JPH02145341A - Printer - Google Patents

Abstract

PURPOSE:To realize hot-melt ink for an ink jet printer, having high printing quality without overheating by employing ink in which magnetic properties are imparted to the hot-melt ink. CONSTITUTION:Hot-melt is attracted by a magnetic force in a pressure chamber 101 filled with water. Since the ink is insoluble with water, they are separated into two layers, and the surface of a heat source 104 is covered with water. In order to inject ink from a head, an electric pulse is applied to the source 104, and film bubbles of steam are generated on the surface of the source. The bubbles are adiabatically expanded to inject the ink in the chamber together with the water from an orifice 107. Heat is derived from the injected ink, steam bubbles are spontaneously erased, injected ink droplets are adhered on a recording sheet face, and solidified to form a hot-melt print.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a printing device using hot-melt ink for inkjet printers, which is melted at high temperatures during recording and has magnetic properties added to it. be.

[Conventional technology] Inkjet printers have many advantages in printing technology, such as noiseless, high-speed printing, high-quality printing, and color printing. Due to the principle of recording, the print quality and print drying time are affected by the type of recording paper, and therefore, when recording on poor quality paper, the print quality deteriorates significantly.

As a means of solving these drawbacks, by using hot-melt ink, the ink, which has a melting point higher than room temperature, solidifies in uniform dot diameters on the paper regardless of the type of recording paper. It is a general fact that it is possible to print on any quality of paper. In addition, such ink compositions include U, S, Patent
There are natural waxes shown in No. 4390369, synthetic waxes shown in JP-A No. 62-295973, and the like.

[Problems to be Solved by the Invention] Print quality, which is considered to be a drawback of inkjet printers, can be solved by using solid ink.

However, there was no good way to spray ink droplets, and its widespread use was delayed.

With the conventional piezo system, maintenance of the printer is not easy, such as inability to print due to air bubbles or inability to print due to clogging of ink. Furthermore, when making a line printer using an inkjet method, it is thought that there is a limit to the ability to use multiple ink heads with the piezo method.

In addition, in the bubble jet method, air bubbles are generated near the nozzle and the ink is ejected using the force of the bubbles, so printing failures due to ink clogging and the like are less likely to occur. Furthermore, the head is a combination of a thermal head and an inkjet, and thin film technology can be applied, making it easy to create high-density, long nozzles.

However, hot melt inks are usually made by dissolving or dispersing dyes or pigments as colorants in a wax-based solvent. The melting point of the wax used as a solvent is 5
0°C to 250°C is preferred.

This is because if the melting point is lower than this, the ink printed on the recording paper will melt at room temperature, staining the paper or degrading the print quality. The boiling point of these waxes is very high, often exceeding their decomposition temperature.
In other words, it is impossible to generate bubbles without changing the composition by heating. Therefore, it has conventionally been thought that it is impossible to eject hot melt ink using a bubble jet method.

The objects of the present invention are: 1) Practical use of hot melt ink with good printing quality, 2) Satisfying 1) and preventing ink clogging and inability to print due to air bubbles, 3) Satisfying 1) and 2). The purpose is to enable a low-cost line head.

[Means for Solving Problem U] The printing device of the present invention includes: (1) a mechanism for heating and melting hot melt ink jetted from an inkjet device at a temperature higher than room temperature, a heat source, an orifice, and a magnetic source; and an ink supply path for supplying the hot melt ink to the orifice, the pressure chamber is filled with a fluid other than the hot melt ink, and the hot melt ink has magnetic properties. It is characterized by the use of
(2) A liquid in which the hot melt ink is insoluble or hardly soluble is used as the fluid.

(3) Water is used as the fluid.

(4) The fluid is characterized in that a property modifier such as a viscosity modifier or a surface tension modifier is added to water as the fluid.

(5) At least 1V% as the hot melt ink
It is characterized by using a hot melt ink composition containing the above magnetic powder.

Hereinafter, the details of the present invention will be shown by examples.

[Embodiment] FIG. 1 is a schematic sectional view showing one embodiment of a head section of an inkjet printer according to the present invention.

FIG. 1(a) is a sectional view taken along a plane parallel to the flying direction of ink droplets, and FIG. 1(b) is a sectional view taken along a plane perpendicular to the flying direction of ink droplets.

In the figure, 101 is a pressure chamber, and a magnetic force source 103 and a heat source 104 are placed on both sides of the pressure chamber.

The inside of the pressure chamber is filled with a fluid 105 in which the hot melt ink is insoluble or hardly soluble. Water is an example of this fluid. In this specification, a case will be described in which water is used, but the present invention is not limited to water only. In FIG. 1(a), the left side of the head section is connected to an ink tank through an ink supply path, and the right side is an orifice. The hot melt ink is heated by a heating mechanism (not shown) and becomes a fluid with an appropriate viscosity. The viscosity at this time is preferably 20 cP or less.

Due to its magnetic properties, the hot melt ink receives an attractive force from the magnetic force source 103, is fixed in the vicinity of the magnetic force source, and further moves to the orifice at the tip of the head section due to the attractive force. In order to efficiently move the ink by this magnetic force, it is desirable that the magnetic force source is capable of creating a magnetic gradient.

Specifically, an electromagnet was used to generate a magnetic gradient.

Hot melt ink is attracted by magnetic force into a pressure chamber filled with water, and hot melt ink and water coexist in the pressure chamber, but since hot melt ink is insoluble in water, they separate into two layers. However, the surface of the heat source 104 was covered with water.

In order to eject ink from this head, the heat source (1
Apply an electric pulse to 04). By rapidly heating the heat source, film bubbles of water vapor are generated on the surface of the heat source before the foaming nuclei pre-existing in the water are activated.
This bubble expands adiabatically and causes the hot melt ink in the pressure chamber to be ejected from the orifice (107) along with water.
Heating is stopped before the bubbles reach their maximum size, allowing the vapor bubbles to naturally disappear after losing heat. The ejected ink droplets adhere to the surface of the recording paper, where they lose heat and solidify to form a hot melt print. In the conventional bubble jet method, bubbles are generated in the ink itself, and the pressure at that time is used as the ink ejection force. In order to generate bubbles in a controlled manner, it is necessary to instantaneously heat the ink to bring it into a superheated state and generate film bubbles. As a result, the ink in contact with the heater surface is overheated to approximately 300 degrees, causing chemical reactions such as thermal decomposition of the ink itself and impurities in the ink, causing ko
Ink ejection was sometimes impossible due to a phenomenon called gation. However, in the present invention, the fluid in direct contact with the heat source of the pressure chamber is not ink, but hot melt ink is an insoluble or poorly soluble fluid, for example, water or water with a small amount of property modifier added. This phenomenon did not occur and reliability was high.

The ejected ink passes through an ink supply path and is replenished from an ink tank. The water ejected together with the hot melt ink is also replenished through the water supply path. Moisture that adheres to the paper dries and is lost. A portion of the ink is absorbed by the paper surface, but since hot melt ink is inherently insoluble or poorly soluble in water, it is unlikely that the ink will bleed.

FIG. 2 is a schematic sectional view showing another embodiment of the head section of the inkjet printer according to the present invention. Figure 2 (
FIG. 2A is a cross-sectional view taken along a plane parallel to the flying direction of the ink droplets, and FIG. 2B is a cross-sectional view taken along a plane parallel to the flying direction of the ink droplets. In FIG. 2(b), the dimensions of the pressure chamber 201 are made vertically long, and the opening area of the orifice portion is made smaller than in the case of FIG. 1, so that only the hot melt ink reaches the orifice and forms a meniscus. . The ink was ejected by applying voltage to the heat source as in the case of FIG. With this configuration, only hot melt ink could be ejected from the orifice.

As mentioned above, ejecting hot melt ink together with water does not have a negative effect on printing quality, but it also eliminates the need for the liquid used to generate bubbles to be simply thrown away, thereby reducing waste. Furthermore, since only the hot melt ink now forms a meniscus, there is also the effect that the ink supply rate is improved due to capillary action at the orifice.

The present invention has a simple structure and extremely high productivity. In the structural diagrams of the head shown in Figs. 1 and 2,
In order to simplify the explanation, an example of a single nozzle is shown, but it is also easy to integrate this into a multi-nozzle. As an example of the process at this time, first, a substrate on which a heat source is integrated is formed by an N film process. Another substrate is processed by means such as etching to form a multi-flow path in which pressure chambers, orifices, ink supply paths, etc. are integrated. A multi-nozzle head is completed by laminating a multi-channel substrate on a substrate with an integrated heat source (Figure 1 (b)).
102. FIG. 2(b) 202).

The multi-channel substrate can be made not only by etching but also by plastic molding.

In the above embodiments, a case has been described in which water is used as the fluid in the pressure chamber of the printing apparatus of the present invention, but fluids other than water can of course be used.

Furthermore, when magnetic powder is included to impart magnetic properties to the hot melt ink, the composition of the magnetic powder is not limited to the composition, Curie point, etc. for the purpose of the invention to impart magnetic properties to the ink. The role of the magnetic powder is to move the ink magnetically and to fix it. The moving speed and fixing force of the ink are proportional to the magnitude of magnetization of the magnetic powder contained in a unit volume of the ink, and increase as the 7% of the magnetic powder increases.

In this embodiment, an example is shown in which thermal energy is used as a mechanism for ejecting ink. This thermal energy is generated by supplying thermal conversion energy to a thermal conversion body. - As an example, we have shown the case where electrical energy is used as thermal conversion energy, but other examples include electromagnetic wave energy, laser light energy, electron beam energy, etc.

In the above embodiment, an example was shown in which paper is used as the recording material by the printing apparatus of the present invention, but it can also be used for printing on transparent OHP sheets, metal surfaces, cloth, etc. was completed.

As described above, the printing device according to the present invention can be applied to general printing devices including inkjet printers, as well as painting devices and textile printing devices, and of course can also be used for the output of copy machines. . Furthermore, it can be applied not only to printing but also to image formation, etc.

[Effects of the Invention] As described above, the greatest effect of the present invention is that it has become possible to practically use hot melt ink that can be printed on any recording material and has high printing quality. be.

Furthermore, since a pressure chamber equipped with a heat source as a mechanism for ejecting ink and an ink supply path for supplying the melted hot melt ink to the orifice of the pressure chamber are individually provided, the mechanism for generating pressure is free. The intensity has increased. In particular, although it is thought that miniaturization and lengthening are easy,
Another major effect is that the bubble jet method, which had problems with reliability because the ink itself had to be heated, can now be used with extremely high reliability.

In addition, by using magnetic ink, 1) ink can be supplied magnetically, increasing the degree of freedom in ink supply;
The ink supply speed was improved by using it together with ink supply by capillary action.

2) Since the ink could be held by magnetic force, the two-layer separation of the hot melt ink and the fluid other than the hot melt ink could be completed. In other words, the two-layer interface could be easily fixed without resorting to means such as balancing the surface tension between the two or adjusting the channel design.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing one embodiment of the head section of an inkjet printer according to the present invention. FIG. 1(a) is a sectional view taken along a plane parallel to the flying direction of ink droplets, and FIG. 1(b) is a sectional view taken along a plane perpendicular to the flying direction of ink droplets. FIG. 2 is a schematic sectional view showing another embodiment of the head section of the inkjet printer according to the present invention. Figure 2 (
FIG. 2A is a sectional view taken along a plane parallel to the flying direction of ink droplets, and FIG. 2B is a sectional view taken along a plane perpendicular to the flying direction of ink droplets. 101. 102. 103, i04. 105. 106. 107, ・Pressure chamber, adhesive surface, magnetic source, heat source, water, hot melt ink, orifice Applicant Seiko Epson Corporation Representative Patent Attorney Kizobe Suzuki (4th 1 person) (a) (b)

Claims (5)

[Claims] (1) A mechanism for heating and melting hot melt ink jetted from an inkjet device at a temperature higher than room temperature, a pressure chamber including a heat source, an orifice, and a magnetic source, and supplying the hot melt ink to the orifice. 1. A printing apparatus, characterized in that the pressure chamber is filled with a fluid other than the hot-melt ink, and the hot-melt ink has magnetic properties. (2) The printing apparatus according to claim 1, wherein a liquid in which hot melt ink is insoluble or hardly soluble is used as the fluid. (3) The printing apparatus according to claim 1, wherein water is used as the fluid. (4) The printing apparatus according to claim 3, wherein a property modifier such as a viscosity modifier or a surface tension modifier is added to water as the fluid. (5) At least 1V% as the hot melt ink
The printing apparatus according to claim 1, characterized in that a hot melt ink composition containing the above magnetic powder is used.