JPS62288043A - Inkjet recording device - Google Patents

Abstract

PURPOSE:To perform high image quality recording regardless of the quality of recording paper, by adhering a recording liquid droplet to the preheated recording paper in a state where it rises by the surface tension of said droplet and holding the recording paper to a heated state to rapidly evaporate the liquid component in the recording liquid droplet to fix a solvent and dye mainly remaining onto the recording paper. CONSTITUTION:A large number of recording liquid emitting orifices 13 a provided to a recording head 5 and, while a dot image is formed on recording paper 3 by a recording liquid emitting means such as a piezoelectric element, an electric field and charging controls and hot ink jet recording. A heat generator 12 is provided to the back surface not opposed to the recording head 5 of a fixed platen 1. The recording paper 3 is slid with the fixed platen 1 heated by the heat generator 12, and preheated and heated over the period before and after ink jet recording by contact heat transmission and the recording liquid recorded is rapidly dried immediately after the adhesion of the recording liquid to a recording surface, and the unnecessary blur of a dot or wrinkles of the paper and contamination by the unfixed recording liquid are prevented to obtain a good printing state. A paper presser 7 prevents the levitation of the recording paper 3 and closely adheres the recording paper 3 to the fixed platen 1 to enhance heat conductive effect. Further, the curling of the recording paper is removed by a decurling roller 14.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention is an inkjet recording method that enables high-quality recording on commercially available general-purpose recording paper such as medium-quality paper regardless of paper quality. Regarding equipment.

[Prior Art] Representative examples of inkjet recording apparatuses having means for heating and drying recording liquid include Japanese Patent Laid-Open Nos. 55-69464 and 55-8.
No. 4670, etc., which heats the entire platen with a heating element installed inside the platen to heat the recording paper from the back side, drying the recording liquid and eliminating unnecessary bleeding, paper wrinkles, and stains caused by unfixed recording liquid. This is an effective means for preventing such problems and realizing high-resolution and high-quality image recording.

[Problems to be solved by the invention] However, during the manufacturing process of commercially available medium-quality paper, which is a typical general-purpose recording paper, there are problems with the configuration of raw material valves, mixed fillers, wire parts of paper machines, size presses, etc. Since the properties vary widely depending on the processing method, the inkjet recording characteristics differ not only depending on the manufacturer and production lot, but also on the front and back sides of the same paper. That is, since the absorbency of the recording liquid differs, the print quality is greatly influenced by the paper quality. The above-mentioned prior art relates only to the recording paper heating means and structure of the platen section, and is technically insufficient to realize high-quality inkjet recording on various general-purpose recording papers regardless of the paper quality.

Another means of accelerating the drying of the recording liquid is to use a strong alkaline solution in the recording liquid. In inkjet recording that ejects droplets (hereinafter referred to as thermal inkjet recording),
Strong alkaline recording liquids are difficult to apply because they significantly reduce the durability of the thin film that generates the thermal energy.

[Means for Solving the Problems] The present invention solves these problems by ejecting recording liquid from a recording liquid ejection port to form a dot image on a recording paper facing the recording liquid ejection port. In an inkjet recording apparatus, the recording droplets are deposited on a preheated recording paper in a swollen state due to their surface tension, and the recording paper is heated and held to maintain the attached state even after inkjet recording. The liquid component contained in the liquid component is rapidly vaporized to reduce the volume of the recording droplet, and the solvent and dye mainly remaining on the recording paper are fixed onto the recording paper.

The solvent component other than the dye contained in the recording liquid and mainly remaining on the recording paper during the heat fixing is glycerin, diethylene glycol, thiodiglycol, or a mixture thereof, and the total amount mixed in the recording liquid is 5 to 20%. It is preferable.

Further, it is desirable that the recording liquid has a pH of 6 to 10, and the preheating and heating temperature of the recording paper is desirably higher than the lowest boiling temperature of the solvent contained in the recording liquid and lower than 140°C.

The above-mentioned commercially available and medium-quality papers include Japanese Industrial Standards Printing Paper A and 8, Japanese Industrial Standards Writing and Drawing Paper (letter paper, drawing paper, Ghent paper, etc.), Japanese Industrial Standards Coated Paper (coated paper, etc.), etc. The present invention can also be applied to lower-grade recording paper such as medium-quality paper or lower quality paper.

Direct dyes for inkjet recording include c, r, Direct Black 19 C, 1, Direct Black 22 C, 1, Direct Black 154 C, 1, Direct Yellow 12 C, 1, Direct Yellow 26 C,! , Direct Red 13 C,1, Direct Red 17 C,1, Direct Blue 8 C,1, Direct Blue 90, etc.As acid dyes, C,1, Acid Black 52 C,1, Acid Yellow 17 C,1 , Acid Yellow 25 C,1, Acid Red 37 C,1, Acid Red 52 C,1, Acid Blue 22, etc.

[Function] According to the present invention, the recording droplets adhering to the preheated and heated general-purpose recording paper are difficult to diffuse and absorb onto the recording paper surface due to capillary phenomenon due to surface tension, and the droplets rise to the top of the recording paper. Immediately after adhering to the recording paper, heating and drying begins while the adhesion state is maintained, and the volume of the recording droplet rapidly decreases and the solvent and dye remaining on the recording paper are removed without vaporization. By being fixed on the recording paper, it is possible to perform high-quality inkjet recording without using a strong alkaline recording liquid and without causing unnecessary recording liquid bleeding or paper wrinkles.

[Example code] The present invention will be explained in detail based on examples.

First, the recording liquid suitable for the inkjet recording apparatus of the present invention will be explained.

First, various recording liquids as described below were produced as prototypes.

Recording liquid a> Dye...C, 1, Direct black 1541% Solvent...water *Remaining amount <Recording liquid b
〉 Dye...C,1, Direct Black 1541% Solvent...Glycerin 10% Water
*Remaining amount <B self-recorded liquid C> Dye...C, 1, Direct black 221% solvent.
...Glycerin 10% methyl alcohol 10% water
*Remaining amount recording liquid d> Dye...C,1, Direct Black 154 1% Solvent...thiodiglycol 10% water
*Remaining amount <Recording liquid e> Dye...C, 1, Direct Black 1541% Solvent...Diethylene glycol 10% water
*Remaining amount <Recording liquid f> Dye...C, 1, Direct Black 1541% Solvent...Triethylene glycol 10% water
*Remaining amount <Recording liquid g> Dye...C, 1, Direct Black 1541% Solvent...Polyethylene glycol 10% water
*Remaining amount recording liquid h> Dye...C, 1, Direct Black 1541% Solvent...Glycerin 5% Diethylene glycol 3% Thiodiglycol 2% Water *Remaining amount recording liquid i> Dye...C, 1. Direct Black 1541% Solvent: Glycerin 5% Polyethylene Glycol 5% Water *Remaining amount [Note] In addition to the above ingredients, each recording liquid also contains 0% Proxel as a preservative.
2% was added.

Commercially available medium-quality paper shown in Table 1 was preheated and heated to room temperature or 130° C., and inkjet recording was performed using the recording liquid. Inkjet recording uses a piezoelectric control method to control the recording liquid to about 11
Recording droplets with a diameter of 00 JJ were ejected at a speed of about 4 m/see and adhered to the recording paper.

Table 1 Table 2 shows the results of examining the recording conditions.

Table 2 From the results shown in Table 2, each recording liquid has extremely better drying properties when recorded on recording paper that has been preheated to 130°C. There was no phenomenon in which the paper surface was stained with unfixed recording liquid or stuck to hands when touched.

Furthermore, with the recording liquids aSb1C% ds e and h, better prints with less bleeding than prints at room temperature were obtained. When using other recording liquids, it was possible to read the recorded characters although there was some smearing compared to the above-mentioned recording liquid.

Also, when recording images on high-density recording paper at room temperature,
There were cases where wrinkles appeared on the recording paper and the wrinkles did not recover even if the recording liquid dried after recording, and unfixed recording liquid flowed on the paper surface and smeared the recorded image. These problems did not occur when recording on paper.

From the above results, recording liquid a to which no solvent was added and recording liquids a, b, c, to which glycerin, diethylene glycol, thiodiglycol, or a mixture thereof was added as a solvent component,
It was found that d, e and h are effective recording liquids for this recording apparatus.

Next, the recording paper preheating/heating temperature appropriate for drying and fixing the recording liquid will be described. The recording liquid C was inkjet recorded on the recording paper shown in Table 1 that had been preheated and heated to various temperatures, and the recording conditions were examined. Table 3 shows the results.

Table 3: If the preheating/heating temperature of the recording paper exceeds 140°C, the recording paper and recording liquid will emit smoke during recording, and if it exceeds 160°C, the moisture in the recording paper will be completely removed and it may break when bent. . Further, if the temperature is lower than 80° C., the drying properties of the recording liquid are poor, it takes time for the recording liquid to be fixed on the recording paper, and the print quality is poor.

Therefore, the recording paper preheating/heating temperature is higher than the lowest boiling point of the solvent contained in the recording liquid (in the case of recording liquid C, the boiling point of methyl alcohol).
It has been found that a temperature of 140° C. or lower is desirable.

Furthermore, the appropriate mixing amount of the solvent was studied as follows. Table 4 shows the results of inkjet recording in the same manner as in Table 3, using several types of recording liquids prepared by varying the amount of solvent mixed in based on the recording liquid.

Table 4 [Note] *Only glycerin is mixed as a solvent.

*The mixing amount of dye for each recording liquid is C and I.

Direct black 1541%.

*Added 0.2% Proxel as a preservative.

*The rest is water.

*The amount of solvent mixed θ% is the same as @liquid a.

From the results shown in Table 2 above, it was found that the recording liquid is applicable to the inkjet recording apparatus of the present invention. However, the recording liquid for inkjet recording must contain a high boiling point solvent in order to prevent clogging of the recording liquid ejection port. It is well known that it is necessary to mix. Therefore, in Table 4, recording liquid a and recording liquid with a solvent content of less than 5% are applicable, but not practical.

In Table 4, even if the amount of solvent mixed was increased, there was almost no effect on the t compression. When the recording liquid ejection port is clogged with 5 to 10% solvent, recording liquid ejection failure occurs when left for a long time, but the drying property is good and it can be used for a while, and there was no problem of ejection failure when the solvent was mixed in an amount of 5 to 10%. If the amount of solvent mixed exceeds 20%, the drying properties of the recording liquid will be poor and immediate drying properties will not be obtained.

Similar results were obtained even when the amount of solvent mixed in was varied based on recording liquids c, d, e, and h, and it was found that the amount of solvent mixed in was preferably 5 to 20%.

In addition, in order to investigate the relationship between the PH degree of the recording liquid and the print quality,
The following recording liquid was prepared based on the recording liquid sample, and inkjet recording was performed in the same manner as in Table 2. The results are shown in Table 5.

<Recording liquid j> C,1, Acid Black 52 1% Glycerin 10% Acetic acid 1% Proxel 0.2% Water Remaining amount PH = 5.5 Recording liquid 1 (> C,1, Acid Black 52 1% Glycerin 10% Proxel 0.2% water
Remaining amount PH = 6 <Recording liquid 1> C, 1, Direct Black 191% Glycerin 10% Proxel 0.2% Water
Remaining amount P H = 8 Recording liquid m> C, 1, Direct black 1541% glycerin
10% Proxel 0.2% water
Remaining amount PH=lO Recording liquid n> C, 1, Direct black 1541% glycerin
10% potassium hydroxide 0.2% Proxel
0.2% water
Remaining amount PH=11.2 Table 5 As in Table 2, bleeding and recording liquid drying properties are better when inkjet recording is performed on recording paper preheated to 130°C. At this time, if the pH of the recording liquid is less than 6, bleeding will occur and various parts of the apparatus will be oxidized, which is not practical.

In addition, at a pH of 11 or more, the recording liquid is strongly alkaline, so it erodes the recording paper fibers and is absorbed into the paper surface, causing bleeding. From the above results, it was found that the pH of the recording liquid is preferably about 6 to 10.

Second, the structure of an inkjet recording apparatus using the above-mentioned recording liquid will be explained.

FIG. 1 is a schematic overall configuration diagram showing an embodiment of an inkjet recording apparatus of the present invention.

In FIG. 1, the recording head 5 is guided by the carriage guide 6 and moves in the direction of the arrow (■) while receiving the recording liquid from the recording liquid tank 15 through the recording liquid supply vibrator 16, and the paper feed roller 2 and the guide roller 4 Inkjet recording is performed on recording paper that is fed intermittently with a line feed in synchronization with the recording head 5.

In FIG. 2, the recording head 5 has a plurality of recording liquid ejection ports 1.
3 is provided, and a dot image is formed on the recording paper 3 by means of recording liquid discharge means such as piezoelectric element control, electric field control, charge control, and thermal ink jet recording. The recording head 5 of this example is a thermal inkjet recording head equipped with 24 recording liquid ejection ports in one vertical column with an interval of 180 dpi, and approximately 9
Recording droplets with a diameter of 0.01 Jm are ejected.

The fixed platen 1 is suitably made of a material with good thermal diffusion, such as an aluminum alloy or a thermally conductive plastic material, and in this example, an aluminum alloy plate with an average thickness of 1 mm and a size of about 250 mm x 30 mm is used. A heating element 12 is provided on the back surface of the fixed platen 1 that does not face the recording head 5, as shown in FIG. The heating element 12 has a rated voltage of 30V and an average resistance value of 2 at normal temperature.
It is appropriate to arrange five 2Ω PTC thermistors for heaters evenly, or to use a sheath heater of about 100V and 250W.

Returning to FIG. 2, the recording paper 3 is in sliding contact with the fixed platen 1 heated by the heating element 12, and is preheated to the above temperature by contact heat transfer before and after inkjet recording, and the recording liquid recorded by the inkjet recording is heated. Immediately after adhering to the recording surface, it dries quickly to eliminate unnecessary dots and paper wrinkles.
To obtain a good printing condition by preventing stains caused by unfixed recording liquid. The paper presser 7 prevents the recording paper 3 from floating and also brings the recording paper 3 into close contact with the fixed platen 1 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 3 is wound around a curl removing roller 14 after inkjet recording, and the curl is removed by curling it in the opposite direction to the curling direction, and the recording paper 3 is taken out in a flat state. be able to.

Using the inkjet recording apparatus of this example, recording liquids b, c, d, and es ks can be applied to Table 1 and various other commercially available and medium-quality papers with a pre-recording preheating time of 4 seconds and a post-recording heating time of 4 seconds.
When we inkjet recorded 1% paper, we were able to record high-quality images regardless of the paper quality and the front and back sides of the paper, and the recording ink dried sufficiently, eliminating paper wrinkles, unnecessary dot smearing, and unfixed recording fluid. There were no stains.

In addition, as in this example, even if a near-neutral recording liquid such as 1 is used as the recording liquid in thermal inkjet recording, high print quality and sufficient recording liquid drying properties can be obtained, and the recording liquid ejected from the recording head. It does not chemically impair the durability of the thin film resistor circuit. Furthermore, since the recording liquid in the recording head section is heated by the heating drying means for the purpose of drying the recording liquid, the viscosity of the recording liquid in a low-temperature environment is reduced, and the recording liquid ejection performance is improved. Inkjet recording was able to reduce the thermal energy required to change the state for ejecting the recording liquid by about 5%.

Although this example is a monochrome inkjet recording apparatus, it is obvious that the present invention can also be applied to a color inkjet recording apparatus.

[Effects of the Invention] As described above, according to the inkjet recording apparatus of the present invention, high-quality inkjet recording can be performed on commercially available general-purpose recording paper such as medium-quality paper regardless of the paper quality.

In addition to improving print quality, it also improves recording liquid ejection performance in low-temperature environments, and in particular, when applied to thermal inkjet recording, chemically improves the durability of the thin film resistor circuit in the recording head that discharges recording liquid. In addition, the energy required for ejecting the recording liquid can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a schematic overall configuration diagram showing an embodiment of an inkjet recording apparatus of the present invention. FIG. 2 is a partial side view of FIG. 1. 4...Guide roller 6...Carriage guide 8...Paper feed gear or higher

Claims (4)

[Claims] (1) In an inkjet recording device that ejects recording liquid from a recording liquid ejection port to form a dot image on a recording paper facing the recording liquid ejection port, recording liquid droplets are raised on the preheated recording paper by their surface tension. The liquid components contained in the recording droplets are rapidly vaporized to reduce the volume of the recording droplets, while maintaining the adhesive state by heating the recording paper even after inkjet recording. An inkjet recording apparatus characterized in that the solvent and dye mainly remaining on the recording paper are fixed onto the recording paper. (2) The solvent component other than the dye contained in the recording liquid and mainly remaining on the recording paper during the heat fixing is glycerin, diethylene glycol, thiodiglycol, or a mixture thereof, and the total amount mixed in the recording liquid is 5 to 20%. %
An inkjet recording apparatus according to claim 1, characterized in that: (3) The inkjet recording apparatus according to claim 1, wherein the recording liquid has a pH of 6 to 10. (4) The inkjet recording apparatus according to claim 1, wherein the preheating and heating temperature of the recording paper is higher than the lowest boiling temperature of a solvent contained in the recording liquid and lower than 140°C.