodium alginate, curdlan, pectin, konjac mannan, gellan gum, xanthan gum, starch, galactomannan, nitrocellulose, pectinin, proteoglycan, glycoprotein, beigelan, and the like. Yes, but not limited to these.

Examples of the metal salt include salts having potassium ion, cesium ion, calcium ion, magnesium ion, strontium ion, barium ion, aluminum ion, iron ion, copper ion, vanadium oxide ion and the like. It is not something that can be done. Further, there are types of metal salts that are preferable depending on the type of polysaccharide polymer used. For example, in the case of sodium alginate, a polyvalent metal salt having a calcium ion, a barium ion, an aluminum ion or the like is preferable. In the case of carrageenan, a metal salt having a potassium ion, a cesium ion, or the like is preferable.

Examples of the polysaccharide polymer will be described in more detail. Examples thereof include algin, alginic acid, and a monovalent salt of alginic acid. Alginic acid is a natural polysaccharide polymer extracted from brown algae, and is contained in seaweed and kelp. Alginic acid is mainly used as a sodium salt in various fields such as foods, pharmaceuticals, cosmetics, etc., as a water-soluble thickener, as a jelly by adding calcium, or as an immobilized enzyme bead. The structure of sodium alginate is a sodium salt composed of a polymer of β-1,4-D-mannuronic acid (M) and α-1,4-L-guluronic acid (G). Sodium alginate forms a chelate with polyvalent metal salts such as calcium and takes in moisture to form a gel. When these are linked to form a polymer, GM, M
The gel forming ability remarkably varies depending on the ratio of M and GG. G
In the G cluster region, molecules are bent, and calcium ions enter therein to form an egg box type structure, and a strong polymer is formed and solidified. The gel formed is
As the molecular weight of alginic acid increases, the film-forming ability increases, and a film that does not dissolve in water or oil is formed. Molecular weight is 1
Suitable is at least 0000, preferably at least 50,000.

The carrageenan mentioned above as an example of the polysaccharide polymer is a seaweed polysaccharide extracted from red algae. The chemical structure of carrageenan is a linear polymer having a molecular weight of hundreds of thousands to millions, and is composed of D-galactose, 3,6-anhydro-D-galactose, and a sulfate group. There are three types, κ-type, λ-type, and τ-type, depending on the content of the sulfate group. The kappa type is preferable in that the mechanical strength of the generated gel is strong. It gels instantaneously in the presence of monovalent or polyvalent cation ions such as potassium and cesium. Carrageenan has a helical structure in its molecular chain. It is said that this helical structure aggregates via cations to form a gel.

The ink is solidified on a recording medium by applying the gelling ability of these polysaccharide polymer gels to form a film. The film after solidification has excellent water resistance. The ink is an aqueous solution comprising a polysaccharide polymer and a colorant. Other generally well-known components such as a colorant dispersant may be added thereto. At this time, the viscosity of the ink is considerably higher than that used in an ordinary ink jet system, so that the ink penetrates into a recording medium, particularly paper, is slow, and no bleeding occurs. Further, immediately after the ink adheres to the paper, the ink is solidified while holding water in the solidifying liquid, so that the paper can be prevented from waving or strike-through, and a high-quality image can be obtained.

As the colorant, well-known water-soluble dyes and organic pigments can be used. Metal ion species involved in gel formation are contained in the image forming agent by a counter ion of the water-soluble dye or pigment. Because it is not preferable to have as, depending on the polysaccharide high molecular species used, dyes that do not participate in gel formation,
Choose a pigment.

In order to further stabilize the dissolving and dispersing state of the dye or pigment, a so-called surfactant, dispersant, clathrate or the like may be added. Is not preferred as a counter ion in the image forming agent, and an additive that does not participate in gel formation is selected according to the type of polysaccharide used.

[0031]

【Example】

(Example 1) Special black Baye as ink
r A-SF (manufactured by Bayer) 1.5% by weight and sodium sulfonic acid formalin condensate 0.1% by weight are dispersed in ion-exchanged water, and subsequently sodium alginate having a molecular weight of 110,000 (manufactured by Wako Pure Chemical Industries) 3% by weight was added and dispersed to prepare a black ink. Next, a 10% by weight aqueous solution of calcium chloride (pH 7.8) was prepared as a solidifying solution.

After the ink is filled in the ink tank 107 shown in FIG. 2, the ink applying roll 101 is rotated to form an ink thin film 110, and the plain paper FX is formed in accordance with the image information.
-Ink was ejected on J paper and FX-L paper (manufactured by Fuji Xerox Co., Ltd.). At this time, the electrode 102 was used as a positive electrode, and a DC voltage of 2 kV was applied to the high-voltage power supply 109. Immediately after printing, the solidifying liquid was applied to the image by the solidifying liquid applying roll 201. As a result, a good output image without bleeding, paper waving, strikethrough or the like was obtained.

[0033]

According to the present invention, it is possible to obtain an ink jet recording apparatus which realizes a high-quality image without causing waviness of a recording medium, ink bleeding, strike-through or the like.

[Brief description of the drawings]

FIG. 1 is a view schematically showing an inkjet recording apparatus according to the present invention.

FIG. 2 is a diagram illustrating details of an ink ejection device and an image fixing device.

FIG. 3 is a diagram illustrating a cross section of the ink ejection device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 recording medium 2 feed roll 100 ink discharging means 101 ink applying roll 102 electrode 103 nozzle 104 insulating plate 105 insulating plate 106 ink thickness regulating blade 107 ink tank 108 ink 109 high voltage power supply 110 ink thin film 111 nozzle opening 200 image fixing means 201 solidification Liquid application roll 202 Pressure roll 203 Blade 204 Solidified liquid

Claims (14)

[Claims] 1. An image forming apparatus comprising: an ink ejection device that ejects ink to a recording medium based on image information; and an image fixing device that applies a solidifying liquid that solidifies the ink to the ink ejected to the recording medium. Characteristic inkjet recording device. 2. The ink ejection device according to claim 1, further comprising an ink applying roll made of a conductive material, a plurality of nozzles arranged in a longitudinal direction of the ink applying roll, and an electrode attached outside the nozzle. The ink jet recording apparatus according to claim 1, wherein: 3. The ink jet recording apparatus according to claim 2, wherein the ink applying roll is common to the plurality of nozzles. 4. An ink jet recording apparatus according to claim 1, wherein a discharge is generated between an ink applying roll or an ink thin film adhering to the ink applying roll and an electrode attached to an outside of an ink ejection nozzle arranged in a longitudinal direction of the ink applying roll. An ink jet recording apparatus comprising: an ink discharge device for discharging ink; and an image fixing device for supplying a solidifying liquid for solidifying the ink discharged from the ink discharge device on a recording medium. 5. The ink jet recording apparatus according to claim 4, wherein the conveyance of the ink to the ink discharge nozzle is performed by rotating the ink applying roll. 6. The ink jet recording apparatus according to claim 4, wherein the ink comprises at least a polysaccharide polymer, a colorant, and water, and the solidified liquid comprises at least a metal salt and water. 7. The ink jet recording apparatus according to claim 6, wherein the polysaccharide polymer is one of algin, alginic acid, a monovalent metal salt of alginic acid, carrageenan, and pectin, or a combination thereof. 8. The polysaccharide polymer having a molecular weight of 10,000
The ink jet recording apparatus according to claim 6, wherein the number is 0 or more and 1,000,000 or less. 9. The ink jet recording apparatus according to claim 6, wherein the proportion of the polysaccharide polymer in the ink is 1% by weight to 20% by weight. 10. The ink jet recording apparatus according to claim 4, wherein a pH of the solidified liquid is in a range of 6 to 9. 11. An ink supply roll provided in contact with an ink tank, a plurality of nozzles disposed in the longitudinal direction of the ink supply roll, and an electrode disposed outside the nozzle. An ink discharge device that discharges ink from the nozzles by applying a voltage according to image information between the electrode and the ink applying roll or an ink thin film attached to the ink applying roll. 12. A solidification liquid container for storing a solidification liquid, a solidification liquid application roll disposed adjacent to the solidification liquid container, a blade for regulating an amount of the solidification liquid attached to the solidification liquid application roll, and the solidification liquid. An image fixing device, comprising: a pressure roll arranged so that a recording medium passes between the liquid application roll and the recording medium; and a pressure roll configured to apply pressure to the recording medium. 13. A step of adhering ink to a surface of an ink applying roll; and a step of moving an ink applying portion to a position of a nozzle arranged in the longitudinal direction of the ink applying roll by rotating the ink applying roll; A step of applying a voltage corresponding to image information between an electrode disposed outside the nozzle and the ink applying roll or ink attached to the ink applying roll, and applying a voltage to the ink ejected from the nozzle to a recording medium by the voltage application. Supplying a solidifying liquid. 14. The ink jet recording method according to claim 13, wherein the solidification liquid is supplied by a solidification liquid application roll.