JP2010143073A - Image forming method and image forming apparatus - Google Patents

Abstract

In image formation in which an ink image is transferred to a recording medium by bringing the recording medium into contact with an ink image containing a photocurable component formed on an intermediate transfer member, the ink image has high curing efficiency and is fixed. It is possible to perform recording with excellent process productivity, extremely low image disturbance and high surface smoothness.
In a state where a recording medium is in contact with an ink image containing a photocurable component formed on an intermediate transfer member, the ink image is irradiated with the active energy rays.
[Selection] Figure 1

Description

  The present invention relates to an image forming method and an image forming apparatus, and more particularly to an intermediate transfer type image forming method and an image recording apparatus to which ink jet recording is applied.

  In ink jet recording, a recording method using a photocurable ink has been proposed and put into practical use. In general, the light used for curing the ink is often ultraviolet rays. The ink to be combined has an advantage that a recorded matter having high abrasion resistance can be obtained even immediately after recording because a polymerization reaction proceeds and cures by ultraviolet irradiation. However, ink used for ink jet recording is generally required to have a low viscosity. For this reason, if a large amount of ink is applied faster than the curing speed of the ink, the ink flows on the recording medium and the image is disturbed, and undesired color mixing occurs when using multicolor ink. There is a problem that it is frustrating.

  Accordingly, the image output speed of ink jet recording using a photocurable ink is often limited by the ink curing speed. Furthermore, since the color material contained in the color ink absorbs the curing light, more light energy is required to be cured. For these reasons, an ink jet recording apparatus using photocurable ink is equipped with a powerful light source so that curing occurs instantaneously, or a serial type recording apparatus increases the number of so-called multi-pass recording passes. Therefore, the current situation is that recording at low speed is unavoidable.

  Further, recorded matter recorded by an ink jet recording apparatus using photocurable ink is often inferior in gloss. This is a problem stemming from the problem that the above-mentioned color mixture or the like is mixed unless the applied ink spreads in the surface direction of the recording medium and is light-cured before becoming smooth (leveling). This problem becomes more prominent as curing is performed at high speed. That is, as the curing rate is increased, it is required to shorten the time until leveling, and it becomes difficult to obtain the surface smoothness of the colored portion.

  On the other hand, there has been proposed a method (transfer type ink jet recording method) in which an ink image is formed on an intermediate transfer member and the ink image formed on the transfer member is transferred to a recording medium. . In particular, Patent Document 1 proposes using a photocurable ink as the ink. In Patent Document 1, the ink is thickened by first irradiating light with the ink image formed on the intermediate transfer member, and then the ink image is transferred to the recording medium, and then the second light irradiation is performed again. There has been proposed a method of fixing an image by performing. According to this method, since the ink is thickened at the stage of transferring the ink image to the recording medium, the problems of ink flow and color mixing described above can be solved.

  However, the problem of surface smoothness as described above remains. In other words, the ink has fluidity until the ink image transferred to the recording medium is cured by the second light irradiation, and the ink image may be deformed before the light irradiation after the transfer process. May be impaired. Conversely, if the initial light irradiation is performed strongly to reduce the fluidity on the recording medium as much as possible, the problem is not solved because the ink is naturally fixed before leveling.

  Furthermore, in Japanese Patent Application Laid-Open No. H11-260260, the ink remains at a low viscosity at the stage of forming the ink image on the intermediate transfer member. Therefore, as the ink image is formed at a higher speed, the image quality such as ink flow and color mixing is impaired. The phenomenon is likely to occur.

  On the other hand, as an application of the photocurable material to the printing field, there is one that has been put to practical use in order to perform surface processing with a varnish using a photocurable transparent material. This is a method in which a transparent photocurable varnish is applied onto a recorded material with a coating device such as a roll coater, and is photocured after waiting for leveling. Since the photocurable varnish is used alone, there is no influence even if it flows or mixes. Moreover, since it is transparent, a coloring material does not absorb curing light, and a practical curing rate is easily obtained.

  A technique excellent in the surface processing method using such a photocurable varnish is disclosed in Patent Document 2. This is a method of performing light irradiation in a state in which a transparent film is adhered after applying a photocurable varnish on a printed material. According to this method, high surface smoothness can be obtained as compared with the conventional method, and since the photocuring efficiency is high, it is possible to cure faster with a smaller dose.

  However, Patent Document 2 is a technique for coating a transparent varnish on the entire surface of a non-fluid image that has already been fixed, and does not solve the problems such as productivity of the image fixing process and image disturbance. Does not give. In particular, the present invention cannot be applied as it is to the ink jet recording technique to which an image is formed by selectively applying ink.

Japanese Patent Laid-Open No. 10-250052 JP-A-2005-225130

  As described above, the inkjet recording method using a photocurable ink requires a large amount of light energy to achieve curing or high speed recording, and the surface of a recorded matter recorded at high speed. Has a problem of poor glossiness.

  Accordingly, an object of the present invention is to make it possible to perform recording with high surface smoothness in addition to high curing efficiency of an ink image containing a photocurable component, excellent fixing process productivity, extremely little image distortion. And

For this purpose, the present invention provides an image formation for transferring an ink image to the recording medium by bringing the recording medium into contact with an ink image containing a component that is cured by irradiation with active energy rays, which is formed on the intermediate transfer member. A method,
Applying ink to form the ink image using an inkjet head;
Irradiating the ink image with the active energy rays while the recording medium is in contact with the ink image on the intermediate transfer member;
It is characterized by comprising.

The present invention also provides an image forming apparatus for transferring the ink image to the recording medium by bringing the recording medium into contact with an ink image containing a component that is cured by irradiation with active energy rays, which is formed on the intermediate transfer member. Because
Means for applying ink to form the ink image using an inkjet head;
Means for irradiating the ink image with the active energy rays while the recording medium is in contact with the ink image on the intermediate transfer member;
It is characterized by comprising.

  According to the present invention, the curing efficiency of an ink image containing a component that is cured by irradiation with active energy rays is high, the productivity of the fixing process is excellent, and the image is hardly disturbed and recording with high surface smoothness can be performed. It becomes like this.

(1) Outline In the present invention, the recording medium is in contact with an ink image formed on an intermediate transfer member and containing a component that is cured by irradiation with active energy rays (that is, the ink image is not in contact with outside air). The main feature is to irradiate the ink image with the active energy rays. According to this, a recorded matter having high abrasion resistance and surface smoothness can be obtained at high speed and using a small amount of energy. Although the mechanism by which such an effect is obtained is not yet clear, the present inventors presume as follows.

  It is considered that the influence of oxygen is a major factor that reduces the curing efficiency of the photocurable ink. The curing mechanism of the photocurable ink is as follows by taking a general radical polymerization type ultraviolet curable ink as an example. First, radicals are generated when the photopolymerization initiator blended in the ink receives ultraviolet light having an absorption wavelength. Upon receiving this radical, the resin component starts to cure. If the ink surface is open at this time, radicals are deprived of atmospheric oxygen, and the efficiency of the curing reaction is greatly reduced.

  Further, regarding the surface smoothness, it is presumed that the influence of the timing of solidifying the liquid component by irradiating the curing light to the ink and the timing of bringing the recording medium into contact with the transfer body is large. That is, when the curing light is irradiated prior to contact with the transfer body, leveling that should occur due to the influence of wetting and gravity is suppressed. On the other hand, if the curing light is irradiated after contact, the surface smoothness is impaired by physical force during transfer and peeling of the recording medium from the transfer body, and leveling due to wetting and gravity It will not be expected.

(2) Embodiment Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the following, the active energy ray is exemplified mainly as ultraviolet rays, and this may be referred to as curing light. Furthermore, an ink or a component that is cured by irradiation with an active energy ray may be referred to as a photocurable ink or a photocurable component.

The image forming method according to an embodiment of the present invention employs the following steps. That is,
a. Forming an ink image containing a component that is cured by irradiation with active energy rays on the intermediate transfer member;
b. Reducing the fluidity of the ink image on the intermediate transfer member; and c. This is a step of irradiating the recording medium with an active energy ray while contacting and transferring the ink image on the intermediate transfer member.

FIG. 1 is a schematic diagram of an embodiment of an image forming apparatus to which the present invention is applied.
What is denoted by reference numeral 1 is an endless belt-like intermediate transfer member, which is laid on rollers 11A to 11C and conveyed in the direction of arrow A. The intermediate transfer member 1 preferably has a surface with high transparency in the light wavelength region used for ink curing. The surface is preferably a non-absorbing surface. A coating device 2, an inkjet head 3, a surplus liquid component removal accelerating device 4, a pressure roller 6, a cleaning unit 7, and the like are provided on the outer periphery of the intermediate transfer body 1, that is, a portion facing the surface.

  The coating device 2 has the form of a roll coater and applies a first liquid that restricts the movement of ink droplets onto the intermediate transfer member 1. The inkjet head 3 discharges photocurable ink onto the intermediate transfer body 1 to form an ink image. The ejected ink reacts in contact with the first liquid applied on the intermediate transfer body 1, and the in-plane movement of the ink droplets is restricted, so that the disturbance of the ink image is minimized.

  Next, the liquid component that is not the final image forming component is reduced from the ink image on the intermediate transfer body 1 to an appropriate amount by the surplus liquid component removal promoting device 4. At this point, the ink image is sufficiently fluid.

  The recording medium 5 is contacted and transferred to the ink image in this state by the pressure roller 6, and at the same time, the curing light source 7 irradiates the ink image with the curing light and is cured. At this time, since the ink is sandwiched between the recording medium 5 and the pressure roller 6 and is almost sealed, the curing efficiency is high. Since the ink image is cured simultaneously with the transfer, the recorded material has high abrasion resistance even immediately after recording. Further, since the surface of the ink image is smoothed in accordance with the surface of the intermediate transfer member 1, the surface smoothness or glossiness of the recorded matter is very excellent.

  Thereafter, if there is a residue or the like on the intermediate transfer body 1, it is removed by the cleaning unit 7 for forming the next ink image to form a clean surface, and the above image forming process is repeated.

  Next, steps a to c according to the present invention and elements applicable thereto will be described in detail.

(2.1) Step (a) of forming an ink image containing a component that is cured by irradiation with active energy rays on the intermediate transfer member
Intermediate Transfer Material When the material suitable for the intermediate transfer body 1 applied to the present invention is irradiated from the back side of the intermediate transfer body 1, it is desirable that the light wavelength used for ink curing is high. The higher the curing light transmittance of the intermediate transfer member, the better, but it is preferably 20% or more, more preferably 60% or more. According to the concept of the present invention, it is only necessary to irradiate the energy beam in a state where the ink image is sandwiched between the intermediate transfer member and the recording medium. Therefore, the irradiation can be performed from the recording medium 5 side. In addition, it is one of preferable modes that both the intermediate transfer member and the recording medium are light transmissive, and the ink is irradiated to the layer from both sides, and FIG. 1 shows the configuration.

  The surface of the intermediate transfer member 1 is preferably made of rubber or plastic having predetermined elasticity and high releasability. When using a type A durometer (according to JIS K 6253), an effect can be obtained by using a material having a hardness in the range of 10 to 100 °, and most of the material in the range of 40 to 80 °. Can be used for recording paper.

The releasability means a state in which the ink image can be removed without being fixed to the surface of the intermediate transfer member. If the surface of the intermediate transfer body 1 does not have releasability, the ink has adhesiveness with a curing reaction when irradiated with light, so that the recording medium 5 and the intermediate transfer body 1 may be bonded as the ink cures. The releasable material preferably used in the present invention preferably has a surface energy of 30 mJ / m ² or less, and specific examples include silicone rubber, fluorosilicone rubber, and fluororubber. Preferred characteristics can also be obtained by coating the surface of the elastic body with fluorine or silicone material.

  However, high releasability generally results in high water repellency and easily repels image forming materials such as ink. Therefore, surface treatment is preferably performed as necessary. Examples of the surface treatment include surfactant coating, ultraviolet ray or excimer irradiation, flame treatment, ozone treatment, corona treatment or plasma treatment. Of these, a surface obtained by subjecting silicone rubber to plasma treatment is suitable for the present invention.

  Further, the shape of the intermediate transfer member is not limited as long as it has a belt shape as shown in FIG. 1 or a roller (drum) shape or a sheet shape that can contact at least the recording medium. FIG. 2 illustrates a case where a drum-shaped intermediate transfer member 21 is applied. Moreover, although it is a batch process, it is applicable even if it is a rubber pad shape like pad printing.

  As described above, the surface of the intermediate transfer member is preferably highly releasable, and if it has a releasable surface, complete transfer of the ink image can be expected. The shape is almost the same as the surface of the body. That is, if an intermediate transfer member having a smooth surface is used, the image on the recording medium is also smoothed and high gloss is obtained. On the contrary, if an intermediate transfer member having a surface with low smoothness is used, it is possible to intentionally create a matte image. Furthermore, a part of the surface of the intermediate transfer member is used as a mat, so that only a desired part can be used as a mat image.

  Further, when the surface layer of the intermediate transfer body 1 is a releasable surface, the cleaning unit 7 is not necessary, or the cleaning unit 7 can be performed with a slight operation.

First liquid In the present invention, the first liquid is applied prior to the formation of the ink image in order to prevent ink flow and color mixing at the time of ink image formation and to prevent image disturbance at the time of transfer / light irradiation. It is preferable to keep it. The first liquid is also called a reaction liquid, and has an effect of restricting the movement of the ink droplets by contacting and reacting with the ink applied on the intermediate transfer body 1. When these reaction solutions are not used, it is possible to use evaporation of volatile components, but this is disadvantageous in terms of productivity (speed).

  Examples of the reaction that lowers the fluidity of the ink include dispersion destruction (aggregation, precipitation, separation), thickening, concentration, and the like of the ink. A material having an action of accelerating these is applied as a reaction liquid. The reaction material used can be appropriately selected depending on the type of ink used for image formation. The object can be achieved even if the form is liquid, solid, or even gas. For example, a solvent that causes a solvent shock to the ink solvent if thickened, and an azeotropic solvent that promotes evaporation if concentrated. Among these, the aggregation reaction when water-based ink is used is suitable for the present invention, and metal ions for the pigment ink are preferable as the reaction liquid of the present invention.

Examples of the metal ions include divalent metal ions such as Ca ²⁺ , Cu ²⁺ , Ni ²⁺ , Mg ²⁺ and Zn ^2+, and trivalent metal ions such as Fe ³⁺ and Al ^3+. Can be mentioned. Reaction occurs even with monovalent metal ions, but its use is limited in terms of speed and strength. And when providing these ions, providing as metal salt aqueous solution is desirable. Examples of the anion of the metal salt include Cl ⁻ , NO ₃ ⁻ , SO ₄ ²⁻ , I ⁻ , Br ⁻ , ClO ₃ ⁻ , RCOO ⁻ (R is an alkyl group) and the like. In addition, a material having a reversal to the ink used can be used as the reaction liquid. For example, if the ink is anionic or alkaline, a cationic or acidic material that is the opposite of the ink can be used as the reaction liquid.

  There is no limitation as a 1st liquid provision means (coating apparatus 2), What is necessary is just to select suitably according to a liquid material. For example, if it is a liquid, the roll coater shown in FIG. 1 is an example. As other coating methods, contact coating methods such as doctor coating, die coating, wire bar coating, and gravure roller, and non-contact coating methods such as spray coating can also be used. As another example of the non-contact coating method, droplet application by an ink jet method may be performed. It is convenient to use an ink jet method, and it is preferable that a necessary amount can be applied only to a necessary portion. Moreover, although the range of application is limited, it can be used without any problem in terms of characteristics even in the case of spin coating, pulling up coating, coating with an air knife, or the like. Moreover, you may combine these.

  In the case of using the first liquid, it is possible to add a photocurable component to the first liquid. In this case, the present invention can be carried out even if the photocurable component is not present in the ink. That is, in the present embodiment, the “ink image including a component that is cured by irradiation with active energy rays” in the present invention is formed by applying an ink containing the component in advance to the intermediate transfer body 1. Means. However, even if the ink does not contain a photocurable component, if the first liquid contains a photocurable component, an ink image formed on the intermediate transfer body 1 by mixing the two is used. Includes a “component that cures upon irradiation with active energy rays”. In other words, the “ink image containing a component that is cured by irradiation with an active energy ray” in the present invention is not limited to an image formed in advance by applying an ink containing a photocurable component, but the component is applied later after application. It also means what came to be included. However, in any case, the inkjet head 3 is used for applying ink for forming an ink image.

Restrictions on the ink-jet head 3 to be used the ink-jet head is not. As energy used for ejecting ink, one using thermal energy (thermal jet method) or one using mechanical energy (piezo method) can be used. Further, not only the on-demand type but also a continuous type ink jet recording method can be appropriately selected and used. Furthermore, as the form of the ink jet head, for example, with respect to the configuration of FIG. 1, an ink jet head in the form of a line head in which ink discharge ports are arranged in a direction crossing the drawing can be used. Further, a recording head may be used in which recording is performed using a head in which ejection openings are arranged in a direction different from the direction intersecting the drawing, for example, a predetermined range in the transport direction of the intermediate transfer body 1, and moving the head in the direction intersecting the drawing. Good. In addition, the number of heads corresponding to the color of the ink used for image formation can be used.

  Also, there are no restrictions on the image to be recorded, and it can be used for all kinds of characters, illustrations, natural images, industrial patterns such as simple patterns and electronic circuits. When forming an image, ink may be ejected to form a mirror image in consideration of reversal of the image by transfer.

The ink used is not particularly limited. In some cases, a transparent ink not containing a colorant (coloring material) may be used. Further, not only the ink containing the photocurable component in advance, but also the photocurable component may be contained as a result of mixing with the first liquid.

  However, in any case, it is preferable that the ink has less fluidity at the time of transfer / energy ray irradiation. Therefore, during the period from the formation of the ink image on the intermediate transfer body using the inkjet head 3 to the pressure bonding of the recording medium to the ink image, the excess liquid component removing device 4 is not the final image forming component in the ink image component. It is desirable to reduce the liquid component. The “liquid component that is not the final image forming component” in this case is mainly a solvent component of the ink, and although there is no particular limitation, a water-based ink using water is preferable from the viewpoint of safety.

  On the other hand, in the case of using 100% curable ink that hardly contains “liquid component that is not the final image forming component”, that is, almost all of the ink applied from the inkjet head 3 is cured to finally form an image. Of course, the present invention is preferably used. In this case, the surplus liquid component removing device 4 becomes unnecessary or does not need to be operated.

  In general, dyes, pigments, and dispersions thereof are preferably used as the ink colorant. In particular, the pigment dispersion is suitable when a metal salt is used as the first liquid reaction material.

  The dye is not limited, and any commonly used dye can be used without any problem. Examples include C.I. I Direct Blue 6, 8, 22, 34, 70, 71, 76, 78, 86, 142, 199, C.I. I Acid Blue 9, 22, 40, 59, 93, 102, 104, 117, 120, 167, 229, C.I. I Direct Red 1, 4, 17, 28, 83, 227, C.I. I Acid Red 1, 4, 8, 13, 14, 15, 18, 21, 26, 35, 37, 249, 257, 289, C.I. I Direct Yellow 12, 24, 26, 86, 98, 132, 142, C.I. I acid yellow 1,3,4,7,11,12,13,14,19,23,25,34,44,71, C.I. I Food Black 1, 2, C.I. I acid black 2, 7, 24, 26, 31, 52, 112, 118 and the like.

  The pigment is not particularly limited, and any commonly used pigment can be used without any problem. Examples include C.I. Pigment Blue 1, 2, 3, 15: 3, 16, 22, C.I. Pigment Red 5, 7, 12, 48 (Ca), 48 (Mn) 57 (Ca), 112, 122, C.I. I Pigment Yellow 1, 2, 3, 13, 16, 83, Carbon Black No 2300, 900, 33, 40, 52, MA7, 8, MCF88 (Mitsubishi Kasei), RAVEN 1255 (Colombia), REGAL 330R, 660R, MOGUL ( Cabot), Color Black FW1, FW18, S170, S150, Printex35 (manufactured by Degussa), and the like.

  As the dispersion resin, a water-soluble resin having a weight average molecular weight of about 1000 to 15000 is preferably used. Examples include styrene and its derivatives, vinyl naphthalene and its derivatives, aliphatic alcohol esters of α, β-ethylenically unsaturated carboxylic acids, acrylic acid and its derivatives, maleic acid and its derivatives, itaconic acid and its derivatives, fumar Examples thereof include block copolymers or random copolymers composed of acids and derivatives thereof, and salts thereof. Moreover, a photocurable resin can also be used independently without using a dispersion resin.

  The present invention is not limited by the form of the ink, and any form such as a self-dispersion type, a resin dispersion type, or a microcapsule type can be used as appropriate.

  As a component that is cured by irradiation with active energy rays, a component that is liquid in an uncured state and becomes a solid by irradiation with curing light is used. As an example, a general ultraviolet curable resin can be used. Although many ultraviolet curable resins are insoluble in water, as a material that can be applied to the water-based ink suitably used in the present invention, the structure has at least two functionalized ethylenic unsaturated bonds that can be cured by ultraviolet rays. In addition, it preferably has a hydrophilic linking group. Examples of the bonding group for having hydrophilicity include a hydroxyl group, a carboxyl group, a phosphoric acid group, a sulfonic acid group, and salts thereof, an ether bond, an amide bond, and the like. The material used in the present invention is preferably dissolved in water by 5% by weight or more.

  Active energy ray curing catalysts used in combination with components that are cured by irradiation with active energy rays have skeletons such as α-hydroxy ketone, benzyl ketal, acylphosphine, and thioxanthone, and maximize their reactivity. Therefore, it is preferably hydrophilic. Examples of the bonding group for having hydrophilicity include a hydroxyl group, a carboxyl group, a phosphoric acid group, a sulfonic acid group, and salts thereof, an ether bond, an amide bond, and the like, any of which can be preferably used. The material used in the present invention is preferably dissolved in water by 1% by weight or more.

  Furthermore, it is also a very preferable form to use a sensitizer having the role of extending the absorption wavelength of light in order to improve the reaction rate.

  The ink may contain an organic solvent in order to control the discharge property and drying property of the inkjet head. It is preferable that the ink image at the time of transfer to the recording medium is substantially only the color material and the organic solvent, and the prescription is designed so that the optimum value is obtained. The organic solvent to be used is preferably a water-soluble material having a high boiling point and a low vapor pressure, such as polyethylene glycol, polypropylene glycol, ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, thiodiglycol, hexylene glycol, diethylene glycol. , Ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, glycerin and the like. In addition, alcohols such as ethyl alcohol and isopropyl alcohol and various surfactants can be added as components for adjusting viscosity, surface tension, and the like.

  The blending ratio is not limited, and can be adjusted within a dischargeable range based on the selected ink jet method, head discharge performance, nozzle diameter, and the like. Generally, the colorant is 0.1 to 10%, the resin is 0.1 to 10%, the solvent is 5 to 40%, the surfactant is 0.1 to 5%, and the rest is pure water.

(2.2) Step (b) of reducing the fluidity of the ink image on the intermediate transfer member
This is a step of reducing the fluidity of the ink image on the intermediate transfer body 1 in a process. This process is important for reducing the disturbance of the ink image in the next transfer / active energy ray irradiation step.

  A method suitably used in an embodiment of the present invention is evaporation concentration in which a liquid component such as water that is not the final image forming component is reduced by evaporation, and a specific means such as the excess liquid removal removal device 4 is used. What performs ventilation or a heating is used. Moreover, these can also be used in combination. Furthermore, it is effective to adjust the temperature of the intermediate transfer member 1 appropriately, and it is also effective to control the humidity of the blown air. Further, in addition to these means for promoting evaporation concentration, it is also effective to lower the fluidity by, for example, making the ink image semi-cured or partially cured.

  However, if the fluidity of the ink image is completely lost, the surface tackiness may be lost, and the adhesion to the recording medium may be weakened. Therefore, it is desirable to leave some ink fluidity in the ink image at the time of transfer. Although the optimum value varies depending on the surface characteristics of the recording medium, the thickness of the ink image, the transfer conditions, etc., it is preferable that the viscosity be in the range of about 100 to 5000 mPa · s.

  Even when evaporation concentration is used, if the liquid component is excessively evaporated, the adhesion of the ink image to the recording medium may be insufficient. In order to prevent this and increase the process margin, it is desirable to add a plurality of materials having different evaporation characteristics to the ink or the reaction liquid. Specifically, it is preferable to use solvents having different boiling points and high-boiling solvents having different vapor pressures.

(2.3) A step of irradiating the recording medium with an active energy ray while contacting and transferring the ink image on the intermediate transfer member (c)
A recording medium is brought into contact with an ink image having sufficiently lowered fluidity, and active energy rays used for ink curing are irradiated. In this case, if one of the intermediate transfer member 1 and the recording medium 5 has the transmission of active energy rays, it is possible to irradiate from one side, and both of them have the transmission of active energy rays. If it has, it can also irradiate from both sides. Considering the case where the recording medium does not have the ability to transmit active energy rays, if the irradiation can be performed from the intermediate transfer body 1, it is possible to deal with a wider variety of recording media. In addition, as shown in FIGS. 1 and 2, if the ink receives the curing light while being sandwiched between the intermediate transfer member and the recording medium, the ink is a high-speed ink that is difficult to transmit light such as black. Even if it exists, it can be hardened efficiently.

  The image recording method of the present invention or embodiment cures the ink simultaneously at the time of transfer, but when seeking a stronger ink image curing, by additionally irradiating or heating the recorded matter, The final curing degree may be increased. It is of course possible and preferable to apply another curing acceleration energy simultaneously with irradiation of the active energy ray, for example, heating energy.

(3) Examples Hereinafter, more specific examples and comparative examples of the present invention will be described. In the following description, “parts” and “%” are based on mass unless otherwise specified.

(3.1) Example 1
Step (a) of forming an ink image containing a component that is cured by irradiation with active energy rays on the intermediate transfer member
In this example, a material obtained by coating a 0.2 mm transparent PET film surface with a silicone rubber (KE42TS manufactured by Shin-Etsu Chemical Co., Ltd.) with a thickness of 0.2 mm on the surface of a transparent PET film having a thickness of 0.2 mm was used. The surface smoothness of this intermediate transfer member was Ra = 0.062, and the ultraviolet light transmittance = 61%.

  First, the surface of the intermediate transfer material was hydrophilized using a parallel plate type atmospheric pressure plasma treatment apparatus (APT-203 manufactured by Sekisui Chemical Co., Ltd.).

(Surface modification conditions)
Gas used; flow rate: air; 1000 cc / min
N ₂ ; 6000 cc / min
Input voltage: 230V
Frequency: 10kHz
Processing speed: 200mm / min
Subsequently, the reaction liquid of the following composition was apply | coated on the intermediate transfer body using the roll coater.

(Reaction solution composition)
MgNO ₃ · 6H ₂ O: 10%
Surfactant (Acetylenol EH manufactured by Kawaken Fine Chemicals): 1%
Diethylene glycol: 5%
Pure water: 84%
A character image that was mirror-reversed using four colors of ink was formed by the inkjet head 3 (nozzle density 1200 dpi, discharge amount 4.8 pl, drive frequency 12 kHz). Here, inks having the following prescription (four color inks each containing a color pigment as a coloring material) were used.

(Ink formulation)
・ Each pigment below: 3 parts Black: Carbon black (MCF88 manufactured by Mitsubishi Chemical)
Cyan: Pigment Blue 15
Magenta: Pigment Red 7
Yellow: Pigment Yellow 74
Styrene-acrylic acid-ethyl acrylate copolymer (acid value 180, weight average molecular weight 4000): 1 part Photocurable resin (water-soluble trifunctional acrylate): 2 parts

  Photoinitiator (water-soluble acyl phosphine): 0.2 part

・ Diethylene glycol: 6 parts ・ Ethylene glycol: 3 parts ・ Surfactant (acetylene EH manufactured by Kawaken Fine Chemicals)
: 1 part ・ Ion-exchanged water: 83.8 parts

Step (b) of reducing the fluidity of the ink image on the intermediate transfer member
The intermediate transfer member was heated from the back side with a heater, and 60 ° C. warm air was blown on the surface of the ink image at a wind speed of 10 m / sec for 4 seconds while maintaining the intermediate transfer member temperature at 60 ° C.

A step (c) of irradiating the recording medium with an active energy ray while contacting and transferring the ink image on the intermediate transfer member;
While bringing the recording medium into contact with the ink image on the intermediate transfer body with a pressure roller, 39 mJ of curing light was irradiated from the back surface of the intermediate transfer body with an ultraviolet lamp (wavelength 365 nm, intensity 6.5 mw / cm ² ). Peeled from the intermediate transfer member. Nippon Paper Industries Aurora Coat 73.3 g / m ² was used as the recording medium. As a result, a high quality image was formed on the recording medium. Further, there was almost no residual ink on the surface of the intermediate transfer body after the transfer, and no adverse effect was observed even if the next ink image was used as it was.

  The gloss of the recorded matter was 52 degrees (measured with IG-330 manufactured by HORIBA), and the abrasion resistance was 1200 g (acrylic ball test using a tripogear manufactured by Shinto Kagaku).

(4) Comparative Example (4.1) Comparative Example 1
In Example 1, the ink image on the intermediate transfer member was irradiated with the curing light of 39 mJ in the open atmosphere without being brought into contact with the recording medium, and was then pressed and transferred to the recording medium. As a result, the gloss of the recorded matter was 50 degrees, which was almost the same value as in Example 1. However, the abrasion resistance was 200 g or less and could not be measured.

(4.2) Comparative Example 2
In the same manner as in Comparative Example 1, the cured light irradiation amount was 160 mJ to obtain a recorded matter. The glossiness was 50 degrees, which was almost the same value as in Example 1. However, despite the fact that the curing light irradiation amount was quadrupled, the abrasion resistance was 500 g, which was less than half that of Example 1. It was.

(4.3) Comparative Example 3
In Example 1, an image was transferred to a recording medium without applying curing light at the time of transfer, and the surface of the obtained recorded material was irradiated with curing light at 39 mJ in the open air. The glossiness was 52 degrees, which was almost the same as in Example 1. However, the ink image surface was in an uncured state with stickiness remaining, and the abrasion resistance was not measurable.

(4.4) Comparative Example 4
In the same manner as in Comparative Example 3, a cured product was obtained with a curing light irradiation amount of 400 mJ. The glossiness was 53 degrees, which was almost the same as that of Example 1. However, although the curing light irradiation amount was increased 10 times, the abrasion resistance was 600 g, which was about half that of Example 1.

(4.5) Comparative Example 5
In Example 1, a recording medium was attached to the surface of the intermediate transfer member, and a recorded material was obtained without performing pressure transfer. The glossiness was 39 degrees, which was clearly lower than that of Example 1. The ink image surface was in an uncured state with stickiness remaining, and the abrasion resistance was not measurable.

(4.6) Comparative Example 6
In the same manner as in Comparative Example 3, a cured product was obtained with a curing light irradiation amount of 800 mJ. The glossiness was clearly low glossiness of 21 degrees, and although the curing light irradiation amount was 20 times, the abrasion resistance was 700 g, which was not much higher than Example 1.

1 is a schematic diagram illustrating an image forming apparatus according to an embodiment of the present invention. It is a schematic diagram which shows the image forming apparatus which concerns on other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 21 Intermediate transfer body 2 Coating apparatus 3 Inkjet head 4 Excess liquid component removal promotion apparatus 5 Recording medium 6 Pressure roller 7 Curing light source

Claims (8)

An image forming method for transferring the ink image to the recording medium by bringing the recording medium into contact with an ink image containing a component that is cured by irradiation with active energy rays formed on the intermediate transfer member,
Applying ink to form the ink image using an inkjet head;
Irradiating the ink image with the active energy rays while the recording medium is in contact with the ink image on the intermediate transfer member;
An image forming method comprising:   The image forming method according to claim 1, wherein at least one of the intermediate transfer member and the recording medium transmits the active energy rays.   The image forming method according to claim 1, wherein the ink contains the component.   4. The liquid according to claim 1, wherein a liquid that restricts movement of the ink applied to form the ink image is applied to the intermediate transfer member prior to the formation of the ink image. The image forming method according to any one of the above.   The image forming method according to claim 4, wherein the liquid contains the component.   The image forming method according to claim 4, wherein the liquid is an aqueous solution containing metal ions.   A liquid component that is not a component for forming an ink image that is finally transferred to the recording medium is reduced from the ink image between the formation of the ink image and the contact with the recording medium. The image forming method according to any one of claims 1 to 3. An image forming apparatus for transferring the ink image to the recording medium by bringing the recording medium into contact with an ink image containing a component that is cured by irradiation with active energy rays, formed on the intermediate transfer member,
Means for applying ink to form the ink image using an inkjet head;
Means for irradiating the ink image with the active energy rays while the recording medium is in contact with the ink image on the intermediate transfer member;
An image forming apparatus comprising:

Images