JP2007210111A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form an image of a high image quality by efficiently curing active energy beam-curing type ink by suppressing radiation of a thermal energy of the ink generated by active energy beams. <P>SOLUTION: A support 34 which supports a sheet 15 when the ink 52 is delivered is equipped with a pedestal 33 formed of aluminum. A radiation preventive plate 54 directly supporting the sheet 15 is placed on the top face of the pedestal 33. A thickness/thermal conductivity of this radiation preventive plate 54 is not smaller than 1×10<SP>-4</SP>[°C/W]. The ink 52 is efficiently cured by suppressing radiation of the thermal energy of the ink 52 generated by ultraviolet rays. The high image-quality image can be obtained accordingly. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus that forms an image by curing ink with activation energy rays.

Some image forming apparatuses form an image by ejecting an actinic ray (active energy ray) curable ink onto a recording medium. (Patent Document 1)
Specifically, this image forming apparatus is configured to polymerize and harden the ink by irradiating the recording medium with the ink and then irradiating with an actinic ray such as an ultraviolet ray. At this time, the ink generates heat due to the polymerization reaction, and the reaction is further promoted by increasing the temperature.

The actinic ray curable ink is an oxetane compound containing at least one oxetane ring and an oxetane compound containing two or more at least one oxetane ring. For this reason, the ink discharge is stable, and a high-quality image can be formed.
JP 2004-25479 A

  However, according to this image forming apparatus, the thermal energy generated by the polymerization by the active energy rays is transmitted to the member that supports the recording medium, and the temperature of the ink is lowered, so that the progress of the polymerization becomes insufficient. May not be cured sufficiently and the image quality may deteriorate.

  In consideration of the above facts, the present invention has an object to efficiently cure an active energy ray-curable ink and obtain a high-quality image by suppressing heat radiation of ink thermal energy generated by active energy rays. .

An image forming apparatus according to a first aspect of the present invention includes a recording head that discharges ink that is cured by active energy rays to a recording medium in accordance with image information, and is disposed adjacent to the recording head and discharged from the recording head. Energy applying means for irradiating the ink with active energy rays, and opposed to the recording head, supports the recording medium when the recording head ejects the ink, and has a thickness / thermal conductivity of 1 × 10. ^-4 [° C./W] or more, and a support means provided at least in part with a heat dissipation preventing member.

  According to the above configuration, the recording head ejects ink that is cured by active energy rays (active energy ray curable ink) to the recording medium according to the image information.

  The ejected ink is polymerized by the active energy rays irradiated from the energy applying means arranged adjacent to the recording head, and is heated and cured.

  On the other hand, when the recording head ejects ink onto the recording medium, the recording medium is supported by a supporting means that is disposed to face the recording head.

Here, since the thickness / thermal conductivity of at least a part of the heat radiation preventing member of the support means is 1 × 10 ⁻⁴ [° C./W] or more, the thermal energy of the ink that has been polymerized and generated is transmitted to the support means. Thus, heat radiation is prevented and the active energy ray-curable ink is efficiently polymerized and cured to obtain a high-quality image.

An image forming apparatus according to a second aspect of the present invention is the image forming apparatus according to the first aspect, wherein the heat dissipation preventing member having a thickness / thermal conductivity of 1 × 10 ⁻⁴ [° C./W] or more provided in the support means is The recording medium is directly supported.

According to the above configuration, the heat radiation preventing member having a thickness / thermal conductivity of 1 × 10 ⁻⁴ [° C./W] or more provided in the support means directly supports the recording medium.

  For this reason, it is effectively prevented that the heat energy is transmitted to the support means and dissipated.

  An image forming apparatus according to a third aspect of the present invention is the image forming apparatus according to the first or second aspect, wherein the energy applying unit is a light emitting diode.

  According to the above configuration, since the energy applying means is a light emitting diode, it is economical because it emits light with low power and high luminance with less heat generation.

  An image forming apparatus according to a fourth aspect of the present invention is the image forming apparatus according to any one of the first to third aspects, wherein the supporting unit is provided with a suction unit that sucks the recording medium.

  According to the above configuration, since the supporting means is provided with the suction means for sucking the recording medium, it is possible to prevent the recording medium from coming into contact with the recording head and deteriorating the image quality.

  An image forming apparatus according to a fifth aspect of the present invention is the image forming apparatus according to any one of the first to fourth aspects, wherein the material for the heat radiation preventing member is polyethylene or polycarbonate.

  According to the said structure, since the material of a heat-radiation prevention member is polyethylene or a polycarbonate, it can be set as an inexpensive structure using a versatile material.

  According to the image forming apparatus of the present invention, it is possible to efficiently cure the active energy ray-curable ink and obtain a high-quality image by suppressing the heat radiation of the ink generated by the active energy ray.

  An image forming apparatus according to an embodiment of the present invention will be described with reference to FIGS.

  As shown in FIG. 4, an inkjet recording apparatus 12 that is an image forming apparatus includes a conveyance roll 16 (see FIG. 1) that conveys a sheet 15 that is a recording medium in a certain direction, and a direction perpendicular to the conveyance direction of the sheet 15. And a guide member 18 provided along the line.

  The recording head carriage 14 is supported by the guide member 18. A maintenance device 20 is disposed below the guide member 18 and adjacent to the conveyance path of the paper 15, and performs maintenance operations such as capping and ink suction on the recording head carriage 14. This maintenance operation is controlled by a control circuit (not shown) so as to be performed at a predetermined condition and timing.

  The home position of the recording head carriage 14 is set at a position facing the maintenance device 20, and this position is detected by the position sensor 22.

  The recording head carriage 14, the transport roll 16, the guide member 18, the maintenance device 20, and the position sensor 22 described above are held in the main body housing 24. Further, image information is sent to the recording head carriage 14 through a signal line formed on the flexible substrate.

  In FIG. 4, the moving direction (main scanning direction) of the recording head carriage 14 is indicated by an arrow M, and the moving direction (sub-scanning direction) of the paper 15 is indicated by an arrow S.

  The recording head carriage 14 includes a carriage frame 26 movably disposed along the guide member 18, recording heads 28 of each color housed in a predetermined housing portion in the carriage frame 26, and LEDs serving as energy applying means. (Light emitting diode) 50. Details of the LED 50 will be described later.

  As shown in FIG. 3, the lower portion of each color recording head 28 is a recording head portion 28A, and a plurality of nozzles (not shown) are provided. The nozzles are arranged at regular intervals in the front and back direction in FIG.

  Further, an ink tank 28B that supplies ink to each recording head unit 28A is disposed above the recording head unit 28A, and the recording head 28 of each color is configured by the ink tank 28B and the recording head unit 28A. .

  The number of ink tanks 28B corresponds to the number of recording heads 28 for each color, and is four in this embodiment.

  Accordingly, by supplying ink of different colors (black (K), yellow (Y), magenta (M), cyan (C)) to the recording head 28 of each color for each ink tank 28B, ink droplets are ejected. A full color image can be recorded.

  As shown in FIG. 1, the ink jet recording apparatus 12 of the present embodiment transports a sheet 15 on a support 34 that is a support means by a transport roll 16, and reciprocates a recording head carriage 14. Ink droplets are ejected according to information to form an image on the paper 15.

The support 34 is disposed to face the recording head 28 and supports the paper 15 when the ink 52 is ejected. Specifically, the support 34 includes an aluminum pedestal 33, and a heat radiation prevention plate 54 as a heat radiation prevention member that directly supports the paper 15 is disposed on the upper surface of the pedestal 33. Further, the thickness / thermal conductivity of the heat radiation prevention plate 54 is 1 × 10 ⁻⁴ [° C./W] or more (preferably 1.5 × 10 ⁻⁴ [° C./W] or more, more preferably 1.7). × 10 ⁻⁴ [° C./W] or more). Here, the thickness is a plate thickness and means a thickness in the vertical direction.

  Next, the configuration of the ink 52, the LED 50, and the support 34 provided in the ink tank 28B will be described in detail.

  As shown in FIG. 1, an ink 52 that is cured by being irradiated with ultraviolet rays as active energy rays is provided inside the ink tank 28B.

Hereinafter, the composition components of the ink 52 will be described.
<Ink composition component>
Monomer: (3 ′, 4′-epoxycyclohexane) methyl 3,4-epoxycyclohexanecarboxylate (Celoxide 2021A: manufactured by Daicel UCB) 30 g
Monomer: Bis [1-ethyl (3-oxetanyl)] methyl ether 70 g
(Aron Oxetane OXT-221 manufactured by Toa Gosei)
Pigment dispersion: Irgalite Blue GLVO (PB-15; 4) (manufactured by Ciba Specialty Chemicals) 20%, Aron Oxetane OXT-221 (manufactured by Toa Gosei) 72%, Solsperse 28000 (manufactured by Lubrizol) 8% ... 10 g
Photopolymerization initiator: (4-isobutylphenyl) 4-methylphenyliodonium hexaloorhophosphate and propylene carbonate (Irgacure 250: manufactured by Ciba Specialty Chemicals) ... 6.0 g
・ Sensitizer: Isopropylthioxanthone (Darocur ITX Ciba Specialty Chemicals) 3.0g
・ Surfactant: Megafuck F476 (manufactured by DIC)… 0.2g
The above components were mixed with stirring and filtered through a 5.0 μm membrane filter to obtain ink 52.

  An image is formed by ejecting this ink onto the paper 15 from a plurality of nozzles of the recording head portion 28A provided below the recording head 28.

  Next to the recording head 28, the LED 50 shown in FIG. 2 is arranged, and the ultraviolet light emitting portions are provided at equal intervals along the direction (S direction) in which the paper 15 (see FIG. 4) is conveyed. It has been. The ink 52 (see FIG. 1) ejected onto the paper 15 is configured to be cured by the ultraviolet light emitted from the LED 50.

  Further, the pedestal 33 and the heat radiation prevention plate 54 are provided with suction holes 56 as a plurality of suction means, and the pump 58 sucks air from the suction holes 56 to prevent the conveyed paper 15 from being lifted. It is the composition to do.

Next, in this configuration, when the ink 52 was ejected onto the paper 15 to form an image, the state in which the ink 52 was cured was confirmed by the following test.
<Test conditions>
-Environment: Test temperature 25 ° C, relative humidity 60%
-Nozzle = head is Spectra SE-128.
-The nozzle density is 50 nozzles per 25.4 mm, for a total of 128 nozzles.
Use five recording heads 28 to eject inks of five colors, cyan, magenta, yellow, black, and white.
Each nozzle discharges at 4 KHz, performs main scanning at 340 mm / s, and is ejected onto the paper 15 at a density of 300 dpi in the main scanning direction by one scanning.
When the main scanning is completed, the recording head 28 forms an image by 24 overlapping droplet ejections while shifting the position after moving a predetermined amount of the paper 15 in the sub-scanning direction, and is 600 dpi in both the main scanning direction and the sub-scanning direction. Form an image.
The LED 50 was NCCU033 (wavelength 365 nm) manufactured by Nichia Corporation, and eight LEDs were arranged in parallel with the nozzle row at intervals of 7 mm.
-The LED consumes 2.25 W of power per chip and emits about 100 mW of light output. These were arranged in a line and arranged at a position about 10 mm away from the paper 15 on which the ink landed, so that the exposure power on the paper 15 was about 170 mW / cm ² .
The ink 52 is ejected from the recording head 28 onto the paper 15 and simultaneously irradiated with ultraviolet rays from the LED, and the recording head 28 and the light source move together in the main scanning direction, so that ultraviolet rays immediately after landing. Is cured, the ink 52 starts to be cured.
The paper 15 on which the ink 52 is landed is placed on a heat dissipation prevention plate 54 joined to the upper surface of an airtight aluminum box. In this aluminum box, the pedestal 33 having a thickness of 5 mm and the heat radiation prevention plate 54 are provided with suction holes 56 having a diameter of 0.5 mm at intervals of 10 mm in length and width, and the pump is connected via a suction tube connected to the box. 58 is aspirated.
・ Exposure power: 170 mW / cm ²
・ Scanning exposure: 340mm / sec
<Evaluation method>
・ Repeat and cure repeatedly as described above, and when ink is transferred to the paper side by applying a pressure of 50 kg / m ² after applying paper to the ink surface immediately after completion, uncured and not transferred In the case, it is judged that it has hardened.

The confirmation of curing was performed in two steps, immediately after the end of printing and 2 minutes later.
Example 1
As shown in FIG. 5A, a polyethylene film layer having a thickness of 50 μm as a heat radiation preventing plate 54 is coated on an aluminum pedestal 33 having a thickness of 5 mm.

The thickness / thermal conductivity of the polyethylene film layer is 1.7 × 10 ⁻⁴ [° C./W].

  In this case, about 55% of the deposited area was cured immediately after the ultraviolet irradiation, and 100% was cured by a dark reaction after 2 minutes.

The thermal conductivity of the polyethylene film was 0.30 [W / m · ° C.].
(Example 2)
As shown in FIG. 5B, a polycarbonate layer having a thickness of 0.15 mm serving as a heat dissipation prevention plate 54 is coated on an aluminum pedestal 33 having a thickness of 5 mm.

The thickness / thermal conductivity of the polycarbonate layer is 7.9 × 10 ⁻⁴ [° C./W].

  In this case, about 90% of the deposited area was cured immediately after the ultraviolet irradiation, and 100% was cured by a dark reaction after 2 minutes.

The thermal conductivity of polycarbonate was 0.19 [W / m · ° C.].
(Example 3)
As shown in FIG. 5C, a polycarbonate layer having a thickness of 0.2 mm serving as a heat dissipation prevention plate 54 is coated on an aluminum pedestal 33 having a thickness of 5 mm.

The thickness / thermal conductivity of the polycarbonate layer is 1.1 × 10 ⁻³ [° C./W].

  In this case, about 100% of the deposited area was cured immediately after the ultraviolet irradiation.

The thermal conductivity of polycarbonate was 0.19 [W / m · ° C.].
Example 4
As shown in FIG. 6A, a polyethylene film layer having a thickness of 0.25 mm serving as a heat dissipation prevention plate 54 is coated on an aluminum pedestal 33 having a thickness of 5 mm.

The thickness / thermal conductivity of the polyethylene film layer is 8.5 × 10 ⁻⁴ [° C./W].

  In this case, about 90% of the deposited area was cured immediately after the ultraviolet irradiation, and 100% was cured by a dark reaction after 2 minutes.

The thermal conductivity of the polyethylene film was 0.30 [W / m · ° C.].
(Example 5)
As shown in FIG. 6B, a polyethylene film layer having a thickness of 0.35 mm serving as a heat dissipation prevention plate 54 is coated on an aluminum pedestal 33 having a thickness of 5 mm.

The thickness / thermal conductivity of the polyethylene film layer is 1.2 × 10 ⁻³ [° C./W].

  In this case, about 100% of the deposited area was cured immediately after the ultraviolet irradiation.

The thermal conductivity of the polyethylene film was 0.30 [W / m · ° C.].
(Comparative Example 1)
The member on which the paper is placed is aluminum having a thickness of 5 mm.

The thickness / thermal conductivity of aluminum is 2.1 × 10 ⁻⁵ [° C./W].

  In this case, almost all of the deposited area was uncured even after 2 minutes.

The thermal conductivity of aluminum was 237 [W / m · ° C.].
(Comparative Example 2)
The member on which the paper is placed is coated with a 25 μm thick polyethylene film layer on 5 mm thick aluminum.

The thickness / thermal conductivity of the polyethylene film is 8.3 × 10 ⁻⁵ [° C./W].

  In this case, about 60% of the deposited area was uncured immediately after UV irradiation, and 25% was uncured after 2 minutes.

  The thermal conductivity of the polyethylene film was 0.30 [W / m · ° C.].

FIG. 7 shows the test results, with the horizontal axis indicating the thickness / thermal conductivity [° C./W] and the vertical axis indicating the curing rate [%]. Since the heat dissipation preventing plate 54 of the present embodiment has a thickness / thermal conductivity of 1 × 10 ⁻⁴ ° C./W or more, it can be seen that the ink 52 is efficiently cured.

  Therefore, by suppressing the heat dissipation of the thermal energy of the ink 52 generated by the ultraviolet light, the ink 52 can be efficiently cured and a high-quality image can be obtained.

  Also, radically active inks and cationically polymerizable inks are known as active energy ray curable inks. However, cationically polymerizable inks tend to be hard to cure due to the influence of humidity. By using the type ink, the ink can be cured more effectively.

  Although the present invention has been described in detail with respect to specific embodiments, the present invention is not limited to such embodiments, and various other embodiments are possible within the scope of the present invention. It is clear to the contractor. For example, in the present embodiment, the paper 15 is used as the recording medium, but instead of that, a PET film, an OPP film, a heat shrink film, plastic, metal, glass, cloth, or the like may be used. Not.

  Moreover, in this embodiment, although the heat radiation prevention plate 54 used a polyethylene film layer or a polycarbonate layer to prevent heat radiation, instead, phenol resin, polyamide, polyimide, polystyrene, polypropylene, methacrylic resin, glass fiber reinforced resin. Etc. may be used to prevent heat dissipation, and those in which bubbles are injected into them are more suitable as a heat dissipation prevention plate because the thermal conductivity is further reduced. In addition, it is also preferable to support the recording medium in a linear or dotted solid form and to use the air layer as a heat dissipation preventing member. Further, heat dissipation may be prevented by using mica, paper, glass, diatomaceous earth, cloth, gypsum, fiber, felt, wood, linoleum, and the like.

  Here, the material having a high heat insulation effect preferably has a thermal conductivity of 10 [W / m · ° C.] or less, more preferably 1.0 [W / m · ° C.] or less, and particularly preferably 0. .3 [W / m · ° C.] or less. Furthermore, the thickness is preferably 1 μm to 10 cm, more preferably 10 μm to 1 cm, and particularly preferably 20 μm to 1 mm.

Further, in the present embodiment, ultraviolet light, which is an active energy ray, is irradiated from the LED 50 element, which is a semiconductor. In this case, heat generated from the LED 50 element is small, and the temperature rise of the recording medium due to this is small. Therefore, it is remarkably effective at the time of low energy irradiation, and the exposure power to the recording medium is preferably 1000 to 1 [mW / cm ² ], more preferably 500 to 10 [mW / cm ² ], particularly Preferably, it is 300 [mW / cm ² ] or less.

  In the present embodiment, an LED (light emitting diode) is used as the energy applying means, but instead, a mercury lamp, a metal halide lamp, a semiconductor laser, a fluorescent lamp, or the like may be used. Further, a light source or an electromagnetic wave that causes a polymerization reaction of ink such as a hot cathode tube, a cold cathode tube, an electron beam, and an X-ray may be used.

  In the present embodiment, the pump 58 is used to prevent the paper 15 from floating by sucking air from the suction holes 56. Alternatively, the paper 15 may be prevented from floating using static electricity or the like. Good.

  Next, an example in which a liquid crystal color filter is created by the image forming apparatus of the present invention will be described with reference to FIGS.

  A glass substrate 100 which is a substrate of a liquid crystal color filter is placed on the heat dissipation prevention plate 54 of the support 34, and the color (red (R), green (G), blue (B)) ink 120 is placed in the black matrix 110. A liquid crystal color filter is formed by ejecting droplets and curing the ink.

  Moreover, although the liquid crystal color filter was formed by ejecting ink 120 onto the glass substrate 100 and curing it, an electric circuit or the like can be obtained by ejecting conductive ink onto the insulator and curing it. May be formed.

  In this embodiment, the image forming apparatus including the scanning head has been described as an example. However, a fixed head including an ink discharge mechanism longer than the width of the recording medium can be applied.

1 illustrates an ink jet recording apparatus according to an embodiment of the present invention, and is a view of a recording head and a support viewed from a main scanning direction. FIG. 2 is a bottom view showing the ink jet recording apparatus according to the embodiment of the present invention when the recording head is viewed from below. 1 illustrates an ink jet recording apparatus according to an embodiment of the present invention, in which a recording head and a support are viewed from a sub-scanning direction. 1 is a perspective view showing an ink jet recording apparatus according to an embodiment of the present invention. (A) The inkjet recording device which concerns on embodiment of this invention is shown, and it is drawing which showed the support body used for Test Example 1. FIG. (B) An inkjet recording apparatus according to an embodiment of the present invention, showing a support used in Test Example 2. (C) An ink jet recording apparatus according to an embodiment of the present invention, showing a support used in Test Example 3. (A) The inkjet recording device which concerns on embodiment of this invention is shown, and it is drawing which showed the support body used for Test Example 4. FIG. (B) The inkjet recording device which concerns on embodiment of this invention is shown, and it is drawing which showed the support body used for Test Example 5. FIG. 2 is a table showing the curing rate of ink in the ink jet recording apparatus according to the embodiment of the present invention, with the vertical axis representing the curing rate and the horizontal axis representing the thickness / thermal conductivity. (A) It is the perspective view which showed the liquid crystal color filter and support body which concern on embodiment of this invention. (B) It is sectional drawing which showed the liquid crystal color filter and support body which concern on embodiment of this invention.

Explanation of symbols

12 Inkjet recording device (image forming device)
15 paper (recording medium)
28 Recording Head 34 Support (Supporting Means)
50 LEDs (energy imparting means)
54 Heat radiation prevention plate 56 Adsorption hole (adsorption means)
100 Glass substrate (recording medium)

Claims (5)

A recording head for discharging ink that is cured by active energy rays to a recording medium according to image information;
Energy applying means that is arranged adjacent to the recording head and that irradiates the ink ejected from the recording head with active energy rays;
A heat dissipation preventing member disposed opposite to the recording head and supporting the recording medium when the recording head ejects the ink and having a thickness / thermal conductivity of 1 × 10 ⁻⁴ [° C./W] or more. Support means provided at least in part;
An image forming apparatus comprising: 2. The image according to claim 1, wherein the heat radiation prevention member having a thickness / thermal conductivity of 1 × 10 ⁻⁴ [° C./W] or more provided in the support means directly supports the recording medium. Forming equipment.   The image forming apparatus according to claim 1, wherein the energy applying unit is a light emitting diode.   The image forming apparatus according to claim 1, wherein the supporting unit is provided with an adsorption unit that adsorbs the recording medium.   The image forming apparatus according to claim 1, wherein a material of the heat dissipation preventing member is polyethylene or polycarbonate.

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