JPH09216453A - Image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the clogging of an ink emitting head by emitting colorless ink droplets having resin solubility or resin swelling properties to form an image and subsequently bringing a powder coloring material (toner) based on a resin capable of being dissolved in ink or swollen by ink into contact with the image to develop the same. SOLUTION: When an image is formed, at first, a colorless liquid having resin solubility or resin swelling properties is emitted as ink droplets by an ink jet system to preliminarily form a transparent image on a material to be recorded as a latent image. Subsequently, toner based on a resin capable of being dissolved in the liquid forming the latent image or swollen by said liquid is brought into contact with the latent image to develop the same. With respect to the developed toner, a fixing process is not especially required and dissolved or swollen toner particles are infiltrated into a material to be recorded or bonded thereto but, if necessary, the close adhesion of the material to be recorded and the toner is enhanced by using a fixing method and a fixing apparatus used in a usual copier or printer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming method using an ink jet type image forming apparatus.

[0002]

2. Description of the Related Art Among non-impact recording methods such as laser printers using electrophotography, high-speed recording is possible and plain paper can be printed without any processing. Inkjet recording methods, which can be made compact and cost-effective, have recently attracted a great deal of attention, and much research has been done so far to develop and commercialize various types of ink jet recording apparatuses. In addition, some of them are still being put into practical use.

In this ink jet recording method, a small droplet of ink, which is a recording medium, is ejected and adhered to a recording medium for recording, and a method of generating this ink droplet and the generated small droplet are recorded. It is roughly classified into several methods according to the method for controlling the flight direction. In general, ink droplets are continuously generated regardless of the presence or absence of an information signal, and the continuously generated ink droplets are selectively used according to a print information signal. There is another method called an on-demand type in which ink droplets are ejected and fly.

In the above continuous type, the ink ejection nozzle is ultrasonically vibrated in the ejection direction, and the ink pressurized at a constant pressure is continuously ejected and made into particles. The ink droplet passes through the charging electrode to be charged, and then is deflected in the deflecting electrode that follows. At that time, ink adheres to the recording medium according to the charge amount of the droplet with respect to the information signal voltage,
Other ink droplets are collected by a charge control method, ink is sprayed at high pressure, and the degree of convergence of the ink spray is changed according to the voltage of the control electrode to form an opening to create density gradation. A mist of ink is generated by a control method and an ultrasonic vibration element, and is sent by an air flow in the same direction as the paper feed at approximately the same speed, and an ion flow by corona discharge is passed through the ink mist layer and sent to the recording medium. At that time, there is an ink mist system or the like in which ink mist is attached to ions to carry the ink onto the recording medium.

On the other hand, in the on-demand type, a piezoelectric vibration element is attached to a recording head having an orifice for ejecting ink, an electric recording signal is applied, and this electric signal is converted into mechanical vibration of the piezoelectric vibration element. , This vibration causes the ink to be made into small droplets from the orifice, ejected, ejected and ejected to adhere to the recording medium, a pressure control system, and a heating resistor element is attached in the ink flow path of a recording head having an orifice for ejecting ink. , The element is momentarily heated to a high temperature in response to an electrical recording signal, and bubbles are generated in the ink by utilizing the film boiling phenomenon at that time, and the pressure causes the ink to be ejected and ejected from the orifice to the recording medium. There is a heat control method for attaching ink.

Each of the above-mentioned various ink jet systems has its own characteristics and has advantages and disadvantages, but nozzle clogging due to precipitates of dyes, which are coloring components existing in the ink, and coarse particles of the pigment, and ink Nozzle clogging due to drying or the like is awaiting the possibility of occurring in any ink jet system, and many researchers are continuing research on methods for preventing such nozzle clogging, and various solutions have been proposed. For example, there are methods of making ink non-drying, and methods of covering ink ejection nozzles when not in use, but these methods are also not fundamental and nozzle clogging is still observed after a long rest. Often occurs, and the reality is that it has not been completely resolved.

Further, in consideration of the above-mentioned problem of nozzle clogging, there is a constraint that a material that can be dissolved or easily dispersed in an ink solvent must be selected as a material used as a colorant, and the degree of dispersion thereof. However, in order to prevent the dispersion from clogging the nozzle, a very high degree of dispersion, such as an average particle size of about 0.05 μm, is required. Further, it is necessary to give due consideration to the dispersant so that coarse particles which cause nozzle clogging due to agglomeration of primary particles due to aging do not occur.

[0008]

DISCLOSURE OF THE INVENTION The present invention is an ink jet system in which ink droplets are adhered to a recording medium in accordance with a print information signal to perform printing, and a dye precipitate or pigment present in the ink as described above. In order to eliminate the clogging of the ink ejection head due to the coarse particles of the ink, and to prevent the clogging of the ink ejection head, there are many restrictions on the selection of the coloring material used in the ink, and it is possible to freely select the coloring material. To solve the point that can not be done. Further, the present invention relates to solving problems such as a coloring material selected for the purpose of use in an ink, which does not contain coarse particles and which requires an advanced coloring agent dispersion technique.

[0009]

SUMMARY OF THE INVENTION According to the present invention, colorless ink droplets of a resin-soluble or resin-swellable liquid are ejected onto a recording medium in accordance with a print information signal by an ink jet method, and the recording medium is previously recorded on the recording medium. An image forming method is characterized in that after forming an image with the ink, the powder coloring material (toner) whose main component is a resin capable of dissolving or swelling is brought into contact with the ink for visualization. .

[0010]

The present invention will be described in more detail below. By using an inkjet method that prints by attaching ink droplets to a recording medium according to a print information signal, a colorless resin-soluble or resin-swelling liquid is ejected as ink droplets and is transparent on the recording medium in advance. Image is formed as a latent image, and the latent image is visualized by contacting a toner containing a resin capable of dissolving or swelling with a liquid forming the latent image as a main component. With regard to the visualized toner, dissolved or swollen toner particles are directly impregnated or adhered to the recording medium without requiring a fixing step, and the fixing used in ordinary copying machines or printers is fixed. By using the method and the fixing device, the adhesion between the recording medium and the toner can be improved. In this method, some dispersed particles that may cause nozzle clogging, or substances that cause solidification and aggregation, in the ink that passes through the ink ejection head because the ink does not contain a precipitation component or a solid component Will not be contained at all. Further, the toner for visualizing is not limited to any material as long as it is formed of a resin that can be dissolved or swollen by ink as a binder.

As the ink jet system which can be used in the present invention, various conventionally known systems and apparatuses can be applied. For example, in the case of a continuous type in which ink droplets are continuously ejected to form particles, it is applicable to a charge control type, a divergence control type, and the like. Further, the on-demand type is applicable to a pressure control method for ejecting ink droplets from an orifice by a mechanical vibration of a piezo vibration element, a heat control method using a heating resistance element, etc. It is not limited.

The transparent ink which can be used in the present invention is a liquid which can dissolve or swell the binder resin constituting the toner and which can be ejected from the above-mentioned inkjet type output device. However, it is not particularly limited. For example, water, ethyl alcohol, isopropyl alcohol, low molecular weight polyethylene glycol (molecular weight 200 to 400), acetone, methyl ethyl ketone and the like can be used. Further, there is no problem to mix and use these liquids according to the characteristics of the ink jet type ink ejecting device or the material of the recording medium on which the latent image is formed. The material to be recorded that can be used in the present invention is not particularly limited, and examples thereof include paper, plastic film, metal plate and wood.

Regarding the binder resin constituting the toner usable in the present invention, a resin which can be dissolved or swollen in the liquid used for the ink may be selected.
There is no particular limitation. Examples of the combination include polyvinyl alcohol, carboxymethyl cellulose, hydroxyethyl cellulose, polyvinyl pyrrolidone, polyacrylamide, polyacrylic acid, high molecular weight polyethylene glycol (molecular weight of 3,000 or more), if the liquid used for the ink is water. Examples of the water-soluble polymer compound include, but are not limited to, of course. Further, when ethyl alcohol is used as the ink, polyvinyl acetate or the like is suitable. When low molecular weight polyethylene glycol is used as the ink, high molecular weight polyethylene glycol is suitable. Furthermore, when acetone or methyl ethyl ketone is used as the ink, many resins can be used, and examples thereof include polyvinyl acetate, polystyrene, polymethyl acrylate, polymethyl methacrylate, and styrene-acrylic acid copolymer. However, styrene-methacrylic acid copolymer, phenol resin, etc. are preferable, but the combination thereof is not limited.

As the colorant for toner used in the present invention, known pigments, dyes or a mixture of both, which have been conventionally used as colorants, can be used.
For example, Hansa Yellow, Benzidine Yellow, Benzidine Orange, Fast Red, Brilliant Carmine 3
B, copper phthalocyanine blue, phthalocyanine green, spirit black, oil blue, alkali blue, rhodamine 6B, nigrosine, carbon black,
Examples thereof include, but are not limited to, dichloroquinacridone and isoindolinone.

Further, as a method for producing the toner usable in the present invention, a conventionally known method can be used. As a general method, a resin serving as a binder and a dye or pigment serving as a coloring component are heated and melted and kneaded with a heat roll such as three rolls, cooled and then pulverized and classified to obtain a powder colorant having a particle diameter of 5 to 15 μm. A method for obtaining the same, a resin as a binder is dissolved and a dye or pigment as a coloring component is mixed, kneaded by a disperser such as a ball mill or an attritor, dried, and then pulverized and classified to obtain a powder coloring having a particle diameter of 5 to 15 μm. There is a method of obtaining materials. Further, there is no problem in adding a third component other than the dye / pigment when manufacturing the toner.

[0016]

The present invention will be described in more detail with reference to the following examples. Example 1 On-demand inkjet output of a pressure control system in which an ink obtained by mixing 1 part of polypropylene glycol (molecular weight 3,000) with 10 parts of water is ejected from an orifice by mechanical vibration of a piezo vibrating element. The latent image formed by the transparent ink was visualized by ejecting it from a machine onto a high-quality paper to form a transparent latent image, and then contacting the colored powder toner before the ink was evaporated. As a result, the polyvinyl alcohol resin used as the main component of the toner was partially dissolved by the water in the ink and fixed to the paper, and an image could be formed without using a special fixing method. Further, the excess toner existing in a portion other than the latent image was sucked and removed by an air suction device, and the toner used in this example was manufactured by the following method.

Polyvinyl alcohol (suspended degree 88 mol%: degree of polymerization 1500) 10% aqueous solution 292.5 parts Pigment (Lionol Blue FG-7351: manufactured by Toyo Ink Mfg. Co., Ltd.) 7.5 parts are mixed and mixed with a paint conditioner ( The mixture was kneaded for 1 hour with a red devil, dried and then pulverized and classified to obtain a colored toner having an average particle size of 7 μm.

Example 2 An ink droplet prepared by mixing 5 parts of low-molecular-weight polyethylene glycol (molecular weight 300), which is a solution at room temperature with 10 parts of water, is ejected from an orifice by mechanical vibration of a piezoelectric vibrating element. A pressure-controlled on-demand inkjet output machine ejects onto a high-quality paper to form a transparent latent image, which is then contacted with colored powder toner before the ink evaporates to form a latent latent image of the transparent ink. The image was visualized. As a result, the high-molecular-weight polyethylene glycol used as the main component of the toner is partially dissolved by the water in the ink or the low-molecular-weight polyethylene glycol and fixed to the paper, forming an image without using a special fixing method. I was able to. Further, the excess toner existing in the portion other than the latent image was sucked and removed by an air suction device. The toner used in this example was manufactured by the following method.

High-molecular-weight polyethylene glycol (molecular weight 20,000) 20% solution 292.5 parts Pigment (Lionol Blue FG-7351: Toyo Ink Mfg. Co., Ltd.) 7.5 parts are mixed and mixed with a paint conditioner (red devil). The mixture was kneaded for 1 hour, dried and then pulverized and classified to obtain a colored toner having an average particle size of 7 μm.

Example 3 Ink mixed with 10 parts of water and 10 parts of acetone was transferred onto fine paper from an on-demand type ink jet output machine of a pressure control system in which ink droplets were ejected from an orifice by mechanical vibration of a piezoelectric vibrating element. The latent image formed by the transparent ink was visualized by discharging to form a transparent latent image, and then contacting the colored powder toner before the ink was evaporated. As a result, the styrene-acrylic copolymer resin used as the main component of the toner was partially dissolved by the solvent in the ink and fixed to the paper, and an image could be formed without using a special fixing method. . Further, the excess toner existing in the portion other than the latent image was sucked by an air suction device.

The toner used in this example was manufactured by the following method. Styrene-acrylic acid copolymer resin 95 parts Molecular weight (Mn: about 8,0000, Mw: about 200,000) Glass transition Tg: 63 ° C, degree of polymerization 800 Pigment (Finess RED F2B: manufactured by Toyo Ink Mfg. Co., Ltd.) ) 5 parts were heated, melted and kneaded with a hot three-roll, cooled and then pulverized and classified to obtain a colored toner having an average particle diameter of 10 μm.

Example 4 An on-demand type ink jet output machine of a pressure control system in which ink mixed with 10 parts of water, 10 parts of methyl ethyl ketone and 4 parts of ethyl alcohol is ejected from an orifice by mechanical vibration of a piezoelectric vibrating element. Was discharged onto a high-quality paper to form a transparent latent image, and then the colored powder toner was brought into contact with the latent image formed by the transparent ink before the ink was evaporated. As a result, the styrene-acrylic copolymer resin used as the main component of the toner was partially dissolved by the solvent in the ink and fixed to the paper, and an image could be formed without using a special fixing method. . Further, the excess toner existing in the portion other than the latent image was sucked and removed by an air suction device. After that, the toner was further passed through a thermocompression roller type fixing device of a commercially available copying machine, whereby the toner could be more strongly fixed to the paper.

The toner used in this example was manufactured by the following method. Styrene-acrylic acid copolymer resin 95 parts Molecular weight (Mn: about 8,0000, Mw: about 200,000) Glass transition conversion Tg: 63 ° C, degree of polymerization 800 Pigment (Black Pearls 480: manufactured by Cabot) 2.5 This part was heated, melted, and kneaded with a three-roll heat roller, cooled, and then ground and classified to obtain a colored toner having an average particle size of 10 μm.

[0024]

As described above, by carrying out the ink jet type image forming method using the method of the present invention, the nozzle of the ink jet head in the ink jet type image forming apparatus, which has been a conventional problem. An object of the present invention is to provide an image forming method which can eliminate clogging and has very few restrictions on selection of coloring materials.

Claims (1)

[Claims] 1. An ink droplet of a colorless resin-soluble or resin-swellable liquid is ejected onto a recording medium in accordance with a print information signal by an ink jet method to previously form an image with the ink on the recording medium. After that, an image forming method is characterized in that a powder coloring material (toner) whose main component is a resin capable of dissolving or swelling is brought into contact with the ink to visualize it.