JPH09188064A - Image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To print on an OHP sheet without deteriorating the image surface due to beading by giving ink containing specific amount of surfactant in a specific range to a medium to be recorded having a porous ink receiving layer containing alumina hydrate and binder as main components. SOLUTION: An ink jet recording system has a plurality of recording elements placed side by side and forms an image by scanning in the direction different from the juxtaposing direction. In this case, an image can be formed without generating beading even in the case of printing on an OHP sheet by giving ink containing 0.2 to 5.0wt.% of surfactant to a medium to be recorded having a porous ink receiving layer containing alumina having a boehmite structure and binder as main components on a base material at 3×10<-3> to 8×10<-3> mg/mm<2> sec. In this case, when the ink containing the surfactant is recorded on the medium, the printing time interval per unit amount of the ink is increased to form a color image.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art In recent years, an ink jet recording system records fine images such as images and characters by ejecting fine ink droplets from fine nozzles according to various operating principles and adhering them to a recording medium such as paper or an OHP sheet. Since it is performed, it has features such as small size, light weight, high speed, low noise, and easy colorization, and it has begun to be used for various applications such as information equipment as a recording device for various images.

In the office, with the spread of personal computers, documents created by personal computers,
As an output terminal for computer graphics of various figures and pictorial images, and for presentation O
Inkjet printers with beautiful ink colors for the production of HP sheets are convenient and are rapidly becoming popular.

Further, for industrial use, it is possible to obtain an image formed by the full-color ink-jet system, which is close to the multi-color printing by the plate making system or the silver salt photographic system. It is cheaper and more suitable than regular multicolor printing. Further, it is being applied to the field of textile printing, in which a design created by a computer is directly recorded on a cloth for clothing or the like.

In the conventional ink jet system, coated paper had to be used as a recording medium.
The width of inkjet recording media for offices is expanding, and recently it is required to be able to record on so-called plain paper (plain paper copier paper or PPC paper), and inkjet printers compatible with plain paper with improved recording ink are also available. Have begun.

OHP sheets for ink jet printers generally have a structure in which an ink absorbing layer is provided on a transparent base material such as PET. The ink absorbing layer includes a resin absorbing type that swells by containing ink, a type that retains ink in the voids of the porous layer, and a type that adsorbs a dye by electrostatic attraction. In addition, an OHP sheet for an inkjet printer is applied, and a photo-like high-gloss film in which the transparent base material of the OHP sheet is a white base material is also on sale. The following are inks that have been improved to be compatible with plain paper. JP-A-55-029546 and JP-A-3-43291 disclose recording inks in which a surfactant is added to the ink in order to improve the ink permeability. This ink quickly absorbs ink when printed on plain paper.

FIG. 1 is a schematic perspective view of an ink jet recording apparatus according to a conventional example. In FIG. 1, the recording material 5 wound into a roll passes through the transport rollers 1 and 2 and then the transport roller 3
Sub-scanning motor 50 sandwiched by
Is sent in the direction of f in the drawing. This recording material 5
Guide rails 6 and 7 are placed in parallel across
The recording head unit 9 mounted on the carriage 8 scans left and right. The carriage 8 has four heads 9Y, 9M, 9C and 9B of yellow, magenta, cyan and black.
k is mounted, and ink tanks of four colors are arranged on it. The recording material 5 is intermittently fed by the print width of the recording head 9, but when the recording material 5 is stopped, the recording head 9 scans in the P direction and ejects ink droplets according to the image signal. .

[0008]

Although the above-mentioned ink has the advantage that it can be printed on plain paper having a high degree of sizing, a porous ink receptive material containing alumina or silica material such as an OHP sheet as a main component can be used. When high-speed printing is performed on a layer, problems such as poor ink absorption and beading occur. Particularly in the case of an ink whose concentration has been increased to near the critical micelle concentration in order to increase the permeability, the printed ink components are likely to aggregate in the ink receiving layer to cause beading.

Here, beading means that a plurality of ink droplets printed on a recording medium are aggregated into large droplets by surface tension on the recording medium during the absorption process.
When this occurs, uneven density of bead-like ink occurs in the recorded image, which leads to image deterioration.

An object of the present invention is to provide an image forming method in which beading does not occur even when an OHP sheet is printed with an ink compatible with plain paper.

[0011]

The above object is achieved by the following invention. That is, the present invention includes a plurality of recording heads in which a plurality of recording elements are juxtaposed, and in an image forming method by an inkjet method of forming an image by scanning in a direction different from the juxtaposition direction of the recording elements, it has a boehmite structure on a substrate. 3 × 1 ink containing 0.2 to 5.0% by weight of a surfactant is added to a recording medium having a porous ink receiving layer containing alumina hydrate and a binder as main components.
0 ⁻³ mg / mm ² sec to 8 × 10 ⁻³ mg / mm ² se
The image forming method is characterized in that the image is imparted by c.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION According to the experimental results of the present inventor,
Beading is particularly likely to occur on a medium such as an OHP sheet that absorbs ink slowly, and becomes more noticeable when the amount of ink printed per unit area and unit time on the recording medium increases. Further, it has been found that when the OHP sheets are left in a high temperature and high humidity environment, the ink absorptivity is deteriorated due to the deterioration of the absorption layer with time, and the beading becomes remarkable. This experiment will be described in detail below.

In an ink jet recording apparatus for ejecting ink droplets by applying thermal energy to the ink of FIG. 1, a recording head of 400 dpi (about 16 nozzles per mm), an ink ejection frequency of 4 kHz, and an OHP for CJ10 manufactured by Canon Inc. The duty is even from the minimum value of 0% to the maximum value of 200% (2 color solid) for the sheet 16
A gradation pattern of stages was printed. 100% duty is the maximum amount of ink per print head (= 1 color),
16 × 16 ink drops are printed per 1 mm ² . The amount of surfactant contained in the ink is 0.1%, 0.2%,
The prints (a) to (e) obtained by changing to 1.0%, 5% and 7% were obtained and observed. As the surfactant, nonionic Surfynol 465 (trade name) manufactured by Nisshin Chemical Co., Ltd. was used.

In (a), beading did not occur, but in the order of (b) to (e), and as the duty increased, beading gradually occurred and the image deteriorated. That is, it was observed that the image deteriorates due to beading as the amount of the surfactant contained in the ink increases and the amount of the ink printed per unit area increases.

Next, the same recording head, ink ejection frequency, and OHP sheet as in the above experiment were used, the surfactant content in the ink was also the same ((a) to (e)), and the duty was 200%, The printing time difference between the first and second colors is 1 second,
Printing was performed for 2 seconds and 3 seconds, and the image was observed. (A) ~
In 2 and 3 seconds of (c), and 3 seconds of (d), beading is inconspicuous, 1 second of (a) to (c), (d)
Beading was observed for 1 and 2 seconds, and (e) for 1 to 3 seconds.

As a result, (a) to (e) It was found that the deterioration of the image due to beading was smaller when the printing time difference was longer as a whole. In other words, it was found that when printing a certain amount of ink, the smaller the amount of ink printed per unit time, the better the beading.

From the above experiment, it was considered that beading can be reduced by suppressing the amount of ink printed per unit area and unit time within a certain range. Specifically, the content of the surfactant in the ink is 0.1.
Since the beading could be reduced up to a printing time difference of 2 seconds at ~ 5.0%, the ink amount printed per unit area per unit time is 30 x 10 ^-6 m per ink drop.
As g, (30 × 10 ^-6 mg × 16 × 16 pieces / mm ² × 2 colors) / 2 seconds = 7.68 × 10
^-3 [mg / mm ² sec].

The surfactant concentration of the ink is 0.1 to 0.1 depending on the image quality when printed on plain paper and the suitability of the recording head.
A large print time difference of 5.0% is a beading countermeasure, but the print speed of the main body of the image recording apparatus is reduced, and therefore it is at most 2 seconds. However, a surfactant concentration of 0.1% is unsuitable for plain paper suitability evaluation as described later. Further, the lower limit of the ink amount was determined to be 3.0 × 10 ³ [mg / mm ² sec] from the filling of solid printing. As the surfactant used by the method of the present invention,
Nonionics are preferred.

[0019]

EXAMPLES The present invention will now be described specifically with reference to examples, but the present invention is not limited to these examples.

The printer head comprises a cyan head 9C, a magenta head 9M, a yellow head 9Y and a black head 9Bk as shown in FIG. 2, each of which has 128 recording elements of 1 m.
The recording element number No. is set to each recording element. 1 to No. 128 is attached. Inkjet head 9 arranged as shown in FIG.
C, 9M, 9Y, and 9Bk perform full-color image recording while performing serial scan.

Further, the amount of ink for monochromatic printing with 16 × 16 dots per mm ² was set to 100%, and the amount of printing ink for two-color printing was 200%, which was twice the amount of monochromatic printing. In a print control example not specified, ink jet recording was performed with an ink ejection amount of about 30 ng and an ink ejection frequency of 4 kHz for each dot printing.

Ink dye Y: C.I. I. Direct Yellow 86 M: C.I. I. Acid Red 35 C: C.I. I. Direct Blue 199 Bk: C.I. I. Food Black 2 Surfactant Surfynol 465 (trade name), Nissin Chemical Ink Composition 1 (monochromatic ink, each part by weight) Dye: 3 parts Diethylene glycol: 5 parts Polyethylene glycol: 10 parts Water: 82 parts Ink composition 2 (Single color ink, addition of surfactant, each part by weight) Dye: 5 parts Surfactant: Ink a: 0.1 part Ink b: 0.2 part Ink c: 1.0 part Ink d: 5.0 part Ink e: 7.0 parts Diethylene glycol: 5 parts Polyethylene glycol: 10 parts Water: 80 parts-Surfactant addition amount (parts) OHP sheet Canon OHP sheet for CJ10 plain paper Proper evaluation Ink absorption time is usually fast Considering that the paper is appropriate, other papers were overlaid immediately after printing and there was no offset, and when the offset occurred, it was rated as x. This was uniquely determined by the amount of surfactant contained in the ink. That is, surfactant: 0.1 part: × 0.2 part, 1.0 part, 5.0 part, 7.0 part: ○ Beading evaluation The beading level was set from the small to large reference levels A to E. Were provided and the beading of the observed sample was compared to these to rank A to E. Those corresponding to A to C are suitable for use, and D and E are not suitable.

Example 1 In this example, a total of 200% of 100% cyan and 100% magenta ink was printed using the printing apparatus. Printing One line was printed in two scans (two-pass printing).

Two-pass printing will be described in detail with reference to FIG. In the first scan, only cyan is printed and magenta is not printed (first scan, first line in FIG. 3). In the second scan, the head scans the same area on the recording material, and only magenta is printed this time, and cyan is not printed (the second line, the second scan). By this, the cyan and magenta lines are printed. That is, one line is printed by scanning twice.

Next, the recording material is fed in the sub-scanning direction by the width of the head to print the second line. Similarly to the first line, the second line prints cyan (first line first scan in FIG. 3) and second magenta (second line second scan in FIG. 3). This is 2
Two-pass printing is to perform full-color printing by repeating from the line to the final line.

On the other hand, the one-pass printing is a normal serial scan printing, and printing is performed by one line and one scan.
That is, the 2-pass printing is performed in twice as long as the 1-pass printing. In this example, the inks b, c and d were used to obtain the beading evaluation shown in Table 1.

Comparative Example 1 The same printing as in Example 1 was carried out except that the inks a and e were used, and the beading evaluation shown in Table 1 was obtained.

Comparative Example 2 Example 1 was repeated except that the inks a to e were used, the printing ink amount was changed as shown in Table 1, and printing was performed by one-pass printing.
The beading evaluation shown in Table 1 was obtained in the same manner as in.

Example 2 In this example, as in Example 1, 100% cyan,
A total of 200% ink of 100% magenta was printed using the printing device. In this example, printing of one line is performed in two scans (two-pass printing) as in Example 1, but the type and amount of ink printed in each scan is different. That is, in the first embodiment, two-pass printing is performed for each color such as cyan in the first scan and magenta in the second scan, but in the present embodiment, 50% cyan and 50% magenta are printed in the first scan. In the second scan, the remaining 50% cyan and 50% magenta are printed. Printing 50% at a time means that dots are printed in a staggered pattern in the first scan, and dots are printed in an inverted zigzag pattern to complement the dots in the second scan. In the printing control method of the second embodiment, three types of ink b having different surfactant contents,
The results of printing c and d are shown in Table 1.

Comparative Example 3 Printing was performed in the same manner as in Example 2 except that the inks a and e were used, and the results shown in Table 1 were obtained.

In Examples 3 and 4 and Comparative Examples 4 to 7, 1-pass printing was performed in Examples 3 and 4 and Comparative Examples 4 to 7, and the ink ejection frequency, which was 4 kHz in Examples 1 and 2, was changed. It is a printing control method. 2 kHz in Example 3 and Comparative Example 4, and 1 kHz in Example 4 and Comparative Example 5.
z, 6 kHz in Comparative Example 6, and 8 kHz in Comparative Example 7. At this time, the scanning speed of the head is 2 in Example 3 as compared with Comparative Example 2 so that the printed images are the same.
1/4, 1/4 in Example 4, 1.5 in Comparative Example 6
Double, and double in Comparative Example 7.

By the printing control methods of Examples 3 and 4 and Comparative Examples 4 to 7, five kinds of inks a, b, c, d, and e in which the content of the surfactant was changed were printed. It became like.

Examples 5 and 6 and Comparative Examples 8 to 13 In these Examples and Comparative Examples, in Examples 1 and 2, 3
This is a printing control method of 1-pass printing in which the ejection amount of ink which was 0 ng was changed. 1 in Example 5 and Comparative Example 8
0 ng, 15 ng in Example 6 and Comparative Example 9, 20 ng in Comparative Example 10, 25 ng in Comparative Example 11, Comparative Example 1
2 was 35 ng, and Comparative Example 13 was 40 ng. As a result of printing the five kinds of inks a, b, c, d, and e in which the content of the surfactant was changed by such a printing control method, the results are shown in Table 1.

[0034]

[Table 1] Ink a containing 0.1 part of a surfactant as shown in Table 1.
In the range of the amount of printing ink shown in the table, although it is suitable for use (A) in terms of beading, it is suitable for plain paper and is disqualified. The ink e containing 7.0 parts of the surfactant is not suitable for use in terms of beading when the printing ink amount is in the range shown in the table. For the inks b, c, and d containing 0.2 part, 1.0 part, and 5.0 parts of the surfactant, respectively, the printing ink amount was 3.84 to the value shown in the table as in Examples 1 to 6. In the range of 7.68, the beading was rated A to C, and it is clear that it is suitable for plain paper and suitable for use.

[0035]

As described above, according to the method of the present invention, beautiful image recording can be performed without deterioration of the screen due to beading even when an OHP sheet is printed with an ink corresponding to plain paper. it can.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration example of an inkjet recording apparatus as a recording apparatus to which the present invention can be applied.

FIG. 2 is a diagram showing an arrangement of inkjet recording heads.

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

[Explanation of symbols]

 1 to 3 Conveying rollers 5 Recording material 6,7 Guide rail 8 Carriage 9 Recording head unit 9Y Yellow head 9M Magenta head 9C Cyan head 9Bk Black head 50 Sub-scanning motor

Claims (4)

[Claims] 1. An image forming method using an ink jet method, comprising a plurality of recording heads having a plurality of recording elements arranged in parallel, and scanning in a direction different from the recording element juxtaposition direction to form a boehmite structure on a substrate. 3 × 10 ⁻³ mg / mm of ink containing 0.2 to 5.0% by weight of a surfactant is added to a recording medium having a porous ink receiving layer containing alumina hydrate and a binder as main components. ² sec-8
× 10 ^{- 3} mg / mm ² image forming method comprising applying a range of sec. 2. The color image is formed by scanning the same scanning region a plurality of times when the ink containing the surfactant is recorded on the recording medium. Image forming method. 3. A color image is formed by increasing a printing time interval per unit amount of ink when recording the ink containing the surfactant on the recording medium. Or the image forming method described in 2. 4. The image forming method according to claim 1, wherein heat energy is applied to the ink to eject ink droplets.