JPH03169644A - Inkjet printer - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an inkjet printer for recording output from computers, word processors, various measuring instruments, and the like.

[Prior art]

In conventional inkjet printers equipped with inkjet nozzles, prints are obtained by ejecting ink from the nozzles onto recording paper. In this case, fixing after printing is done by using an ink that easily evaporates into a solvent, or by using paper that easily absorbs the solvent, or using ink that easily absorbs the solvent into the paper and drying it naturally. It's here. On the other hand, as the demand for faster recording has increased in recent years, improvements in the performance of these materials have been required. However, there are limits to these improvements in performance; for example, if a solvent that evaporates too easily is used, problems such as clogging of the ink at the nozzle ejection port may occur. If processed paper with excellent properties is used, an increase in cost is unavoidable from the viewpoint of paper-free properties.

In addition, drying properties are particularly problematic in color recording, which requires overprinting of ink on paper.

[Problem to be solved by the invention]

The purpose of the present invention is to solve the above-mentioned problems in the prior art, and by attaching a specific heat fixing device after the inkjet device, it is possible to achieve excellent high-speed followability and excellent fixing performance even on plain paper. It is an object of the present invention to provide an inkjet printer which exhibits the following characteristics and can therefore produce inexpensive prints and also exhibits excellent drying properties even in color recording.

[Structure and operation of the invention]

The inkjet printer of the present invention combines an inkjet device having a nozzle for jetting and printing ink onto recording paper, and a fixing device consisting of a heating roller or a heating plate and a pressure roller for fixing the printed surface. That's what happens.

An example of the printer of the present invention is shown in FIG. In the figure, A is an inkjet device consisting of a multi-nozzle head 1 and an ink chamber 2, B is a fixing device consisting of a heating roller 4 with a built-in heater 3 and a pressure roller 5, P is a recording paper, 6
is the platen roller. The liquid chamber 2 is applied from the nozzle of the nozzle head 1 onto the recording paper P that is set on the platen roller 6 and advances in the direction of the arrow in synchronization with the rotation of the roller.
The ink inside is jetted and printed as a dotted line. Next, the printed paper P is immediately introduced between a heating roller 4 and a pressure roller 5 placed in pressure contact therewith, and the printed surface is thermally fixed by the heating roller 4 heated by the heater 3. Note that the surface of the heating roller 4 is coated with a fluororesin to improve mold releasability.

In the fixing device used in FIG. 1, the printed surface of the paper directly contacts the heating roller 4 side to thermally fix the paper, but the thermal fixing may also be performed from the back side of the printed surface. Figures 2 and 3 are examples of this, and the fixing device in Figure 2 has heater 1.
3 built-in heating roller 14 and pressure roller 15a.
15b, heat fixing is performed from the back side of the printed surface. Also, in Figure 3, instead of the heating roller,
This type uses a heating plate 24 with a built-in heater 23, and uses this and a pressure roller 25 to perform heat fixing from the back side of the printed surface.

In addition, there is also a type of fixing device used in FIG. 1 in which the heating roller 4 and the pressure roller 5 are switched vertically so that thermal fixing is performed from the back side.

However, in consideration of ink matching, energy saving, etc., a surface heating and pressure type fixing device as used in FIG. 1 is preferable.

Next, the ink used in the inkjet printer of the present invention will be explained.

In order to obtain high-density prints with excellent fixability using an inkjet printer, ink performance is required to have particularly good drying properties and not to cause ink clogging at the nozzle outlet. Another reason is that bubbles are less likely to be generated in the ink. As an ink having these properties, an oil-based ink using an organic solvent is suitable. Note that, in the case of water-based ink, there is a problem in that bubbles are particularly likely to occur in the ink flow path, and it is difficult to remove the bubbles. The oil-based ink suitable for the present invention contains, in addition to the main solvent, a coloring dye, a fixing resin, a wetting agent and auxiliary solvent, and a silicone oil-based auxiliary solvent.

The organic solvent serving as the main solvent satisfies conditions such as having a low vapor pressure to prevent the formation of bubbles and high solubility for dyes and wetting agents, and is preferably an aliphatic hydrocarbon. Specifically, octane, nonane, decane, undecane, dodecane,
Aliphatic hydrocarbons having straight or side chains, such as tridecane and tetradecane, are suitable, and these may be used alone or in combination. The amount added is 30 to 70 wt%, preferably 30 to 50 wt% of the total amount of ink to obtain a low viscosity ink.
% is appropriate.

The wetting agent (also auxiliary solvent) lowers the vapor pressure of the entire ink to slow down the evaporation of other solvents in the ink, and also prevents nozzle clogging by dissolving the dye. Therefore, liquid fatty acids or derivatives thereof, such as polyethylene glycol ethers, are preferably used as wetting agents, since organic solvents with particularly high solubility for dyes and low vapor pressure are preferred. Specific examples include oleic acid, linoleic acid, polyethylene glycol monooleyl ether, and the like. The appropriate amount of the wetting agent added is 10 to 30 wt%. If the amount is less than this range, clogging in the nozzle tends to occur, and if it is too much, the viscosity of the ink as a whole increases, which is not preferable.

As a co-solvent, silicone oil is used to greatly increase the amount of wetting agent added and improve its dissolving effect. When silicone oil is not added, the amount of wetting agent added is limited to a range of 5 to 30 wt% due to increased viscosity, but when silicone oil is added, the amount of wetting agent added is limited to 10 to 60 wt%.
can be increased to The requirements for silicone oil are that it is compatible with the main solvent and wetting agent, and that it significantly increases the solubility of oil-soluble dyes without increasing the viscosity even when the amount of wetting agent is increased. Dimethyl silicone (KF-96L manufactured by Shin-Etsu Silicone), methylphenyl silicone (KF-56, KF-58 manufactured by Shin-Etsu), cyclic dimethyl polysiloxane (KF-994, KF-
995) etc.

As the dye, an oil-soluble dye is used that has high solubility in the above-mentioned main solvent and auxiliary solvent and can stably exist in the ink for a long period of time. Examples of such dyes include Nigrosine Base EX. HR-2L,
AP-2, AP-8, AY-8, 185L, 308L,
7BL (all manufactured by Orient Chemical), etc. It is better to add a large amount of dye to obtain sufficient contrast, but if it becomes saturated, the nozzle is likely to become clogged. It is desirable that the amount does not exceed 20 wt%.

As the fixing resin, a thermally crosslinkable resin is used which has high solubility in the above-mentioned main solvent and auxiliary solvent and is compatible with the dye. Specifically, alkyd resin (Penkosol J-820 manufactured by Dainippon Ink Chemical Co., Ltd.). Rosin-modified maleic acid resin (Betsukasite F-231 manufactured by the same company). Rosin modified polyester (RM-1000 manufactured by Hitachi Chemical Co., Ltd.)
, styrenated alkyd resin (Styresol 4440 manufactured by Dainippon Ink Chemical Co., Ltd.), and the like. The amount of these fixing resins added is 10 to 50 wt%, preferably lO to 25 wt%.
is appropriate.

Note that the ink manufacturing method is, for example, as follows. First, a certain amount of auxiliary solvents is placed in a container equipped with a stirrer and a reflux device, and while stirring, the oil-soluble dye is gradually added. The container is gradually heated, and when the dye is sufficiently dissolved, the main solvent is added and stirring is continued for 6 hours while keeping the temperature inside the container constant at 80°C. After cooling to room temperature, the fixing resin is dissolved, and after being left for about 24 hours, the desired ink is obtained by filtering with a milliteflon filter of about 1 μm. [Examples] The present invention will be explained below using examples. Note that all percentages are by weight.

Example l Nigrosine base HR-2L 6.5% Nigrosine base AP-2 3.5% Leic acid
20% Pesocozole J-820
20% silicone oil 1
Using 0% n-dodecane 40%, the viscosity was 6.8 cp (20°C) and the surface tension was 33. Odyn
I made e/cm ink. This is filled into the multi-nozzle head (prototype manufactured by Borisulfone) 1 from the liquid chamber 2 of the inkjet device A shown in FIG. When the image was thermally fixed by passing it between a heating roller 4 and a pressure roller 5 at ±20° C., a clear and high-quality fixed black record was obtained.

The drying time of the ink on the recording paper after printing was within 5 seconds, indicating good quick-drying properties. In addition, the above-mentioned ink was placed in a borosilicate glass container, the container was tightly capped, and the container was left at a high temperature of 70°C for 3 months, but no insoluble matter was observed in the ink. Furthermore, its low vapor pressure makes it possible to significantly suppress the generation of bubbles in the flow path at high temperatures compared to conventional water-based inks, and even if bubbles do occur, they can be removed with a simple operation. It was possible.

Next, using the inkjet printer shown in FIG. 1, printing was performed for 30 minutes in the same manner for fixing, and then the nozzle was left open to the atmosphere for about 100 hours.

When the ink of this example was ejected again, high-density ejected prints were obtained without any clogging. The ink also had good storage stability at high temperatures; when left in an environment of 70°C for 8 months, the ink was always stable and no insoluble matter was observed.

Example 2 Nigrosine base HR-2L 10% Nigrosine base AP-2 0.5% Leic acid
20% Betsukasite F-231
20% silicone oil 15
Viscosity using % Isopar H 34, 5%? ．． Ocp (20℃), surface tension 30.0d
I made ink of yne/cm.

When printing and fixing were performed using this ink in the same manner as in Example 1, similarly good results were obtained. Also, this ink showed excellent performance similar to the ink of Example 1. Example 3 Nigrosine base HR-2L 13.5% Nigrosine base AP-2 0.5% oleic acid
21%RM-1.000
20% silicone oil 1
Using 5% Isopar L 30%, viscosity 6, Sep (20°C), surface tension 31.5 dyn
I made e/Cm ink.

When printing and fixing were performed using this ink in the same manner as in Example 1, similarly good t,1 results were obtained.

Also, this ink showed excellent performance similar to the ink of Example 1.

Example 4 Nigrosine base HR-2L 13.5% Nigrosine base AP-2 0.5% oleic acid
21% styresol 4440
20% silicone oil
Viscosity 4.1 using 15% Isopar L 30%. Ocp (20°C), surface tension 33, 4
I made an ink of dyne/cm.

When printing and fixing were performed using this ink in the same manner as in Example 1, similarly good results were obtained. Also, this ink showed excellent performance similar to the ink of Example 1.

[Function and effect of the invention]

The inkjet printer of the present invention is equipped with a heat fixing device consisting of a heating roller or a heating plate and a pressure roller after the inkjet printing device so that it can immediately heat fix images after printing on the recording paper, so it has high-speed followability. It has excellent drying properties even in color recording. It also exhibits excellent fixing properties on plain paper, so
We can provide inexpensive prints. Furthermore, since the heat fixing device as described above is used, it is possible to efficiently apply heat to the recording paper, and the consumption of excess f, l-heat can be suppressed as much as possible.

Furthermore, the method of simply passing the recording paper over a heating plate or the method of passing it through a high-temperature atmosphere differs in the evaporation of moisture in the recording paper, and this unevenness causes differential shrinkage of the paper, causing the recording paper to become uneven. However, the heating and pressure fixing method such as the apparatus of the present invention can uniformly heat the recording paper, and in combination with the fact that gloss is produced by the pressure of the pressure roller, the finish is good.

On the other hand, if oil-based ink is used as the ink, the nozzle will not clog even when printing at high density, and it also tends to generate air bubbles as seen with water-based ink, and it is difficult to remove air bubbles that form in the flow path. This problem can also be improved, making it ideal for inkjet recording. Furthermore, if a thermally crosslinkable resin is used as the resin component of the ink, heating during fixing increases not only the bonding force between the inks but also the bonding force of the ink to the paper, thereby preventing the ink from adhering to the surface of the heating roller or heating plate. As a result, high-quality fixed records with no print offset can be obtained. Similarly, if a thermal crosslinking resin is used, printing can be fixed without completely evaporating the solvent present inside the ink, so the fixing temperature can be kept low, which is economical, and the solvent vapor It is possible to keep the odor of ink to a low level and completely eliminate the odor of ink.Furthermore, due to its chemical stability and property that it hardly evaporates at room temperature and evaporates only during heat fixing,
Good results can be obtained in terms of storage stability as an ink, stability as a printing device, and quality of printed matter.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an example of a printer of the present invention, and FIGS. 2 and 3 are sectional views of an example of a fixing device used in the printer of the present invention. 1...Multi-nozzle head 2...Ink liquid chamber 3
, 13.23... Heater 4, l4... Heating roller 5. 15a, +5b...pressure roller
25... Heating plate A... Inkjet device B...
・Fixing device P... Recording paper funeral map P Figure 2 Figure 3

Claims (1)

[Scope of Claims] 1. An inkjet device having a nozzle for jetting and printing ink onto recording paper, and a fixing device comprising a heating roller or a heating plate and a pressure roller for fixing the printed surface. An inkjet printer that combines 2. Claim 1, characterized in that the ink is an oil-based ink whose main components are an oil-soluble dye, a thermally crosslinkable resin, a liquid fatty acid or its derivative, an aliphatic hydrocarbon, and a silicone oil, and which has a viscosity of 10 cps or less. printer.