JP2003170579A - Ink jet recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve such a problem that paper powder generated from a recording sheet deposits in the vicinity of an ink ejection nozzle hole to react on an ink material or aggregate a coloring agent thus thickening ink, a problem that image quality deteriorates when ink is not ejected due to the thickened ink, and such a problem that although nonejection of ink can be prevented by wiping the vicinity of the nozzle hole using a rubber, or the like, print speed decreases because print operation is interrupted. <P>SOLUTION: The ink jet recorder for forming record dots by ejecting ink liquid drops to a recording sheet is provided with a means for coating a specified part of the recording sheet with liquid. <P>COPYRIGHT: (C)2003,JPO

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 for forming recording dots by ejecting ink droplets on a recording sheet, and more particularly to an ink jet recording apparatus characterized by suppressing generation of paper dust from the recording sheet. It is a thing.

[0002]

2. Description of the Related Art In recent years, the use of recycled paper in consideration of the natural environment and inkjet-dedicated paper for improving the image quality of inkjet recording has increased. It is said that these recycled papers and special inkjet papers generate a large amount of paper dust. Therefore, the applications for the recording medium itself from each paper manufacturer are increasing. There are many things related to the component constitution of the ink receiving layer that does not fall off powder and the manufacturing method thereof. It suppresses the scattering of fibers from the surface and enhances the adhesive strength of the ink receiving layer.

However, not only these papers provided with these measures but also ordinary papers have a considerable amount of paper dust attached thereto. Further, the paper dust is also generated by contact with the paper transport roller and hitting with the wire at the time of printing. These gradually accumulate inside the printer, copier, etc., and interrupt the optical paths of the paper detector and the recording / writing unit, causing problems such as defective detection and defective recording / writing. Furthermore, in the inkjet recording device,
These paper powders are deposited in the vicinity of the ink ejection nozzle holes, causing a reaction with the ink material, agglomeration of the colorant, and an increase in the viscosity of the ink, which causes ejection failure of the ink.

Therefore, it is necessary to take measures on the device side, and many proposals for preventing paper dust have been made. In many cases, a scraping means such as a brush or a scraper, a biased roll, or the like is installed in front of the printing unit, or a cleaning paper removes paper dust on a transport path such as a platen.

For example, Japanese Unexamined Patent Publication No. 11-035186 describes a method in which a paper dust suction tube communicating with a suction fan is provided near the recording head and the paper dust adhering to the paper is removed every time it is conveyed. ing. Japanese Patent No. 2796719 proposes to remove the paper dust adhering to the paper feed roller with a cleaning tool having an adhesive layer. JP 2001-1
In Japanese Patent No. 71072, it is reported as a means for removing paper dust generated during lithographic printing. Further, JP-A-11-123
Japanese Patent No. 811 describes a method of applying an adhesive material or a liquid on the paper surface, forming a thin resin coating on the paper surface before printing, and removing paper dust by contact with a roller, a blade, or the like. ing.

With respect to the method of applying a liquid, Japanese Patent Application Laid-Open No. 8-230278 proposes a paper moisturizing device for moisturizing a paper having a reduced moisture content for another purpose. The present invention relates to an erasing device for erasing a photochemically erasable toner fixed on a sheet for reuse of a recorded document for protection of earth resources. Decoloring requires a considerably large amount of heat energy and light energy, so the heat causes the water in the paper to evaporate,
The paper is intended to solve the problem of partial microdeformation.

On the other hand, as a line type ink jet printer for the purpose of high speed printing, there have been proposed many apparatuses using a continuous ink jet type recording head and an apparatus using an on-demand ink jet type recording head. Among them, the line-type inkjet printer of the on-demand inkjet system is not as fast as the recording speed of the continuous inkjet system device, but the ink system is very simple, so a popular high-speed printer is provided. Suitable to do. On the other hand, the on-demand inkjet type line-type recording head ejects ink particles when it is necessary to form recording dots according to the recording data, unlike the continuous inkjet method in which ink particles are ejected from each nozzle at all times. Therefore, the ink in the vicinity of the nozzle hole is dried, and the ejection of recording dots tends to be unstable. Further, not all of the nozzle holes generate ink droplets uniformly, but there are nozzle holes in which the frequency of ink ejection is extremely low depending on the arrangement position, so clogging easily occurs.

In order to solve such a problem, when the printing operation is continued for a certain period of time, the recording head is retracted to the non-printing area, and the ink droplets are forcibly ejected from all the nozzle holes. An inkjet recording device provided with an ejection device has been proposed.

Further, in order to reduce the time loss required to move the recording head to a place where ink is received, Japanese Patent Laid-Open No.
Japanese Patent Laid-Open No. 00-111159 discloses a device that moves an ink receiver between a head and a recording sheet without moving the head.

Further, in Japanese Patent Laid-Open No. 11-334106, an ink receiver is installed between a recording sheet and a recording head at a position displaced from the ink ejection direction, and an air flow or an electrostatic force is preliminarily ejected during preliminary ejection. An apparatus is disclosed which acts on particles to block the adhesion of preliminary ink particles to a recording sheet by an ink receiver.

However, in any of the methods, the recording speed is substantially reduced due to the interruption of the recording operation, and the ink amount is wasted by preliminarily ejecting the nozzles which are frequently used due to the apparatus configuration and need not be preliminarily ejected. However, there are problems that it is difficult to accurately stop and restart the traveling of the recording sheet due to the interruption of the recording operation, and the recorded image on the recording sheet is easily disturbed.

[0012]

The paper dust generated from the recording paper accumulates in the vicinity of the ink ejection nozzle holes, causing reaction with the ink material, aggregation of the colorant, and thickening of the ink. If ink ejection failure occurs due to these, the image quality will be degraded. By pre-ejection operation of ink and cleaning around the nozzle hole with a wipe using rubber etc.,
Although it is possible to prevent non-ejection of ink, the printing operation is interrupted and the printing speed is reduced.

The present invention has been made in view of the above problems, and an object of the present invention is to suppress the generation of paper dust due to the running of a recording medium and to provide an ink jet having a long-term printing reliability. A recording device is provided.

In order to solve the above problems, in the present invention, an ink jet recording apparatus for ejecting ink droplets onto a recording sheet to form recording dots,
It is characterized in that it has means for applying a liquid to a specific portion of the recording paper.

Further, it is characterized in that the specific portion of the recording paper is a non-image portion and includes at least one of a cutting portion of the paper, a perforation, and a processed portion consisting of a perforation.

Further, the recording paper is characterized in that it passes through a means for applying a liquid before an ink jet recording means for ejecting ink droplets to form a recording dot.

Further, the liquid to be applied contains at least one of water and an organic solvent.

Printing is performed at a recording speed such that the relative speed between the nozzles and the recording paper is 10 inches / second (ips) or more.

Further, the print head for ejecting ink droplets is a line type which is fixed during printing.

Further, it is characterized in that printing is carried out on a continuous recording sheet having a sheet conveying narrow hole.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As a result of intensive studies conducted by the present inventors, most of the paper dust can be easily cut into a paper cutting portion, a hole (solid line portion), or a booklet after printing as shown in FIG. It was found that it occurs at the perforation part (dotted line part) for doing.

Therefore, in the step of applying the liquid to the recording paper in the present invention, the application of the liquid to the edges of these papers greatly reduces the generation of paper dust. The step of applying the liquid may be a contact type method using a roller or the like, or a method of applying the liquid in a mist state by spraying or ultrasonic waves. Further, it is possible to apply the liquid by using a print head different from the recording head. Further, these two or more methods may be combined. These methods can significantly reduce the generation of paper dust from the recording paper.

When a continuous recording sheet having a sheet-conveying hole is conveyed at a high speed, the amount of liquid applied is controlled so that the relative humidity in the vicinity of the sheet-conveying hole immediately after the application of liquid is 80 RH% or less. Good to do. Although it depends on the sheet transport speed and the type of sheet, it is preferable that the relative humidity in the vicinity of the sheet transport narrow hole immediately after the liquid application is 65 RH% or less. When a continuous recording sheet having a sheet conveying narrow hole is conveyed at a high speed, when the recording sheet is exposed to a high humidity environment, the hole diameter of the narrow hole is deformed due to the swelling of the cellulose fiber, and unevenness occurs.
This is because the paper transport speed is likely to change.

The liquid to be applied may be any liquid containing at least one of water and an organic solvent. The organic solvent is not particularly limited, but high-speed printing can be achieved by mixing an organic solvent having a boiling point and a vapor pressure lower than that of water. This is because if the liquid applied for a long period of time remains, a problem may occur in the conveyance of the paper, causing paper wrinkles and paper jams, leading to serious quality defects. As the organic solvent having a low boiling point and a low vapor pressure, for example, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, methanol, ethanol and isopropanol, and lower alcohols can be used alone or as a mixed solvent.

There are various types of recording heads or recording methods for on-demand type ink jet recording, such as line type recording, serial type recording, transfer type (shuttle type) recording and the like. When is fixed and only the paper moves, the paper movement speed (paper feed speed) corresponds to the above relative speed, and serial type recording, that is, the head moves vertically in the paper feed direction and sequentially records, and intermittent paper feed occurs. When it is performed, the head moving speed (carriage speed) corresponds to the relative speed. In the case of a transfer type in which the paper is installed on a rotating drum or the like for recording, or for recording on the drum and then transferring this to the paper, the speed at which the relative position between the moving paper or drum surface and the nozzle changes Understand. In either case, the printing speed is directly related to the nozzle ejection frequency and the printing resolution.

For example, the paper feed speed for line type recording or the head moving speed (recording speed) for serial type V
Is V depending on the ink droplet ejection frequency f and the recording resolution R.
= F / R. The present invention is at least 10 ips or more, preferably 15 ips or more, more preferably 20 ips or more.
It can be effectively used in high speed recording of ips or more. In particular, in a line type in which a print head that ejects ink droplets is fixed during printing, and an inkjet device for high-speed printing in which recording paper is continuous paper, the number of print interruptions such as preliminary ejection that reduces the actual printing speed is reduced. It is very effective because it can do things.

Further, in order to increase the speed, it is effective to heat the liquid to be applied and the recording paper. The heating means may be a contact-type heating means or a non-contact-type heating means such as irradiation with infrared rays or blowing hot air. The appropriate temperature for ink drying is the settability of the high boiling organic solvent (apparently the time until it becomes dry. Specifically, until the ink does not transfer even when lightly pressed with a finger or paper. 80 ° C. or higher is desirable for improvement. However, it does not need to be particularly limited because it depends on the printing speed. Although the upper limit temperature can be changed from the configuration of the apparatus, if the temperature is too high, smoke may be emitted from the recording sheet or the recording sheet may be discolored.

As the paper classification, the classification method used in the production statistics of the Ministry of Economy, Trade and Industry is often used. According to this, it is roughly classified into printed information paper, packaging paper, sanitary paper,
The printing information paper is classified into miscellaneous paper and is classified into non-coated paper, slightly coated paper, coated paper, special printing paper, and information paper. Paper for the purpose of the present invention belongs to a part of uncoated paper, special printing paper and information paper. Further, as the recording medium, besides the paper, it is possible to effectively use a medium such as wood or cloth which may generate powder.

An appropriate amount of the ink colorant added is 1 to 10% by weight. If the amount is less than 1% by weight, the image quality is deteriorated, and 10
If it is more than weight%, the ink viscosity characteristics are adversely affected. In addition, two or more kinds of colorants can be appropriately mixed and used for color adjustment or the like. To further exhibit functionality, light stabilizers, surface treatment agents, surfactants, viscosity reducers, antioxidants, antioxidants, crosslinking accelerators, oxygen absorbers, plasticizers, preservatives, rust inhibitors , An evaporation accelerator, a pH adjuster, an antifoaming agent, a moisturizing agent, a dispersant, a dye and the like can be mixed.

The viscosity of the ink composition used in the present invention is not particularly limited, but the viscosity at 25 ° C. is 5 to 20 mP.
The range of a · s is preferable for maintaining stable ejection characteristics. If the viscosity is less than 5 mPa · s, the shape of the ink droplet and the high-speed ink ejection frequency characteristic are likely to be poor,
If the viscosity exceeds Pa · s, it is difficult to eject ink and it is difficult to stabilize the ink. In addition, it is desirable that the ink composition exhibits Newtonian fluid behavior under the temperature conditions used, but if the shear speed normally used for measurement (about 100 rpm) meets the above conditions, the apparent viscosity will be a little. The presence of dependencies does not matter.

A stirrer, a bead mill and a homogenizer are most suitable for mixing / dispersing the above-mentioned pigment and other components, but various known stirring, pulverizing or dispersing devices can be used without particular limitation.

The ink composition of the present invention meets several well known requirements for application in ink jet printers. That is, this ink has sufficient stability at room temperature and has reliable storage before printing and image quality after printing.
After adhering and curing on a recording medium, it has sufficient transparency and saturation and forms a uniform thin film to give a printed matter of good image quality. It is necessary that the composition is such that offset does not occur in the state where printed materials are piled up and that the composition is highly safe considering the environment and human body.

Next, the present invention will be specifically described by way of examples, but the present invention is not limited to the examples.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram of an ink jet recording apparatus provided with a liquid coating section according to the present invention. Recording paper 2
Is conveyed in the sheet feeding direction by the guide rollers from the sheet feeding section 5. First, the surface of the recording paper 2 is applied with the liquid in the liquid applying section 3. Next, the recording paper 2 forms an image with the ink droplets ejected from the print head 1, and then is stored in the paper stacker unit 8. The paper dust protection cover 4 is not always necessary, but by installing it, stable printing can be performed for a longer period of time.
In addition, the hygrometer 7 is necessary especially when a continuous recording sheet having a sheet conveying hole is conveyed at a high speed.

Immediately after the application of the liquid, the amount of application of the liquid is controlled so that the relative humidity in the vicinity of the paper transport narrowing hole is 80 RH% or less. When a continuous recording paper having a paper conveyance narrow hole is conveyed at a high speed, when the recording paper is exposed to a high humidity environment, the diameter of the hole is deformed and uneven due to the swelling of the cellulose fiber and the like. This is because the fluctuation easily occurs.

FIG. 2 is a plan view of a cut sheet for specifically explaining the end portion of the sheet in the present invention. The solid line portion is called the end portion.

FIG. 3 is a plan view of a continuous paper having perforations for folding the paper for specifically explaining the end portion of the paper in the present invention. The perforations and the solid line portions for folding the paper, which are indicated by the dotted lines, are referred to as the end portions.

FIG. 4 is a plan view of a continuous paper having a narrow hole for conveying the paper for specifically explaining the end portion of the paper in the present invention. The perforations and the solid line portions for folding the paper, which are indicated by the dotted lines, are referred to as the end portions.

FIG. 5 is a partially enlarged view of the ink jet recording apparatus in which the continuous liquid application section and the intermittent liquid application section according to the present invention are combined. As the continuous liquid application section, a contact type method using a roller or the like or a continuous type fog generating method using ultrasonic waves is suitable. As the intermittent liquid application section, it is effective to apply the liquid to the perforation for folding the paper by using an intermittent mist blowing or a print head different from the recording head. [Example 1] 35 parts by weight of purified water, 60 parts by weight of glycerin (manufactured by Wako Pure Chemical Industries), and 5 parts by weight of ethylene glycol monoisobutyl ether (manufactured by Wako Pure Chemical Industries) were mixed,
Further, an aqueous pigment dispersion (CAB-O-JET200 manufactured by Cabot Specialty Chemicals, pigment content 19.5
(% By weight) is mixed so that the pigment concentration is constant, and 300 g of the composition is dispersed using a homogenizer (HG30 manufactured by Hitachi Koki) at a rotation speed of 2,000 rpm until a homogeneous mixture is obtained, and further filtered. Impurities and the like were removed to obtain a homogeneous ink composition. Rotational viscometer (Tokimec EL
As a result of measuring the ink viscosity at 25 ° C. using the D model), it was 8.9 mPa · s.

Direct plate making machine (SJ0 manufactured by Hitachi Koki
2A) Head part is extracted and fixed and used for printing. Maximum ink ejection frequency is 6 kHz and paper feed speed is 10 ip.
As s, printing with a resolution of 600 (× 600) dpi was performed.

The recording paper is recycled paper NIP1500RGT.
(Made by Kobayashi recording paper) was used. This is a continuous paper having a narrow hole for paper transport as shown in FIG.

The liquid to be applied was a solution in which water and ethanol were mixed at a weight ratio of 1: 1. Using Quick Spray EH-53 (manufactured by As One Co., Ltd.), it was applied to both ends of the recording paper, pin holes for conveying the paper, and perforations in the paper running direction. Further, the head portion of a direct plate making machine (SJ02A manufactured by Hitachi Koki) was extracted and fixed, and this solution was applied to perforations in the direction perpendicular to the paper running direction.

RION PARTICLE COUNT
Using the TER KC-01A, place the air inlet at a position of about 2 mm below the print head, and 0.5 L / m
The flow rate of in was measured for 2 minutes.

The amount of paper dust was compared when the paper was not conveyed and when the paper was conveyed. The measured results are shown in Table 1. The increase in the amount of paper dust of 0.3 μm or more when the paper is conveyed is 2,514 when the paper is not conveyed,
The increase was about 10% of the total. Further, after printing for 10 minutes, the vicinity of the nozzle hole of the print head was observed, and it was confirmed that paper dust did not adhere. This amount of paper dust has almost no effect on ink ejection. Comparative Example 1 Using the same ink composition as in Example 1,
The same experiment as in Example 1 was conducted without applying the liquid.
The amount of paper dust was compared when the paper was not conveyed and when the paper was conveyed. The results of measuring the amount of paper dust are shown in Table 1. Compared to the case where the paper is not conveyed, the increase in the amount of paper dust of 0.3 μm or more is 22,126 when the paper is conveyed.
It was about twice as large as the whole. Further, after the printing for 10 minutes, the vicinity of the nozzle hole of the print head was observed, and the adhesion of paper dust was confirmed. Further, the ink ejection at the position corresponding to the adhesion of the paper dust is unstable, and the printing quality is deteriorated.

[0045]

[Table 1]

[0046]

EFFECT OF THE INVENTION The ink jet recording apparatus of the present invention can suppress the generation of paper dust and can perform ink jet recording with good long-term printing reliability.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an ink jet recording apparatus including a liquid application section according to the present invention.

FIG. 2 is a plan view of a cut sheet for specifically explaining an end portion of a sheet according to the present invention.

FIG. 3 is a plan view of a continuous sheet having perforations for folding a sheet for specifically explaining an end portion of the sheet in the present invention.

FIG. 4 is a plan view of a continuous paper having a paper transport narrow hole for specifically explaining an end portion of the paper in the present invention.

FIG. 5 is a partially enlarged view of an ink jet recording apparatus in which a continuous liquid application unit and an intermittent liquid application unit according to the present invention are combined.

[Explanation of symbols]

1 is a print head, 2 is a recording sheet, 3 is a liquid application section,
4 is a paper dust protection cover, 5 is a paper supply unit, 6 is a paper stacker unit, 7 is a hygrometer, 8 is perforations for folding paper, and 9
Is a narrow hole for transporting paper, 10 is a continuous liquid application section, 11
Is an intermittent liquid application part.

Continued front page    (72) Inventor Hidetoshi Fujii             Hitachiko, 1060 Takeda, Hitachinaka City, Ibaraki Prefecture             Machine Co., Ltd. (72) Inventor Kunihiro Tamahashi             Hitachiko, 1060 Takeda, Hitachinaka City, Ibaraki Prefecture             Machine Co., Ltd. (72) Inventor Hiroshi Shoji             Hitachiko, 1060 Takeda, Hitachinaka City, Ibaraki Prefecture             Machine Co., Ltd. (72) Inventor Hiroshi Takahagi             Hitachiko, 1060 Takeda, Hitachinaka City, Ibaraki Prefecture             Machine Co., Ltd. F term (reference) 2C056 EA14 EA16 EC13 FB01 FB03                       HA33                 2C060 AA04                 2C061 AQ05 AS02 AS07 CJ01 CJ02                       CJ03

Claims (8)

[Claims] 1. An inkjet recording apparatus for forming recording dots by ejecting ink droplets onto a recording sheet, the inkjet recording apparatus comprising means for applying a liquid to a specific portion of the recording sheet. 2. A specific region of the recording paper is a non-image area and is an area characterized by including at least one of a cut portion of the paper, a perforation, and a processed portion including a perforation.
The inkjet recording device described. 3. The recording paper passes through a means for applying a liquid before the ink jet recording means for ejecting ink droplets to form recording dots.
The inkjet recording device described. 4. The ink jet recording apparatus according to claim 2, wherein the liquid to be applied contains at least one of water and an organic solvent. 5. The relative speed between the nozzle and the recording paper is 10
The inkjet recording apparatus according to claim 4, wherein printing is performed at a recording speed of at least inches / second (ips). 6. The ink jet recording apparatus according to claim 5, wherein the print head for ejecting ink droplets is a line type which is fixed during printing. 7. The ink jet recording apparatus according to claim 5, wherein printing is performed on a continuous recording sheet having a sheet conveying hole. 8. The ink jet recording apparatus according to claim 7, wherein the amount of liquid applied is controlled so that the relative humidity in the vicinity of the sheet conveying narrow hole immediately after the liquid application is 80 RH% or less.