JPH09295408A - Recording apparatus having ink tank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To supply ink at a high speed and to reduce the residual amt. of ink by inserting a porous member into an ink tank so that the direction small in fluid resistance of the porous member itself is allowed to coincide with the supply direction of the ink in the ink tank. SOLUTION: A porous member 2 is inserted into an ink tank 3 so that the direction 1 small, in fluid resistance of the porous member 2 is allowed to coincide with the supply direction of the ink in the ink tank 3. As the porous member, polyurethane foam is economical and, since many spaces are formed as compared with the direction vertical to a foaming direction, polyurethane foam is easy to pass a liquid and suitable characteristically. Especially, a polyether type urethane foam is pref. because it is reduced in the elution to aq. ink and has durability. By using aq. ink to which a surfactant is added in addition to a coloring agent and a wetting agent, the wettability to the porous member and other ink passages is enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording apparatus having an ink tank such as an inkjet recording apparatus, and more particularly to a recording apparatus having an ink tank capable of storing and supplying ink capable of high speed recording.

[0002]

2. Description of the Related Art Inkjet printers that eject ink droplets from nozzles to write characters and the like on recording paper according to recording information have been put to practical use as small-sized and inexpensive recording apparatuses. Among them, it is general to mount an ink tank containing a porous body impregnated with ink on a carriage and reciprocate integrally with a recording head along a recording paper.

[0003]

However, in recent years, there has been a strong demand for high speed printing of this ink jet printer, and the number of nozzles in the recording head has been increased and the ink ejection frequency has been increased. Therefore, the flow rate of the ink from the ink tank to the recording head is significantly increased, and therefore, there is a problem that the supply of the ink is not in time and the ejection failure occurs. Further, as a conventional problem of the ink tank configured to absorb the ink in the porous body, a large amount of ink is not supplied to the recording head,
There is a problem that it remains in the porous body and is wasted.

On the other hand, regarding the porous body, Japanese Patent Laid-Open No. 63-8
7242 discloses the use of polyurethane foam for the porous body, and JP-A-5-16381 discloses that the compression direction of the porous body is designated to secure the ink holding force and stabilize the ink supply. In JP-A-5-16385, the amount of pores and the compression ratio of the porous body are designated to secure the ink holding force. In JP-A-5-229134, a porous body having a thin film wall is used. It has been proposed to supply the device at low cost, but none of them sufficiently satisfies the above-mentioned problems.

The present invention has been made in view of the above circumstances. First, it is possible to obtain a recording apparatus having an ink tank capable of supplying ink at a high speed and having a small amount of remaining ink. To obtain a recording device using a porous body that is inexpensive and has excellent characteristics as the porous body, and thirdly, a porous body that can be stably stored and supplied for a long period of time with little deterioration particularly to aqueous ink. It is an object of the present invention to obtain a recording apparatus using the above, and fourthly, to obtain a recording apparatus which also works as an effective means for supplying the ink at a high speed and reducing the remaining ink amount.

[0006]

According to the present invention, firstly, in a recording apparatus having an ink tank containing a porous material to be impregnated with ink, the porous material is provided in the ink tank. There is provided a recording apparatus having an ink tank, which is characterized in that a direction in which the fluid resistance of the body itself is small and an ink supply direction in the ink tank are aligned and inserted. Secondly, in the recording apparatus having the ink tank described in the first item, polyurethane foam is used as the porous body, and the polyurethane foam is made to match the foaming direction of the polyurethane foam and the ink supply direction in the ink tank. There is provided a recording device having an ink tank characterized by inserting a foam into the ink tank. Thirdly, in the recording device having the ink tank described in the above second, there is provided a recording device having the ink tank, wherein the polyurethane foam has an ether bond. Fourth, in the recording device having the ink tank described in the first, second, or third, the porous body in the ink tank is impregnated with an aqueous ink containing a surfactant. A recording apparatus having a characteristic ink tank. Fifth, the first,
The recording apparatus having the ink tank described in the first or third is an inkjet recording apparatus that supplies ink to the recording head from the ink tank and ejects ink droplets from the nozzles of the recording head to perform recording on recording paper. A recording apparatus having an ink tank is provided.

As described above, according to the recording apparatus of the present invention, when the porous body is inserted into the ink tank, the direction in which the fluid resistance of the porous body itself is small and the ink supply direction in the ink tank are aligned with each other. With such a structure, the speed of the ink passing through the inside of the porous body is increased, and it is possible to supply the ink from the inside of the ink tank to the outside of the ink tank in a short time. It is possible to reduce the amount of ink remaining on the base material.

Incidentally, in the case of polyurethane foam which is often used as a porous body, after mixing and foaming main raw materials such as polyether polyol, isocyanate, foaming agent and catalyst, the thin film wall is removed by the post-treatment of the explosion method. It is manufactured through steps. Among them, in the foaming step, since the foaming continuously progresses in one direction, the structure of the manufactured polyurethane foam porous body, when observed in an enlarged manner, faces the foaming direction as shown in FIGS. 2 and 3. The structure is like a stack of standing rugby balls. Therefore, as is clear from comparison between FIG. 2 and FIG. 3, the fluid resistance when a liquid is passed through the polyurethane foam is higher in the foaming direction (FIG. 2) than in the direction perpendicular to the foaming direction (FIG. 3). Significantly less.

Further, by using the polyether-based urethane foam, the elution of the substance into the water-based ink is small and the deterioration of the water-based ink can be suppressed. This is because ester-based urethane foam easily breaks the ester bond in the molecular structure, hydrolyzes easily in alkaline ink, and loses its mechanical strength, whereas the ether-based urethane foam dissolves in the ink. Because it is chemically stable against the above ink.

When a water-based ink containing a surfactant is used as the ink to be impregnated into the porous body, the wettability of the ink with respect to the porous body and other ink flow paths can be improved.

[0011]

Embodiments of the present invention will be described below. FIG. 1 shows the insertion direction of the porous body 2. As shown in FIG. 1, the porous body 2 is inserted into the ink tank 3 so that the direction 1 having a small fluid resistance matches the direction of ink supply in the ink tank 3. Polyurethane foam is economical as the porous body, and as is clear from FIGS. 2 and 3, a larger space is formed in the foaming direction (FIG. 2) than in the direction perpendicular to the foaming direction (FIG. 3). Therefore, it is easy for liquid to pass through and is suitable in terms of characteristics. Among them, the polyether urethane foam is preferable because it is less liable to the aqueous ink and has durability as described above. Further, by using an aqueous ink in which a colorant, a wetting agent, and a surfactant are further added to the ink used, the wettability with respect to the porous body and other ink flow paths is improved, and the ink supply capability is improved.

[0012]

The present invention will be described more specifically with reference to the following examples. The percentages shown below are based on weight.

[Embodiment] In FIG. 1, Everlite SF (polyether urethane foam) manufactured by Bridgestone Corporation is used as the porous body 2, and the foaming direction of the Everlite SF and the ink supply direction in the ink tank 3 are made to coincide with each other. The Everlight SF was inserted into the ink tank 3. Then, a lid (not shown) was bonded and filled with ink. As the ink, the composition of the following formulation was dissolved by stirring at 60 ° C., and after standing to cool at room temperature, lithium hydroxide 10 was added to adjust the pH to 8.5.
% Aqueous solution and filtered through a Teflon filter having a pore diameter of 0.22 μm to prepare ink 1. [Ink formulation A] Projet Fast Black 23% manufactured by Zeneca Co., Ltd. 5% Glycerol 5% N-hydroxyethylpyrrolidone 5% Polyoxyethylene alkylphenyl ether 0.1% Sodium dehydroacetate 0.2% Deionized water remaining amount

[Comparative Example] Ink was prepared in the same manner as in Example 1 except that the foaming direction of the Everlight SF used in Example 1 and the ink supply direction were shifted by 90 ° and the Everlight SF was inserted into the ink tank 3. Filled.

Reference Example An ink was filled in an ink tank 3 in exactly the same manner as in Example 1 except that the ink formulation A used was replaced with the following ink formulation B. [Ink formulation B] Projet Fast Black 3% manufactured by Zeneca Co., Ltd. 3% Glycerol 5% N-hydroxyethylpyrrolidone 5% Sodium dehydroacetate 0.2% Ion-exchanged water Remaining amount

The ink tanks of Examples, Comparative Examples and Reference Examples obtained as described above were set in an ink jet printer in order, and solid printing was performed on the entire surface of A4 size recording paper under the following printing conditions, and the printing evaluation was performed. went. The ink tank obtained in Example 1 was allowed to stand at room temperature for 6 months and then printed under the following printing conditions 2 to evaluate printing. Table 1 shows the evaluation results.

Printing condition 1 Number of ejection nozzles: 128, ink ejection frequency: 4 kHz Printing condition 2: Number of ejection nozzles: 128, ink ejection frequency: 16 kHz Evaluation ◯: Printing can be performed on the entire surface of A4 recording paper without image distortion Δ: During printing The image is faint or missing from the image x: Cannot be printed

[0018]

[Table 1] It can be seen from Table 1 that the examples can be normally printed by high-speed printing at 16 kHz, whereas the comparative examples and reference examples can be printed at a low speed of 4 kHz, but at 16 kHz, ink supply is not in time and the image is disturbed. You know that it will happen. Further, it can be seen that the example can perform high-speed printing even after being left for 6 months.

Experiment on Remaining Ink Further, when the ink tank was filled with 33 ml of ink and the dischargeable amount was measured, the following results were obtained. Foaming direction: Horizontal Filling amount: 33 ml Remaining amount after discharging: 9 ml (27%) Foaming direction: Vertical Filling amount: 33 ml Remaining amount after discharging: 7 ml (21%) Starting from this example, 2 ml of ink is used extra I see what I can do.

[0020]

As described above, by inserting the porous body in the ink tank so that the direction in which the fluid resistance of the porous body itself is small and the ink supply direction in the ink tank coincide with each other, it is possible to increase the number of nozzles and height. Even if the ejection frequency is printed, ejection failure due to insufficient ink supply does not occur. In addition, the remaining amount of ink also decreases. Also, by using polyurethane foam as the porous body, it is possible to obtain the ink tank at a high speed and with a small amount of ink remaining, at a low cost. Furthermore, by using a polyether-based urethane foam as the polyurethane foam, deterioration with respect to the water-based ink is small, and elution of impurities is small. Therefore, it is possible to store and supply the ink without changing the physical properties of the ink for a long period of time. Further, by using a water-based ink in which a surfactant is added to the ink filled in the ink tank, it is possible to improve the wettability of the ink with respect to the porous body and other ink flow paths,
In combination with the effect of the direction of insertion of the porous body, the ink supply capacity is further improved, and even when printing with multiple nozzles and high ejection frequency, ejection failure due to insufficient ink supply does not occur, and ink remaining amount is also Less. It goes without saying that the ink tank of the present invention described above can be applied not only to an inkjet recording apparatus but also to any apparatus as long as it is an apparatus for recording while supplying ink using liquid ink.

[Brief description of drawings]

FIG. 1 is an explanatory view of an ink tank according to the present invention.

FIG. 2 is a drawing in which a polyether-based urethane foam used in the present invention is observed from a foaming direction.

FIG. 3 is a drawing in which a polyether urethane foam used in the present invention is observed from a direction perpendicular to a foaming direction.

[Explanation of symbols]

1 Direction in which fluid resistance of porous body is small or direction of foaming of urethane foam 2 Porous body or polyether urethane foam 3 Ink tank 4 Ink outlet

 ─────────────────────────────────────────────────── --- Continuation of the front page (72) Inventor Akiko Konishi 1-3-3 Nakamagome, Ota-ku, Tokyo Stock company Ricoh Co., Ltd. (72) Hirotaka Mochizuki 1-3-6 Nakamagome, Ota-ku, Tokyo Shares In Ricoh Company (72) Inventor Masayuki Oyano 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Ricoh (72) Inventor Ikuko Yamada 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Ricoh

Claims (5)

[Claims] 1. A recording apparatus having an ink tank containing a porous body to be impregnated with ink, wherein the porous body is provided in the ink tank in a direction in which the fluid resistance of the porous body itself is small and the ink in the ink tank. A recording apparatus having an ink tank, wherein the recording apparatus is inserted so as to match the supply direction. 2. A recording apparatus having an ink tank according to claim 1, wherein polyurethane foam is used as the porous body, and the direction of foaming of the polyurethane foam and the direction of ink supply in the ink tank are made to coincide with each other. A recording apparatus having an ink tank, wherein the recording medium is inserted into the ink tank. 3. A recording apparatus having an ink tank according to claim 2, wherein the polyurethane foam has an ether bond. 4. A recording apparatus having the ink tank according to claim 1, 2 or 3, wherein a porous body in the ink tank is impregnated with an aqueous ink containing a surfactant. Recording device having. 5. A recording apparatus having the ink tank according to claim 1, 2, 3 or 4, wherein ink is supplied from the ink tank to the recording head and ink droplets are ejected from nozzles of the recording head to record on recording paper. A recording apparatus having an ink tank, which is an inkjet recording apparatus for performing.