JP2003305846A - Inkjet recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording method which is superior in the friction resistance or the like after printing without clogging a recording head and without printing bleeding and enables highly fine printing, and an inkjet recording method in which highly fine images can be printed stably to every recording material. <P>SOLUTION: In the inkjet printing method, ultraviolet rays are applied after images are formed on a body to be recorded by discharging an ink containing a photopolymerizable compound and a color agent from nozzle openings of the recording head through the expansion and contraction of pressure generation chambers by piezoelectric elements. In the inkjet recording method, when ink drops are discharged, a position of a meniscus formed by the ink in the nozzle and farthest from an end face of the nozzle opening when measured from the end face is not smaller than a nozzle diameter (μm) and not larger than a (nozzle diameter + 50) (μm). Moreover, the ink is heated by a heating means to 40-150°C to be discharged. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inkjet recording method using an ink suitable for recording on any medium including a medium having no ink absorbability.

[0002]

2. Description of the Related Art Conventionally, a water-soluble liquid ink composition has been widely used as an ink composition for ink jet recording. In addition, a hot-melt ink composition that is made of a wax that is solid at room temperature is used to liquefy by heating, etc., to be jetted by applying some energy, and to cool and solidify while adhering to the recording medium to form recording dots. A hot-melt type ink jet recording method has been proposed. Since this ink is solid at room temperature, it does not become dirty during handling, and the amount of evaporation of the ink at the time of melting can be minimized so that the nozzle is not clogged. Further, since it solidifies immediately after being adhered, there is no "bleeding", and various recording media such as Japanese paper, drawing paper, postcards, and plastic sheets can be used without pretreatment. U.S. Pat. Nos. 4,391,369 and 4,484,948 describe ink compositions that provide good print quality regardless of paper quality.

Further, Japanese Patent Application Laid-Open No. 56-93776 discloses an ultraviolet curable resin type ink composition having good adhesion to a metal surface, and further, an ink for ink jet recording which is cured by exposure to ultraviolet rays. As
As disclosed in US Pat. No. 4,228,438, an ink using an epoxy-modified acrylic resin and a urethane-modified acrylic resin as a binder and using a pigment having a particle size of 5 μm or less as a coloring component, or a special ink. Inks using a cationically polymerizable epoxy resin as a binder disclosed in JP-A-58-32674, and water-soluble or water-insoluble dyes as described in JP-A-5-186725 are used. Some of them have been disclosed to facilitate printing on plain paper and recycled paper.

As described above, there is a demand for an ink jet recording method capable of high-definition printing of photographic image quality on various recording media such as plastic sheets without using ink-jet dedicated paper.

However, when the water-based ink is used for printing, it is difficult to print on a recording medium having no ink absorption, and a large-sized ink drying device is required even when using special paper. Is. Further, due to the problem of bleeding, high-definition printing is difficult and the resolution is limited, so that the application is limited.

Further, hot-melt type ink using wax can print on a recording material having no ink absorbency, and high-speed printing is possible, but printing is extremely low in abrasion resistance. Later reliability is difficult to obtain, and smoothness is poor.

On the other hand, the ink jet recording method using an organic pigment as a colorant has many advantages over the ink jet recording method using a dye, particularly in terms of weather resistance, and therefore, OA equipment, general household printers, facsimiles. It is expected to be applied not only to office printers, but also to indoor and outdoor posters, large signs, cars, glass, elevators, wall and building decorations, and even printing on cloth.

The method of curing the recording liquid with light such as ultraviolet rays enables printing on a recording medium that does not absorb ink. However, in the ink jet recording method using a pigment, which does not substantially contain water and an organic solvent, and which cures the recording liquid with light such as ultraviolet rays, high-definition printing with a dot diameter controlled up to now has been achieved. There are no known examples of what can be done.

In high-definition printing, it is important that the diameter of dots formed is controlled to a certain size. When using ink-jet paper with high absorbency, the dot diameter that can be formed can be adjusted only by the amount of ink droplets, but when using inkjet to print onto a recording medium that does not absorb ink In particular, it is difficult to control the dot diameter only by the ink droplet amount, and particularly it is difficult to control the dot diameter formed from small droplets.

[0010]

DISCLOSURE OF THE INVENTION The present invention is an epoch-making one that solves all of the above-mentioned problems, and is effective in preventing clogging of a recording head, bleeding resistance, stability after printing (rubbing resistance, etc.), etc. An object of the present invention is to provide an inkjet recording method that is excellent and that enables high-definition printing with a controlled dot diameter, and an inkjet recording method that can stably print a high-definition image on any recording material.

[0011]

The above object of the present invention can be achieved by the following means.

1. Ink containing a photopolymerizable compound and a colorant is ejected as an ink droplet from a nozzle opening of a recording head by expanding and contracting a pressure generating chamber with a piezoelectric element,
In an inkjet recording method of irradiating ultraviolet rays after forming an image on a recording medium, when ejecting the ink droplet, the position of the meniscus formed in the nozzle farthest from the nozzle opening end face is the nozzle opening. Nozzle diameter (μm) or more when measured from the end face, and
An ink jet recording method, which has a nozzle diameter of +50 (μm) or less, and heats the ink to 40 to 150 ° C. by a heating means and ejects the ink from the nozzle opening.

2. Ink containing a photopolymerizable compound and a colorant is ejected as an ink droplet from a nozzle opening of a recording head by expanding and contracting a pressure generating chamber with a piezoelectric element,
In an inkjet recording method of irradiating ultraviolet rays after forming an image on a recording medium, when ejecting the ink droplet, the position of the meniscus formed in the nozzle farthest from the nozzle opening end face is the nozzle opening. Nozzle diameter (μm) or more when measured from the end face, and
A position where the nozzle diameter is +50 (μm) or less, and when the meniscus is farthest from the nozzle end face, the pressure generating chamber is contracted to eject ink, and
The ink is heated to 40 to 150 ° C. by a heating means,
An ink jet recording method, characterized in that the ink is discharged from the nozzle opening.

3. Ink containing a photopolymerizable compound and a colorant is ejected as an ink droplet from a nozzle opening of a recording head by expanding and contracting a pressure generating chamber with a piezoelectric element,
In an inkjet recording method of irradiating ultraviolet rays after forming an image on a recording medium, when ejecting the ink droplet, the position of the meniscus formed in the nozzle farthest from the nozzle opening end face is the nozzle opening. When measured from the end surface, the pressure generation chamber is contracted and ink is ejected when the meniscus is at a position that is the nozzle diameter (μm) or more and the nozzle diameter +50 (μm) or less, and the meniscus is farthest from the nozzle end face. In addition, the contraction in the step of ejecting the ink by contracting the pressure generating chamber is multi-staged, and the ink is heated to 40 to 150 ° C. by the heating means and ejected from the nozzle opening. An inkjet recording method characterized by the above.

4. The ink jet recording method according to any one of items 1 to 3, wherein the ink containing the photopolymerizable compound and the colorant has a viscosity at 30 ° C of 10 to 500 mPa · s.

5. The partition between the ink channels of the pressure generating chamber is composed of a piezoelectric element
5. The inkjet recording method according to any one of 4 above.

6. The ejection amount per dot is 2 pl to 2
Any one of 1 to 5 above, which is 0 pl
Inkjet recording method according to item.

7. The dot diameter formed on the recording medium is 5
7. The ink jet recording method as described in any one of 1 to 6 above, which is 0 to 200 μm.

8. Any one of the above items 1 to 7, wherein the ink does not substantially contain water and an organic solvent.
Inkjet recording method according to item.

9. 9. The inkjet recording method according to any one of 1 to 8 above, wherein the recording medium has no ink absorbability.

10. The ink contains 0.5 to 30% by mass of a pigment as a coloring agent.
10. The inkjet recording method according to any one of 9 above.

The present invention will be described in detail below. Figure 1
1A and 1B are configuration diagrams showing an example of a recording head used in an inkjet recording apparatus according to the present invention. FIG. 1A is a sectional view and FIG. 1B is a sectional view of FIG. A
FIG. 7 is an enlarged view taken along line A-A. In the figure, 1 is a substrate, 2 is a piezoelectric element, 3 is a flow path plate, 3a is an ink flow path, 3b is a wall portion, 4 is a common liquid chamber constituent member, 4a is a common liquid chamber, 5 is an ink supply pipe, 6 Is a nozzle plate, 6a is a nozzle, 7 is a drive circuit printed board (PCB), 8 is a lead wire, 9 is a drive electrode, 10 is a groove in which a filler is filled, 11 is a protective plate, 12
Is a fluid resistance, 13 and 14 are electrodes, 15 is an upper partition wall, 16
Is a heater, 17 is a heater power source, 18 is a heat transfer member, and 19 is a recording head. 2 is an exploded view of the recording head.

In the integrated head, the electrodes 13,
The laminated piezoelectric element 2 having the ink flow path 3a
Corresponding to, groove processing is performed in the ink flow path 3a direction,
It is divided into a groove 10, a driving piezoelectric element 2b, and a non-driving piezoelectric element 2a. A filling material is enclosed in the groove 10. The grooved piezoelectric element 2 is connected to the flow path plate 3 through the upper partition wall 15.
Are joined together, and the wall portion 3b of the flow path plate 3 and the non-driving piezoelectric element 2a
And form a partition wall of the ink flow path 3a that serves as a pressure generating chamber. That is, the upper partition wall 15 is supported by the non-driving piezoelectric element 2a and the wall portion 3b that separates the adjacent flow path. The width of the driving piezoelectric element 2b is slightly narrower than the width of the ink flow path 3a, and the driving piezoelectric element 2b selected by the driving circuit on the driving circuit printed board (PCB) is driven by applying a pulse signal voltage. The piezoelectric element 2b changes in the thickness direction, the volume of the ink flow path 3a changes via the upper partition wall 15, and as a result, ink droplets are ejected from the nozzles 6a of the nozzle plate 6.

Heaters 16 are adhered to the flow path plate 3 via heat transfer members 18, respectively. The heat transfer member 18 is provided around the nozzle surface. The heat transfer member 18 is intended to efficiently transfer the heat from the heater 16 to the flow path plate 3 and also to transfer the heat from the heater 16 to the vicinity of the nozzle surface to warm the air near the nozzle surface. A good material is used. For example, aluminum,
Metals such as iron, nickel, copper, stainless steel, or S
Ceramics such as iC, BeO, AlN and the like are mentioned as preferable materials.

The ink jet recording head thus constructed expands the pressure generating chamber when a drive signal is selectively applied to the piezoelectric element of the pressure generating chamber which communicates with the nozzle opening through which ink droplets are to be ejected. As a result, the ink meniscus is drawn to the pressure generating chamber side. When the piezoelectric element is charged after a lapse of a predetermined time, the piezoelectric element is flexibly displaced toward the pressure generating chamber side to contract the pressure generating chamber. In this process, the ink in the pressure generating chamber is pressurized and ejected as an ink droplet from the nozzle opening.

In the present invention, in the ink meniscus formed before ink ejection, the position of the meniscus farthest from the nozzle opening end face is the nozzle diameter (μm) or more and the nozzle diameter +50 (μm) or less from the nozzle opening end face. is there. Preferably, the nozzle diameter (μm) or more and the nozzle diameter +30 (μm) or less. If the position where the meniscus is drawn is less than the nozzle diameter, the injection stability deteriorates, and if the position is larger than the nozzle diameter +50 μm, the injection speed becomes slow.

FIG. 3 is an enlarged sectional view of the nozzle plate 6 and the nozzle 6a when the ink is most drawn into the nozzle. The position of the ink meniscus formed by the ink 100 is a distance from the nozzle opening end surface of the nozzle 6a to the farthest liquid surface of the formed meniscus (the center of the meniscus in the figure). In the figure, d represents the nozzle diameter, and l represents the distance (the position of the ink meniscus) from the end surface of the nozzle opening of the ink meniscus.

According to the present invention, when ejecting the ink droplet, the ink is once drawn into the nozzle by expanding the pressure generating chamber, but the drawn ink is
As described above, the position of the meniscus formed in the nozzle farthest from the end surface of the nozzle opening is at least the nozzle diameter (μm) from the end surface of the nozzle opening, and the nozzle diameter +5.
In addition to the position of 0 (μm) or less, when the meniscus is furthest from the nozzle end face, contracting the pressure generating chamber to eject ink greatly improves ejection stability. FIG. 4 shows an example showing the waveform of the drive signal of the piezoelectric element that expands and contracts the pressure generating chamber in this manner.

In FIG. 4A, the voltage application in the direction in which the pressure generating chamber expands is represented by + application. First, + V
By applying 1, the pressure generating chamber is expanded and the ink meniscus is pulled in. The retracting position of the meniscus is determined by adjusting the value of V1 (and the application time). After that, the V1 potential is maintained (the holding time is usually 1 to 10 μsec per ejection of an ink droplet in the case of high-precision printing). The meniscus is reversed from the most drawn state to the opening. At the point of time of heading out, -V2 is applied and ink is ejected. After the ink is ejected, the applied voltage is normally returned to the ground state after a time about double the application time of the V1 potential.

Further, it is more preferable that the step of contracting the pressure generating chamber by the piezoelectric element is changed in multiple steps. Particularly, 2 to 3 steps are preferable, and changing in 2 steps is most preferable. By making the shrinkage in multiple stages, the injection stability is further improved. In order to make the contraction of the pressure generating chamber for ejecting ink in multiple stages, as shown in FIG. 4B, the pressure generating chamber is expanded by applying + V1, and the ink meniscus is pulled in, and then the V1 potential is maintained ( Hold time is 1 to 10 μsec per discharge of ink droplet
When the meniscus is reversed from the most retracted state to the opening, the potential is once set to 0, for example, and after a certain time elapses (V1 is applied). As much as time is preferred, eg 5
μsec), and −V2 is further applied to eject ink. In this way, the contraction can be multistaged by reversing the potential in multiple stages. After the ink is ejected, the application of -V2 is usually about twice as long as the application time of the above-mentioned V1 potential, and then the ground state is restored. In this way, by applying the driving potential to the piezoelectric element in multiple stages, ink ejection is further stabilized.

Regarding the mechanism of pressure generation of the recording head,
The invention is not necessarily limited to the above example, and is disclosed in, for example, JP-A-11-587.
No. 26, etc., it has a form in which electrodes are arranged so as to oppose each partition formed by a piezoelectric element that separates the ink flow path, and the partition itself is displaced by the application of a potential, whereby the pressure generating chamber (ink It is also preferable that the flow path) expands and contracts.

FIGS. 5A and 5B are views for explaining how ink is ejected as ink droplets, and FIG.
5A is a cross-sectional view of the head portion, and FIG. 5B is a plan view of the nozzle plate. In the figure, 20 is a recording medium, 6 is a nozzle plate, and 6a is a nozzle. The ink droplets ejected from the nozzle 6a fly and adhere to the recording medium 20.

In the ink jet recording method of the present invention, the ink is cured after being attached to a recording medium and then irradiated with ultraviolet rays, so that the ink has excellent bleeding resistance and stability (rubbing resistance, etc.) after printing. A high-definition image can be obtained.

In the present invention, the ejection amount per dot is 2 pl to 20 pl. It is preferably 10 pl or less, more preferably 4 pl to 7 pl. If it exceeds 20 pl, high-definition printing is difficult, and if it is 2 pl or less, the density of the formed image becomes low.

The diameter of dots formed on the recording medium is 50 to 200 μm. Preferably 50 to 150 μ
m, and more preferably 55 to 100 μm. 50 μm
If it is less than 200 μm, the density of the formed image becomes low, and if it exceeds 200 μm, high-definition printing is difficult.

It is difficult to obtain a high-definition image by controlling the dot diameter only by the droplet amount. Therefore, in addition to the ink droplet amount, the ink viscosity, the ultraviolet ray intensity, and the irradiation timing are adjusted so that the present invention can be performed. It is possible to control various dot diameters and achieve high-definition printing.

The ink according to the present invention preferably contains substantially no water or organic solvent. The term "substantially free from" means that the content of water and the organic solvent is less than 1% by mass. The organic solvent referred to here is shown below.

Preferred examples of the organic solvent include high boiling point and low volatility polyhydric alcohols such as glycerin, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, hexylene glycol, polyethylene glycol and polypropylene glycol. Can be mentioned. Further, mono-ether compounds, di-ether compounds and ester compounds thereof such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether and diethylene glycol monobutyl ether can be mentioned. Further, cellosolves such as methyl cellosolve and ethyl cellosolve, carbitols such as methyl carbitol and ethyl carbitol, morpholines such as morpholine and N-ethylmorpholine, and pyrrolidones such as N-methyl-2-pyrrolidone. Be done. Furthermore, highly volatile monohydric alcohols such as ethanol, propanol, isopropanol and butanol.

Alternatively, ethyl acetate, butyl acetate, methyl benzoate, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, N-methyl-2-pyrrolidone,
Examples thereof include N, N dimethylformamide, ethylene glycol ethers, ethylene glycol acetates, propylene glycol ethers and propylene glycol acetates.

As an ultraviolet ray source for curing the ink,
A mercury lamp, a metal halide lamp, an excimer lamp, an ultraviolet laser, an LED, etc. can be used. The basic irradiation method is disclosed in JP-A-60-132767. According to this, the light source is provided on both sides of the head unit, and the head and the light source are scanned by the shuttle method. Irradiation is performed after a certain time has elapsed after the ink has landed. Further, curing is completed by another light source that is not driven. WO9954415 discloses, as an irradiation method, a method using an optical fiber and a method of irradiating a recording section with UV light by applying a collimated light source to a mirror surface provided on the side surface of the head unit. In the recording method of the present invention, these irradiation methods can be used.

Specifically, a strip-shaped metal halide lamp tube and an ultraviolet lamp tube are preferable. The radiation source is substantially fixed to the recording device, and the moving part is eliminated, so that an inexpensive structure can be obtained.

Irradiation is preferably performed for each printing of each color. That is, in any exposure method, it is preferable that two kinds of radiation sources are prepared and the curing is completed by the second radiation source. is there. This contributes to obtaining the wettability of the second color landing ink and the adhesiveness between the inks, and to assemble the radiation source at low cost.

It is preferable that the first radiation source and the second radiation source have different exposure wavelengths or exposure illuminances. The first irradiation energy is smaller than the second irradiation energy, that is, the first irradiation energy is 1 to 20 of the total irradiation energy.
%, Preferably 1 to 10%, more preferably 1 to 5%. By performing irradiation with different illuminance, the molecular weight distribution after curing becomes preferable. That is, when irradiation with high illuminance is performed at one time, the polymerization rate is increased, but the molecular weight of the polymerized polymer is small, and strength cannot be obtained. For compositions with extremely low viscosity, such as inkjet ink,
A remarkable effect is obtained.

Further, the first irradiation is performed with the second longer wavelength so that the surface layer of the ink is cured in the first irradiation to suppress ink bleeding, and the irradiation line is used in the second irradiation. It is possible to cure the ink in the vicinity of the recording medium, which is hard to reach, to improve the adhesion. In order to accelerate the curing inside the ink, the second irradiation ray wavelength is preferably long wavelength.

The feature of the recording method of the present invention is that the ink is heated to a constant temperature and the time from landing to irradiation is 0.01 to 0.5 seconds, preferably 0.01 to 0.3.
The irradiation is performed after a second, more preferably 0.01 to 0.15 seconds. By controlling the time from landing to irradiation to an extremely short time in this way, it becomes possible to prevent the landing ink from bleeding before curing. In addition, since it is possible to expose the porous recording medium before the ink penetrates to a deep portion where the light source does not reach, residual unreacted monomer can be suppressed and odor can be reduced. This will bring about a great synergistic effect by using the ink of the present invention. Particularly, the viscosity at 30 ° C. is 10 to 500 mP
A great effect can be obtained by using the ink of a · s. By adopting such a recording method, the dot diameter of the landed ink can be kept constant even on various recording media having different surface wettability, and the image quality is improved. Note that in order to obtain a color image, it is preferable to superimpose the colors in order of low lightness. When inks of low lightness are piled up, it is difficult for the irradiation line to reach the lower ink, and the curing sensitivity is impaired, the residual monomer increases, odor is generated, and the adhesiveness is apt to deteriorate. In addition, it is possible to irradiate all colors and expose them collectively, but it is preferable to expose each color one by one from the viewpoint of accelerating curing.

Further, in a unit composed of a plurality of heads, it is preferable that the space between the respective colors is substantially transparent to the irradiation rays. Specifically, the heads are made of a radiation-transmissive member or the members are not arranged. With the configuration of the present invention, with such a simple configuration, it is possible to quickly irradiate each color immediately after landing, and especially to prevent bleeding of secondary colors and to go and return in bidirectional drawing. It is preferable because it can prevent the difference in dot bleeding (prevent the difference between the going color and the going color).

In the recording method of the present invention, 40
From the viewpoint of injection stability, it is preferable to heat the ink to a temperature of 150 ° C. to lower the ink viscosity before ejecting. More preferably, 40 ° C
~ 100 ° C. Below 40 ° C and above 150 ° C,
Injection becomes difficult. Since the radiation-curable ink generally has a higher viscosity than the water-based ink, the fluctuation range of viscosity due to temperature fluctuation is large. Since the viscosity variation directly affects the droplet size and the droplet ejection speed and deteriorates the image quality, it is necessary to keep the ink temperature as constant as possible. The ink temperature control range is set temperature ± 5 ° C, preferably set temperature ±
The temperature is 2 ° C, more preferably the set temperature ± 1 ° C. Although the recording device is provided with a means for stabilizing the ink temperature, all parts of the ink tank (intermediate tank if there is an intermediate tank), the piping system from the nozzle ejection surface, and the members are targeted for a portion that maintains a constant temperature.

In order to control the temperature, it is preferable to provide a plurality of temperature sensors at each piping portion to control the heating according to the ink flow rate and the environmental temperature. Further, it is preferable that the head unit to be heated is thermally shielded or insulated so as not to be affected by the temperature from the apparatus body and the outside air. In order to shorten the printer startup time required for heating and to reduce the loss of heat energy, it is preferable to perform heat insulation from other parts and reduce the heat capacity of the entire heating unit.

Recording material having no ink absorption property or recording material having low ink absorption property (or ink non-absorptive recording material)
Is a recording material made of a material having no ink absorption or a material having a low ink absorption (or an ink non-absorption material), or a material having no ink absorption or a material having a low ink absorption (or an ink non-absorption material). A material having a surface layer (printing layer) made of an absorptive material, and a material having no ink absorptivity or a material having a low ink absorptivity (or an ink non-absorptive material) is, for example, various plastics or It is a metal.

The ink of the present invention is a liquid having a viscosity at 30 ° C. of 10 to 500 mPa · s. Preferably,
40 to 500 mPa · s is preferable. If it is less than 10 mPa · s, blurring is deteriorated, and if it exceeds 500 mPa · s, smoothness of image quality is lost. In addition, the ink is 60
It is preferably a liquid of 3 to 30 mPa · s at ℃,
More preferably, it is 3 to 20 mPa · s. 3 mPa
・ If it is less than s, a problem occurs in high-speed injection, and
If it is mPa · s or more, the injection property deteriorates.

The photopolymerizable compound is a radically polymerizable compound, for example, JP-A-7-159983 and JP-B-7-31.
399, JP-A-8-224982 and 10-863.
Photo-curable materials using the photo-polymerizable composition described in each of the publications, etc. and photo-curable resins of cationic polymerization type are known, and recently, they are sensitized to a long wavelength region of visible light or longer. The above-mentioned photo-cationic polymerization type photo-curable resin is also disclosed in, for example, JP-A-6-
Nos. 43633 and 8-324137 are disclosed.

The radical-polymerizable compound is a compound having a radical-polymerizable ethylenically unsaturated bond, and may be any compound as long as it has at least one radical-polymerizable ethylenically unsaturated bond in the molecule. Often,
Those having chemical forms such as monomers, oligomers and polymers are included. The radical-polymerizable compound may be used alone, or two or more kinds thereof may be used in combination at an arbitrary ratio in order to improve target properties.

Examples of the radically polymerizable compound having an ethylenically unsaturated bond include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid and maleic acid, and salts and esters thereof.
Radical polymerizable compounds such as urethane, amide and anhydride, acrylonitrile, styrene, and various unsaturated polyesters, unsaturated polyethers, unsaturated polyamides and unsaturated urethanes can be mentioned. Specifically, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, butoxyethyl acrylate, carbitol acrylate, cyclohexyl acrylate, tetrahydrofurfuryl acrylate, benzyl acrylate, bis (4-acryloxypolyethoxyphenyl) propane,
Neopentyl glycol diacrylate, 1,6-hexanediol diacrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate, pentaerythritol triacrylate. , Pentaerythritol tetraacrylate, dipentaerythritol tetraacrylate, trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, oligoester acrylate, acrylic acid derivatives such as N-methylol acrylamide, diacetone acrylamide, epoxy acrylate, methyl methacrylate, n- Butylme Acrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, allyl methacrylate, glycidyl methacrylate, benzyl methacrylate, dimethylaminomethyl methacrylate, 1,
6-hexanediol dimethacrylate, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, trimethylolethane trimethacrylate, trimethylolpropane trimethacrylate, 2,2-bis (4-methacryloxy) Methacryl derivatives such as polyethoxyphenyl) propane, other, allyl glycidyl ether, diallyl phthalate, derivatives of allyl compounds such as triallyl trimellitate, more specifically, Shinzo Yamashita, "Crosslinking agent handbook", (1981 Taiseisha); Kiyomi Kato, "UV / EB curing handbook (raw materials)" (1985, Kobunshi Kogyokai); Radtech Research Group, "UV / EB" Application of technology and the market ", 79
Page, (1989, CMC); Eiichiro Takiyama,
Commercially available products described in "Polyester Resin Handbook" (1988, Nikkan Kogyo Shimbun) and the like, or radically polymerizable or crosslinkable monomers, oligomers and polymers known in the art can be used. The amount of the radically polymerizable compound added is preferably 1 to 97% by mass, more preferably 30 to 95% by mass.

As a radical polymerization initiator, Japanese Examined Patent Publication No. S59
-1281, Japanese Patent Publication No. 61-9621, and JP-A-6-6
Triazine derivatives described in each publication such as 0-60104,
JP-A-59-1504 and JP-A-61-243807
Organic peroxides described in each publication such as Japanese Patent Publication No. 43-23
684, Japanese Patent Publication No. 44-6413, Japanese Patent Publication No. 44-64
No. 13 and Japanese Patent Publication No. 47-1604, and diazonium compounds described in US Pat. No. 3,567,453, US Pat. Nos. 2,848,328, 2,852,379, and No. 2,940,853, organic azide compounds described in each specification, JP-B-36-2206
No. 2, JP-B-37-13109, JP-B-38-180
No. 15, Japanese Patent Publication No. 45-9610 and other orthoquinone diazides, Japanese Patent Publication No. 55-39162, Japanese Patent Publication No. 59-14023 and the like, and “Macromolecules, 10”. roll,
Various onium compounds described on page 1307 (1977), azo compounds described in JP-A-59-142205, JP-A-1-54440, and European Patent No. 1
09,851, European Patent No. 126,712, etc., "Journal of Imaging Science" (J.Imag.Sci.) ", Volume 30, p.174 (1986). Metal allene complex, (oxo) sulfonium organic boron complex described in Japanese Patent Application No. 4-56831 and Japanese Patent Application No. 4-895535, titanocene described in JP-A-61-151197, Coordination Chemistry Review (Coordination Chemistry)
Review, "Vol. 84, pp. 85-277 (1.
1988) and a transition metal complex containing a transition metal such as ruthenium described in JP-A-2-182701, 2,4,5-triarylimidazole dimer described in JP-A-3-209477, tetramer Carbon bromide and JP-A-59-
Examples thereof include organic halogen compounds described in Japanese Patent No. 107344. These polymerization initiators are preferably contained in the range of 0.01 to 10 parts by mass with respect to 100 parts by mass of the compound having a radically polymerizable ethylenic unsaturated bond.

As the cationic polymerization type photo-curable resin, an epoxy type ultraviolet curable prepolymer of a type (mainly an epoxy type) in which polymerization is caused by cationic polymerization, and a monomer has two or more epoxy groups in one molecule. The prepolymer contained can be mentioned. Examples of such prepolymers include alicyclic polyepoxides, polyglycidyl esters of polybasic acids, polyglycidyl ethers of polyhydric alcohols, polyglycidyl ethers of polyoxyalkylene glycols, and polyglycidyl aromatic polyols. Examples thereof include ethers, hydrogenated compounds of polyglycidyl ethers of aromatic polyols, urethane polyepoxy compounds and epoxidized polybutadienes. These prepolymers can be used alone, or in addition,
It is also possible to use a mixture of two or more thereof.

Other cationically polymerizable compounds contained in the cationically polymerizable composition include, for example, the following (1) styrene derivatives, (2) vinylnaphthalene derivatives, and (3).
Examples thereof include vinyl ethers and (4) N-vinyl compounds. (1) Styrene derivative For example, styrene, p-methylstyrene, p-methoxystyrene, β-methylstyrene, p-methyl-β-methylstyrene, α-methylstyrene, p-methoxy-β-
Methylstyrene etc. (2) Vinylnaphthalene derivative, for example, 1-vinylnaphthalene, α-methyl-1-vinylnaphthalene, β-methyl-1-vinylnaphthalene, 4
-Methyl-1-vinylnaphthalene, 4-methoxy-1-
(3) Vinyl ethers such as vinyl naphthalene, for example, isobutyl vinyl ether, ethyl vinyl ether, phenyl vinyl ether, p-methylphenyl vinyl ether, p-methoxyphenyl vinyl ether,
α-Methylphenyl vinyl ether, β-methyl isobutyl vinyl ether, β-chloroisobutyl vinyl ether, etc. (4) N-vinyl compounds such as N-vinylcarbazole, N-vinylpyrrolidone, N-vinylindole, N-vinylpyrrole, N-
Vinylphenothiazine, N-vinylacetanilide, N
-Vinylethylacetamide, N-vinylsuccinimide, N-vinylphthalimide, N-vinylcaprolactam, N-vinylimidazole and the like.

The content of the above cationically polymerizable compound in the cationically polymerizable composition is preferably 1 to 97% by mass, more preferably 30 to 95% by mass.

Examples of the initiator for the cationically polymerizable photocurable resin include aromatic onium salts. As the aromatic onium salt, a salt of a group Va element of the periodic table, for example, a phosphonium salt (for example, triphenylphenacylphosphonium hexafluorophosphate), a salt of a group VIa, for example, a sulfonium salt (for example, triphenylsulfonium tetrafluoroborate). , Triphenylsulfonium hexafluorophosphate, tris (4-thiomethoxyphenyl) hexafluorophosphate, sulfonium and triphenylsulfonium hexisafluoroantimonate), and salts of Group VIIa elements, such as iodonium salts (eg, diphenyliodonium chloride). Such)
Can be mentioned.

The use of such an aromatic onium salt as a cationic polymerization initiator in the polymerization of an epoxy compound is described in US Pat. Nos. 4,058,401 and 4,0.
69,055, 4,101,513 and 4,161,478.

Preferred cationic polymerization initiators include
Examples thereof include sulfonium salts of Group VIa elements. Among them, from the viewpoint of ultraviolet curability and storage stability of the ultraviolet curable composition, triarylsulfonium hexafluoroantimonate is preferable. Also, Photo Polymer Handbook (Photo Polymer Conversation Edition, Industrial Research Committee issue 1
989), pages 39 to 56, known photopolymerization initiators, and compounds described in JP-A-64-13142 and JP-A-2-4804 can be optionally used.

As an additive to the ink according to the present invention,
Other additives such as reaction diluents, fillers, flow aids, thixotropic agents, wetting agents, defoamers, plasticizers may be included. In addition, a light resistance agent, an ultraviolet absorber, an antioxidant,
A stabilizer such as a polymerization inhibitor or a corrosion inhibitor, or a Si compound, wax or the like may be added.

As the coloring agent in the ink composition according to the present invention, conventionally known dyes and pigments can be used. As the coloring agent in the present invention, a pigment is more preferable.

Examples of the water-soluble dye include C.I. I. Direct Black-2, -4, -9, -11, -17,-
19, -22, -32, -80, -151, -154,
-168, -171, -194; C.I. I. Direct Blue-1, -2, -6, -8, -22, -34, -7
0, -71, -76, -78, -86, -112, -1
42, -165, -199, -200, -201, -2
02, -203, -207, -218, -236, -2
87; C.I. I. Direct Red-1, -2, -4,-
8, -9, -11, -13, -15, -20, -28,
-31, -33, -37, -39, -51, -59,-
62, -63, -73, -75, -80, -81, -8
3, -87, -90, -94, -95, -99, -10
1, -110, -189; C.I. I. Direct Yellow-1, -2, -4, -8, -11, -12, -26,-
27, -28, -33, -34, -41, -44, -4
8, -58, -86, -87, -88, -135, -1
42, -144; C.I. I. Food black-1, -2;
C. I. Acid Black-1, -2, -7, -16,
-24, -26, -28, -31, -48, -52,-
63, -107, -112, -118, -119, -1
21, -156, -172, -194, -208;
I. Acid Blue-1, -7, -9, -15, -2
2, -23, -27, -29, -40, -43, -5
5, -59, -62, -78, -80, -81, -8
3, -90, -102, -104, -111, -18
5, -249, -254; C.I. I. Acid Red-
1, -4, -8, -13, -14, -15, -18,-
21, -26, -35, -37, -110, -144,
-180, -249, -257; C.I. I. Acid Yellow-1, -3, -4, -7, -11, -12, -1
3, -14, -18, -19, -23, -25, -3
4, -38, -41, -42, -44, -53, -5
5, -61, -71, -76, -78, -79, -12
2 etc.

Examples of oil-soluble dyes include azo dyes, metal complex dyes, naphthol dyes, anthraquinone dyes, indigo dyes, carbonium dyes, quinoimine dyes, cyanine dyes, quinoline dyes, nitro dyes, nitroso dyes, benzoquinone dyes, naphthoquinone dyes, and naphthalene dyes. Phthalimide dye,
Examples include perinone dyes and phthalocyanine dyes,
It is not limited to these.

The water-insoluble dyes and pigments are not particularly limited, but include organic pigments, inorganic pigments, colored polymer particles, disperse dyes, oil-soluble dyes and the like. Examples of black pigments include carbon black pigments such as furnace black, lamp black, acetylene black, and channel black. For example, Raven 7
000, Raven 5750, Raven 525
0, Raven 5000 ULTRA II, Rave
n 3500, Raven 2000, Raven 1
500, Raven 1250, Raven 120
0, Raven 1190 ULTRA II, Rav
en 1170, Raven 1255, Raven
1080, Raven 1060 (above, Colombian Carbon Co., Ltd.), Regal 400R, Regal
330R, Regal 660R, Mogul L,
Black Pearls L, Monarch 70
0, Monarch 800, Monarch 88
0, Monarch 900, Monarch 100
0, Monarch 1100, Monarch 13
00, Monarch 1400 (above made by Cabot), Color Black FW1, Color
Black FW2, Color Black FW2
V, Color Black 18, Color Bl
ack FW200, Color Black S15
0, Color Black S160, Color
Black S170, Pritex 35, Prit
ex U, Printex 140U, Printex
140V, Special Black6, Speci
al Black 5, Special Black
4A, Special Black 4 (above, manufactured by Degussa), No. 4A. 25, no. 33, No. 40, N
o. 47, No. 52, No. 900, No. 230
0, MCF-88, MA600, MA7, MA8, MA
100 (above, manufactured by Mitsubishi Chemical Corporation) or the like can be used. Further, magnetic fine particles such as magnetite and ferrite, titanium black and the like can be used as the black pigment.

Cyan color pigments include C.I. I. Pigment Blue-1, C.I. I. Pigment Blue-2,
C. I. Pigment Blue-3, C.I. I. Pigment Blue-15, C.I. I. Pigment Blue-15:
1, C.I. I. Pigment Blue-15: 3, C.I. I.
Pigment Blue-15: 34, C.I. I. Pigment Blue-16, C.I. I. Pigment Blue-22,
C. I. Pigment Blue-60 and the like.

Examples of magenta pigments include C.I. I. Pigment Red-5, C.I. I. Pigment Red-7,
C. I. Pigment Red-12, C.I. I. Pigment Red-48, C.I. I. Pigment Red-4
8: 1, C.I. I. Pigment Red-57, C.I. I.
Pigment Red-112, C.I. I. Pigment Red-122, C.I. I. Pigment Red-123,
C. I. Pigment Red-146, C.I. I. Pigment Red-168, C.I. I. Pigment Red-
184, C.I. I. Pigment Red-202 and the like.

Examples of the yellow pigment include C.I. I. Pigment
Yellow-1, C.I. I. Pigment Yellow-2,
C. I. Pigment Yellow-3, C.I. I. Pigment yellow-12, C.I. I. Pigment Yellow-
13, C.I. I. Pigment Yellow-14, C.I. I.
Pigment yellow-16, C.I. I. Pigment Yellow-17, C.I. I. Pigment Yellow-73,
C. I. Pigment Yellow-74, C.I. I. Pigment Yellow-75, C.I. I. Pigment Yellow-83, C.I. I. Pigment Yellow-93, C.I.
I. Pigment Yellow-95, C.I. I. Pigment Yellow-97, C.I. I. Pigment Yellow-9
8, C.I. I. Pigment Yellow-114, C.I. I.
Pigment Yellow-128, C.I. I. Pigment
Yellow-129, C.I. I. Pigment Yellow-1
51, C.I. I. Pigment Yellow-154 and the like.

In addition to the above three primary color pigments of black and cyan, magenta and yellow, specific color pigments such as red, green, blue, brown and white, metallic luster pigments such as gold and silver, colorless extender pigment,
It is also possible to use a plastic pigment or the like. In addition to the above, a newly synthesized pigment may be used. Further, these pigments may be surface-treated. Examples of the surface treatment method include treatment with a coupling agent such as alcohol, acid, base and silane compound, polymer grafting treatment, and plasma treatment. The coloring material used in the present invention preferably has a small content of organic and inorganic impurities. Generally, since commercially available coloring materials have a large content of impurities, it is desirable to use a purified product thereof. The coloring material used in the solid ink composition of the present invention is used in an amount of 0.1 to 30% by mass, preferably 1 to 15% by mass based on the mass of the ink.

In the present invention, it is preferable to use a dispersed pigment. Examples of the dispersant used to disperse the pigment include higher fatty acid salts, alkyl sulfates, alkyl ester sulfates, alkyl sulfonates,
Sulfosuccinate, naphthalene sulfonate, alkyl phosphate, polyoxyalkylene alkyl ether phosphate, polyoxyalkylene alkyl phenyl ether, polyoxyethylene polyoxypropylene glycol, glycerin ester, sorbitan ester, polyoxyethylene fatty acid amide, Activator such as amine oxide, or 2 selected from styrene, styrene derivative, vinylnaphthalene derivative, acrylic acid, acrylic acid derivative, maleic acid, maleic acid derivative, itaconic acid, itaconic acid derivative, fumaric acid, fumaric acid derivative Examples thereof include block copolymers composed of one or more kinds of monomers, random copolymers and salts thereof.

For dispersing the pigment, various types such as a ball mill, a sand mill, an attritor, a roll mill, an agitator, a Henschel mixer, a colloid mill, an ultrasonic homogenizer, a pearl mill, a wet jet mill and a paint shaker can be used. It is also preferable to remove coarse particles from the pigment dispersion using a centrifugal separator or using a filter.

The average particle diameter of the pigment dispersion used in the ink of the present invention is preferably 200 nm or less, more preferably 100 nm or less.

The addition amount of the pigment dispersion used in the ink according to the present invention is generally preferably in the range of 0.5 to 30% by mass, more preferably 1 to 20% by mass.

If necessary, a water-soluble organic solvent can be added to the ink according to the present invention. The water-soluble organic solvent preferably used, for example, alcohols (eg, methanol, ethanol, propanol, isopropanol, butanol, isobutanol,
Secondary butanol, tertiary butanol, pentanol, hexanol, cyclohexanol, benzyl alcohol, etc., polyhydric alcohols (eg ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene) Glycol, hexanediol, pentanediol, glycerin, hexanetriol, thiodiglycol, etc.), polyhydric alcohol ethers (eg, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl) Ether, diethylene glycol Bruno ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether,
Triethylene glycol monobutyl ether, ethylene glycol monophenyl ether, propylene glycol monophenyl ether, etc.), amines (eg, ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine) ,
Ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, polyethyleneimine, pentamethyldiethylenetriamine, tetramethylpropylenediamine, etc., amides (eg, formamide, N, N-dimethylformamide, N, N-
Dimethylacetamide, etc.), heterocycles (eg, 2-pyrrolidone, N-methyl-2-pyrrolidone, cyclohexylpyrrolidone, 2-oxazolidone, 1,3-dimethyl-2-imidazolidinone, etc.), sulfoxides (eg, dimethyl) Sulfoxide, etc.), sulfones (eg,
Sulfolane etc.), urea, acetonitrile, acetone and the like.

In addition to the above, the ink contains an antiseptic agent, an antifungal agent, and
Viscosity modifiers and the like may be included as necessary.

The pH of the ink according to the present invention is 4 to 10.
Is preferred. Furthermore, it is preferably 5 to 9.

In the ink according to the present invention, the surface tension of the ink needs to be in the range of 20 to 60 mN / m, preferably 25 in consideration of the wettability with respect to the recording medium and the head nozzle member. It is set in the range of ˜50 mN / m. When the surface tension of the ink is lower than 25 mN / m, the ink easily overflows from the nozzle, and when it is higher than 60 mN / m, the drying time becomes long.

To adjust the surface tension, a surfactant may be contained, if necessary. As the surfactant preferably used in the ink of the present invention, for example, anionic surfactants such as dialkylsulfosuccinates, alkylnaphthalenesulfonates and fatty acid salts, polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyls. Examples thereof include nonionic surfactants such as ethers, acetylene glycols, polyoxyethylene / polyoxypropylene block copolymers, and cationic surfactants such as alkylamine salts and quaternary ammonium salts. Of these, anionic surfactants and nonionic surfactants are particularly preferable.

[0079]

The present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.

Example 1 The ink was prepared as follows.

<Ink 1>; Solid Ink (Comparative) The following composition was heated to 150 ° C. and mixed and stirred, and then the obtained liquid was filtered with a filter under heating and cooled to obtain Ink 1. .

[0082]   C. I. Pigment Blue 15: 3 (Average dispersed particle size: 100 nm)                                                               5 parts by mass   Paraffin wax (manufactured by Nippon Seiro 155) 45 parts by mass   Behenic acid (Wako Pure Chemical Industries) 30 parts by mass   Oleic acid amide (made by Kao, fatty acid amide ON) 20 parts by mass The following pigment dispersion was prepared.

(Cyan Pigment Dispersion) C.I. I. Pigment Blue 15: 3 20 parts by mass Polymeric dispersant (Solsperse series manufactured by Zeneca) 5 parts by mass Stearyl acrylate 75 parts by mass In addition, the average particle size of each pigment particle is 0.2 to 0.3.
The dispersion conditions were appropriately adjusted at a temperature of 60 ° C. using a known dispersing device so that the range was in the range of μm, and then filtered under heat (60 ° C.) to prepare a cyan pigment dispersion ( Average dispersed particle size: 100 nm).

Next, inks 2 to 4 were prepared using the prepared cyan pigment dispersion. <Ink 2> Cyan pigment dispersion 5 parts by mass Photopolymerizable compound: Lauryl acrylate (monofunctional) 10 parts by mass Ethylene oxide modified trimethylolpropane triacrylate (trifunctional) 10 parts by mass Caprolactam modified dipentaerythritol hexaacrylate (hexafunctional) ) 10 to 40 parts by mass Tetraethylene glycol diacrylate (bifunctional) 5 to 30 parts by mass (addition amount was adjusted so that the viscosity becomes the value in Table 1) Polymerization initiator: Irgacure 184 (manufactured by Ciba Geigy Ltd.) 2 2.5 parts by mass Irgacure 907 2.5 parts by mass The composition prepared by mixing under heating (60 ° C.) as described above was filtered under heating (60 ° C.) with a filter having an absolute filtration accuracy of 2 μm to obtain ink 2.

<Ink 3> Cyan pigment dispersion 5 parts by mass Photopolymerizable compound: Lauryl acrylate (monofunctional) 10 parts by mass Ethylene oxide modified trimethylolpropane triacrylate (trifunctional) 10 parts by mass AT-600 (Kyoeisha Chemical Co., Ltd. 10-40 parts by mass Tetraethylene glycol diacrylate (bifunctional) 5-30 parts by mass (addition amount is adjusted so that the viscosity becomes a value in the table) Polymerization initiator: Irgacure 184 (manufactured by Nippon Ciba Geigy) 2 2.5 parts by mass Irgacure 907 2.5 parts by mass Under heating (60 ° C.), the prepared composition was mixed and filtered under heating (60 ° C.) with a filter having an absolute filtration accuracy of 2 μm to obtain ink 3.

Ink 4 Cyan pigment dispersion 5 parts by weight Photopolymerizable compound: 1,6-hexanediol diacrylate 15 parts by weight 2-phenoxyethyl acrylate 20 parts by weight Polypropylene glycol diacrylate 10 to 20 parts by weight Octyl acrylate 10 -29 parts by mass (adjust the amount added so that the viscosity becomes the value in Table 1) Polymerization initiator: Irgacure 184 (manufactured by Ciba Geigy) 5 parts by mass 2-phenoxyethanol 1 part by mass The composition prepared by mixing as above. The product was filtered with a filter having an absolute filtration accuracy of 2 μm to obtain ink 4 (comparative UV curable ink).

Next, FIGS. 6 to 8 show an ink jet recording apparatus having a piezo type recording head used for the printing test.

FIG. 6 is a schematic bottom view of a recording head unit (carriage) having a radiation irradiating section of the ink jet recording apparatus used for the printing test. Carriage 10
5 has recording heads 4Y to 4K, and a radiation irradiation unit (UV light irradiation unit) 103 connected to the ultraviolet light source 101 and the optical fiber 102 is provided adjacent to each recording head. While moving the carriage 105 in the main scanning direction, each recording head 4Y including a plurality of nozzles
After the ink is made to land on the recording medium from 4K, ultraviolet rays are immediately irradiated by the radiation irradiation unit 103 provided in the downstream portion to cure the landed ink droplets.

FIG. 7 shows a former tank (not shown),
Ink supply pipe 108, ink supply tank 106 immediately before the recording head, ink supply system such as filter 107, piezo type recording heads 4Y to 4K, heating unit 109 for performing heat insulation and heating from the ink supply tank to the recording head portion. , The UV light source 1 adjacent to the heating unit 109
1 shows a schematic configuration of a carriage 105 including a radiation irradiating unit (UV light irradiating unit) 103 and the like, which are connected to 01 by an optical fiber 102. In addition, each recording head 4Y-4K
The pair of shielding plates 11 so that they are not directly exposed to ultraviolet rays.
2 are provided respectively. Similar to FIG. 6, each of the recording heads 4Y to 4K having a plurality of nozzles kept at a constant temperature while moving the carriage 105 in the main scanning direction.
Immediately after the ink droplets 111 have landed on the recording medium 110, the radiation irradiating sections 10 provided immediately downstream of the recording medium 110 are immediately exposed.
3, the ink droplets 111 radiated with ultraviolet rays and landed
Is to be cured.

FIG. 8 is a schematic view of the entire ink jet recording apparatus, in which the recording medium 110 conveyed from the original roll 117 is conveyed to the printing section via the support roll 114, and FIG. Ink droplets 111 are ejected from each recording head in the carriage 105 shown by 7, and are landed and cured on the recording medium 110. Then chiller roll 1
After cooling the recording medium 110 at 15, in order to completely cure the unreacted polymerizable compound, ultraviolet rays are emitted again by the post-treatment exposure device 116 provided downstream thereof to complete the curing reaction. Next, the recording medium 110 on which the image printing and fixing are completed is wound up by a winding roll.

In the ink jet recording apparatus having the above structure, the nozzle hole diameter of each recording head can be processed as shown in Table 1. The temperature sensor was provided in the vicinity of each of the ink supply tank and the nozzle of the recording head, and the temperature was controlled so that the nozzle portion was always set temperature ± 2 ° C. The piezo type recording head is shown in FIG.
Drive signal shown in (b) (waveforms A and B, respectively)
2 to 30 pl of multi-sized dots using
It is possible to eject at a resolution of 720 dpi.

Further, with respect to the ink meniscus position, the position from the end face of the nozzle opening can be adjusted within the range of 15 to 90 μm by changing the waveform of the drive signal (potential and its holding time, etc.).

UV light irradiation after landing of ink droplets is variable such that the illuminance on the exposure surface is 1 to 100 mW / cm ² , and the illuminance is increased to decrease the dot diameter, and the illuminance is decreased to increase the dot diameter. The dot diameter can be adjusted. Exposure system so that irradiation starts after ink has landed on the recording medium,
The main scanning speed and ejection frequency were adjusted. D in the present invention
pi represents the number of dots per 2.54 cm.

The above ink jet recording apparatus was filled with each of the inks prepared as described above and having different viscosities (in this example, all the heads were supplied with the same ink and tested), as shown in Table 1. Printing tests 1 to 22 were conducted by changing the printing conditions to. That is, the nozzle diameter of the recording head at the time of printing is changed as shown in Table 1, and the applied voltages V1 and V2 for driving the piezoelectric elements are set so that the ink droplet ejection speed is 5 to 10 m / s. Adjusted to Figure 4 (a),
The drive signal (waveforms A and B, respectively) shown in (b) was used, and the holding time was changed, and the ink meniscus position before ink ejection and the ink droplet ejection amount were adjusted as shown in Table 1. Further, the temperature of the head and the diameter of the formed dots were adjusted as shown in Table 1 by changing the illuminance of the exposed surface during UV light irradiation. A PET film roll was used as the recording medium.

After printing, the post-processing exposure apparatus 1 shown in FIG.
16, the ambient temperature was 25 ° C., and ultraviolet rays were emitted again to complete the curing reaction. The total exposure energy per head of one color was 300 mJ / cm ² as the energy for completely curing so that the tackiness disappeared by touch.

(Viscosity) The viscosity of each ink at 30 ° C. was measured using a rotational viscometer (EDL model manufactured by Tokimec).

(Head Temperature) For each ink, the recording head temperature was set to the temperature shown in Table 1, except that the comparative solid ink (ink 1) was 150 ° C. and the comparative UV curable ink (ink 4) was 25 ° C. And printed each.

[0098]

[Table 1]

The following evaluations were carried out for each printing test and each printing test sample. The results are shown in Table 2.

<Evaluation><Continuous printing test (evaluation of bleeding)> A 100-sheet continuous printing test was conducted with the above-mentioned piezo type ink jet recording apparatus, the bleeding was visually observed and evaluated according to the following criteria. Indicated. ⊚: No nozzle missing and good printability ○: No nozzle missing but slight print irregularity △: No nozzle missing, print irregularity ×; Nozzle frequent occurrence Disturbance in printing <Restart test (ink clogging)> After printing with the above-mentioned piezo-type inkjet recording device, the printer is left at the printing temperature for 6 hours and then restarted for printing to print the ink clogging. The results are shown in Table 2. ⊚: No clogging and good printability ○: Slight omission can be observed Δ: Clogging but printing is possible with a simple recovery operation ×: Printing is not possible <Image durability test> The scratch strength tester HEIDON-18 is applied to the solid portion printed by the piezo type inkjet recording device of No. 1 and cured by irradiating ultraviolet rays.
(Manufactured by HEIDON) and a 0.8 mm R sapphire needle was used as a measuring needle. Measurement is a constant load 10
The scratch test of cm was carried out three times, and the limit load at which there was no scratched portion up to the support was taken as the scratch strength of the present invention, and judged according to the following criteria. ◯: 200 g or more Δ: less than 200 g, 100 g or more ×: less than 100 g <Smoothness> Solid areas were printed and irradiated with ultraviolet rays, and then the ink film thickness was measured. ⊚: Thickness is thin and good ○: There is no problem in high-definition printing although there is thickness Δ: Lower limit of thickness ×: Thickness is unusable level <Print quality> 8-point characters are printed Letters of rustling,
And the shape of 1 dot was magnified and evaluated with a magnifying glass. ⊚: There is no roughness, and the dot shape is a perfect circle. ◯: There is slight roughness. The dot shape is a perfect circle Δ: Roughness is visible and the dot shape is slightly disturbed (a level that can be used at the last minute) ×; Roughness is visible and the dot shape is also bad.

[0101]

[Table 2]

In the continuous printing test, the image printed by the method of the present invention has no bleeding due to nozzle deficiency or printing dripping, ink clogging in the restart test, stable ejection, and smoothness of the image. It can be seen that the durability, print quality, etc. are good.

The same test was carried out using a surface-treated transparent biaxially oriented polypropylene film having printability, a soft vinyl chloride sheet, an aluminum vapor-deposited paper, a polyethylene film, and a polystyrene film. The result was obtained.

[0104]

EFFECT OF THE INVENTION An ink jet recording method using an ink suitable for recording on any medium including a recording medium having no ink absorbability can be obtained.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an example of a recording head used in an inkjet recording apparatus according to the present invention.

FIG. 2 is an exploded configuration diagram of a recording head.

FIG. 3 is an enlarged cross-sectional view of a nozzle plate and a nozzle.

FIG. 4 is a diagram showing a waveform of a drive signal for a piezoelectric element.

FIG. 5 is a diagram for explaining how ink is discharged as ink droplets.

FIG. 6 is a schematic bottom view of a recording head unit having a radiation irradiating section of an inkjet recording apparatus used for a print test.

FIG. 7 is a schematic configuration diagram of a carriage including a recording head having a radiation irradiation unit and a heating unit.

FIG. 8 is a schematic view of the entire inkjet recording apparatus used in a print test.

[Explanation of symbols]

1 substrate 2 Piezoelectric element 3 flow path plates 3a ink flow path 3b wall 4 Common liquid chamber components 4a Common liquid chamber 5 Ink supply pipe 6 nozzle plate 6a nozzle 7 Drive circuit printed board 8 lead wires 9 Drive electrode 10 grooves 11 Protective plate 12 Fluid resistance 13, 14 electrodes 15 Upper partition 16 heater 17 Heater power supply 18 Heat transfer member 19 recording head 101 UV light source 102 optical fiber 103 Radiation irradiation unit 105 carriage 106 ink supply tank 107 Filter 108 supply piping 109 heating unit 110 Recorded material 111 ink droplets 115 Chiller roll 116 Post-processing exposure apparatus 4Y, 4M, 4C, 4K recording head

Claims (10)

[Claims] 1. An ink containing a photopolymerizable compound and a colorant is expanded and contracted in a pressure generating chamber by a piezoelectric element and ejected as an ink droplet from a nozzle opening of a recording head to form an image on a recording medium. After that, in the inkjet recording method of irradiating with ultraviolet rays, when ejecting the ink droplet, the position of the meniscus formed in the ink that is farthest from the nozzle opening end face in the nozzle is the nozzle diameter when measured from the nozzle opening end face. (Μm) or more, and
An ink jet recording method, which has a nozzle diameter of +50 (μm) or less, and heats the ink to 40 to 150 ° C. by a heating means and ejects the ink from the nozzle opening. 2. An ink containing a photopolymerizable compound and a coloring agent is expanded and contracted in a pressure generating chamber by a piezoelectric element and ejected as an ink droplet from a nozzle opening of a recording head to form an image on a recording medium. After that, in the inkjet recording method of irradiating with ultraviolet rays, when ejecting the ink droplet, the position of the meniscus formed in the ink that is farthest from the nozzle opening end face in the nozzle is the nozzle diameter when measured from the nozzle opening end face. (Μm) or more, and
A position where the nozzle diameter is +50 (μm) or less, and when the meniscus is farthest from the nozzle end face, the pressure generating chamber is contracted to eject ink, and
The ink is heated to 40 to 150 ° C. by a heating means,
An ink jet recording method, characterized in that the ink is discharged from the nozzle opening. 3. An ink containing a photopolymerizable compound and a colorant is expanded and contracted in a pressure generating chamber by a piezoelectric element and ejected as an ink droplet from a nozzle opening of a recording head to form an image on a recording medium. After that, in the inkjet recording method of irradiating with ultraviolet rays, when ejecting the ink droplet, the position of the meniscus formed in the ink that is farthest from the nozzle opening end face in the nozzle is the nozzle diameter when measured from the nozzle opening end face. A position that is equal to or more than (μm) and is equal to or less than the nozzle diameter +50 (μm), and when the meniscus is farthest from the nozzle end face, contracts the pressure generating chamber to eject ink, and Shrinkage in the step of contracting the pressure generating chamber and ejecting ink is multi-staged, and the ink is heated to 40 to 150 ° C. by the heating means. The inkjet recording method characterized by discharging from the nozzle openings. 4. The ink jet recording method according to claim 1, wherein the ink containing the photopolymerizable compound and the colorant has a viscosity at 30 ° C. of 10 to 500 mPa · s. . 5. A partition between ink channels of the pressure generating chamber is formed of a piezoelectric element.
5. The inkjet recording method according to any one of 4 above. 6. The ejection amount per dot is from 2 pl to 20.
It is pl, Any 1 of Claims 1-5 characterized by the above-mentioned.
Inkjet recording method according to item. 7. A dot diameter formed on a recording medium is 50.
The ink-jet recording method according to any one of claims 1 to 6, wherein the ink-jet recording method is about 200 to 200 µm. 8. The ink according to claim 1, wherein the ink is substantially free of water and an organic solvent.
Inkjet recording method according to item. 9. The ink jet recording method according to claim 1, wherein the recording medium has no ink absorbability. 10. The ink comprises a pigment as a colorant.
5 to 30% by mass is contained.
The inkjet recording method according to any one of 1.