JPH06239013A - Ink-jet recording method - Google Patents

Abstract

PURPOSE:To achieve the compatibility of a color picture without bleeding and a sharp character/line picture image without impairing the speed of a medium to be recorded, whose ink absorption is slow, by performing recording under the state, wherein the absorption coefficient and wetting time of water color ink into the medium to be recorded are specified. CONSTITUTION:When recording paper 10 is conveyed on a platen 2 with conveying rollers 3 and 4 and the tip is detected with a paper detecting sensor 7, a heater 8 is conducted, and the recording paper 10 is heated. A recording head is moved. The picture image of four colors using water color ink obtained by dissolving water soluble dye is printed on the recording paper 10 through recording parts 1a-1d. At this time, the heating temperature of the recording paper 10 is set at 50 deg.C or higher, and the paper is heated. Thus, the absorption coefficient (Ka) of the ink into the recording paper 10 is set at 0.5ml/m<2>.ms<1/2> or more, and a wetting time (Tw) is set at 10msec or more. The recording is performed under this state. Thus, the compatibility of the color picture image without bleeding and the sharp character/line picture is achieved.

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 method, and more particularly to an ink jet recording method capable of recording a good image on plain paper such as xerographic paper generally used in electrophotographic copying machines. is there.

[0002]

2. Description of the Related Art Conventionally, in an ink jet recording method, an ejection energy generator composed of a piezoelectric element, an electrothermal conversion element or the like is used as an ejection driving source to eject ink droplets from nozzles and cause them to fly, as shown in FIG. An image is recorded by adhering and absorbing the ink 101 to a recording medium 100 such as a recording paper, a film, a cloth, etc., and it is possible to record not only black and white but also full-color image without performing a special fixing process. It has the feature that it can be done.

By the way, in order to perform full-color image recording in the above-mentioned ink jet recording method, in order to obtain good image quality with good absorption and fixing of ink to a recording medium, SiO ₂ or CaO is formed on the surface. Applying fine particles dispersed in a hydrophilic binder onto the recording base paper,
In many cases, recording paper dedicated to ink jet recording is used as a coat layer, and the price for obtaining one print, so-called running cost, is high.

On the other hand, in the above-mentioned ink jet recording method, the recording of an image is not a recording paper dedicated to ink jet recording, but a recording material having poor ink absorbability such as xerographic paper or high quality paper generally used in electrophotographic copying machines and the like. When full-color image recording is performed on the body, the following problems occur. That is, when xerographic paper or high-quality paper, which does not have good ink absorption, is used as the recording medium, a slow-drying type ink with relatively good image quality of characters and line images is used as the ink for full color printing. When the image recording is performed, as shown in FIG.
The ink droplets 101 recorded on 00 are not dried immediately, and the ink droplets 101 flow and diffuse, the ink droplets printed adjacent to each other are connected to each other, and the ink droplets of different colors adjacent to each other are colored. Bleeding, which is called bleeding, occurs, and there is a problem that undesired color mixing occurs and the image quality deteriorates.

Further, when xerographic paper or high-quality paper having poor ink absorbability is used as the recording medium and ink having a relatively fast drying / permeating is used as the ink, the color gap in a full-color image is Although the bleeding of the ink droplets can be suppressed, as shown in FIG. 11, since the ink droplets 101 immediately penetrate deep into the recording medium and no coloring material remains on the paper surface, the ink droplets 101 are printed. The area is small and the density is low, the range of color reproducibility is narrow, and the ink droplets 101 printed next to each other spread independently without drying, and the characters and lines are thick and the image quality is poor. There is a problem that it becomes.

As described above, in the above conventional ink jet recording method, when a recording medium having a slow ink absorption other than the recording paper for exclusive use of ink jet recording is used, both the full color image and the character / line image are improved in image quality. There was a problem that it was very difficult to do. Therefore, in the conventional ink jet recording method, a recording paper dedicated to ink jet recording has to be used as a recording medium, resulting in high price for obtaining one print, so-called running cost. Was also one obstacle to its widespread adoption.

Therefore, as a technique that can be used to solve the above problems, many techniques have already been proposed, as shown below.

First, the ink jet recording apparatus disclosed in JP-A-57-102364 has an on-demand type ink jet head having a plurality of nozzles.
In an ink jet recording apparatus for recording characters and images by dots formed by ink droplets ejected from the nozzles, when the image is printed, the density of the dots is made lower than that when the characters are printed. is there.

The color recording apparatus disclosed in Japanese Patent Laid-Open No. 59-67060 has at least two ink jet nozzles, and ink droplets of different colors are ejected from each nozzle. When a character is printed, the dots of two or more colors are printed so as to overlap each other, and when a pattern is printed, the dots are printed so that the dots do not overlap each other.

Further, in the case of the color ink jet recording apparatus disclosed in Japanese Patent Application Laid-Open No. 58-212458, color recording is performed by ejecting ink droplets of a plurality of colors from nozzles and superimposing dots of the ink. In a color inkjet recording apparatus, when recording with a single color, ink droplets are ejected multiple times to form one dot by superimposing ink droplets, and when color recording is performed by superimposing a plurality of colors, ink droplets are superposed with one ejection from each nozzle. It is configured to form one dot by combining.

Furthermore, in the case of the method for manufacturing a color printed matter disclosed in Japanese Patent Laid-Open No. 61-293885, an ink jet printing apparatus is used which prints by controlling ink droplets on a printing paper under the control of a printing signal. In the method for manufacturing a color printed matter, the amount of ink discharged from the nozzle is set to 1
It is set to 1/2 of an appropriate amount per dot, and in the case of a single color, an ink ejection drive signal that continuously outputs two ink ejection signals for ejecting a fixed amount of ink droplets from the nozzles is used to output two inks of the same color. It is configured such that individual dots are ejected and inks of different colors are ejected one by one to the same dot printing position during mixed color display to print one dot.

Further, the ink jet recording apparatus disclosed in Japanese Patent Laid-Open No. 1-144447 has a conversion means for converting color information into color ink information based on subtractive color mixing, and two or more conversion means based on the conversion result of the conversion means. It is configured so as to have means for limiting the ejection amount of each color ink when mixing the color inks to an amount equal to or less than the ejection amount of one color ink.

Further, in the case of the recording method of the liquid jet recording apparatus disclosed in Japanese Patent Application Laid-Open No. 1-281944, in a method of recording a plurality of colors by a liquid jet recording apparatus having a plurality of liquid jet recording heads. The dot configuration to be recorded is divided into a plurality of groups, scanning is performed separately for each group, and the dot configuration is recorded by combining the scanning.

Further, in the case of the ink jet recording apparatus disclosed in Japanese Patent Laid-Open No. 3-146345, it is executed in the ink jet recording apparatus for recording an image based on image information on a recording medium by using recording liquid droplets. Identification information generating means for generating identification information indicating whether the recording mode is designated paper or non-designated paper mode, and when the identification information from the identification information generating means indicates the non-designated paper mode, the image information includes a plurality of pixels. It is configured to include a divided recording control unit that records the image by dividing the image into dot patterns and sequentially performing recording for each divided pattern.

Further, the color ink jet recording apparatus disclosed in Japanese Patent Laid-Open No. 3-146351 records a multicolor image corresponding to input image information on a recording medium by a subtractive color mixing method using a plurality of color inks. In a color ink jet recording apparatus, a unit for generating identification information as to whether or not a recording medium to be used is designated according to the specifications of the apparatus, and a color for each color to be recorded according to the identification information. It is configured to include an output control unit that thins out the recording information and performs recording output.

Further, in the case of the color ink jet recording apparatus disclosed in Japanese Patent Laid-Open No. 1-144448,
A plurality of inkjet heads corresponding to each color, and means for scanning the heads a plurality of times on the same position of the recording medium so as to obtain a predetermined color ink ejection time interval between the inkjet heads in a mixed color mode of a plurality of colors. It is configured to get.

Further, in the case of the ink jet print assembly disclosed in Japanese Patent Laid-Open No. 215535/1990, ink jet pen means for supplying ink drops forming a printer line on a sheet, and the print line. First heating means for heating a localized area of the paper along the inkjet pen means so as to be adjacent to each other near the surface of the paper to be printed;
It comprises a supporting means for supporting the heating means, and is configured such that the ink is heated along the print line by the first heating means immediately before the ejection from the ink jet pen means.

Further, in the case of the ink jet recording method disclosed in Japanese Patent Laid-Open No. 3-45379, an ink jet recording is carried out by applying a droplet of a recording liquid containing a pigment and a liquid medium in which the pigment is dispersed to a recording paper. In the recording method, the absorption coefficient Ka of the recording liquid on the recording paper is 2 to 10 ml.
It is configured to be in the range of / m ² .

[0019]

However, the above-mentioned prior art has the following problems. That is, the above-mentioned JP-A-57-102364 and JP-A-59.
-67060, JP 58-212458, JP 61-293885, and JP 1-1.
As disclosed in Japanese Patent No. 14447, in the case of a method of making the dot density of an image image lower than that of a character image, a method of arranging dots side by side, and a method of reducing the ink amount in a color image rather than a monochrome image, However, although some effects are recognized in places and cases where ink coverage (recording density) is low, problems such as bleeding between colors occur when ink coverage is high have not been solved.

Further, the above-mentioned JP-A-1-281944, JP-A-3-146345, and JP-A-3-146.
As disclosed in Japanese Patent No. 351 and Japanese Patent Laid-Open No. 1-144448, a method of printing by dividing one band into a plurality of scans, and a method of providing a sufficient time difference between ink ejections of respective colors However, there is a new problem that the printing speed is sacrificed in order to improve the effect.

Further, as disclosed in JP-A-2-215535, heaters are provided before and after the main scanning direction of the recording head, and the recording medium is heated immediately before and after printing to dry and fix the ink. In the case of the method of promoting, it is possible to prevent the recording paper from being contaminated by the transport roller,
It has a problem that it has not been possible to prevent bleeding between colors.

Furthermore, as disclosed in the above-mentioned Japanese Patent Laid-Open No. 3-45379, in the case of a pigment dispersion ink, it is very difficult to stabilize the dispersion of the pigment, and the density and color reproducibility are improved. However, there is a problem that high image quality cannot be obtained.

Therefore, the present invention was made in order to solve the above-mentioned problems of the prior art, and the purpose thereof is to sacrifice the effective speed for a recording medium having a slow ink absorption. It is another object of the present invention to provide an inkjet recording method capable of achieving both a color image without blurring and a sharp character / line image.

[0024]

That is, the present invention is
In an inkjet recording method of recording an image on a recording medium using a plurality of recording heads that eject ink droplets of different colors using a water-based ink in which a water-soluble dye is dissolved, the ink on the recording medium Absorption coefficient (K
a) is 0.5 ml / m ² · ms ^1/2 or more, wetting time (T
Recording is performed in a state in which w) is 10 msec or more.

In the present invention, for example, a recording medium
By heating the temperature of the recording medium to 50 ° C or higher, the recording medium
Ink absorption coefficient (Ka) to the body is 0.5 ml / m²・
ms ^1/2As above, the wetting time (Tw) is 10 msec or more.
To be done.

The above conditions are achieved by changing the state of the constituent material of the paper which is the recording medium, such as the shrinkage rate of fibers, the porosity, the pore size, etc., by heating, irradiation with electromagnetic waves or the like.

[0027]

To effectively record a character image and a color image on plain paper such as xerographic paper generally used in electrophotographic copying machines by using a water-based ink prepared by dissolving a water-soluble dye in an ink jet recording apparatus. The problem is that the state of ink penetration into the recording paper is a problem. Ink absorption coefficient and wetting time are used as a method for evaluating the state of the ink permeation into the recording paper.

Here, the absorption coefficient (Ka) and the ink wetting time (Tw) are as shown in Japan Tappi Paper Pulp Test Method No. 51-87 according to Bristow Te
measured by ster. For the measurement, as shown schematically in FIG. 12, a certain amount of ink was put in the head box,
The ink is transferred to a paper attached around a rotatable cylinder to determine the transfer amount. By changing the rotation speed of the cylinder, it is possible to measure the transfer amount during the contact time of 0.004 to 2 seconds. FIG. 13 is an example of a graph showing the relationship between the contact time and the transfer amount.
Shown in. Here, the contact time is shown on a scale by the square root of time. The inclination of this graph is the absorption coefficient (Ka), and the ink transfer amount when the contact time is 0 sec is called the roughness coefficient (Vr), and represents the amount of ink that enters the irregularities on the paper surface. In addition, there is a time (Tw) in which the ink is not absorbed at the initial stage of contact, and this portion is called the ink wetting time. This is the time it takes for the paper to get wet with the ink. The absorption coefficient matches the coefficient when the absorption time (t) is used as a parameter in the Rucas-Washborn equation (the following equation).

V = (ε / τ) √ {(rcos θ) · γt / 2η} where V: ink absorption amount per unit time ε: void ratio of paper τ: bending ratio of capillary tube on paper surface r: paper Capillary diameter of the surface cos θ: contact angle between paper and ink γ: surface tension of ink t: ink absorption time η: ink viscosity.

That is, the ink absorption coefficient (Ka) is determined by the state of the paper surface, the physical properties of the ink, and the wettability between the ink and the paper.

A change in the state of the constituent material of the paper, which is the recording medium, due to heating, electromagnetic wave irradiation, etc.
Ink absorption coefficient (Ka) due to changes in porosity, pore size, etc.
Grows larger. The ink absorption coefficient (Ka) also increases due to the temperature of the ink adhering to the paper instantaneously rising and the ink viscosity η decreasing. On the other hand, the ink wetting time (Tw) is affected by the wettability between the ink and the paper, that is, the contact angle between the paper and the ink and the surface tension of the ink. The ink wetting time (Tw) is substantially determined by the ink and the paper itself.

Therefore, by increasing the ink absorption coefficient (Ka) by changing the state of the paper surface by means such as heating or electromagnetic wave irradiation, character image quality such as edge sharpness and density is maintained, and multi-color printing is performed. In this case, it is possible to suppress the bleeding of the color overlapping portion and perform high-quality color printing.

In the present invention, as a result of various experiments,
In order to print high-quality color images while maintaining the character image quality, the ink absorption coefficient (Ka) on the recording medium is 0.5 ml / m ² · ms ^1/2 or more, the wetting time It was clarified that the recording should be performed in the state that (Tw) is 10 msec or more.

The ash content of the paper is 2.0-20.0%,
Thickness 75 to 120 μm, basis weight 50 to 100 g / m ² or more, Steckigt size degree 0 to 60 seconds, smoothness 10 to 15
It is desirable to satisfy the condition of 0 second. These papers include Sanyo Kokusaku L paper, Sanyo Kokusaku P paper, and Xerox 202.
There are plain papers for copiers such as 4 papers. Similarly, the contact angle θ between the ink and the recording medium that affects the wettability of the ink is 90 °> θ
It is desirable to satisfy the condition of> 30 °.

[0035]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to illustrated embodiments.

FIG. 1 shows an embodiment of an ink jet recording apparatus to which the ink jet recording method according to the present invention is applied.

In the figure, reference numeral 1 denotes a recording head, and the recording head 1 can be moved by a driving means (not shown) along a direction perpendicular to the drawing.
In addition, as shown in FIG.
4 corresponding to 4 colors of cyan, magenta and yellow
The recording units 1a, 1b, 1c, and 1d are provided, and the recording units 1a, 1b, 1c, and 1d respectively supply black, cyan, magenta, and yellow inks from the ink ejection ports according to image information. The image is recorded on the recording paper 10 as the recording medium over a predetermined print width by ejecting the image. The recording units 1a, 1b, 1c, 1d of the recording head 1 have, for example, 30
A device that prints an image with a recording density of 0 DPI is used. Further, as the above ink, black, cyan,
A water-based ink prepared by dissolving water-soluble dyes of magenta color and yellow color is used.

Below the recording head 1, a platen 2 made of a thin metal flat plate is fixedly arranged.
The recording paper 10 is transported on the platen 2 by the transport rollers 3 and 4 for feeding the paper in the arrow direction. Further, the transport rollers 3 and 4 for feeding the paper
Flat plate-like pressing plates 5 and 6 for preventing the recording sheet 10 from floating are arranged inside the disk.
Of these pressing plates 5 and 6, the pressing plate 6 on the downstream side in the paper feeding direction is normally slightly raised to receive the recording paper 10, and moves downward as the recording paper 10 enters and moves downward. Is pressed from above. Further, a paper detection sensor 7 for detecting the leading edge of the recording paper 10 is arranged between the pressing plate 6 and the paper feed transport roller 4.

Further, in this embodiment, the platen 2 is
A planar heater 8 is arranged on the back surface of the recording head 1 at a position corresponding to the lower side of the recording head 1, and the heater 8 heats the recording paper 10 positioned on the platen 2 to a predetermined temperature.

The recording paper 10 is detected by the paper detection sensor 7 when the leading edge of the recording paper 10 is caught by the paper feed roller 4, and the heater 8 is energized based on the detection signal from the paper detection sensor 7, The recording paper 10 is heated by the heater 8. On the other hand, the recording head 1 at the home position (not shown) moves along a carriage (not shown) to start printing. At this time, the temperature of the printing surface side of the recording paper 10 is set to be 50 ° C. or higher, and preferably 70 ° C. to 100 ° C.
Is the temperature of. When the recording head 1 finishes printing the image and the paper detection sensor 7 detects that the recording paper 10 is not present, the power supply to the heater 8 is turned off.

With the above-mentioned structure, in the ink jet recording apparatus to which the ink jet recording method according to this embodiment is applied, a color image is recorded as follows.
That is, in the above-mentioned inkjet recording apparatus, as shown in FIG. 1, the recording paper 10 is supplied from a paper feed cassette (not shown), and the recording paper 10 is conveyed on the platen 2 by the conveyance rollers 3 and 4 for paper feeding. It And
When the front end of the recording paper 10 reaches the paper feed roller 4, the front end of the recording paper 10 is detected by the paper detection sensor 7. Then, the heater 8 is energized based on the detection signal from the paper detection sensor 7, and the recording paper 10 is heated to a predetermined temperature by the heater 8. At this time, the temperature on the printing surface side of the recording paper 10 is
The temperature is set to 50 ° C or higher, preferably 7
The temperature is from 0 ° C to 100 ° C.

The recording head 1 at the home position (not shown) moves along a carriage (not shown) in a direction perpendicular to the drawing, and the recording head 1 is black.
4 corresponding to 4 colors of cyan, magenta and yellow
By the recording units 1a, 1b, 1c, and 1d, images of four colors in the order of black, cyan, magenta, and yellow are formed.
The printing is sequentially performed on the recording paper 10 over a predetermined printing width. Thereafter, the recording paper 10 is conveyed by a predetermined amount on the platen 2 by the paper feed conveying rollers 3 and 4, and image printing is sequentially performed.

Experimental Example By the way, the inventors of the present invention, in the ink jet recording apparatus constructed as described above, record on a recording medium such as xerographic paper or high quality paper which is generally used in an electrophotographic copying machine or the like, which does not have good ink absorption. The following experiments were conducted to clarify the conditions under which a water-based ink made by dissolving a water-soluble dye in a medium can be used to successfully print both a color image without bleeding and a sharp character / line image. I went.

That is, in the ink jet recording apparatus according to the first embodiment, by using the recording head 1 having a print density of 300 DPI, a black character image and four color images of black, cyan, magenta and yellow are formed. Was printed. The physical properties of the ink used in this Example 1 are shown in FIG.

As the recording medium 10, Sanyo Kokusaku L paper is used, and the surface temperature of the paper due to heating by the heater 8 is 70 ° C.
Set to.

Comparative Example The ink used in Comparative Example 1 is an ink having the physical properties shown in FIG. 3 and having good absorption on the paper. In Comparative Example 1, the same paper as in Example 1 is used. Further, Comparative Example 2 is a case where printing is performed at room temperature (25 ° C.) without using the heater 8 under the same conditions as in Example 1.

The print results are shown in FIG. In the printing in Example 1, the character / line image quality and the color image quality were better than those in the comparative example. In Comparative Example 1, only the intercolor bleeding was good, but all others were poor. Comparative Example 2 was inferior due to intercolor bleeding and poor color reproduction range.

By the way, the inventors of the present invention, in the combination of ink and paper in Example 1 and Comparative Examples 1 and 2 above, the ink wetting time (Tw) and the ink absorption coefficient (K).
As a result of measuring a), the results shown in FIGS. 5 and 6 were obtained.

As is clear from these figures, the ink absorption coefficient (Ka) on the recording paper is 0.5 ml / m ² · m.
It is understood that high-quality color images can be printed while maintaining the character image quality by recording in a state where the s ^1/2 or more and the wetting time (Tw) are 10 msec or more.

Second Embodiment FIG. 7 shows a second embodiment of the present invention. The same parts as those of the first embodiment will be designated by the same reference numerals and will be described below.
In this embodiment, a lamp house 21 having built-in high-power far-infrared lamps 20 on both sides of a recording head 1 having recording portions 1a, 1b, 1c, 1d for four colors mounted on a carriage.
Is installed and moves left and right on the recording paper 10 on the platen 2 along the main scanning direction as the carriage moves.
In response to a signal to start printing, the carriage moves to the side opposite to the home position and moves to the home position side at a speed slower than the speed at the time of printing, for example, 50 mm / sec. Lamp 20
Is operated to irradiate the recording paper 10 with high-energy infrared rays 22 which are easily absorbed to raise the temperature of the printing surface of the recording paper 10. When the recording head 1 returns to the printing start point, the recording head 1 moves in the opposite direction and starts printing. At this time, the high-output far-infrared lamp 20 is still operating and the paper 1
Pre-heating of 0 and heating after printing are performed. With this repetition,
When the carriage moves from the home position side to the opposite side, the paper 10 is heated and printing is performed, and when the carriage moves in the opposite direction, the carriage speed is reduced and only heating is performed. Further, reciprocal printing can be performed by dividing the print nozzles into odd number / even number for each color. This makes it possible to print without dropping the print.

In this embodiment, the recording sheet 10 is used as described above.
By irradiating the surface with far infrared rays, recording is performed in a state where the ink absorption coefficient (Ka) to the recording paper is 0.5 ml / m ² · ms ^1/2 or more and the wetting time (Tw) is 10 msec or more. By doing so, it is possible to print a high-quality color image while maintaining the character image quality.

The other structure and operation are the same as those of the first embodiment, and the description thereof will be omitted.

Third Embodiment FIG. 8 shows a third embodiment of the present invention. The same parts as those of the first embodiment will be designated by the same reference numerals and will be described below.
In this embodiment, 30 is the recording medium 1 of the platen 2.
0 and the back surface side of the recording head 1, which is an electromagnetic wave irradiator that irradiates the recording medium 10 with electromagnetic waves through a ceramic grid 32 that is adjusted to the same height as the platen 2 and positioned. Reference numeral 31 is a shield manufactured so as not to leak electromagnetic waves to the outside.

In this embodiment, the recording medium 10 is conveyed by the paper feed roller 3 along the platen 2 and reaches the printing area while being pressed by the float pressing plate 5. At this time, the pressing plate 6 is slightly raised to receive the recording medium 10, and is lowered and pressed as the recording medium 10 enters. Then, when the front end of the recording medium 10 is caught by the paper feed roller 4, it is detected by the paper sensor 7, the electromagnetic wave irradiation body 30 is driven,
The recording medium 10 is irradiated with electromagnetic waves. Moisture of the recording medium 10 is evaporated by the energy of the electromagnetic waves, and the porosity of the printed surface becomes larger than that in the initial state. Then, the recording head 1 in the home position moves along a carriage (not shown) to start printing. At this time, the ink absorption coefficient (Ka) of the recording medium 10 becomes 0.5 or more, and the ink absorption is improved. On the other hand, the ink wetting time Tw has not changed. Printing is completed, paper sensor 7
When it is detected that the recording medium 10 is not present, the electromagnetic wave irradiation body 30 is turned off.

The results of printing according to the second and third embodiments are also shown in FIG. In addition, in these Examples 2 and 3, the same ink and recording medium 10 as those in Example 1 were used. In these Embodiments 2 and 3, as in Embodiment 1, it was confirmed that both the character / line image quality and the color image quality were at acceptable levels.

The rest of the configuration and operation are the same as in the first embodiment, so the description thereof is omitted.

[0057]

The present invention has the above-mentioned structure and operation, and has an ink absorption coefficient (Ka) of 0.
5ml / m ² · ms ^1/2 or more, wetting time (Tw) is 10
By recording in a state of msec or more, it is possible to print a high-quality color image while maintaining the character image quality on plain paper such as xerographic paper generally used in electrophotographic copying machines and the like. .

[Brief description of drawings]

FIG. 1 is a cross-sectional configuration diagram showing an embodiment of an inkjet recording apparatus to which an inkjet recording method according to the present invention is applied.

FIG. 2 is a front view of the same.

FIG. 3 is a table showing ink jet physical properties according to Example 1 and Comparative Example.

FIG. 4 is a chart showing a printing result of an example.

FIG. 5 is a graph showing experimental results and a table showing experimental conditions.

FIG. 6 is a graph showing experimental results and a table showing experimental conditions.

FIG. 7 is a cross-sectional configuration diagram showing another embodiment of an ink jet recording apparatus to which the ink jet recording method according to the present invention is applied.

FIG. 8 is a front view of the same.

FIG. 9 is a schematic diagram showing a permeation state of ink into a recording medium.

FIG. 10A and FIG. 10B are schematic diagrams showing ink permeation states into a recording medium.

11A and 11B are schematic diagrams showing ink permeation states into a recording medium.

FIG. 12 is a schematic diagram showing a test device for testing the permeation state of ink into a recording medium.

FIG. 13 is a graph showing characteristics of ink permeation state into a recording medium.

[Explanation of symbols]

1 recording heads 1a, 1b, 1c, 1d recording unit, 1
0 recording paper.

Claims (2)

[Claims] 1. An inkjet recording method for recording an image on a recording medium using a plurality of recording heads for ejecting ink droplets of different colors, using a water-based ink in which a water-soluble dye is dissolved. The ink absorption coefficient (Ka) to the recording medium is 0.5 ml / m ² · ms ^1/2 or more,
An ink jet recording method, wherein recording is performed in a state where the wetting time (Tw) is 10 msec or more. 2. An absorption coefficient (K) of ink to a recording medium by heating the temperature of the recording medium to 50 ° C. or higher.
a) is 0.5 ml / m ² · ms ^1/2 or more, wetting time (T
The inkjet recording method according to claim 1, wherein w) is 10 msec or more.