JPH0729476B2 - Inkjet recording method - Google Patents

Description

TECHNICAL FIELD The present invention relates to an ink jet recording method capable of performing high-quality recording on general-purpose recording paper such as commercially available and high-quality paper regardless of paper quality.

[Conventional technology]

Typical examples of the ink jet recording apparatus having a heating / drying means for the recording liquid are JP-A-55-69464 and 55-84670, and the recording paper is heated by heating the entire platen with a heating element provided inside the platen. This was an effective means for achieving high resolution and high quality image recording by heating from the back side and drying the recording liquid to prevent unnecessary bleeding, paper wrinkles and stains due to unfixed recording liquid.

[Problems to be solved by the invention]

However, the properties of commercially available mid- and high-quality paper, which are typical general-purpose recording papers, vary widely in the manufacturing process, depending on the raw pulp, the mixed filler, the wire part of the paper machine, the size press, and other configurations and processing methods. Therefore, the ink jet recording characteristics are completely different not only by the manufacturer and the manufacturing lot but also on the front and back of the same paper. That is, the print quality is greatly influenced by the paper quality because the recording liquid absorbency is different. The above-mentioned prior art relates only to the recording paper heating means and structure of the platen portion, and is technically insufficient to realize high-quality ink jet recording on various general-purpose recording papers regardless of paper quality. Therefore, the present invention solves such a problem, and an object of the present invention is to provide an ink jet recording method which enables high quality printing regardless of paper quality.

[Means for solving problems]

In the inkjet recording method of the present invention, recording and writing are performed on a recording medium heated to 80 to 140 ° C. and having a size degree of 5 sec or more with an ink having a contact angle of 20 ° or more (at 80 ° C.) with respect to the recording medium. Is characterized by.

Further, the solvent contained in the ink is 5 to 20% by weight.

Furthermore, the solvent is characterized by being selected from glycerin, diethylene glycol, ethylene glycol, and thiodiglycol.

The present invention achieves the object by using, for example, the ink jet recording apparatus shown in FIGS. The structure of the ink jet recording apparatus will be described.

FIG. 1 is a schematic overall configuration diagram showing a first example of an apparatus used in the ink jet recording method of the present invention.

In FIG. 1, the recording head 5 is guided by the carriage guide 6 while being supplied with the ink from the ink tank 15 through the ink supply pipe 16, and moves in the direction of arrow I. Then, ink jet recording is performed on the recording paper which is fed in an intermittent line feed in synchronization with the recording head 5.

In FIG. 2, the recording head 5 has a plurality of ink ejection ports 13
Is provided, and a dot image is formed on the recording paper 3 by an ink ejection means such as piezoelectric element control, electric field control, charge control, film boiling phenomenon control utilizing heat energy. The recording head 5 of this example has a pitch of 0.141 mm and has a length of 1 row 2.
Approximately 0.5 μg from 4 ink ejection ports by controlling the piezoelectric element
The recording liquid droplet of is ejected.

The stationary platen 1 is preferably made of an aluminum alloy or a material having good heat diffusion such as a heat conductive plastic material. In this example, an aluminum alloy plate having an average plate thickness of 1 mm and a size of about 250 mm × 30 mm is used. As shown in FIG. 2, a heating element 12 is provided on the back surface of the fixed platen 1 which does not face the recording head 5. As the heating element 12, five PTC thermistors for heaters having a rated voltage of 30V and a room temperature average resistance value of 22Ω are evenly arranged, or a sheath heater of 100V250W is suitable.

The recording paper 3 is brought into sliding contact with the fixed platen 1 heated by the heating element 12, and is preheated and heated to 80 ° to 140 ° C. before and after the ink jet recording by contact heat transfer, and the ink recorded by the ink jet is recorded. Immediately after the surface is attached, the paper retainer 7 is quickly dried to prevent unnecessary dot bleeding and stains due to unfixed ink to obtain a good printing state. 3 is closely attached to enhance the heat conduction effect.

By preheating and heating the recording paper 3, the recording paper 3 is curled along the shape of the fixed platen 1. In order to remove this curl, the recording paper is wound around the curl removing roller 14 after ink jet recording, and the curl is removed by curling in the opposite direction to take out the recording paper 3 in a flat state. You can

FIG. 3 is a schematic overall configuration diagram showing a second example of an apparatus used in the ink jet recording method of the present invention.

The recording head 5 is guided by the carriage guide 6 to move in the direction of the arrow I, and ink jet recording is performed on the recording paper 3 which is intermittently fed by the paper feed roller 2 and the guide roller 4 in synchronism with the recording head 5. . On the other hand, the light emission from the heat source lamp 17 is focused on the recording area on the surface of the recording paper 3 in the heating range 27 before and after recording by the reflection plate 19 having a curved surface such as a paraboloid, an ellipsoid, and a hyperboloid. It is irradiated and heats by radiative heat transfer. Further, the air flow sent from the blower device 23 passes through the air carry-in passage 24 as shown by arrows II and III, and is sent to the lamp house portion constituted by the reflection plate 19, the reflection plates 21a and 21b and the transparent protective glass 22. The heat source lamp 17 and the lamp house are air-cooled. After cooling, the air flow passes through the air discharge passage 25 as shown by IV and V, and the air outlet 26
Is discharged from the recording paper 3 toward the recording surface of the recording paper 3 and the heat source lamp
The convective heat and conductive heat generated by 17 are transferred to the recording paper surface by blowing air.

The recording head 1 has a plurality of ink ejection openings 13 as shown in FIG.
Is provided, and a dot image is formed on the recording paper 3 by means of ink ejection control means such as piezoelectric element control, electric field control, charge control, etc. for image recording. In this example, a piezoelectric element is used.
With a 141mm pitch, it has 24 rows of ink ejection ports in a row and approximately 0.5
Ink droplets of μg are ejected.

The heat source lamp 17 is an incandescent lamp typified by a halogen lamp, a xenon lamp, or an infrared lamp, and in this example, a rod-shaped halogen lamp having a length of 200 W and a length of 250 mm is used. The recording width of the recording paper 3 is 220 mm, and a lamp having an effective light emitting portion having a length longer than this is required.
The heat source lamp 17 is set at a distance of 60 mm from the paper feed roller 2 and radiatively heats the heating range 27 as described above. The heating state of the recording paper 3 is detected by the temperature sensor 28 as shown in FIG. 4, and the temperature of the recording paper 3 is almost equalized by comparing the set temperature with the comparison circuit built in the light amount control circuit 18 and the light amount feedback. It is kept to the set value. Temperature sensor
Although 28 is provided on the front side of the recording paper 3 in FIG. 4, it may be provided on the front side of the recording paper 3. Further, the set temperature can be freely controlled by the user according to the paper quality.

The blower 7 is a blower fan with an air volume of about 3 m ² / min. The discharge air flow from the air flow outlet 26 is designed so that the flow direction does not affect the ink discharge. The light-shielding cover 20 prevents the recording head 5 from being directly exposed to light radiation and prevents the recording head from being radiatively heated. Further, the transparent protective glass 22 prevents dust from adhering to the heat source lamp 17 and the reflection plate 19.

Regarding the appropriate preheating / heating temperature of the recording paper, if it exceeds 140 ° C, the recording paper may cause smoke or discoloration, and if it is less than 80 ° C, the evaporation of the recording liquid is slow and it takes a long time for the recording liquid to be fixed on the recording paper. Therefore, the print quality is poor. Therefore, it is desirable that the preheating / heating temperature of the recording medium and the attached recording liquid is 80 to 140 ° C.

Next, the present invention will be described in detail.

Among the general-purpose recording papers, in order to perform excellent printing on the high quality paper by using the above-mentioned ink jet recording apparatus, the present inventor made a study focusing on the sizing degree of the paper and the wettability of the ink.
As a result, the above-mentioned ink jet recording device preheats the paper,
It has been discovered that when the heating is carried out at 80 ° C to 14.0 ° C, high quality recording can be obtained when the contact angle showing the wettability of the ink is 20 ° or more at 80 ° C for medium-quality paper having a size degree of 5 seconds or more. . The contact angle referred to in the present invention is the angle θ between the tangent to the liquid and the solid surface at three intersecting points of gas-liquid-fixing when the liquid is dropped on the solid surface as shown in FIG. Is assumed to be part of a perfect sphere. Paper size is JISP
It can be easily measured according to 8122. The present inventor investigated the sizing degree of various medium-quality papers, and the results are shown in Table 1.

The sizing degree of commercially available medium-quality paper is 5 seconds or more, and the sizing degree of 5 seconds or less is extremely rare. With medium-quality paper of size less than 5 seconds, even if the paper is heated to 80 to 140 ° C, high quality recording cannot be obtained because the ink penetrates into the paper faster than the ink evaporates after the ink adheres to the paper. . Therefore, in the present invention, paper having a sieving degree of 5 seconds or more is useful.

In the recording method of the present invention, in order to investigate the characteristics of the ink capable of performing high-quality recording on recording paper having a size degree of 5 seconds or more, different contact angles are shown for typical medium and high quality papers shown in Table 1. When the contact angle of the ink with respect to the recording paper was 20 ° or more at 80 ° C., it was possible to print with high image quality without bleeding.

The ink composition having a contact angle of 20 ° or more at 80 ° C. with respect to the recording paper differs depending on the type of the recording paper, but is based on a solvent that prevents water dye and clogging in the outflow holes. Is. In the case of water alone, the recording paper shows a contact angle of 20 ° or more at 80 ° C., but when a dye or solvent is added, the contact angle decreases depending on the type and amount of the dye or solvent.
Therefore, in order to have a contact angle of 20 ° or more at 80 ° C, it is necessary to select a dye or solvent and appropriately adjust the amount to be mixed.

As the dye, many conventionally known dyes and pigments are effective. Particularly, what is heavy is that the dye does not contain a component such as a surfactant for decreasing the contact angle. Direct dyes, basic dyes and acid dyes are generally used as dyes, specifically CI direct black 19, CI direct CI black 22, CI direct black 38, C.
I. Direct CI Black 154, CI Direct Yellow 12, CI Direct CI Yellow 26, CI Direct Red 13, CI Direct Red 17, CI Direct Blue 78, CI Direct Blue 90, CI Assisted Black 52, CI Assisted Yellow 25, CI Assisted Thread 3
7, CI Acid Red 52, CI Acid Blue 22 and the like. If the amount of purified dye is 10% by weight, the contact angle at 80 ° C. can be maintained at 20 ° or more.

As the solvent, polyhydric alcohols and their derivatives that have been used in conventional inks for ink jet recording can be used. Among them, glycerin, diethylene glycol, ethylene glycol can be used to maintain the ink contact angle at 80 ° C of 20 ° or more. , Thiodiglycol is most suitable. When adding a solvent, if the amount is too small, the wetting ability of the ink is reduced, and the nozzle of the ink jet head is clogged. If the amount is too large, the heat fixing time on paper is delayed.
20% by weight is suitable.

Further, in the ink used in the present invention, in addition to the above-mentioned components, an antiseptic agent, an antifungal agent, a pH adjusting agent and a chelating agent can be appropriately added.

〔Example〕

Examples of the present invention will be described below. An ink having a contact angle of 20 ° or more at 80 ° C. was prepared on paper having a size degree of 5 sec or more. For comparison, paper with a size of 5 seconds or more
An ink having a contact angle of less than 20 ° at 80 ° C was prepared. Table 2 shows the composition of the prepared ink. Table 3 shows the contact angle of each ink with respect to the paper having a size of 5 sec or more.
The contact angle was measured using a contact angle meter CA-D type manufactured by Kyowa Interface Science Co., Ltd., with the surface temperature of the paper at 80 ° C.

The above ink was placed in a container, heated to about 50 ° C., sufficiently mixed and dissolved, and pressurized with a membrane filter having a pore size of 1 μm,
After degassing, it was used as ink and the heating element was heated so that the surface temperature of the recording medium was 100 ° C. by a recording device having a heating element on the fixed platen portion as shown in FIG. It was ejected as an ink droplet of μg, and adhered on the recording medium shown in Table 4 and fixed by heating and drying. Table 4 shows the results of image quality evaluation of the obtained recording state.

With ink having a contact angle of 20 ° or more at 80 ° C with paper having a size degree of 5 sec or more, high quality recording was obtained on any commercial medium-quality paper.

〔The invention's effect〕

In the ink jet recording method of the present invention in which the heat fixing temperature is 80 ° to 140 ° C., the dye or solvent is appropriately added so that the contact angle is 20 ° or more at 80 ° C. with respect to the recording paper having a size degree of 5 seconds or more. High-quality recording can be realized on various commercial medium / high-quality paper by using the ink selected and the amount mixed is adjusted. Also, the recording ink is hot-footed, so the drying property is sufficient and unfixed. There is no stain due to ink,
Furthermore, because of its high quick-drying property, when color ink jet recording is used, the color inks can be superimposed on each other, resulting in excellent color reproducibility and great effect.

[Brief description of drawings]

FIG. 1 is a schematic overall configuration diagram showing an embodiment of an ink jet recording apparatus using the ink jet recording method of the present invention. Second
The figure is a partial side view of FIG. FIG. 3 is a schematic overall configuration diagram showing a second example of a recording apparatus used in the ink jet recording method of the present invention. FIG. 4 is a partial side view of the device shown in FIG. FIG. 5 is a diagram showing a contact angle.

Claims (3)

[Claims] 1. A recording medium having a size degree of 5 seconds or more heated to 80 to 140 ° C. has a contact angle of 20 with respect to the recording medium.
An ink jet recording method, wherein recording and writing are performed with an ink having a temperature of 80 ° C. or higher (at 80 ° C.). 2. The ink jet recording method according to claim 1, wherein the solvent contained in the ink is 5 to 20% by weight. 3. The ink jet recording method according to claim 2, wherein the solvent is selected from glycerin, diethylene glycol, ethylene glycol and thiodiglycol.