JPH04323045A - Inkjet printing method and printing device - 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]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-impact printing method and printing apparatus, and more particularly to an inkjet printing method and printing apparatus that perform printing by ejecting ink to form ink droplets on a substrate.

[0002] In this specification, "printing" is used as a concept that includes printing and printing.

0003

BACKGROUND OF THE INVENTION With the development of the information society, high-speed printing technology has been rapidly developed. For high-speed printing of documents and images that do not require multiple copies, non-impact printing, which is different from conventional printing techniques in which ink is transferred to the surface of a printing medium by mechanical or mechanical means, is becoming mainstream. Non-impact printing methods include inkjet methods, thermal transfer methods, and electrophotographic methods. Each method has its own advantages and disadvantages. The inkjet method, along with the electrophotographic method, is characterized by high quality printing and quietness, and is rapidly becoming popular.

FIG. 7 shows inkjet printing according to the prior art. FIG. 7(A) shows a state in which ink is ejected from the nozzle, and FIG. 7(B) shows a state in which the ejected ink droplets adhere to paper to form a print.

In FIG. 7A, a nozzle 52 has a small inner diameter of, for example, 30 to 100 μm, and ejects liquid ink 51 to form ink droplets 53 . Printing is performed by making the ink droplets 53 adhere to the surfaces of opposing sheets of paper 54 disposed opposite each other as shown in FIG. 7(B).

As a mechanism for forming droplets and ejecting them onto paper, there is a method in which a piezoelectric element is provided in an ink reservoir immediately before the nozzle 52, and the volume of the ink reservoir is instantaneously changed by applying a pulse voltage to eject ink. A method is used in which a heating electrode is provided inside the nozzle to instantaneously heat the ink, evaporate the ink, generate high-pressure bubbles, and eject the ink.

Water-soluble or oil-soluble dyes and pigments are used as colorants for inks. In addition to these colorants, ink also contains solvents (dispersants), fixing agents, stabilizers,
Contains humectants, etc.

[0008] After the jet ink is transferred to the printing material, it is desirable that the jet ink is immediately fixed on the surface of the printing material. However, the fast immobilization speed means that it is easy to immobilize even at the open end of the nozzle, causing clogging. Conventionally, countermeasures against clogging have been taken by adopting a print head mechanism that seals the nozzles when not in use.

[0009] Furthermore, pigment-based inks tend to cause nozzle clogging and have not been used much in the past. Therefore, conventional jet inks have mainly used water-soluble dyes as colorants. However, such ink has the disadvantage that printing may bleed depending on the paper used. This problem can be solved by using special paper, but this will result in an increase in running costs.

0010

[Problem to be solved by the invention] As explained above,
Ink has components such as dyes or pigments, and is in a liquid phase, but when dried, solid phase components remain. While not printing,
When the ink 51 is exposed to the air at the nozzle opening, the liquid phase component evaporates and the solid phase component remains, which tends to cause nozzle clogging. In addition, dye-based inks are often used because pigments are difficult to use, but depending on the type of paper used, dye-based inks may bleed into the paper, have low light fastness and water resistance, and are pure black dyes. There are problems such as not having one.

[0011] An object of the present invention is to provide an inkjet printing method in which clogging is less likely to occur due to ink drying, and a printing apparatus for carrying out the method.

Another object of the present invention is to provide an inkjet printing method with fewer restrictions on ink components and a printing apparatus for carrying out the method.

[0013]

[Means for Solving the Problems] FIG. 1 shows the principle of the present invention. Printing is performed by dividing the ink components into a plurality of components 1, 2, . . . , and mixing these components 1, 2, .

[0014] Each ink component divided into a plurality of components is
It may be separated into a solid phase and a liquid phase, or it may be a plurality of liquid phase components that can be mixed to form an ink.

[0015]

[Operation] By dividing the ink components into a plurality of components, clogging due to ink drying can be prevented and reduced.

[0016] Furthermore, it becomes possible to use various materials as ink components.

[0017]

[Examples] The present invention will be explained below with reference to Examples.

Various pigments can be used, but
For example, Hansa Yellow 10G, Pigment Yellow 14, and Pigment Yellow 16 are used for yellow, Permanent Orange and Vulcan Orange are used for orange, and Permanent Rubin F6B and Watching Red Sr are used for red.
Salt, Watching Red Ba salt, cyanine blue for indigo, cyanine green for green, nithol violet, violet lake for purple, titanium oxide for white, carbon black, aniline black, cyanine black, iron black, etc. for black. can be used. As the dye, an azo dye or the like can be used. For example, indigo carmine, methylene blue, Nile blue A, methylene green, indigo as cyan, amaranth, new coccin, xylene red, rhodamine 5G extra, Congo red as magenta,
Thioindigo, bat scarlet GG, fluorescein as yellow, flavanthrone, azobenzene,
Direct deep black EX, C1 as black
There are Acid Black 1, C1 Acid Black C3, etc.

The main components of pigment-based ink are pigment, dispersion medium, and fixing agent. Water or an organic solvent is used as a dispersion medium, and a soluble polymer or the like is used as a fixing agent.

FIG. 2 shows that pigments, fixing agents, etc. are in a solid phase;
Examples will be shown in which the dispersion medium and the like are liquids.

As shown in FIG. 2, a solid phase component 7 containing a pigment 4 and a fixing agent 6 is prepared, while a liquid phase component 8 such as a dispersion medium is prepared.
Prepare separately. When printing, these solid phase components 7
and liquid phase component 8 are mixed. The fixing agent 6 is dissolved in the liquid phase component 8 and the pigment 5 is suspended in the liquid phase component 8. The ink droplets 9 thus formed are deposited onto the printing substrate and fix the pigment 5.

The solid phase component 7 undergoes almost no change during non-printing. Although the volume of the liquid phase component 8 decreases due to evaporation, almost no side effects occur due to evaporation, such as when it is formed only from a solvent. When the solid phase component and the liquid phase component are mixed to form ink, droplets momentarily pass through the nozzle. Therefore, nozzle clogging can be effectively prevented.

Clogging of inkjet nozzles occurs particularly when the fixing agent solidifies. FIG. 3 shows a printing method using liquid phase/liquid phase ink components. For example, a dispersion containing a pigment as an ink component and a monomer which is a precursor of a polymer serving as a fixing agent, and a solution containing a catalyst for initiating a polymerization reaction are prepared separately. These liquid phase components 8a, 8
b is ejected by the liquid ejectors 10a and 10b, respectively, and is sent to the main nozzle 1 through the sub nozzles 11a and 11b.
3 and injected from the tip of the main nozzle 13. When the two liquid phase components are mixed, a polymerization reaction occurs due to the contact between the polymerization initiation catalyst and the monomer, and a polymer serving as a fixing agent is formed. As in the previous embodiment, the liquid phase in which the ink is formed momentarily passes through the noise.

In the case of this embodiment, the two liquid phase components are concentrated by evaporation, but since the polymeric fixing agent has not yet been formed, clogging is unlikely to occur. By ejecting both liquid components synchronously, it is possible to mix both components and form ink droplets only when necessary. Each liquid ejector 10
The device includes a piezoelectric element or a heating element, and ejects a predetermined amount of liquid phase component only when driven by an input signal.

[0025] The smaller the size of the droplet, the greater the surface energy. Therefore, when droplets with a diameter of, for example, several tens of micrometers are used, the droplets grow into larger droplets with smaller surface energy due to collisions between the droplets. At this time, small droplets are rarely scattered. Note that a nozzle cleaning function may be provided.

Note that both liquid phase components may be sprayed separately and mixed on paper. It is also possible to mix solid particles and liquid droplets on the substrate.

FIG. 4 shows a printing method according to another embodiment of the invention. In this embodiment, the ink components are separated into a solid phase component and a liquid phase component. The solid phase component contains a pigment, a fixing agent, etc., and is prepared as a microcapsule whose surface is electrically charged. The microcapsule reservoir is connected to the sub-nozzle 14 via a conveyance pipe. The liquid component includes a dispersion medium and the like, is accommodated in a liquid component reservoir, and is connected to another sub-nozzle 15. These sub nozzles 14 and 15 are in the mixing chamber 2
0, and each component can be supplied into the mixing chamber 20. Further, an electrode 30 is provided on the surface facing the sub-nozzle 14 that supplies the charged solid phase component particles 7a, and the electrode 30 is connected to the DC voltage source 17 via the switch means 18.
It is connected to the. When the solid phase component particles 7a are negatively charged, the DC voltage source 17 is capable of applying a positive voltage to the electrode 30.

[0028] In the preparatory stage when printing is not yet performed, the switch means 18 is kept in an off (open) state. The solid phase component 7a and the liquid phase component 8 are not supplied.

When printing, as shown in FIG. 4(B), the switch means 18 is closed, a positive voltage is applied to the electrode 30, and the charged solid phase component particles 7a are transferred to the sub nozzle 14.
suction from. The liquid phase component 8 is ejected as droplets 19 from the sub nozzle 15 . The droplet 19 is ejected and the solid phase component particles 7 are traveling towards the electrode 30 while flying in the air.
A is taken into the droplet. In this way, contact between the solid phase component and the liquid phase component is initiated.

[0030] The solid phase component and the liquid phase component are mixed to form ink, and the ink droplets 9 are jetted forward from the main nozzle 16, as shown in FIG. 4(C). Printing is performed by placing a printing medium such as paper in front of this. Note that after a predetermined amount of ink has been ejected, the switch means 18 is opened as shown in FIG. 4(C), and the supply of the solid phase component particles 7a is stopped. The supply of liquid phase component 8 is also stopped. As described above, the sub-noise 15 includes a piezoelectric element and a foaming heater, and is driven in synchronization with the switch means 18.

Note that the charge polarity of the solid phase component particles can also be reversed. In that case, the polarity of the voltage applied to the electrode 30 is also reversed.

[0032] When the solid phase component and the liquid phase component are mixed immediately before printing and deposited on the printing substrate, it is preferable that the desired solid phase component is dissolved and dispersed in the liquid phase component immediately after mixing.

[0033] When a solid phase substance is made into fine particles and the diameter of the particles is reduced, the physical and chemical properties of the material change considerably when the diameter reaches a certain level or less. In order to perform precise printing, it is effective to use ultrafine pigment particles with extremely small particle sizes (for example, several tens of nanometers or less). In printing, ultrafine particles have characteristics such as (1) high dispersibility in solvents such as water, (2) narrow particle size distribution, and (3) high surface activity due to large specific surface area. . Therefore, ultrafine particles have significantly improved miscibility and wettability with liquids compared to bulk materials. When separating an ink component into a solid phase component and a liquid phase component and instantaneously mixing them before printing, if the solid phase component is formed of ultrafine particles, it becomes easy to instantly mix the ink component with the liquid phase component.

[0034] Techniques for producing ultrafine particles include methods such as a pulverization method, a spray drying method, and an evaporation method in a gas, and the evaporation method in a gas is particularly preferred. When ultrafine particles are formed using the evaporation method in purified gas, the ultrafine particles are created in a dry and clean atmosphere, so it is difficult for impurities to get mixed in with the ultrafine particles that are created.By vaporizing the raw material at a specific temperature, Effects such as being able to improve the purity of the collected ultrafine particles can also be obtained. Commercially available dyes and pigments are mixed with impurities and additives, but by creating ultrafine particles of dyes and pigments using the in-gas evaporation method, it is also possible to improve their purity at the same time. Further, when creating ultrafine particles in an inert gas atmosphere, the particle size can also be controlled by adjusting the inert gas pressure.

FIG. 5 shows another embodiment of the present invention. In this example, ultrafine pigment particles are used as the solid phase component. Because ultrafine particles have high surface activity, they also tend to aggregate depending on their handling. The aerosol generator 21 aerosolizes ultrafine particles, suspends them in the air, and supplies them into the mixing chamber 20 from the sub-nozzle 14 . Sub nozzle 14
The aerosol of ultrafine pigment particles ejected from the nozzle is sucked into the collection pipe 22 located directly below the nozzle by the airflow. The collected ultrafine pigment particles are circulated to the aerosol generator 21 again. In this way, the pigment ultrafine particles are constantly circulated through the mixing chamber 20.

When the printing signal is supplied, the piezoelectric element, heating element, etc. are excited, and the liquid component 8 is ejected from the sub-nozzle 15 into the mixing chamber 20. The ejected droplets 19 intersect with the aerosol containing ultrafine pigment particles and take in the ultrafine pigment particles. The ultrafine pigment particles immediately mix into the liquid phase components to form ink droplets. The ink droplets thus formed are ejected from the main nozzle 16 and collide with a printing medium such as paper to form a print.

According to this embodiment, by using ultrafine particles as the solid phase component, various advantages based on the characteristics of ultrafine particles can be obtained.

FIG. 6 shows another embodiment of the invention. In this embodiment, a heater 24 is provided downstream of the aerosol generator 21 . Primary particles of a solid phase component such as a pigment are supplied to an aerosol generator 21 to generate an aerosol of the solid phase component, which is ejected from a sub nozzle 14.
It is circulated through a recovery tube 22 by a circulator.

When there is no printing signal, the heater 24 is not heated, and the solid phase component primary particles 7 purify the circulation path.

When the print signal is supplied, the heater 24 disposed between the aerosol generator 21 and the sub-nozzle 14
is excited, and the solid phase component particles 7 supplied from the aerosol generator 21 are heated and evaporated. Evaporated pigment etc. 2
5 is gradually cooled while passing through the conveying pipe in the air current, and solidifies to form ultrafine particles. These ultrafine particles gradually increase in diameter by repeating collisions between particles, and form predetermined ultrafine particles that are secondary particles of the pigment. The aerosol of ultrafine particles thus formed is ejected from the sub-nozzle 14 into the mixer 20.

Furthermore, when the print signal is supplied, the liquid ejector connected to the sub-nozzle 15 that supplies the liquid phase component 8 is excited and jets droplets 19 of the liquid phase component. The droplets 19 intersect with the aerosol passage zone, thereby capturing ultrafine particles such as pigments into the droplets 19 to form ink droplets. The ink droplets thus formed are ejected through the main nozzle 16 onto the substrate.

According to this embodiment, the solid phase component is made into ultrafine particles only during printing, so the primary particles do not need to be ultrafine particles, and the solid phase component can be easily handled.

Furthermore, since the solid phase component is made into ultrafine particles during printing, the advantages of ultrafine particles and effects such as improved purity can be obtained.

In the examples shown in FIGS. 4, 5, and 6, the flow rate, flow distribution, particle size, etc. of solid particles, the flight speed of droplets, trajectory, etc. Particles are selected for entrapment. Furthermore, the internal shape of the nozzle can be modified.

[0045] Alternatively, a mechanism may be adopted in which mixed droplets are first formed and then air is immediately sent to the main nozzle to push out the droplets, or the droplets are ejected after mixing.

The present invention has been described above with reference to several embodiments, but in all of them, dividing the ink components into a plurality of parts makes it difficult to achieve both prevention of ink fixation during storage and rapid fixation during printing. It becomes easier to meet the requirements. By making each of the plurality of components difficult to solidify, an effect of preventing solidification can be obtained during storage, and by mixing only during printing, rapid solidification can be achieved.

[0047] Since the ink exists only momentarily in the nozzle, clogging of the ink can be easily prevented, making it easy to use pigment-based ink. Therefore, it is possible to use a pigment-based colorant that is easily compatible with multicolor printing and color printing. Furthermore, by using a pigment-based colorant, high-quality printing with less bleeding becomes possible. Also,
It is also possible to print in pure black, making it easier to deal with color mixing in multicolor printing. Furthermore, compared to dyes, printing can be performed with higher water resistance and light resistance. In addition, by adjusting the components of the ink, it can be used not only for paper but also for plastics,
Printing on metal, fiber, wood, glass, etc. is also possible.

Of course, dye-based colorants can also be used. In this case, clogging prevention would be easier.

Although the present invention has been described above with reference to examples, the present invention is not limited to these examples. For example, it will be obvious to those skilled in the art that various changes, improvements, combinations, etc. are possible.

[0050]

[Effects of the Invention] As explained above, according to the present invention,
The problem of nozzle clogging is reduced in an inkjet printing method or printing device.

It also facilitates the use of pigments as colorants. By using a solid phase component such as a pigment as an ultrafine particulate material, high-quality, high-speed printing becomes easy.

[Brief explanation of drawings]

FIG. 1 is a conceptual diagram showing the principle of the present invention.

FIG. 2 is a conceptual diagram showing a solid phase/liquid phase component separation/mixing type embodiment according to an embodiment of the present invention.

FIG. 3 is a partial block diagram schematically showing a liquid phase/liquid phase component separation/mixing type printing apparatus according to an embodiment of the present invention.

FIG. 4 shows the main steps of a printing method according to an embodiment of the invention. FIGS. 4A, 4B, and 4C are schematic cross-sectional views of the printing device.

FIG. 5 is a schematic partial cross-sectional view of a printing device showing another embodiment of the present invention.

FIG. 6 is a schematic partial cross-sectional view of a printing device showing another embodiment of the present invention.

FIG. 7 shows a conventional technique. FIGS. 7A and 7B are schematic cross-sectional views showing an ink conveying process using conventional printing technology.

[Explanation of symbols]

1, 2 Ink components 3 Mixer 4 Nozzle 5 Pigment 6. Fixing agent 7 Solid phase component 8 Liquid phase components 9 Ink droplets 10 Liquid ejector 11 Sub nozzle 13 Main nozzle 14, 15 Sub nozzle 16 Main nozzle 17 DC voltage source 18 Switch means 19 Droplet 20 Mixing chamber 21 Aerosol generator 22 Recovery pipe 24 Heater 25 Evaporated solid phase components 26　Coagulated ultrafine particles

Claims (9)

[Claims] Claim 1: An inkjet printing method that performs printing by jetting ink to form ink droplets on a printing substrate, the method comprising the steps of separating and preparing ink components into a plurality of components, and at the time of printing. An inkjet printing method comprising the step of mixing and jetting the plurality of ink components. 2. The inkjet printing method according to claim 1, wherein the plurality of ink components include two components: a solid phase component and a liquid phase component. 3. The inkjet printing method according to claim 1, wherein the plurality of ink components include two components: a liquid phase component containing a polymer precursor and a liquid phase component containing a polymerization initiation catalyst. 4. The inkjet printing method according to claim 2, wherein the solid phase component contains a pigment. 5. The inkjet printing method according to claim 2, further comprising the step of evaporating the solid phase component in a gas before mixing and solidifying it into ultrafine particles during transportation. 6. An inkjet printing device for printing by ejecting ink to form ink droplets on a printing substrate, the device comprising: means for dividing and holding ink components into a plurality of parts; an inkjet printing device comprising a mixing and ejecting means for mixing and ejecting the plurality of ink components when printing. 7. The inkjet printing apparatus according to claim 6, wherein the mixing and ejecting means includes a sub-nozzle for ejecting a solid phase component and a sub-nozzle for ejecting a liquid phase component. 8. The inkjet printing apparatus according to claim 7, further comprising means for supplying the solid phase component in aerosol form. 9. The inkjet printing apparatus according to claim 7, further comprising means for supplying ultrafine particles by evaporating the solid phase component and solidifying it in a gas.