JPH10250217A - Method for forming image - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress occurrence of beading by giving ink containing surfactant of a range of predetermined wt.% under the condition that an ink amount per unit area and unit time becomes a predetermined value or less. SOLUTION: Ink containing at least surfactant of a range of 0.2 to 5.0wt.% is given under the condition that an ink amount per unit area and unit time becomes 8×10<-3> mg/mm<2> .sec or less. In a printed image using the ink containing 0.1wt.% of the surfactant amount, no beading occurs, but in a printed image using ink except it, the beading easily occurs as the surfactant amount is increased, and the image is deteriorated. If the ink amount printing per unit area and unit time is set substantially to 8×10<-3> mg/mm<2> .sec or less, occurrence of the beading can be effectively alleviated. Thus, an apparatus for suitably controlling the ink amount to be printed per unit area and unit time on a medium to be recorded is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image recording method for recording using ink, and more particularly, to an image recording method comprising, as main components, an alumina hydrate having a boehmite structure on a substrate and a binder. The present invention relates to an image recording method particularly useful for forming a color image on a recording medium having a light-transmitting porous ink receiving layer.

[0002]

2. Description of the Related Art In recent years, an ink jet recording system has been known in which minute droplets of ink are ejected from minute nozzles according to various operating principles and adhere to a recording medium such as paper or an OHP sheet to record images, characters, and the like. It is characterized by its small size, light weight, high speed, low noise, and easy colorization. It is used as a recording device for various images in various applications including information equipment.

In the office, with the spread of personal computers, they are widely used as output terminals for computer graphics of documents, various figures, and pictorial images created by personal computers. In addition, an ink jet printer with a beautiful coloration of ink is easy to use for producing an OHP sheet for presentation, and is rapidly spreading in this application. On the other hand, for industrial use, images formed by the full-color ink jet recording method can obtain images approaching multicolor printing or silver halide photographic methods by the plate making method, and when printing a large number of small copies. Are especially cheaper than normal multi-color printing, and are particularly used in such cases. Furthermore, it is also being applied to the field of textile printing in which a computer-generated design is directly recorded on clothing fabrics or the like.

In the conventional ink jet recording system, coated paper is used as a recording medium. However, it is required that recording can be performed on so-called plain paper (plain paper copier paper or PPC paper). Ink jet printers which can improve plain ink and have improved inks have become mainstream. Therefore, in the image forming method to be developed, having a suitability for plain paper is a major factor.

One type of recording medium is an OHP sheet. An OHP sheet used in an ink jet recording system generally has a light-transmitting ink-receiving layer on a light-transmitting substrate such as polyethylene terephthalate. It has a configuration provided. The ink-receiving layer is mainly composed of a light-transmitting resin, and is mainly composed of a resin-absorbing type that absorbs and swells the ink, or is mainly composed of fine particles such as alumina hydrate and colloidal silica. There are a type in which the dye is held by voids in the layer and a type in which the dye is absorbed by electrostatic attraction. Further, as an application of an OHP sheet for an ink jet printer, a photographic high gloss film using a white base as a light-transmitting base of the OHP sheet has been released.

On the other hand, there are the following ink jet recording inks which are improved to be compatible with plain paper. Japanese Patent Application Laid-Open No. 55-029546,
JP-A-43291 discloses a recording ink in which a surfactant is added to the ink in order to improve the permeability of the ink. When printing on plain paper using these inks, ink absorption is performed quickly.

However, these inks have the advantage that they can be printed on plain paper having a certain degree of size. However, using these inks, for example, a light-transmitting material mainly containing the above-mentioned alumina hydrate or silica material is used. When high-speed printing is performed on an OHP sheet having a porous ink receiving layer, problems such as poor ink absorption and beading occur. In particular, in the case of an ink in which the concentration of the surfactant is increased to near the critical micelle concentration in order to increase the permeability, the printed ink components are aggregated in the surface of the ink receiving layer or in the ink receiving layer to cause beading. It will be easier. Here, beading is a process in which a plurality of ink droplets printed on a recording medium are aggregated into large droplets on the recording medium due to surface tension during the absorption process. Density unevenness of the bead-like ink occurs therein, which leads to image deterioration.

[0008]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for printing on a recording medium having a light-transmitting porous ink-receiving layer by using an ink which can also be used for plain paper. It is an object of the present invention to provide an image recording method capable of suppressing the occurrence of image padding.

[0009]

The above object is achieved by the present invention described below. That is, the present invention relates to a recording medium having a light-transmitting porous ink-receiving layer, wherein at least a surfactant is used in an inkjet recording system at a concentration of 0.2 to
An ink having a content of 5.0 wt% in an amount of 8 × 10 ⁻³ [mg / mm ^2.
[sec] is provided under the following conditions.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail with reference to preferred embodiments. The present inventors have conducted intensive studies on the above-mentioned problems of the prior art, and as a result, beading is likely to occur on a recording medium having a porous ink receiving layer having a light-transmitting property and having a low ink absorption. An experimental result was obtained that when the amount of ink printed per unit area and per unit time increases, the ink becomes more noticeable. For example,
OHP sheets for ink-jet recording are usually provided with a light-transmitting ink-receiving layer to facilitate the absorption of moisture, so that when left in a high-humidity environment, they absorb moisture in the air. As a result, there is a possibility that the ink absorbency may be deteriorated.
Among the OHP sheets, a recording medium having a light-transmitting porous ink receiving layer is particularly preferable because it has a relatively good ink absorbency and a high quality image can be obtained. Similarly, when left in a high humidity environment, it was also found that the ink absorbing layer was reduced due to the deterioration over time of the ink receiving layer, and that the beading became remarkable. Hereinafter, experiments on these will be described in detail.

First, in the image forming method of the present invention,
A device that can appropriately control the amount of ink printed per unit area and per unit time on a recording medium is suitably used. In the present invention, for example, a plurality of recording heads in which a plurality of recording elements are juxtaposed are provided, and the recording head is scanned in a direction perpendicular to the juxtaposition direction of the recording elements, and the recording head is moved from the recording head to a recording medium. It is preferable to form an image using an ink jet recording type recording apparatus that forms an image by applying ink thereon. That is, according to such an apparatus, when applying ink to a recording medium, printing can be performed by scanning the recording head a desired number of times in the same scanning area, and a unit amount of ink to be applied can be obtained. Printing can be easily performed by appropriately controlling the printing time required per unit, so that the amount of ink printed per unit area and per unit time on a recording medium can be easily optimized. .

FIG. 1 is a schematic perspective view of a conventionally known ink jet recording apparatus having the above-mentioned configuration and usable in the present invention. The apparatus shown in FIG. 1 is of an ink jet type in which thermal energy is applied to ink to eject ink droplets. Hereinafter, this device will be described. In FIG. 1, a recording medium 5 wound in a roll shape
Is conveyed in the direction f in the figure by the drive of the sub-scanning motor 50 coupled to the conveying roller 3 via the conveying rollers 1 and 2, and nipped by the conveying roller 3. On the other hand, guide rails 6 and 7 are placed in parallel across the recording medium 5, and the carriage 8 is arranged so as to be movable along these. Since the recording head unit 9 is mounted on the carriage 8, the recording head unit 9
Is scanned in the left-right direction with respect to the recording medium 5. The recording head unit 9 is composed of heads 9Y, 9M, 9C and 9Bk of four colors of yellow, magenta, cyan and black, and each recording head has a plurality of recording elements juxtaposed as described later. On the carriage 8, these recording heads and ink tanks (not shown) for supplying four color inks to the recording heads are arranged and mounted.
According to the inkjet recording apparatus having the above configuration,
The recording medium 5 is intermittently fed in the f direction by the print width of the recording head 9, and when the recording medium 5 is stopped, the recording head 9 is scanned in the P direction in the drawing to generate an image signal. An ink droplet is ejected onto the recording medium 5 by the action of the corresponding thermal energy to form an image.

The following experiment was conducted using the above-described ink jet recording apparatus as shown in FIG. 400
Using a recording head of dpi (approximately 16 nozzles per 1 mm) and an ink ejection frequency of 4 kHz, on a light-transmissive substrate as a recording medium, a translucent material mainly composed of an alumina hydrate having a boehmite structure and a binder is used. A light-transmitting sheet provided with an optical porous ink receiving layer is used, and the duty is set to a minimum value of 0% to a maximum value of 200% with respect to the sheet.
A gradation pattern of 16 steps even (up to two colors solid) was printed. 100% duty is one print head (= 1
The maximum amount of ink per color), 1 mm ² per 16 × 1
Print six ink drops. The amount of the surfactant contained in the ink was 0.1 wt.
%, 0.2 wt%, 1.0 wt%, 5 wt% and 7 wt%
%, And the obtained printed image was observed. The surfactant to be contained in the ink includes Surfynol 4 which is a nonionic surfactant.
65 (trade name, manufactured by Nissin Chemical Co., Ltd.) was used.

As a result, the amount of the surfactant is 0.1 wt%
No beading occurred in the printed image using the ink of the above, but in the printed image using other inks, as the amount of the surfactant in the ink increased, the beading was likely to occur, and the image was It got worse. Further, as the duty of the printed image became higher, beading gradually occurred more frequently, and the image deteriorated. That is, it was observed that with an increase in the amount of the surfactant contained in the ink and an increase in the amount of the ink printed per unit area, the beading of the printed image became severe and the image deteriorated.

Next, using the same recording head, ink ejection frequency and translucent sheet as used in the above experiment,
The same surfactant as described above is used in which the content of the surfactant is graded, and the printing time difference between the first color and the second color is set to 1 second, 2 seconds, and 3 seconds, respectively, with a duty of 200%. Printing was performed, and the obtained printed image was observed. As a result, the content of the surfactant was 0.1 wt%, 0.2 wt%
% And 1.0 wt% of the printed images with a printing time difference of 2 seconds and 3 seconds, and a surfactant content of 5.0 wt%
%, The beading was inconspicuous in the print image with a print time difference of 3 seconds using the ink of 0.1% by weight and 0.1% by weight.
Using a print image with a print time difference of 1 second using 2 wt% and 1.0 wt% ink, a print image with a print time difference of 1 second and 2 seconds using 5.0 wt% ink, and using 7.0 wt% ink In each print image with a print time difference of 1-3 seconds,
Beading was observed. As a result of the above study, it was found that overall, the longer the printing time difference when applying the ink on the recording medium, the smaller the deterioration of the image due to beading. In other words, if a certain amount of ink is to be printed, a smaller amount of printing per unit time gives a better result in preventing beading.

From the results of the above experiments, in the image formation by the ink jet recording apparatus having the above-mentioned configuration used in the present invention, the amount of the surfactant in the ink printed per unit area and per unit time is determined. It is considered that the occurrence of beading can be reduced by keeping the content within the range. When the amount of ink that can reduce the occurrence of beading is specifically calculated from the above experiment, the following results are obtained. In the above experiment, the ink having a surfactant content of 0.1 to 5.0 wt% in the ink was used, and if the printing time difference was 2 seconds or more, beading could be reduced. Therefore, when one ink droplet is calculated as 30 × 10 ⁻⁶ mg, the unit area,
The amount of ink printed per unit time is obtained from the following equation. (30 × 10 ^-6 mg / piece × 16 × 16 pieces / mm ² × 2 colors)
/ 2 seconds = 7.68 × 10 ⁻³ [mg / mm ² · sec]

As a result, in the image formation having the above structure, the content of the surfactant in the ink is 0.1 to 0.1.
When printing is performed using ink in the range of 5.0 wt%, the amount of ink printed per unit area and per unit time is reduced to about 8 × 10 ⁻³ [mg / mm ² · sec] or less. Then, it can be said that the occurrence of beading can be effectively reduced. In particular, in order to suppress the occurrence of beading without lowering the printing speed, it is preferable to perform multi-pass printing (printing of one line is performed by two or more scans) under conditions that satisfy the above ink amount.

Here, the surface activity concentration in the ink is usually preferably in the range of 0.1 to 5.0 wt% from the viewpoint of image quality when printed on plain paper and suitability for a recording head. . However, an ink having a surfactant concentration of 0.1 wt% in the ink causes another problem that it is unsuitable for use on plain paper, as described later. Therefore, in the present invention, in order to satisfy the suitability for plain paper, it is preferable to use an ink having at least a surfactant in the range of 0.2 to 5.0 wt%.

From the above experiment, it was found that increasing the printing time difference between the first color and the second color is effective as a measure for preventing beading. On the other hand, however, the printing speed of the image recording apparatus is reduced. Will be. That is, it is preferable that the time is at most about 2 seconds. Also, 400dp
When printing at a recording density of i, the ink ejection amount of one nozzle is preferably about 30 ng in practical use in consideration of the filling state of solid printing, and about 20 ng at a recording density of 600 dpi. Is preferred.

In the present invention, the content of the surfactant in the ink used for image formation is set to 0.2 to 5.0 wt% based on the total amount of the ink as described above. The type is not particularly limited, but it is preferable to use, for example, a nonionic surfactant such as Surfynol 465 (trade name, manufactured by Nissin Chemical Co., Ltd.). The constituent materials of other inks are also not particularly limited, and any conventionally known ink-jet ink materials can be used.

As the ink jet apparatus suitably used in the image recording method of the present invention, an ink jet recording apparatus having the above-described structure can be used as long as it can appropriately control the amount of ink printed per unit area and per unit time. Not limited to the apparatus, as long as it is an ink jet system that performs recording on a recording medium by discharging ink droplets from an orifice according to a recording signal, even if it is based on the action of thermal energy,
Any type such as a piezo method using a piezoelectric element may be used.

The recording medium used in the present invention may be any recording medium having a light-transmitting porous ink receiving layer. For example, a translucent recording material having a translucent porous ink receiving layer containing alumina hydrate having a boehmite structure and a binder as main components on a translucent polyethylene terephthalate sheet substrate was used. In this case, a remarkable effect of the present invention can be obtained.

[0023]

Next, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples. In the following description, “parts” or “%” is based on weight unless otherwise specified. <Printing Apparatus> As a printing apparatus used in each Example and Comparative Example, an ink jet recording apparatus having a recording head as shown in FIG. 2 and having the configuration shown in FIG. 1 was used. That is,
The head was a cyan head 9C, as shown in FIG.
It comprises a magenta head 9M, a yellow head 9Y and a black head 9Bk, each having 128 printing elements at a nozzle spacing of 16 nozzles per 1 mm. 1 to No. 128 is attached. The inkjet heads 9C, 9M, 9Y and 9Bk arranged as shown in FIG. 2 are mounted on the head portion of the apparatus shown in FIG. 1 described above, and usually perform full-color image recording while performing serial scan. Will be

In the present embodiment and the comparative example, the amount of ink for single-color printing at 16 × 16 dots per mm ² when recording was performed using the above-described apparatus was set to 100%. Accordingly, the printing ink amount in the two-color printing is twice as large as that in the single-color printing, and the ink amount is 200%. In an example of print control not particularly specified, ink jet recording was performed with an ink ejection amount per dot of about 30 ng and an ink ejection frequency of 4 kHz, and other conditions were examined based on these.

In this example and the comparative example, the recording material was composed mainly of alumina hydrate having a boehmite structure on a light-transmitting polyethylene terephthalate sheet and a binder composed of polyvinyl alcohol (PVA). A light-transmitting sheet provided with a light-transmitting porous ink-receiving layer was used.

In recording, each color ink having the following ink compositions a to e was used. The following dyes were used as the dyes used at that time. In recording, each color ink having the following ink compositions a to e in which the content of the surfactant in the ink was changed stepwise was prepared and used. At that time, the following dyes were used as colorants. -Magenta M: C.I. I. Acid Red 35 Cyan C: C.I. I. Direct blue 119

<Ink composition a> • Dye 5% • Surfactant Surfynol 465 (trade name, manufactured by Nissin Chemical Co., Ltd.) 0.1% • Diethylene glycol 5% • Polyethylene glycol 10% • Water (the total weight of the ink is 100) % Remaining)

<Ink composition b> Dye 5% Surfactant Surfynol 465 (trade name, manufactured by Nissin Chemical Co., Ltd.) 0.2% Diethylene glycol 5% Polyethylene glycol 10% Water (total weight of ink is 100) % Remaining)

<Ink Composition c> Dye 5% Surfactant Surfynol 465 (trade name, manufactured by Nissin Chemical Co., Ltd.) 1.0% Diethylene glycol 5% Polyethylene glycol 10% Water (total weight of ink is 100) % Remaining)

<Ink Composition d> Dye 5% Surfactant Surfynol 465 (trade name, manufactured by Nissin Chemical Co., Ltd.) 5.0% Diethylene glycol 5% Polyethylene glycol 10% Water (total weight of ink is 100) % Remaining)

<Ink composition e> Dye 5% Surfactant Surfynol 465 (trade name, manufactured by Nissin Chemical Co., Ltd.) 7.0% Diethylene glycol 5% Polyethylene glycol 10% Water (total weight of ink is 100) % Remaining)

<Evaluation> Images were formed under various recording conditions using the inks having the above-described ink compositions. The obtained images were evaluated for suitability for plain paper and beading by the following methods, and the optimum ink composition and printing conditions in the present invention were examined. 1. The ink absorption time when the plain paper suitability evaluation ink was applied was measured, and the quick absorption of the ink was evaluated by considering that the ink was suitable for plain paper. That is, the paper was superimposed and observed immediately after printing each ink on plain paper, and was evaluated as ○ when no offset occurred, and as X when offset occurred. As a result, suitability for plain paper was uniquely determined by the amount of surfactant contained in the ink. That is, as shown in Table 1, in the case of the ink composition a in which the amount of the surfactant was 0.1 wt%, offset occurred in any of the inks, and the suitability for plain paper was poor. In addition, the content of the surfactant is set to 0.2 to 7.
When it was 0 wt%, it was suitable for plain paper.

[0033]

[Table 1] Table 1: Evaluation results of suitability for plain paper

[0034] 2. For images with five levels of beading evaluation ,
Small to large reference levels AE were given and the beadings of the observed samples were ranked AE relative to this reference level. Then, those corresponding to the reference levels A to C are evaluated as suitable for use, and those of the reference levels D and E are
It was evaluated as unsuitable for practical use.

Example 1 In this example, two colors of ink of 100% cyan and 100% magenta were printed using the printing apparatus shown in FIGS. 1 and 2 described above. At this time, printing was performed by a method in which one line printing was performed in two scans (hereinafter, referred to as two-pass printing), and the recording head was scanned a plurality of times in the same scanning area to form a color image. The two-pass printing will be described in detail with reference to FIG.

First, as shown in FIG. 3A, in the first scan, printing of only cyan is performed, and printing of magenta is not performed. In the second scan to be printed next, the head scans the same position as the first scan on the recording medium in the second scan, but this time prints only magenta,
No cyan printing is performed. This means that the cyan and magenta printing of the first line has been performed (FIG. 3B).
Illustrated). That is, one line is printed by two scans. Next, the recording medium is fed by the width of the head in the sub-scanning direction (the direction f in FIG. 1), and printing of the second line is performed. Similarly to the first line, the second line prints cyan (shown in FIG. 3C) for the first scan and magenta (shown FIG. 3D) for the second scan.
Then, this is set to the second line and subsequent lines (FIG. 3 (f)).
Color printing is performed by repeating the above steps.

On the other hand, in the case of one-pass printing, normal serial scan printing is performed, and printing of one line is performed by one scan. For example, as described above, cyan 100
When printing is performed for a total of 200%, i.e.,% and magenta 100%, cyan and magenta are printed in one scan. That is, in the case of two-pass printing, it takes twice as long as one-pass printing to print one line. Therefore, as the number of passes increases, the printing speed decreases, and the printing time required per unit amount of applied ink increases.
In the present example, printing was performed at 200% duty by two-pass printing using various inks having the ink compositions b, c, and d, and beading was evaluated for the obtained printed image. The printing conditions and the results of the beading evaluation are shown in Table 2. In each case, they were suitable for use.

Comparative Example 1 Two-pass printing was performed in the same manner as in Example 1 except that the inks having the ink compositions a and e were used, and the obtained printed image was evaluated for beading. The printing conditions and the evaluation results of beading are shown in Table 2. When the ink of the ink composition a was used, no beading was observed and the ink composition was suitable for use. ,
Beading occurred and was not suitable for use. That is, from Example 1 and Comparative Example 1, when the content of the surfactant in the ink is in the range of 0.1 to 5.0 wt%, beading is suitable for use. It was found that the range could be suppressed. However, when the content of the surfactant in the ink is 0.1 wt%, the suitability for plain paper is inferior as shown at the bottom of Table 2 and is not preferable for another practical reason. It has been confirmed that the content of the surfactant in the ink used in the present invention is preferably limited to the range of 0.2 to 5.0% by weight.

Comparative Example 2 Printing was performed in the same manner as in Example 1 except that printing was performed by one-pass printing using inks of ink compositions a to e. The printing conditions and the results of the beading evaluation are shown in Table 2. In this case, unlike the case of the first embodiment, for example, magenta and cyan inks are simultaneously printed in one scan in one pass printing. The amount of ink printed per unit area and per unit time is twice as large as that in the first embodiment. As a result, as shown in Table 2, when the inks of the ink compositions a and b were used, no beading was observed and the ink was suitable for use. However, when the inks of the ink compositions c to d were used, Beading occurred and was not suitable for use.
That is, the content of the surfactant in the ink is from 0.2 to 5.
Even when the ink within the range of 0 wt% is used, if the amount of ink applied to the recording medium per unit area and per unit time increases, beading easily occurs and becomes unsuitable for use. It has been found that it is necessary to control the amount of ink in order to prevent the above.

Embodiment 2 In this embodiment, as in the case of the first embodiment, two-pass printing is performed using a printing apparatus similar to that used in the first embodiment, using a total of 200% ink of 100% cyan and 100% magenta. did. However, in this embodiment, two-pass printing was performed by the following method. The two-pass printing used in this embodiment is the same as the first embodiment in that one line is printed by two scans.
The type of ink to be printed in each scan and the amount of printing ink are different as described below. That is, in the first embodiment, the first scan is cyan, the second scan is magenta, and so on.
In the present embodiment, 50% of cyan and 50% of magenta are simultaneously printed in the first scan, and the remaining 50% of cyan and 50% of magenta are printed in the second scan. 50% printing is 1
In the scan, dots are printed in a zigzag pattern, and in the second scan, the data is printed in a zigzag pattern to complement the dots, thereby completing the printing of one line. In the above-described printing control method, two-pass printing was performed using inks having three kinds of ink compositions b, c, and d having different surfactant contents, and beading was evaluated for the obtained printed image. . The printing conditions and the results of the beading evaluation are shown in Table 2, and all of the cases were suitable for use.

Comparative Example 3 Two-pass printing was performed in the same manner as in Example 1 except that the ink compositions a and e were used, and the resulting printed image was evaluated for beading. The printing conditions and the results of the beading evaluation are shown in Table 2. As in Comparative Example 2, when the ink having the ink composition a was used, no beading was observed and the ink was suitable for use. When the ink having the composition e was used, beading occurred and was not suitable for use.

[0042] Examples 3 and 4, Comparative Examples 4-7 Example 3 and 4, even Comparative Example 4-7, 100% cyan,
One pass printing was performed using two colors of ink of 200% in total of 100% of magenta. At that time, printing was performed by changing the ink ejection frequency. That is, the ejection frequency of the ink was 4 kHz in Examples 1 and 2 and Comparative Examples 1 to 3, and 2 kHz in Example 3 and Comparative Example 4, respectively.
The frequency was 1 kHz in Comparative Example 5, 6 kHz in Comparative Example 6, and 8 kHz in Comparative Example 7. At this time, when compared with Comparative Example 2 having the same printing method, the scan speed of the recording head in Example 3 was 1/2 that in Comparative Example 2 and 1/4 in Example 4, and the printing time was As compared with the case of the comparative example 2, it is doubled in the example 3 and quadrupled in the example 4. In Comparative Example 6, the scan speed was 1.5 times,
In Comparative Example 7, the printing time was doubled, and the printing time was 2/3 each.
Or 1/2.

In the printing control method described above, in Examples 3 and 4, inks having three kinds of ink compositions b, c and d having different surfactant contents were used, and in Comparative Examples 4 and 5, the inks were used. Using inks having compositions a and e, and in Comparative Examples 6 and 7, one-pass printing was performed using each of the five types of inks of ink compositions a, b, c, d, and e. Was evaluated for beading.
Table 2 shows the printing conditions and the evaluation results of beading.
Examples 3 and 4 were suitable for use. However, in the case of the comparative example, first, when an ink having a surfactant content of 7.0 wt% of the ink composition e was used, beading occurred and was not suitable for use. Further, even when an ink having a surfactant content in the range of 0.2 to 5.0 wt% is used, the scanning speed of the recording head is increased, and the unit area and the unit area applied to the recording medium are increased. When the amount of ink per unit time increases, beading easily occurs, and the ink is not suitable for use. Therefore,
In order to prevent beading, it has been found that, at the time of printing, it is necessary to control the ink ejection frequency to optimize the scan speed and control the amount of ink per unit area and unit time.

Examples 5 and 6, Comparative Examples 8 to 13 In Examples 5 and 6, and Comparative Examples 8 to 13, the same printing apparatus as used in Example 1 was used.
As in Comparative Example 2, one-pass printing was performed with a total of 200% ink of 100% cyan and 100% magenta, by changing the amount of ink ejection from 30 ng of each ink droplet.
That is, the ink ejection amount was 10 ng in Example 5 and Comparative Example 8, 15 ng in Example 6 and Comparative Example 9, 20 ng in Comparative Example 10, 25 ng in Comparative Example 11, and Comparative Example 1, respectively.
In Comparative Example 13, printing was performed at 35 ng, and in Comparative Example 13, printing was performed at 40 ng. The resulting printed image was evaluated for beading.

Table 2 shows printing conditions and evaluation results of beading.
As shown in Table 2, the amount of ink applied to the recording medium per unit area and per unit time increases as the ink ejection amount increases.
It will increase as shown. Examples 5 and 6
In Comparative Examples 8 and 9, two types of inks having the ink compositions a and e were used, and in Comparative Examples 10 to 13, the ink compositions a, An image was formed using five types of inks having b, c, d, and e.

As a result, as shown in Table 2, Examples 5 and 6 were all suitable for use. However, in the case of the comparative example, first, when an ink having a surfactant content of 7.0 wt% of the ink composition e was used, beading occurred and was not suitable for use.
Further, even when an ink having a surfactant content in the range of 0.2 to 5.0 wt% is used, if the size of each ink droplet is increased and the ink ejection amount is increased, recording is performed. The amount of ink per unit area and per unit time applied to the medium is increased, and beading is liable to occur, making the medium unsuitable for use. Therefore, in order to prevent beading, it has been found that it is necessary to control the amount of ink per unit area and per unit time as an optimum amount by controlling the amount of ink ejected during printing.

Embodiment 7 In this embodiment, printing is performed by a method of forming a color image by scanning the recording head a plurality of times in the same scanning area as in Embodiment 2. In this embodiment, the number of times the print head is scanned is set to four times, and 100% of cyan and 10 magenta are used.
A total of 200% of the ink, 0%, was printed. That is, in this embodiment, as shown in FIG. 4, printing of one line is performed by four scans (four-pass printing). That is, in the first scan, 25% of cyan and 25% of magenta are simultaneously printed, respectively.
Similarly, 25% of cyan and 25% of magenta are printed at the third, fourth, and fourth scans, respectively. That is, printing by 25% in 4 scans means that only 1 pixel of continuous 4 pixels is printed in the first scan,
The second scan prints the second pixel of the continuous four pixels, the third scan prints the third pixel, the fourth scan prints the fourth pixel, and prints one line. For this reason, it takes four times as long to print as compared with the method of printing in one pass. By the above printing method, printing was performed using three types of inks having different contents of the surfactants having the ink compositions b, c, and d, and the obtained printed image was evaluated for beading. The printing conditions and the results of the beading evaluation are shown in Table 2, and all of the cases were suitable for use.

Comparative Example 14 Four-pass printing was performed in the same manner as in Example 7, except that the ink compositions a and e were used, and the obtained printed image was evaluated for beading. The printing conditions and the evaluation results of beading are shown in Table 2. When the ink of the ink composition a was used, no beading was observed and the ink was suitable for use.
When the ink having the ink composition e was used, beading occurred and was not suitable for use.

Embodiment 8 This embodiment is the same as Embodiment 7 except that the number of times the print head scans the same scanning area is set to eight and one line is printed by eight scans (8-pass printing). And printing was performed. That is, 12.5% cyan at the first scan,
12.5% of magenta is printed, and 12.5% of cyan and 1
Print 2.5% each. Printing at 12.5% in 8 scans means that only one pixel of continuous eight pixels is printed in the first scan, and the second pixel of continuous eight pixels is printed in the second scan, and three scans are performed. The method is to print up to the 8th scan, like the third pixel,
In other words, this is a method of performing 100% printing of each ink by 8 scans. For this reason, printing requires eight times as long as the method of printing in one pass. In the above printing method, printing is performed using three types of inks having different contents of the surfactants having the ink compositions b, c, and d,
The obtained printed image was evaluated for beading. The printing conditions and the results of the beading evaluation are shown in Table 2, and all of the cases were suitable for use.

Comparative Example 15 8-pass printing was performed in the same manner as in Example 8 except that the ink compositions a and e were used, and the obtained printed image was evaluated for beading. The printing conditions and the evaluation results of beading are shown in Table 2. When the ink of the ink composition a was used, no beading was observed and the ink was suitable for use.
When the ink having the ink composition e was used, beading occurred and was not suitable for use.

Embodiment 9 This embodiment is the same as Embodiment 7 except that the number of times the print head scans the same scanning area is set to 16 times and one line is printed by 16 scans (16 pass printing). And printing was performed. That is, cyan 6.25 in the first scan
% And magenta 6.25%, respectively, and from the second scan
Similarly, at the 16th scan, 6.25% of cyan and 6.25% of magenta are printed, respectively. 6.25% printing in 16 scans means that the first scan is
Only one pixel of the six pixels is printed, the second scan prints the second pixel of the continuous 16 pixels, the third scan prints the third pixel, and so on. , 16 scans and 100% printing of each ink. For this reason, 16 times as much time is required for printing as compared with the method of printing in one pass. By the above printing method, printing was performed using three types of inks having different contents of the surfactants having the ink compositions b, c, and d, and the obtained printed image was evaluated for beading. The printing conditions and the results of the beading evaluation are shown in Table 2, and all of the cases were suitable for use.

Comparative Example 16 16-pass printing was performed in the same manner as in Example 9 except that the ink compositions a and e were used, and the obtained printed image was evaluated for beading. The printing conditions and the evaluation results of beading are shown in Table 2. When the ink of the ink composition a was used, no beading was observed and the ink composition was suitable for use. , Beading occurred and was not suitable for use.

[0053]

[Table 2] Table 2 Relationship between printing conditions and beading evaluation

To summarize the above results, first, as shown in Table 2, the ink containing 0.1 wt% of the surfactant of the ink composition a was suitable for use in the evaluation A in terms of beading. As shown in Table 1, the suitability for plain paper is inferior, so that it is not preferable to apply for practical use. Therefore, as the ink used in the present invention, an ink having a composition containing 0.1 wt% of a surfactant in the ink was excluded. The ink containing 7.0% by weight of the surfactant of the ink composition e is
Regardless of whether the amount of ink was large or small, all of the ranges shown in the table were unsuitable for beading.

Further, as is clear from Examples 1 to 9 in Table 2, the ink compositions b, c and d contain 0.2 wt%, 1.0 wt% and 5.0 wt% of the surfactant, respectively. When ink is used, regardless of the scanning method, a unit applied to a recording medium having a light-transmitting porous ink receiving layer on a base material by controlling the ink ejection frequency, the ink ejection amount, and the like. Area, the amount of printing ink per unit time,
0.96 × 10 ⁻³ mg / mm ² · sec to 7.68 × 1
When the range was 0 ^-3 mg / mm ² · sec, the beading evaluations A to C were all found, and it was found to be suitable for use. The inks of these compositions have good suitability for plain paper as shown in Table 1, and are different from inks containing 0.1% by weight of the surfactant of the ink composition a. . From the above results, when the content of the surfactant in the ink is from 0.2 wt% to 0.5 wt%, the printing ink amount per unit area and unit time can be 0.96 × 10 ^-3 mg / mm ² · se
Similarly, it is easily assumed that the effect of preventing beading can be obtained even when the value is c or less.

Therefore, when an image is formed on a recording medium having a light-transmitting porous ink-receiving layer, the content of the surfactant in the ink is 0.2 wt% to 0.5 wt%. And the amount of ink per unit area and per unit time applied to the recording medium is 7.68 × 10
^{-3 mg / mm 2 · sec ≒} 8 × 10 -3 mg / mm 2 · se
If it is c or less, it can be said that it is suitable for use in terms of beading prevention and suitability for plain paper. However, if the amount of ink is too small, it takes a long time to print, so it is considered that there is necessarily a lower limit of the amount of ink suitable for practical use.

[0057]

As described above, according to the present invention,
Even when printing on a recording medium having a light-transmitting porous ink receiving layer using ink compatible with plain paper, image formation that can provide a beautiful image recording without deterioration of the image due to beading. A method is provided.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view illustrating a configuration example of an ink jet recording apparatus.

FIG. 2 is a schematic diagram illustrating an example of an inkjet recording head.

FIG. 3 is an explanatory diagram of two-pass printing.

FIG. 4 is an explanatory diagram of 4-pass printing.

[Explanation of symbols]

 1-3: transport rollers 5: recording medium 6, 7: guide rails 8: carriage 9: recording head unit 9Y: yellow head 9M: magenta head 9C: cyan head 9Bk: black head 50: sub-scan motor

Claims (8)

[Claims] A recording medium having a light-transmitting porous ink-receiving layer is coated with an ink containing at least a surfactant in the range of 0.2 to 5.0 wt% by an ink-jet recording system in a unit area and a range of 0.2 to 5.0 wt%. The amount of ink per unit time is 8
× 10 ⁻³ [mg / mm ² · sec] or less. 2. The amount of ink per unit area and per unit time is 0.96 × 10 ^{−3 to} 7.68 × 10 ⁻³ [mg / m
m ² · sec]. 3. An ink jet recording system comprising: a plurality of recording heads each having a plurality of recording elements juxtaposed therein; and scanning the recording heads in a direction perpendicular to the juxtaposition direction of the recording elements. 2. The image recording method according to claim 1, wherein a color image is formed by applying ink to a recording medium. 4. The image recording method according to claim 1, wherein when applying the ink to the recording medium, the recording head scans the same scanning area a plurality of times to form a color image. 5. The image recording method according to claim 1, wherein, when the ink is applied to a recording medium, a printing time required per unit amount of the applied ink is increased to form a color image. 6. The image recording method according to claim 1, wherein the ink is applied to the recording medium by ejecting ink droplets by applying thermal energy to the ink. 7. A recording medium comprising a base material, and a light-transmitting porous ink receiving layer mainly composed of alumina hydrate having a boehmite structure and a binder provided on the base material. The image recording method according to claim 1. 8. The recording medium having a light-transmitting property.
The image recording method described in 1.