JPH05116279A - Jet recording method - Google Patents

Abstract

PURPOSE:To stably perform recording by preventing the mixing of an air bubble and the damage of an apparatus by mounting an ink receiving part having the heating means connected to an ink injection means and melting solid ink and successively melting or solidifying the ink present between the ink injection means and the ink receiving part from a specific position. CONSTITUTION:A heater 2 for applying the heat energy corresponding to a recording signal is provided on the substrate 1 on the way of each nozzle 15 and a bubble is generated in a recording medium by the heat energy from the heater 2 to emit the recording medium from the emitting orifice 5 of the nozzle 15. Therefore, the bubble generated in the recording medium by the application of heat energy expands to become a predetermined size and thrusts through the emitting orifice 5 to communicate with the open air and the recording medium present between the bubble and the emitting orifice 5 is substantially entirely emitted. As a result, the volume of an emitted small droplet always becomes constant and the scattering of the mist like recording medium unnecessary for recording can be prevented and a material to be recorded or an apparatus is not contaminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a jet recording method in which a recording medium which is solid at room temperature is flown onto a recording material to perform recording.

[0002]

2. Description of the Related Art A jet recording method is one in which a droplet of a recording medium (ink) is ejected and adhered to a recording material such as paper for recording. Among the jet recording methods, the applicant of the present invention has disclosed in Japanese Patent Publication No. 61-59911 and Japanese Patent Publication No. 61-59.
As disclosed in Japanese Patent Publication No. 912 and Japanese Patent Publication No. 61-59914, an ink that is liquid at room temperature is used, and thermal energy is applied to the ink to generate bubbles in the ink, and the droplets are generated by the bubbles generated in the ink. According to the method of ejecting from the ejection port (orifice), it is possible to easily realize the high density multi-orifice of the recording head, and it is possible to record an image with high resolution and high quality at high speed.

According to the jet recording method using an ink which is liquid at room temperature, there are the following other than the above.

In Japanese Examined Patent Publication No. 54-161935, as shown in FIG.
There is disclosed a method in which 1 is gasified and the gas 32 is ejected together with the ink droplet 33 from the ejection port. According to this method, the clogging of the orifice can be prevented by ejecting the gas 32 from the nozzle. In addition, 35 is an electrode.

Further, in Japanese Patent Laid-Open No. 61-185455, a plate member 4 having a small opening 40 as shown in FIG.
1 and the heating element head 42, the liquid ink 44 filled in the minute gap 43 is heated by the heating element head (see FIG.
6 (a) and 6 (b), the generated bubbles 45 cause the ink droplets 46 to fly from the small openings 40, and the gas forming the bubbles is also ejected from the small openings 40 (FIG. 1).
6 (c)) There is a description regarding a recording method for forming a surface image on a recording paper. In Japanese Unexamined Patent Publication No. 61-249768, as shown in FIG. 17, heat energy is applied to the liquid ink 50 to form bubbles, and the ink droplets 58 are formed and fly based on the expansion force of the bubbles, and at the same time the bubbles are formed. The recording method is also described in which the gas forming the gas is ejected into the atmosphere through the large opening 52. In addition, 51 is a heating element.

Japanese Unexamined Patent Publication No. 61-197246 discloses a plurality of holes 6 formed in a film 60 as shown in FIG.
There is described a recording method in which the ink 62 filled in 1 is heated by the recording head 64 having the heating element 63 to generate bubbles 67 in the ink 62 and the ink droplets 65 fly to the recording material 65.

On the other hand, the ink used in the jet recording method is required to have contradictory characteristics that it quickly dries and fixes on a recording material, but does not easily dry in a nozzle and is unlikely to cause nozzle clogging.

To meet this requirement, conventional inks which are solid at room temperature generally contain water as a main component and a water-soluble high-boiling solvent such as glycol for the purpose of preventing drying and clogging. When recording on plain paper with such ink, the ink does not dry and fix quickly, and if you touch the character immediately after printing with your hand, the ink may get in your hand or the character may be rubbed and the print quality may deteriorate. There was a problem such as doing.

Further, since the penetrability of the ink varies greatly depending on the type of recording paper, there is a problem that only a specific recording paper can be used when the conventional ink containing water as a main component is used. Particularly in recent years, it has been required to perform good recording on so-called plain paper such as copy paper, report paper, notebooks, and notepapers that are often used in offices.

In response to this demand, US Pat. No. 5,006,006
170, JP-A-58-108271, JP-A-6-
1-83268, JP 61-159470, JP 62-48774, or JP 5
Japanese Patent Laid-Open No. 5-54368 discloses a jet recording method in which a solid hot-melt ink is heated and melted at room temperature to fly.

However, the ink that is solid at room temperature has a higher viscosity than the water-based ink that is liquid at room temperature even if it is heated and melted, and has a large resistance to the generation and expansion of bubbles. Therefore, in the conventional ejection recording method using solid ink at room temperature, even if bubbles are generated in the ink, sufficient ejection energy cannot be obtained and the ejection speed of the ink is slow,
Or the shape of bubbles became non-uniform. as a result,
The volume of ink droplets became uneven. In the worst case, the ink may not be ejected from the ejection port.

Further, in order to prevent the ink from rising on the recording material, JP-A-1-242672 and JP-A-2-51570 disclose a solid ink at room temperature to which a supercooling agent is added. Has been done.

[0013]

However, the conventional ink, which is solid at room temperature and to which the supercooling agent is added, can prevent the ink swelling, but it takes time to completely fix the ink, and it takes a sufficient amount of time to form a recorded image. If you don't have time
There is a problem in that the recorded image may stain the hands or the recorded image may be disturbed.

In addition to the above, conventional inks that are solid at room temperature used in the jet recording method include the above-mentioned JP-A-1-236.
Nos. 287, 1-263170, and 1-263171 disclose inks containing xylenol, diacetamide, and 2,2-dimethyl-1-propanol as main components, respectively. When the solid ink of No. 2 was left in a heated and melted state without recording, the physical properties of the ink changed, nozzle clogging was likely to occur, and the recorded image sometimes bleeded depending on the recording paper.

Therefore, the present applicant has filed Japanese Patent Application No. 3-249217.
Japanese Patent Laid-Open Publication No. 2004-242242 has already proposed to improve the previously known recording technique.

According to the method of Japanese Patent Application No. 3-249217,
Solves problems with previously known recording technology, such as ejection failure due to bubble accumulation in the nozzle, non-uniform volume of ejected ink droplets, and poor accuracy of ink droplet landing position on the recording material We were able to.

This application is a development of the above-mentioned Japanese Patent Application No. 3-249217, and in the recording method of Japanese Patent Application No. 3-249217, it has a heating means connected to the ink ejecting means to melt the solid ink. An ink storage unit is provided, and when the ink from the ink ejecting unit to the ink storage unit is melted or solidified, the ink is sequentially melted or solidified from a specific position. In the conventional recording method using solid ink at room temperature, when the solid ink is melted or solidified, the volume of the ink changes, which may cause bubbles to be mixed into the ink or damage to the recording head. It was

Here, the recording head, which is an ink ejecting means, is composed of an ejection orifice and a liquid flow path, and is connected to the ink storage portion through the liquid flow path ink supply pipe. Here, when the above-mentioned series of devices are uniformly heated and solidified, the solid ink generally shrinks by about 10 to 20% upon solidification, so that the solidification progresses unevenly and a means for compensating for the volume decrease is provided. Unless taken, bubbles are generated in the liquid flow path of the recording head by the reduced volume. The bubbles remain in the ink when the ink is heated and melted. In the on-demand type ink jet recording method that uses thermal energy as a discharge source, if bubbles are present near the thermal energy generating means, there are cases where ejection is stopped in accordance with a recording signal. Further, when the ink is heated and melted, the recording head may be damaged if the ink is non-uniformly melted due to the volume expansion of the ink.

Further, the present invention provides a recording method capable of preventing recording of bubbles due to melting and solidification of ink and damage to the apparatus and enabling stable recording operation.

[0020]

In the jet recording method of the present invention, a recording medium that is solid at room temperature is heated and melted, and thermal energy corresponding to a recording signal is applied to generate bubbles in the recording medium. A recording method for performing recording by ejecting the recording medium by communicating the bubbles with the outside air from an ejection port, comprising an ink storage unit having a heating unit that is connected to an ink ejection unit and melts solid ink. When the ink from the means to the ink storage portion is melted or solidified, the ink is sequentially melted or solidified from a specific position.

In the jet recording method of the present invention, as will be described later, a solid recording medium (ink) is heated and melted at room temperature (5 ° C. to 35 ° C.), and thermal energy corresponding to a recording signal is applied to the melted recording medium. Is applied to eject the ink from the ejection port (orifice) to perform recording.

When thermal energy corresponding to a recording signal is applied to the recording medium in a molten state, bubbles are generated in the recording medium, and the generation of the bubbles causes ejection energy for ejecting the recording medium from the ejection port. ..

The apparatus shown in FIG. 1 is an apparatus for carrying out the recording method of the present invention (which will be described in more detail later). The recording medium contained in the tank 20 is supplied to the recording medium contained in the tank 21. It is supplied to the recording head 23 through the path 22. The recording head shown in FIG. 2 can be used as the recording head 23. Tank 21, supply path 22 and recording head 23
In addition, the heat of the heating means 20 and 24 keeps the recording medium in the apparatus in a liquid state. The heating means 20 and 24 are 10 ° C. to 50 ° C. above the melting point of the recording medium by the temperature control means 26.
It is better to set it to a higher temperature. A print signal is sent from the drive circuit 25 to the print head 23, and ejection energy generation means (for example, a heater) of the print head 23 according to the print signal.
Is driven.

The head 23, as shown in FIG.
A wall 8 arranged in parallel above and a wall 1 forming a liquid chamber 10.
And 4 are provided. Further, the top plate 4 is arranged on the walls 8 and 14. In FIG. 2A, the top plate 4 is shown separated from the walls 8 and 14 so that the inside of the recording head can be easily seen. An ink supply port 11 is formed in the top plate 4, and the melted recording medium flows into the liquid chamber 10 through the ink supply port 11. A nozzle 15 through which a molten recording medium passes is provided between the walls 8 and a heater 2 for applying heat energy according to a recording signal to the recording medium on the substrate 1 in the middle of each nozzle 15. Is provided. Bubbles are generated on the recording medium by the heat energy from the heater 2, and the recording medium is ejected from the ejection port 5 of the nozzle 15.

In the recording method of the present invention, when the bubbles generated on the recording medium due to the application of thermal energy expand to a predetermined size, the bubbles penetrate through the ejection port 5 and communicate with the outside air.
Hereinafter, this point will be described.

FIG. 3 is a cross section of one nozzle 15 provided in the recording head 23, and FIG. 3A shows a state before foaming. First, an electric current is applied to the heating means 24 to melt the solid recording medium 3 at room temperature. After the recording medium 3 is liquefied, when a current is momentarily applied to the heater 2 to heat the recording medium 3 near the heater 2 in a pulsed manner, the recording medium 3 abruptly boils and a bubble 6 is vigorously generated to expand the recording medium 3. Start (Figure 3
(B)). The bubble 6 continues to expand, grows particularly toward the discharge port 5 side having a small inertance (inertia), and further penetrates from the discharge port 5 to communicate with the outside air (FIG. 3C). The recording medium 3 on the ejection port 5 side of the bubble 6 jumps forward due to the momentum given from the bubble 6 up to this moment, and eventually becomes an independent droplet 7.
And fly to a recording material such as paper (FIG. 3D).
After the recording medium 3 is ejected, the gap created at the tip of the nozzle 15 is filled with the new recording medium 3 due to the surface tension of the recording medium 3 at the rear and the wetting of the nozzle wall, and the state before ejection is restored.

The recording head 23 is provided at a position closer to the position of the heater 2 in the direction of the ejection port 5 than the conventional recording head. This is the most convenient configuration for communicating bubbles with the outside air. The amount of heat energy generated by the heater 2, the physical properties of the ink, the size of each part of the recording head 23 (the distance between the discharge port 5 and the heater 2, the width and height of the discharge port 5 and the nozzle 15), etc. can be selected as desired. The bubbles can be communicated with the outside air by selecting.

How close the heater 2 is to the discharge port 5 to communicate the bubbles with the outside air cannot be generally stated, but the distance from the discharge port side end of the heater 2 to the discharge port 5 (recording shown in FIG. 9). In the case of a head, the distance from the surface of the heater 2 to the ejection port 5) is preferably 5 μm or more and 80 μm or less, and more preferably 10 μm or more and 60 μm or less.

In order to ensure that the bubbles communicate with the outside air, it is preferable that the height H of the discharge port (see FIG. 2A) is equal to or smaller than the nozzle width W measured at the heater.

In order to communicate the bubbles with the outside air, the width of the heater 2 is preferably 50% to 95%, more preferably 70% to 90% of the width of the nozzle. Furthermore, heating means 2
It is preferable that the viscosity of the ink in the molten state according to No. 4 is 100 cps or less. It is also possible to make the bubbles communicate with the outside air when the bubbles have a maximum volume of 70% or more, or more preferably 80% or more of the maximum volume of the bubbles that will be reached when the bubbles do not communicate with the outside air. It is preferable.

In the present invention, since the bubbles generated in the recording medium communicate with the outside air, substantially all the recording medium between the bubbles and the discharge port 5 is discharged. Therefore, the volume of the ejected droplet is always constant. In the conventional jet recording method, bubbles generated in the recording medium do not normally communicate with the outside air, and after the maximum growth, the bubbles contract and disappear. When the bubbles generated in the recording medium do not communicate with the outside air as in the conventional case, the recording medium between the bubbles and the ejection port 5 is not entirely ejected but only partially ejected.

Further, in the jet recording method in which the bubble contracts after reaching the maximum without communicating with the outside air, even if the bubble contracts, the bubble may not completely disappear but may remain on the heater. If the small bubbles remain on the heater in this way, there is a problem that the bubbles will not be generated and grown correctly due to the small bubbles remaining on the heater when the next small droplet is ejected. In this respect, in the jet recording method of the present invention in which bubbles are communicated with the outside air, the recording medium between the bubbles and the discharge port is entirely discharged, so that small bubbles do not remain on the heater.

In the recording method of the present invention, since the inertance from the heater 2 of the recording head 23 to the ejection port 5 is small, the momentum of the generated bubble is efficiently received by the droplet 7. Therefore, it is possible to stably eject even a high-viscosity recording medium such as a recording medium that is difficult to eject by the conventional recording method, that is, a recording medium that is solid at room temperature is heated to a temperature higher than the melting point to be liquefied. Further, in the recording method of the present invention,
Since the bubbles generated in the recording medium communicate with the outside air when the recording medium is ejected, the ejection speed of the recording medium becomes very fast. For this reason, the small droplets of the recording medium accurately adhere to the target point on the recording material, and they adhere thinly without rising on the solid recording medium or the recording material. The advantage that the solid recording medium adheres thinly on the recording material is particularly effective when the recording media are superposed on the recording material to form a multicolor color image.

Further, in the present invention, when the bubbles generated from the heater 2 communicate with the outside air from the discharge port 5, it is preferable that the bubbles are communicated under the condition that the internal pressure of the bubbles is equal to or lower than the outside atmospheric pressure.

FIG. 4 is a graph showing the relationship between the foam internal pressure (graph a) and the foam volume (graph b). However, FIG.
Is a graph when bubbles do not communicate with outside air. In FIG. 4, when a pulse current is passed through the heater 2 at time T = t0, bubbles are generated in the recording medium, and the internal pressure of the bubbles rises sharply. The bubbles start to expand as soon as they occur.

The expansion of the bubbles does not end immediately after the application of the current to the heater 2 ends, but continues for a while. As a result, the internal pressure of the bubble drops sharply and becomes lower than the external pressure at time T = t1. The bubble continues to expand to some extent, then contracts and disappears.

Therefore, as shown in FIG. 5, time T = t1
If the bubbles are made to communicate with the outside air at a subsequent time, for example, at time ta, the internal pressure of the bubbles immediately before they are made to be equal to or lower than the outside atmospheric pressure.

When the bubbles are communicated with the outside air to eject small droplets under the condition that the internal pressure of the bubbles is equal to or lower than the external pressure, it is possible to prevent the mist-like recording medium unnecessary for recording from scattering, and Does not pollute the inside of the device.

Conventionally, in the jet recording method, a splashed mist-like recording medium (hereinafter referred to as splash or mist) is often ejected in addition to the small droplets for recording. According to the present invention, splash and mist can be prevented by lowering the internal pressure of the foam below the atmospheric pressure when communicating the foam with the outside air.

Since it is difficult to directly measure the internal pressure of the bubble, the magnitude relation between the internal pressure of the bubble and the external atmospheric pressure may be determined as follows.

That is, the volume Vb of the bubble from the time when the recording medium starts to bubble until the bubble communicates with the outside air is measured, and the second derivative d ² Vb / dt ² of Vb is calculated to determine the internal pressure of the bubble. It is possible to know the magnitude relationship between and the atmospheric pressure.
If d ² Vb / dt ² > 0, the internal pressure of the bubble is higher than the external pressure, and if d ² Vb / dt ² ≦ 0, the internal pressure of the bubble is the external pressure or less. Referring to FIG. 6, the foaming start T = t0 to T =
Up to t1, the internal pressure of bubbles is higher than the external pressure, d ² Vb / dt ²
> 0, the internal pressure of the bubble is equal to or lower than the external pressure until T = ta from T = t1 until the bubble communicates with the outside air, and d ² V
b / dt ² ≦ 0. As described above, the second derivative d ² of Vb
By obtaining Vb / dt ² , it is possible to know the magnitude relationship between the internal pressure of the bubble and the external pressure.

Instead of measuring the above Vb, the ejection port 5 is provided from the time when the bubble is generated until the droplet on the recording medium is ejected (between (a) and (c) in FIG. 3). The recording medium 3a (see FIG. 3B) protruding from the recording medium 3a (hereinafter referred to as the recording medium ejection portion 3a) is measured to obtain a second derivative d ² V of Vd.
It is also possible to know the magnitude relationship between the internal pressure and the external atmospheric pressure of the bubble by obtaining d / dt ² . That is, d ² Vd / dt ² >
If 0, the internal pressure of the bubble is higher than the external pressure, and d ² Vd / d
If t ² ≦ 0, the internal pressure of the bubbles is below the atmospheric pressure.

The volume of the recording medium projecting portion 3a at each time is observed by the microscope 201 while illuminating the recording medium projecting portion 3a with pulsed light using a light source 200 such as a strobe, an LED, or a laser as shown in FIG. Can be measured by That is, by causing the recording head, which ejects small droplets continuously at a constant frequency, to emit pulsed light in synchronization with the drive pulse and after a predetermined delay time, the recording medium is projected at a predetermined time. Part 3a
The projected shape of can be measured. At this time, the pulse width of the pulsed light can be more accurately measured if the pulse width is as small as possible within a range in which a sufficient amount of light can be secured for measurement. The volume of the recording medium protruding portion 3a can be converted from the measurement from one direction, but in order to obtain it more accurately, FIG.
As shown in, it is desirable to measure the projected shape of the recording medium projecting portion 3a at the same time from two directions, y and z, which are orthogonal to the x-axis and are orthogonal to the x-axis, and the ejection direction of the droplet is x. At this time, it is desirable that either the measurement direction y or z in the microscope 201 be parallel to the direction in which the ejection ports 5 are arranged.

As shown in FIGS. 8 (a) and 8 (b), the widths a (x) and b (x) of the recording medium protrusion 3a with respect to the x-coordinate value of the images measured in the two directions as described above. To measure. The volume Vd of the recording medium protruding portion 3a at a predetermined time can be obtained by calculating from these values according to the following equation. The following formula is obtained by approximating the yz cross section of the recording medium protrusion 3a with an ellipse, and can be obtained with sufficient accuracy for calculating the volume of the recording medium protrusion 3a and the bubble 6.

Vd = (π / 4) ∫a (x) · b (x) dx In this way, recording is performed after bubbles are generated by sequentially changing the lighting delay time of the pulsed light from the light source 200 from 0. It is possible to determine the change in Vd until the droplet of the medium flies.

The bubble volume Vb in the nozzle 15 can also be measured by applying the method shown in FIG. However, in order to measure the bubble volume Vb, it is necessary to configure a part of the recording head with a transparent member so that the bubble can be observed from the outside of the recording head.

An infrared LED is preferable as the pulse light source 200 because the time resolution of about 0.1 μsec is necessary to observe the behavior of the recording medium protruding portion 3a and the bubble 6, and the pulse width of the light source is 50 nsec is preferable. An infrared camera is preferably connected to the microscope 201 to take an image.

Further, ink mist and splash can be further prevented by making the bubbles communicate with the outside air through the discharge ports 5 under the condition that the first differential value of the moving speed of the bubbles toward the discharge ports 5 is negative.

Further, referring to FIG. 3B, the distance 1a from the end of the heater 2 which is the discharge energy generating means to the end on the discharge port 5 side to the end on the side opposite to the discharge port of the air bubbles is measured by the discharge of the heater. Immediately before the bubbles communicate with the outside air for a distance 1b from the end opposite to the outlet 5 to the end opposite to the bubble outlet, 1a / 1b ≧ 1, preferably 1a / 1b ≧
2, more preferably by setting 1a / 1b ≧ 4,
It is possible to shorten the time until a new recording medium is filled in the void portion formed near the ejection port after the recording medium is ejected.
Higher speed recording is possible. 1a / 1b becomes larger when the position of the heater 2 is brought closer to the discharge port 5, for example.

FIG. 9 shows another example of the recording head, in which the ejection port 5 is provided in the lateral direction of the nozzle 15.
Even when the recording head of FIG. 9 is used, the bubbles 6 communicate with the outside air as in the recording head of FIG. That is, when the recording medium 3 is melted by the heating means 24 from the state before foaming shown in FIG. 9A and the heater 2 is energized, bubbles 6 are generated on the heater 2 (FIG. 9B). Thereafter, the bubble 6 continues to expand (FIG. 9 (c)), the bubble 6 communicates with the outside air, and the droplet 7 is ejected from the ejection port 5 (FIG. 9 (d)).

Further, according to the present invention, an ink containing portion having a heating means for melting the solid ink, which is connected to the ink ejecting means, is provided, and when the ink from the ink ejecting means to the ink containing portion is melted or solidified. By sequentially melting or solidifying from a specific position, it is possible to prevent the mixing of bubbles due to the melting and solidification of ink and the damage to the apparatus, and to provide a recording method capable of stable recording operation. Will be described.

In the present invention, when the ink is melted from the ink ejecting means to the ink containing portion, or when the ink is solidified, by sequentially melting or solidifying from a specific position,
Since there is no pressure loss due to local volumetric shrinkage due to solidification, no bubbles are generated. Further, even when the ink is melted, local volume expansion does not occur, so that the recording head is not damaged.

Next, a solid recording medium (ink) at room temperature (5 ° C. to 35 ° C.) will be described.

In the present invention, as described in detail above, the recording medium which is solid at room temperature is heated and melted, and thermal energy corresponding to a recording signal is applied to the melted recording medium so that the ejection port 5 is discharged.
The ink is discharged from and recorded. Therefore, the room-temperature solid recording medium of the present invention contains at least a heat-melting solid substance and a colorant, and is an organic solvent which is liquid at room temperature such as an additive or alcohol for adjusting physical properties as necessary. And the like.

The recording medium of the present invention has a melting point of 36.degree.
It is preferably in the range of 200 ° C. When the temperature is lower than 36 ° C., the recording medium may melt depending on the change in room temperature and stain hands, and when the temperature is higher than 200 ° C., a large amount of energy is required to liquefy the recording medium.
More preferably, the melting point is desirably in the range of 36 ° C to 150 ° C.

Further, in the recording method of the present invention, recording is performed by ejecting the recording medium by the action of heat energy, so that a component having a boiling point (760 mmHg) of 150 ° C. or higher is used as a component for efficiently converting heat energy into ejection energy. Three
It is desirable to include a substance at 70 ° C.

Examples of the heat-fusible solid substance for efficiently converting the heat energy contained in the solid recording medium of the present invention into the ejection energy include acetamide, p-vanillin, o-vanillin, dibenzyl, m-acetotoluidine, and the like. Phenyl benzoate, 2,6-dimethylquinoline,
2,6-dimethoxyphenol, p-methylbenzyl alcohol, p-bromoacetone, homocatechol, 2,
3-dimethoxybenzaldehyde, 2,4-dichloroaniline, dichloroxylylene, 3,4-dichloroaniline, 4-chloro-m-cresol, p-bromophenol, dimethyl oxalate, 1-naphthol, dibutylhydroxytoluene, 1 , 3,5-trichlorobenzene, p
-Tert-pentylphenol, durene, dimethyl-p-phenylenediamine, tolan, styrene glycol, propionamide, diphenyl carbonate, 2-chloronaphthalene, acenaphthene, 2-bromonaphthalene, indole, 2-acetylpyrrole, dibenzofuran, p-
Chlorobenzyl alcohol, 2-methoxynaphthalene,
Tiglic acid, p-dibromobenzene, 9-heptadecanone, 1-tetradecanamin, 1,8-octanediamine, glutaric acid, 2,3-dimethylnaphthalene, imidazole, 2-methyl-8-hydroxyquinoline, 2-methylindole , 4-methylbiphenyl, 3,6-dimethyl-4-octyne-diol, 2,5-dimethyl-3
-Hexyne-2,5-diol, 2,5-dimethyl-2,5-hexanediol, ethylene carbonate, 1
-8-octanediol, 1,1-diethylurea, p-
Butyl hydroxybenzoate, methyl 2-hydroxynaphthoate, 8-quinolinol, stearylamine acetate, 1,3-diphenyl-1,3-propanedione, m
-Methyl nitrobenzoate, dimethyl oxalate, phthalide, 2,2-diethyl-1,3-propanediol, 8
-Quinolinol, N-tert-butylethanolamine, glycolic acid, diacetylmonooxime, acetone oxime and the like can be used alone or in combination of two or more.

Further, the following waxes and resins may be contained.

Waxes such as carnauba wax, paraffin wax, sazol wax, microcrystalline wax and ester wax, stearic acid,
Fatty acids such as palmitic acid, higher alcohols such as cetyl alcohol and stearyl alcohol, diols such as 1,8-octanediol, 1,10-decanediol and 1,12-dodecanediol, and other fatty acid esters and aromatics Aromatic compounds such as esters and aromatic alcohols, polyamide resins, polyester resins, polyurethane resins, epoxy resins, polyolefin resins, polyacrylic resins and the like.

The above-mentioned heat-fusible solid substance has various characteristics such as a substance having particularly excellent ejection characteristics, a substance having particularly excellent storability, and a substance having extremely little bleeding on the recording material, depending on the type. .. Therefore, the heat-melting solid substance can be appropriately selected from the above-mentioned heat-fusible solid substances and used for the recording medium.

In the recording medium of the present invention, if necessary, an organic solvent which is liquid at room temperature, such as 1-hexanol or 1-hexanol.
Alcohols such as heptanol and 1-octanol, polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol and triethylene glycol, other ketones, keto alcohols, amides,
Ethers and the like can also be contained. These organic solvents greatly grow bubbles generated in the recording medium.

As the colorant contained in the recording medium of the present invention, various known dyes and pigments such as direct dyes, acid dyes, basic dyes, disperse dyes, vat dyes, sulfur dyes and oil-soluble dyes are effective. Is. The dyes that can be particularly preferably used include the oil-soluble dyes described in the following Color Index.

C. I. Solvent Yellow
1,2,3,4,6,7,8,10,12,13,1
4,16,18,19,21,25,25: 1,28,
29, 30, 32, 33, 34, 36, 37, 38, 4
0, 42, 43, 44, 47, 48, 55, 56, 5
8, 60, 62, 64, 65, etc. C.I. I. Solvent Orange 1, 2, 3,
4,4: 1,5,6,7,11,16,17,19,2
0,23,25,31,32,37,37: 1,38,
40,40: 1,45,54,56,59,60,6
2, 63, 67, 68, 71, 72, 73, 74, 75
Etc. C. I. Solvent Red 1, 2, 3, 4,
7,8,13,14,17,18,19,23,24,
25, 26, 27, 29, 30, 33, 35, 37, 4
1, 42, 43, 45, 46, 47, 48, 49, 4
9: 1, 52, 68, 69, 72, 73, 74, 80,
81, etc. C.I. I. Solvent Violet 2, 3, 8,
9, 10, 11, 13, 14, 21, 21, 1: 1, 24
31, 32, 33, 34, 36, 37, 38, 45, 4
6,47 C.I. I. Solvent Blue 2, 4, 5, 7,
10, 11, 12, 22, 25, 26, 35, 36, 3
7,38,43,44,45,48,49,50,5
1, 63, 64, 66, 67, 68, 70, etc. C.I. I. Solvent Green 1, 3, 4,
5,7,8,9,20,26,28,29,30,3
2, 33 etc. C.I. I. Solvent Brown 1,1: 1,
2, 3, 4, 5, 6, 12, 19, 20, 22, 25,
28, 29, 31, 37, 38, 42, 43, 44, 4
8, 49, 52, 53, 58, etc. C.I. I. Solvent Black 3, 5, 6,
7,8,13,22,22: 1,23,26,27,2
8, 29, 33, 34, 35, 39, 40, 41, 4
2,43,45,46,47,48,49,50 etc.

Further, inorganic pigments such as calcium carbonate, barium sulfate, zinc oxide, lithopone, titanium oxide, chrome yellow, cadmium yellow, nickel titanium yellow, naples yellow, yellow iron oxide, red iron oxide, red cadmium, cadmium red, mercury cadmium sulfide, navy blue and ultramarine blue. Organic pigments such as carbon black, azo pigments, phthalocyanine pigments, triphenyl metal pigments and bad pigments are also preferably used. Color index No. of the pigment that can be preferably used. Is shown below. C. I. Pigment Yellow 1, 2, 3,
5, 12, 13, 14, 15, 17, 83 C.I. I. Vat Yellow 1, C.I. I. Pigment Orange 1, 5, 1
3, 16, 17, 24 C.I. I. Vat Orange 3 C.I. I. Pigment Red 1, 2, 3, 4,
5,7,9,12,22,23,37,38,48,4
9,50,51,53,57,58,60,63,8
1,83,88,112 C.I. I. Pigment Violet 1, 3, 1
9,23 C.I. I. Vat Violet 2 C.I. I. Pigment Blue 1, 2, 15, 1
6,17 C.I. I. Vat Blue 4 C.I. I. Pigment Green 2,7,8,1
0 C. I. Pigment Black 1

The content of the colorant is preferably 1 to 20% by weight, more preferably 3 to 15% by weight based on the recording medium.

Embodiments embodying the present invention will be described below with reference to the drawings.

[0067]

EXAMPLE FIG. 10 is a perspective view of a recording apparatus to which the present invention is applied. Reference numeral 100 denotes a recording head with an ink storage portion, which has, for example, 44 nozzles at a pitch of 16 lines / mm. Recording is performed by ejecting a recording medium, which is solid at room temperature, toward the recording material 105 by the recording head 100 with an ink storage unit.

The recording head with an ink accommodating portion shown in FIG. 10 has a tank for accommodating a recording medium and a recording head integrally formed, as will be described later in detail.

The carriage 104 includes the guide rail 10
6 and 107 are slidably supported. An endless belt 110, which is wound around a motor pulley 108 and a tension pulley 109, is fixed to the carriage 104. A carriage motor 111 is attached to the center of rotation of the motor pulley 108, and the carriage pulley 111 is driven by a scanning signal to rotate the motor pulley 108. As a result, the carriage 104 scans along the guide rails 106 and 107 as the endless belt 110 rotates. Clogged, and the carriage 104 scans according to the scan signal.

The recording material 105 is sandwiched and held by the paper feed roller 112 and the paper feed pinch roller 113, and further by the tension roller 114 and the tension pinch roller 115. The recording material 105 is fed to the paper feed roller 112 and the tension roller 114 in the direction of arrow P according to the rotation of the motor 119 via the gears 116, 117 and 118.

A platen 12 is provided at a position facing the recording head 100 with an ink containing portion through the recording material 105.
0 is provided. The distance between the recording material 105 and the ejection port (not shown) of the recording head with the ink storage portion is maintained at 0.5 mm, for example.

The ink storage portion has an ink supply port 1 at the top.
No. 01 is provided, and when the ink in the ink storage portion is running low, a columnar shape, a pellet shape,
Replenish solid state ink such as granules or powder. When the remaining amount of ink in the ink storage portion is low, it may be detected by, for example, an ink amount sensor. Next, the heating method will be described.

FIG. 11 is a view (a) and a cross-sectional view (b) seen from above the recording head with the ink containing portion. The configuration of the recording head is similar to that shown in Fig. 2. (The recording medium 3 in a molten state is supplied to the liquid chamber 121b of the head 121 through the ink supply pipe and ejected from the ejection port 121c. The method of heating the ink storage portion and the recording head will be described in the present embodiment, in which the ink is sequentially melted from the nozzles and sequentially solidified from the ink storage portion. The solid ink is started from the nozzle, and as the heat of the heating means is transferred to the heat conductor 124, the melting area spreads from the nozzle to the liquid chamber, the ink supply pipe, and the ink storage portion.
Since the volume increase when the ink is melted is constantly discharged, the ink pressure in the flow path does not rise significantly. And
When all of the ink in the recording head and ink storage section melts,
A meniscus is formed at the ejection port, and ejection can be started.

On the other hand, when the ink is solidified, the heating means 123 is kept at the lowest temperature at which the ink is liquefied. By doing so, solidification is started from the ink storage portion distant from the heating means, and the solidification region is expanded with the ink supply pipe, the liquid chamber. Next, the heating means is stopped and the nozzle is solidified. As a result, it is possible to prevent bubbles from entering the ink.

In the above-described embodiment, an example is described in which solid ink is sequentially melted from the nozzle and solidified sequentially from the ink storage portion, but the present invention is not limited to this embodiment, and the melting start position is also the same. is there. However, it is necessary to sequentially melt or solidify the adjacent portions from the starting position.

Next, an image was formed by the apparatus shown in FIG. 10 using the same recording head as that shown in FIG.

This recording head is constructed such that each liquid flow path 1 is formed on the substrate 1.
It is composed of a wall 8 arranged so as to separate 5 from each other, a transparent top plate 4 of glass in contact with the wall, and a heater 2 provided in each liquid flow path 15. The heater 2 is energized according to an image signal by an electrode (not shown). The nozzle composed of the liquid passage 15, the heater 2 and the orifice 5 has a height of 27
μm, width 40 μm, heater size is width 32 μm,
The length of the heater 2 is 40 μm, the length from the end of the heater 2 closest to the orifice 5 to the orifice 5 is 20 μm, and 44 nozzles are arranged at a density of 400 nozzles per inch.

C. I. Solvent Black 3 5.0 parts by weight Ethylene carbonate (melting point 39 ° C.) 42.5 parts by weight 1,12-dodecanediol (melting point 82 ° C.) 42.5 parts by weight

The above components were stirred in a container at 100 ° C., uniformly mixed and dissolved, filtered with a Teflon filter having a pore size of 0.45 μm while heating, and then cooled to obtain a solid ink. The ink was supplied to the recording head with the first ink supply section and the second ink supply section, and the ejection was tried. The temperature of the recording head with the second ink supply unit was maintained at 100 ° C.

The conditions for energizing the heater 2 of the recording head were an applied voltage of 16.0 V, a pulse width of 2.5 μsec and a driving frequency of 1 KHz.

Separately from this, the state of ejecting ink was observed. The observation was performed with the apparatus shown in FIG. A microscope 16 is arranged above the recording head 130 so that the inside of the nozzle 15 can be observed through a transparent top plate. A strobe 17 is attached to the microscope 16 so that the bubbling and ejection states of the recording medium can be observed only when the strobe 17 emits light. The strobe 17 is configured to emit light after a lapse of a delay time that can be arbitrarily set after the heater 2 starts applying heat by the strobe drive circuit 18 and the delay circuit 19. The recording head 130 is provided with a heating unit 24, which heats the recording head 130 to a temperature 10 ° C. to 20 ° C. higher than the melting point of the recording medium to keep the recording medium in a molten state. 28 is a head drive circuit,
29 is an external power supply. In this way, the liquid chamber 10 of the recording head 130 was filled with the molten recording medium, and the heater 2 was pulse-energized to observe bubbles generated on the heater 2 while changing the delay time of stroboscopic light emission. still,
The recording medium used in the examination of ejection characteristics did not contain a coloring agent or had a very small amount even if it contained it, depending on the ink composition described above.

First, when the state of ejecting ink from 16 continuous nozzles was observed from above the transparent top plate 4 using a pulse light source and a microscope, it was found that the bubbles were communicated with the outside air about 3 μsec after the start of foaming, and were stable. It was confirmed that the liquid was being discharged.

Then, using FIG. 10, image signals are applied to the 16 heaters 2 so as to form a checkered pattern for each pixel, and ink is ejected and attached to plain paper (commercial copy paper). The fixing time of the image was short, and even if the image was rubbed by hand 5 seconds after recording, no stain was generated.

[0084]

As is apparent from the above description, it is possible to stably discharge a recording medium that is solid at room temperature, which has been difficult to obtain stable discharge in the conventional case, and
Stable recording operation is possible by preventing bubbles from being mixed with ink due to melting and solidification of ink and damage to the apparatus. Further, the fixing on the plain paper is fast, and high-quality recording becomes possible.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of a recording apparatus used in a recording method of the present invention.

FIG. 2 is a schematic view showing an example of a recording head used in the recording apparatus shown in FIG.

FIG. 3 is a cross-sectional view showing an example of a recording head supplied with a recording medium to show the principle of the recording method of the present invention.

FIG. 4 is a graph showing an example of changes in the internal pressure of the foam and changes in the volume of the foam when the foam does not communicate with the outside air.

FIG. 5 is a graph showing an example of changes in the internal pressure of the foam and changes in the volume of the foam when the foam communicates with the outside air.

FIG. 6 is a graph showing an example of changes in the internal pressure of the foam, changes in the volume of the foam, and the rate of change in the volume of the foam when the foam communicates with the outside air.

FIG. 7 is a perspective view showing an example of a method for measuring the volume of the recording medium protruding from the ejection port.

FIG. 8 is a diagram showing an example of a measurement result by the measuring method shown in FIG.

FIG. 9 is a cross-sectional view showing another example of a recording head supplied with a recording medium in order to show the principle of the recording method of the present invention.

FIG. 10 is a perspective view showing an example of a recording apparatus used in the recording method of the present invention.

FIG. 11 is a diagram illustrating a heating method of the recording method of the present invention.

FIG. 12 is a schematic view showing an example of a recording apparatus that enables observation of a foaming state and a discharging state of a recording medium.

FIG. 13 is a cross-sectional view showing an example of a conventional recording method.

FIG. 14 is a cross-sectional view showing an example of a conventional recording method.

FIG. 15 is a cross-sectional view showing an example of a conventional recording method.

FIG. 16 is a cross-sectional view showing another example of a conventional recording method.

[Explanation of symbols]

 1 Substrate 2 Heater 3 Ink 4 Top plate 5 Orifice 6 Bubble 7 Droplet 8 Wall 10 Liquid chamber 11 Ink supply port 14 Wall 15 Nozzle 16, 201 Microscope 17 Strobe 18 Strobe drive circuit 19 Delay circuit 20, 24 Heating means 21 Ink storage Part 23 Recording head 25 Drive circuit 26 Temperature control means 27 Recording paper 100 Recording head with second ink storage part 104 Carriage 106, 107 Guide rail 120 Platen 123 Heating means 124 Thermal conductor 200 Light source

Claims (2)

[Claims] 1. A recording medium that is solid at room temperature is heated and melted, and thermal energy corresponding to a recording signal is applied to generate bubbles in the recording medium, and the bubbles are communicated with the outside air through an ejection port. A recording method for ejecting a recording medium to perform recording, comprising an ink storage unit having a heating unit that is connected to an ink ejection unit and melts solid ink, and melts ink from the ink ejection unit to the ink storage unit, or A jet recording method characterized by melting or solidifying sequentially from a specific position when solidifying. 2. When the internal pressure of the foam is below atmospheric pressure,
The jet recording method according to claim 1, wherein the bubbles communicate with outside air.