JP6832241B2 - Printing method, printing equipment - Google Patents

Description

The present invention relates to a printing technique for performing printing by transferring ink discharged from a transfer member from a transfer member to a printing target by an inkjet method.

Conventionally, a printing apparatus for printing an image by transferring an image formed on a transfer member such as a blanket from the blanket to a printing target has been known. Further, the printing apparatus described in Patent Documents 1 to 3 forms an image on a transfer member by ejecting ink by an inkjet method.

JP-A-2010-155430 Japanese Unexamined Patent Publication No. 2005-153368 Japanese Unexamined Patent Publication No. 2006-130725

In printing using transfer as described above, it is important to reliably transfer the ink from the transfer member to the printing target. On the other hand, in Patent Document 1, an anchor agent is superimposed on the ink ejected to the transfer member, and in Patent Document 2, a high-viscosity material is applied to the transfer member in advance and then the ink is ejected to the transfer member. , We are trying to realize reliable transcription. Further, in Patent Document 3, reliable transfer is realized by increasing the viscosity of the photocurable ink ejected to the transfer member by irradiation with light.

However, it is necessary to separately prepare an anchor agent in Patent Document 1 and a material having an adjusted viscosity in Patent Document 2. On the other hand, Patent Document 3 has an advantage that it is not necessary to prepare a material different from these inks. However, since it is difficult to adjust the viscosity of the ink by irradiating light, the ink that has been over-cured does not adhere to the print target, and the ink may not be reliably transferred to the print target.

The present invention has been made in view of the above problems, and an object of the present invention is to enable reliable transfer of ink from a transfer member to a printing target without requiring a material different from ink.

The printing method according to the present invention includes a first ejection step of ejecting a photocurable ink that is cured by irradiation with light to a transfer member by an inkjet method to form a first ink layer on the transfer member, and a first ejection step of the first ink layer. A first light irradiation step in which the first ink layer is cured by irradiating light, and a photocurable ink is ejected by an inkjet method toward the first ink layer cured on the transfer member and superposed on the first ink layer. The second ejection step of forming the second ink layer and the transfer step of transferring the first ink layer and the second ink layer from the transfer member to the print target by bringing the uncured second ink layer into contact with the print target. And.

In the printing apparatus according to the present invention, the transfer member and the photocurable ink that is cured by irradiation with light are ejected to the transfer member by an inkjet method to form a first ink layer on the transfer member and the first ink layer. Light that cures the first ink layer by irradiating the ink ejection portion forming the second ink layer and the first ink layer formed on the transfer member with light before forming the second ink layer. By bringing the irradiated portion and the uncured second ink layer superimposed on the cured first ink layer into contact with the printing target, the first ink layer and the second ink layer are transferred from the transfer member to the printing target. It has a part.

In the present invention (printing method, printing apparatus) configured in this way, the first ink layer and the second ink layer are formed on the transfer member in this order. Further, the first ink layer is pre-cured by being irradiated with light before the formation of the second ink layer. As a result, the cured first ink and the uncured second ink are laminated in this order on the transfer member. Then, by bringing the uncured second ink into contact with the print target, the first ink layer and the second ink layer are transferred from the transfer member to the print target. At this time, since the first ink layer is cured, it is easily peeled off from the transfer member, and since the second ink layer is uncured and liquid, it is easily adhered to the printing target. Moreover, both the first ink layer and the second ink layer are formed of photocurable ink and have a high affinity for each other. Therefore, the second ink layer is transferred to the printing target while being mixed with the first ink layer, and the first ink layer is peeled off from the transfer member along with the second ink layer. In this way, it is possible to reliably transfer the ink from the transfer member to the printing target without requiring a material different from the ink.

Further, in the first light irradiation step, the printing method may be configured so as to completely cure the first ink layer. As a result, the first ink layer can be easily peeled off from the transfer member, and the ink can be more reliably transferred from the transfer member to the printing target.

Further, the printing method may be configured so as to further include a second light irradiation step of completely curing the second ink layer by irradiating the second ink layer transferred to the printing target in the transfer step with light. .. As a result, the ink can be reliably fixed on the print target.

Further, as compared with the period from the ejection of the photocurable ink in order to form the first ink layer in the first ejection step to the curing of the photocurable ink in the first light irradiation step, the second ejection step The printing method may be configured so that the period from the formation of the second ink layer to the transfer of the first ink layer and the second ink layer in the transfer step is long. In such a configuration, since the period from the ejection of the photocurable ink to the curing of the photocurable ink in order to form the first ink layer is suppressed, the first ink layer is repelled by the transfer member. Can be suppressed. Further, since the time from the formation of the second ink layer to the transfer of the first ink layer and the second ink layer is secured, the first ink layer and the second ink layer can be mixed firmly. The first ink layer can be reliably transferred to the print target along with the second ink layer.

Incidentally, the compositions of the first ink layer and the second ink layer may be the same or different. For example, the printing method may be configured so that the first ink layer and the second ink layer are formed of photocurable inks of the same color. Alternatively, the printing method may be configured such that one of the first ink layer and the second ink layer is a colored photocurable ink and the other is a transparent photocurable ink.

Further, in the first light irradiation step, light is irradiated by a light irradiator facing the transfer member, and the light irradiator starts forming the second ink layer after the first ink layer is cured. The printing method may be configured so that the light is turned off before the light is turned off. As a result, it is possible to prevent the second ink layer from being cured by the light from the light irradiator before the transfer to the print target, and the second ink layer can be reliably transferred to the print target.

Further, the transfer member is a roller that rotates in a predetermined rotation direction. In the first ejection step, a first ink layer is formed by an inkjet head facing the transfer member, and in the second ejection step, the transfer member is rotated. The printing method may be configured so that the second ink layer is formed by the inkjet head so as to be overlapped with the first ink layer that has returned to the position facing the inkjet head. In such a configuration, since the first ink layer and the second ink layer are formed by the same inkjet head, it is possible to easily overlap the formation position of the first ink layer and the formation position of the second ink layer. Further, since the same inkjet head is shared for forming the first ink layer and the second ink layer, the number of parts can be reduced.

Further, the transfer member is a roller that rotates in a predetermined rotation direction. In the first ejection step, the photocurable ink is ejected by the first inkjet head facing the transfer member, and in the second ejection step, the first inkjet member. The printing method may be configured so that the photocurable ink is ejected by the second inkjet head facing the transfer member on the downstream side in the rotation direction. In such a configuration, it is not necessary to rotate the transfer member once in order to superimpose the second ink layer on the first ink layer, and the throughput can be improved.

As described above, according to the present invention, it is possible to reliably transfer the ink from the transfer member to the printing target without requiring a material different from the ink.

The figure which shows typically an example of the mechanical structure of the printing apparatus which concerns on 1st Embodiment of this invention. The figure which shows typically an example of the electric structure of the printing apparatus which concerns on this invention. A flowchart showing an example of printing processing. A timing chart showing an example of an operation executed according to the printing process of FIG. FIG. 6 is a diagram schematically showing a procedure for forming an image on a blanket executed in the printing process of FIG. The figure which shows typically the image transfer procedure executed by the printing process of FIG. The figure which shows typically an example of the mechanical structure of the printing apparatus which concerns on 2nd Embodiment of this invention. The figure which shows an example of the mechanical structure of the printing apparatus which concerns on 3rd Embodiment of this invention schematically. The figure which shows an example of the specific experimental result of this invention.

FIG. 1 is a diagram schematically showing an example of a mechanical configuration of a printing apparatus according to a first embodiment of the present invention. FIG. 2 is a diagram schematically showing an example of an electrical configuration of the printing apparatus according to the present invention. The printing device 1 prints an image on the substrate B by transferring the image formed on the transfer member to the substrate B to be printed. Although the shape of the substrate B is shown flat in FIG. 1, it may be curved or may have irregularities.

The printing apparatus 1 includes a blanket roller 2 as a transfer member and a blanket driving unit M2 for driving the blanket roller 2. The blanket roller 2 is rotatable around its central axis in the rotation direction D2, and has a material having liquid repellency against photocurable ink (UV ink described later), for example, an elastic body made of silicone. Have in. The blanket drive unit M2 rotationally drives the blanket roller 2 in the rotation direction D2 by, for example, a servomotor.

The printing device 1 includes an inkjet head 31 facing the peripheral surface of the blanket roller 2. The inkjet head 31 has a plurality of nozzles arranged parallel to the central axis of the blanket roller 2, and ink is ejected from each nozzle to the peripheral surface of the blanket roller 2. In particular, the inkjet head 31 ejects UV ink that is cured by being irradiated with UV (ultraviolet).

The printing device 1 includes a UV irradiator 4 facing the peripheral surface of the blanket roller 2 on the downstream side of the rotation direction D2 of the inkjet head 31. The UV irradiator 4 can irradiate the UV irradiation range R4 with UV. Then, the UV irradiator 4 cures the UV ink adhering to the blanket roller 2 by irradiating the peripheral surface of the blanket roller 2 passing through the UV irradiation range R4 with UV. As will be described in detail later, the cooperation between the inkjet head 31 and the UV irradiator 4 forms an image in which uncured UV ink is laminated on the cured UV ink on the peripheral surface of the blanket roller 2. Will be done.

The printing device 1 includes a stage 5 and a stage drive unit M5 that drives the stage 5 in the transport direction D5. The stage 5 and the stage drive unit M5 cooperate with each other to transfer an image of the peripheral surface of the blanket roller 2 to a transfer position. Transfer to substrate B with Pt. That is, the stage 5 holds the substrate B received from the outside. On the other hand, the stage driving unit M5 drives the stage 5 in the transport direction D5 to feed the substrate B to the transfer position Pt as the image reaches the transfer position Pt as the blanket roller 2 rotates. As a result, the substrate B comes into contact with the peripheral surface of the blanket roller 2 at the transfer position Pt, and the image is transferred from the peripheral surface of the blanket roller 2 to the surface of the substrate B. In FIG. 1, the stage 5 and the substrate B in the standby position on the upstream side of the transfer position Pt in the transport direction D5 are represented by solid lines, and these moving from the standby position to the transport direction D5 are represented by broken lines. ..

The printing apparatus 1 includes a UV irradiator 6 facing the surface of the substrate B that moves downstream of the transfer position Pt in the transport direction D5. The UV irradiator 6 can irradiate the UV irradiation range R6 with UV. Then, the UV irradiator 6 completely cures the UV ink adhering to the substrate B by irradiating the surface of the substrate B passing through the UV irradiation range R6 with UV. As a result, the image can be fixed on the substrate B.

Further, the printing device 1 includes a controller 9 that controls a blanket drive unit M2, an inkjet head 31, a UV irradiator 4, a stage drive unit M5, and a UV irradiator 6. The controller 9 is a processor having a CPU (Central Processing Unit) and a RAM (Random Access Memory), and executes the printing process described below.

FIG. 3 is a flowchart showing an example of the printing process. FIG. 4 is a timing chart showing an example of an operation executed according to the printing process of FIG. FIG. 5 is a diagram schematically showing a procedure for forming an image on a blanket executed in the printing process of FIG. In FIG. 5, the peripheral surface of the blanket roller 2 is shown in a straight line.

When the printing process of FIG. 3 starts, the blanket driving unit M2 starts rotating the blanket roller 2 (step S101). Subsequently, the first ink layer L1 is formed on the peripheral surface of the blanket roller 2 (step S102). Specifically, the controller 9 transmits the first drive signal S1 to the inkjet head 31, and the inkjet head 31 starts ejecting UV ink at time t1 based on the first drive signal S1. The first drive signal S1 indicates the position and the amount of ink of each of the dots constituting the image I, and the inkjet head 31 follows the first drive signal S1 to direct the position corresponding to each dot on the peripheral surface of the blanket roller 2. A predetermined amount of UV ink droplets are ejected. Subsequently, the UV irradiator 4 irradiates UV (step S103). Specifically, the UV irradiator 4 lights up at the time t2 when the first ink layer L1 reaches the UV irradiation range R4 by the UV irradiator 4.

Then, at time t3, the inkjet head 31 finishes ejecting the UV ink. In this way, as shown in the column of "forming the first ink layer" in FIG. 5, the first ink layer L1 composed of a plurality of dots (ink droplets) indicated by the first drive signal S1 is the peripheral surface of the blanket roller 2. Is formed in. Further, when it is confirmed that the first ink layer L1 has passed the UV irradiation range R4 at time t4 (“YES” in step S104), the UV irradiator 4 is turned off at time t5 (step S105). By such UV irradiation, the first ink layer L1 on the peripheral surface of the blanket roller 2 is completely cured. The timing control of turning on / off the UV irradiator 4 can be executed by the controller 9 based on, for example, the encoder output of the blanket drive unit M2.

Subsequently, the second ink layer L2 is formed by laminating on the first ink layer L1 (step S106). Specifically, the controller 9 transmits the second drive signal S2 to the inkjet head 31, and the inkjet head 31 starts ejecting UV ink at time t6 based on the second drive signal S2. The second drive signal S2 indicates the position and the amount of ink of each of the dots constituting the image I, and the inkjet head 31 follows the second drive signal S2 toward a position corresponding to each dot on the peripheral surface of the blanket roller 2. A predetermined amount of UV ink droplets are ejected. At this time, the time t6 at which the UV ink is started to be ejected is controlled according to the timing at which the first ink layer L1 returns to the position facing the inkjet head 31. Therefore, a plurality of dots forming the second ink layer L2 are ejected so as to overlap the plurality of dots forming the first ink layer L1. It should be noted that such timing control can be executed by the controller 9 based on, for example, the encoder output of the blanket drive unit M2. Then, at time t7, the inkjet head 31 ends the ejection of the UV ink. In this way, as shown in the column of "forming the second ink layer" in FIG. 5, the second ink layer L2 composed of a plurality of dots (ink droplets) indicated by the second drive signal S2 becomes the first ink layer L1. The layers are stacked to form the image I.

At time t8, the transfer of the substrate B is started from the upstream side in the transfer direction D5 toward the transfer position Pt (step S107). The transfer of the substrate B is controlled according to the timing at which the image I on the blanket roller 2 reaches the transfer position Pt. Such timing control can be executed by the controller 9 based on the encoder outputs of the blanket drive unit M2 and the stage drive unit M5. Since the timing is controlled in this way, the image I on the blanket roller 2 reaches the transfer position Pt at time t9 and comes into contact with the substrate B. Then, the image I is transferred from the blanket roller 2 to the substrate B during the period from time t9 to t10 when the image I passes through the transfer position Pt (step S108).

When the image I is transferred to the substrate B, the UV irradiator 6 irradiates the UV (step S109). Specifically, the UV irradiator 6 lights up at the time t11 when the image I reaches the UV irradiation range R6 by the UV irradiator 6. Then, when it is confirmed that the image I has passed the UV irradiation range R6 at time t12 (“YES” in step S110), the UV irradiator 6 is turned off at time t13 (step S111). By such UV irradiation, the image I (first ink layer L1 + second ink layer L2) on the substrate B is completely cured. The timing control of turning on / off the UV irradiator 6 can be executed by the controller 9 based on, for example, the encoder output of the stage drive unit M5. Then, at time t14, the transfer of the substrate B is stopped (step S112), and the printing process of FIG. 3 is completed.

As described above, in the first embodiment, the first ink layer L1 and the second ink layer L2 are formed on the blanket roller 2 in this order. Further, the first ink layer L1 is pre-cured before the formation of the second ink layer L2 by being irradiated with light. As a result, the cured first ink layer L1 and the uncured second ink layer L2 without being irradiated with UV are laminated in this order on the blanket roller 2. Then, by bringing the uncured second ink layer L2 into contact with the substrate B, the first ink layer L1 and the second ink layer L2 are transferred from the blanket roller 2 to the substrate B. At this time, since the first ink layer L1 is cured, it is easily peeled off from the blanket roller 2, and since the second ink layer L2 is uncured and liquid, it is easily attached to the substrate B. .. Moreover, the first ink layer L1 and the second ink layer L2 are both formed of UV ink and have a high affinity for each other. Therefore, the second ink layer L2 is integrally transferred to the substrate B while being mixed with the first ink layer L1, and the first ink layer L1 is peeled off from the substrate B along with the second ink layer L2. In this way, it is possible to reliably transfer the UV ink from the blanket roller 2 to the substrate B without requiring a material different from the UV ink.

This point will be described in more detail with reference to FIG. Here, FIG. 6 is a diagram schematically showing an image transfer procedure executed in the printing process of FIG. Note that FIG. 6 shows a state in which the peripheral surface of the blanket roller 2 is developed in a straight line and the peripheral surface faces downward in the figure. In the “Before curing” column of FIG. 6, the state before the first ink layer L1 adhering to the peripheral surface of the blanket roller 2 is cured is shown. At this stage, since the first ink layer L1 is liquid, the solvent of the first ink layer L1 is absorbed by the blanket roller 2 and evaporates from the surface of the first ink layer L1. Therefore, the properties of the first ink layer L1 approach from liquid to solid.

In the column of "before transfer" in FIG. 6, a state in which the first ink layer L1 adhering to the peripheral surface of the blanket roller 2 is cured and the second ink layer L2 is further laminated on the first ink layer L1 is shown. There is. At this stage, since the first ink layer L1 is cured and becomes a solid state, the adhesive force F1 acting on the interface between the blanket roller 2 and the first ink layer L1 is weakened, and the blanket roller of the first ink layer L1 is weakened. The peelability from 2 is improved. On the other hand, since the first ink layer L1 and the second ink layer L2 are both UV inks and have high affinity with each other, they are mixed at the interface between the first ink layer L1 and the second ink layer L2. Therefore, at the interface between the first ink layer L1 and the second ink layer L2, an ink cohesive force F2 (internal bonding force) stronger than the adhesion force F1 acts.

In the “Transferring” column of FIG. 6, a state in which the image I formed on the peripheral surface of the blanket roller 2 is in contact with the substrate B is shown. At this stage, since the second ink layer L2 of the image I in contact with the substrate B is liquid, an adhesion force F3 stronger than the adhesion force F1 acts on the interface between the substrate B and the second ink layer L2. On the other hand, since the affinity between the substrate B and the second ink layer L2 is weaker than the affinity between the first ink layer L1 and the second ink layer L2, the adhesion force F3 between the substrate B and the second ink layer L2 Is weaker than the ink cohesive force F2.

As described above, the ink cohesive force F2 between the first ink layer L1 and the second ink layer L2> the adhesion force between the substrate B and the second ink layer L2 F3> the adhesion force between the blanket roller 2 and the first ink layer L1. A relationship such as F1 is established. Therefore, the first ink layer L1 adheres to the blanket roller 2 with a weak adhesive force F1 while binding the first ink layer L1 to the second ink layer L2 that adheres to the substrate B with the adhesive force F3 with a strong ink cohesive force F2. L1 can be peeled off from the blanket roller 2. As a result, the image I composed of the first ink layer L1 and the second ink layer L2 can be reliably transferred from the blanket roller 2 to the substrate B.

Further, in step S103, the first ink layer L1 is completely cured. As a result, since the first ink layer L1 is completely solid, it can be easily peeled off from the blanket roller 2, and the UV ink can be more reliably transferred from the blanket roller 2 to the substrate B. ing.

Further, a step S109 is further provided in which the image I transferred to the substrate B in step S108 is irradiated with light to completely cure the second ink layer L2 in the uncured state. This makes it possible to reliably fix the UV ink on the substrate B.

Further, the period until the formation of the first ink layer L1 is started in step S102, the formed first ink layer L1 reaches the UV irradiation range R4, and the first ink layer L1 is cured in step S103 (time t1). Compared with ~ t2), the period (time t6 to t9) from the formation of the second ink layer L2 in step S106 to the transfer of the first ink layer L1 and the second ink layer L2 in step S108 is longer. In such a configuration, the period of time t1 to t2 is suppressed, and the first ink layer L1 adhering to the blanket roller 2 is rapidly cured, so that the first ink layer L1 is repelled by the blanket roller 2. It can be suppressed. Further, since the period from time t6 to t9 is secured, the first ink layer L1 and the second ink layer L2 can be firmly mixed, and the first ink layer L1 is combined with the second ink layer L2. It can be reliably transferred by the substrate B. As a result, a good image I can be transferred to the substrate B.

Further, the UV irradiator 4 is turned off at a time t5 after the time t4 when the first ink layer L1 is cured and before the time t6 when the formation of the second ink layer L2 is started (step S105). .. As a result, it is possible to prevent the second ink layer L2 from being cured by the UV from the UV irradiator 4 before the transfer to the substrate B, and the second ink layer L2 can be reliably transferred by the substrate B. ..

Further, the first ink layer L1 and the second ink layer L2 are laminated on the blanket roller 2 while rotating the blanket roller 2. That is, in step S102, the first ink layer L1 is formed by the inkjet head 31 facing the blanket roller 2. Further, in step S106, the second ink layer L2 is formed by the inkjet head 31 so as to be superimposed on the first ink layer L1 that has returned to a position facing the inkjet head 31 as the blanket roller 2 rotates. In such a configuration, since the first ink layer L1 and the second ink layer L2 are formed by the same inkjet head 31, the formation position of the first ink layer L1 and the formation position of the second ink layer L2 can be easily overlapped. Is possible. Further, since the same inkjet head 31 is shared for forming the first ink layer L1 and the second ink layer L2, the number of parts can be reduced.

FIG. 7 is a diagram schematically showing an example of the mechanical configuration of the printing apparatus according to the second embodiment of the present invention. In the following, the differences from the first embodiment will be mainly described, and the common parts are designated by corresponding reference numerals and the description thereof will be omitted as appropriate. However, it goes without saying that the same effect can be obtained by providing the same configuration as that of the first embodiment.

The difference between the second embodiment and the first embodiment is that in the rotation direction D2 of the blanket roller 2, the inkjet that faces the peripheral surface of the blanket roller 2 on the downstream side of the UV irradiator 4 and on the upstream side of the transfer position Pt. This is a point where the head 32 is provided. The inkjet head 32 has the same configuration as the inkjet head 31, and ejects UV ink having the same composition as the UV ink ejected by the inkjet head 31. Then, under the control of the controller 9, the UV ink is ejected toward the peripheral surface of the blanket roller 2.

In the printing process of the second embodiment (FIG. 3), after steps S101 to S105 are executed, the inkjet head 32 is laminated on the first ink layer L1 to form the second ink layer L2 (step S106). Specifically, the controller 9 transmits the second drive signal S2 to the inkjet head 32, and the inkjet head 32 starts ejecting UV ink based on the second drive signal S2. At this time, the time at which the inkjet head 32 starts ejecting UV ink is controlled according to the timing at which the first ink layer L1 reaches the inkjet head 32. Therefore, a plurality of dots forming the second ink layer L2 are ejected so as to overlap the plurality of dots forming the first ink layer L1. It should be noted that such timing control can be executed by the controller 9 based on, for example, the encoder output of the blanket drive unit M2. In this way, as shown in the column of "forming the second ink layer" in FIG. 5, the second ink layer L2 composed of a plurality of dots (ink droplets) indicated by the second drive signal S2 becomes the first ink layer L1. The layers are stacked to form the image I. After that, steps S107 to S112 are executed in the same manner as in the first embodiment, and the printing process of FIG. 3 is completed.

Also in the second embodiment, the first ink layer L1 and the second ink layer L2 are formed on the blanket roller 2 in this order. Further, the first ink layer L1 is pre-cured before the formation of the second ink layer L2 by being irradiated with light. As a result, the cured first ink layer L1 and the uncured second ink layer L2 without being irradiated with UV are laminated in this order on the blanket roller 2. Then, by bringing the uncured second ink layer L2 into contact with the substrate B, the first ink layer L1 and the second ink layer L2 are transferred from the blanket roller 2 to the substrate B. Therefore, it is possible to reliably transfer the UV ink from the blanket roller 2 to the substrate B without requiring a material different from that of the UV ink.

Further, the first ink layer L1 and the second ink layer L2 are laminated on the blanket roller 2 while rotating the blanket roller 2. That is, in step S102, the first ink layer L1 is formed by the inkjet head 31 facing the blanket roller 2. Further, in step S106, the second ink layer L2 is formed on the first ink layer L1 by the inkjet head 32 facing the blanket roller 2 on the downstream side in the rotation direction D2 from the inkjet head 31. In such a configuration, when the second ink layer L2 is superposed on the first ink layer L1, it is not necessary to rotate the blanket roller 2 once as in the first embodiment, and the throughput can be improved.

As described above, in each embodiment, the printing device 1 corresponds to an example of the "printing device" of the present invention, the blanket roller 2 corresponds to an example of the "transfer member" of the present invention, and the UV irradiator 4 corresponds to the present invention. Corresponds to an example of the "light irradiation unit" of the above, and stage 5 corresponds to an example of the "transfer unit" of the present invention. Further, in the first embodiment, the inkjet head 31 corresponds to an example of the "ink ejection unit" of the present invention, and in the second embodiment, the inkjet heads 31 and 32 cooperate with each other to form the "ink ejection unit" of the present invention. It functions as an example.

Further, in each embodiment, the printing process of FIG. 3 corresponds to an example of the "printing method" of the present invention, step S102 corresponds to an example of the "first ejection step" of the present invention, and step S103 corresponds to the present invention. Step S106 corresponds to an example of the "first light irradiation step", step S106 corresponds to an example of the "second discharge step" of the present invention, step S108 corresponds to an example of the "transfer step" of the present invention, and step S109 corresponds to the example. The UV irradiator 4 corresponds to an example of the "light irradiator" of the present invention, and the blanket roller 2 corresponds to the "transfer member" or the "roller" of the present invention, which corresponds to an example of the "second light irradiation step" of the present invention. Corresponds to one example. Further, in the first embodiment, the inkjet head 31 corresponds to an example of the "injection head" of the present invention, and in the second embodiment, the inkjet head 31 corresponds to an example of the "first inkjet head" of the present invention. The inkjet head 32 corresponds to an example of the "second inkjet head" of the present invention.

Further, in each embodiment, the UV ink corresponds to an example of the "photocurable ink" of the present invention, UV corresponds to an example of the "light" of the present invention, and the first ink layer L1 corresponds to the "first" of the present invention. The second ink layer L2 corresponds to an example of the "second ink layer" of the present invention, and the substrate B corresponds to an example of the "printing target" of the present invention.

The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit of the present invention. For example, although not described in detail in the above embodiment, the amount of UV ink constituting the first ink layer L1 (first ink amount) and the amount of ink constituting the second ink layer L2 (second ink amount). There are variations in the relationship between. Specifically, there are variations in which the first ink amount is smaller than the second ink amount, variations in which the first ink amount and the second ink amount are equal, and variations in which the first ink amount is larger than the second ink amount. Each of these variations has its advantages. For example, when the first ink amount and the second ink amount are equal, a common drive signal can be used as the first drive signal S1 and the second drive signal S2, which has an advantage that control becomes simple.

In addition, there are variations in the relationship between the amount of UV energy given to the UV ink from the UV irradiator 4 (first energy amount) and the amount of UV energy given to the UV ink from the UV irradiator 6 (second energy amount). Specifically, there are variations in which the first energy amount is less than the second energy amount, variations in which the first energy amount and the second energy amount are equal, and variations in which the first energy amount is larger than the second energy amount. Each of these variations has its advantages. For example, when the second energy amount is equal to or more than the first energy amount, there is an advantage that the image I (UV ink) transferred to the substrate B can be reliably cured. In particular, when the first energy amount and the second energy amount are equal, a common signal can be given to UV irradiators 4 and 6 having the same configuration, which further has the advantage of simplifying the configuration and control. is there.

In addition, there are variations in the composition of the UV ink forming the first ink layer L1 and the UV ink forming the second ink layer L2. That is, as described above, the first ink layer L1 and the second ink layer L2 may be composed of UV inks having the same composition, or may be composed of UV inks having different compositions. In the latter case, one of the first ink layer L1 and the second ink layer L2 may be composed of colored UV ink and the other may be composed of transparent UV ink. Each of these variations has its advantages. For example, when the first ink layer L1 is composed of transparent UV ink and the second ink layer L2 is composed of colored UV ink, the image I after being transferred to the substrate B has a glossy feeling.

Further, it is not always necessary to completely cure the first ink layer L1 with the UV irradiator 4. That is, even if the first ink layer L1 is not completely cured, the peelability of the first ink layer L1 from the blanket roller 2 can be improved by curing it to some extent by irradiating a certain amount of UV.

Further, the printing device 1 is not limited to printing a single-color image I as in the above embodiment, and may print a color image I. Such a change to color image printing can be executed for each of the first and second embodiments. For example, when changing the first embodiment, a plurality of inkjet heads 31 that eject UV inks of different colors are arranged in the rotation direction D2 so as to face the blanket roller 2, and UV is directed downstream of the rotation direction D2. The irradiator 4 may be arranged. Then, after forming the first ink layer L1 for each color, UV may be irradiated from the UV irradiator 4 to the first ink layer L1 of the color formed by these.

Alternatively, when changing the second embodiment, a plurality of inkjet heads 31 that eject UV inks of different colors are arranged in the rotation direction D2, and UV inks of different colors are further downstream of the rotation directions D2. A plurality of inkjet heads 32 for ejecting ink are arranged in the rotation direction D2, and these are made to face the peripheral surface of the blanket roller 2. Then, the UV irradiator 4 may be arranged between the inkjet head 31 and the inkjet head 32. Then, after the first ink layer L1 is formed by the inkjet head 31 for each color, the first ink layer L1 of the colors formed by these is irradiated with UV from the UV irradiator 4 to the first ink layer L1. The second ink layer L2 may be formed by superimposing the first ink layer L1 on the first ink layer L1 by the inkjet head 32.

Further, the specific configuration of the transfer member is not limited to the blanket roller 2 described above. Therefore, for example, it may be applied to a blanket on a flat plate having an elastic body on the surface.

Further, in the above embodiment, the dots of the first ink layer L1 and the dots of the second ink layer L2 ideally overlap each other (for example, FIG. 5). However, there is a possibility that the landing positions of the dots of the first ink layer L1 and the second ink layer L2 may deviate due to variations in the accuracy of the landing positions of the dots. However, even if these landing positions deviate within the range of accuracy variation, the dots of the first ink layer L1 and the dots of the second ink layer L2 can be partially overlapped. Moreover, all of these dots are composed of UV ink and have an affinity for each other. Therefore, since they are mixed at the interface with each other as described above, a desired effect can be obtained.

Further, in the above embodiment, UV irradiation from the UV irradiator 4 is started during the formation of the first ink layer L1. This is because the head of the first ink layer L1 reaches the UV irradiation range R4 during the formation of the first ink layer L1. That is, when the dimension of the rotation direction D2 of the first ink layer L1 is short, the UV irradiation from the UV irradiator 4 is started after the formation of the first ink layer L1 is completed.

By the way, in the printing apparatus 1 using the UV irradiator 4, when the UV from the UV irradiator 4 is incident on the nozzle portion of the inkjet head 31, the UV ink adhering to the nozzle portion may be cured and the nozzle may be clogged. is there. Therefore, the printing device 1 may be configured as shown below.

FIG. 8 is a diagram schematically showing an example of the mechanical configuration of the printing apparatus according to the third embodiment of the present invention. The printing device 1 of FIG. 8 further includes a light-shielding member 7 arranged between the inkjet head 31 and the UV irradiator 4 in the printing device according to the first embodiment, and the light-shielding member 7 inkjets from the UV irradiator 4. It blocks the progress of light to the head 31. Therefore, it is possible to suppress the occurrence of nozzle clogging. Further, according to the printing apparatus 1, the UV irradiator 4 may be kept lit at all times until the second ink layer L2 is formed. This makes it possible to simplify the control of turning on / off the UV irradiator 4.

Alternatively, when the light-shielding member 7 is provided in the printing apparatus according to the second embodiment, the light-shielding member 7 is provided between the inkjet head 31 and the UV irradiator 4 and between the UV irradiator 4 and the inkjet head 32, respectively. Is provided. In such a configuration, each light-shielding member 7 blocks the progress of light from the UV irradiator 4 to the inkjet head 31 and the inkjet head 32. Therefore, it is possible to suppress the occurrence of nozzle clogging. Further, according to the printing device 1, the UV irradiator 4 may be kept lit at all times. This makes it possible to simplify the control of turning on / off the UV irradiator 4.

Further, in the above embodiment, the image I is composed of two layers, the first ink layer L1 and the second ink layer L2, but the present invention is not limited to the two layers, and is not limited to two layers. Is also good. For example, when it is desired to increase the density, the ink layers may be overlaid and printed until the desired density is reached.

Further, the intensity of UV emitted from the UV irradiator 4 does not have to be uniform and may be distributed. For example, the intensity of UV to be irradiated may be changed according to the amount of ink adhered per unit area. Specifically, the UV intensity is increased in a place where the amount of ink adhered per unit area is large, while the UV intensity is weakened in a place where the amount of ink adhered per unit area is small. At this time, the amount of ink adhered per unit area can be determined based on the drive signals S1, S2 and the like.

Next, an embodiment of the present invention will be described. Of course, the present invention is not limited by the following examples, and it is of course possible to carry out the present invention with appropriate modifications within a range that can meet the purpose of the preceding and following description. Yes, they are all within the technical scope of the invention.

FIG. 9 is a diagram showing an example of specific experimental results of the present invention. Comparative Example 1 shows a printing result when the UV ink ejected on the bracket is transferred to white PET (Polyethylene terephthalate) without being cured. Comparative Example 2 shows the printing result when the UV ink ejected on the bracket was cured and then transferred to the white PET. An example shows a printing result when a completely cured first ink layer L1 and an uncured second ink layer L2 are laminated on a bracket and then transferred to PET. In Comparative Example 1, bleeding is observed in the printed image, and in Comparative Example 2, a portion where the background is exposed is observed in the printed image. On the other hand, in the examples, it can be seen that a good printed image is obtained and reliable transfer is realized.

The present invention can be applied to all printing techniques for performing printing by transferring ink ejected from a transfer member to a printing target by an inkjet method.

1 ... Printing device, 2 ... Blanket roller, 31 ... Ink head, 32 ... Ink head, 4 ... UV irradiator, 5 ... Stage, L1 ... First ink layer, L2 ... Second ink layer, B ... Substrate

Claims (10)

A first ejection step of ejecting a photocurable ink that is cured by irradiation with light to a transfer member by an inkjet method to form a first ink layer on the transfer member.
A first light irradiation step of curing the first ink layer by irradiating the first ink layer with light,
A second ejection step of ejecting the photocurable ink toward the first ink layer cured on the transfer member by the inkjet method and superimposing the photocurable ink on the first ink layer to form a second ink layer.
A transfer step of transferring the first ink layer and the second ink layer from the transfer member to the print target by bringing the uncured second ink layer into contact with the print target is provided.
The transfer member is a roller that rotates in a predetermined rotation direction.
In the first ejection step, the first ink layer is formed by an inkjet head facing the transfer member.
In the second ejection step, a printing method in which the second ink layer is formed by the inkjet head so as to be superimposed on the first ink layer that has returned to a position facing the inkjet head as the transfer member rotates. The printing method according to claim 1, wherein in the first light irradiation step, the first ink layer is completely cured. The printing according to claim 1 or 2, further comprising a second light irradiation step of completely curing the second ink layer by irradiating the second ink layer transferred to the printing target in the transfer step with light. Method. Compared with the period from the ejection of the photocurable ink in order to form the first ink layer in the first ejection step to the curing of the photocurable ink in the first light irradiation step, the first. 2. The method according to any one of claims 1 to 3, wherein the period from the formation of the second ink layer in the ejection step to the transfer of the first ink layer and the second ink layer in the transfer step is long. Printing method. The printing method according to any one of claims 1 to 4, wherein the first ink layer and the second ink layer are formed of the photocurable ink of the same color. The method according to any one of claims 1 to 4, wherein one of the first ink layer and the second ink layer is a colored photocurable ink and the other is a transparent photocurable ink. Printing method. A first ejection step of ejecting a photocurable ink that is cured by irradiation with light to a transfer member by an inkjet method to form a first ink layer on the transfer member.
A first light irradiation step of curing the first ink layer by irradiating the first ink layer with light,
A second ejection step of ejecting the photocurable ink toward the first ink layer cured on the transfer member by the inkjet method and superimposing the photocurable ink on the first ink layer to form a second ink layer.
A transfer step of transferring the first ink layer and the second ink layer from the transfer member to the print target by bringing the uncured second ink layer into contact with the print target.
With
In the first light irradiation step, light is irradiated by a light irradiator facing the transfer member.
A printing method in which the light irradiator is turned off after the first ink layer is cured and before the formation of the second ink layer is started. The transfer member is a roller that rotates in a predetermined rotation direction.
In the first ejection step, the photocurable ink is ejected by the first inkjet head facing the transfer member.
The printing method according to claim 7 , wherein in the second ejection step, the photocurable ink is ejected by the second inkjet head facing the transfer member on the downstream side in the rotation direction from the first inkjet head. Transfer member and
A first ink layer is formed on the transfer member by ejecting a photocurable ink that has an inkjet head facing the transfer member and is cured by irradiation of light from the inkjet head to the transfer member by an inkjet method. In addition, an ink ejection unit that is superposed on the first ink layer to form a second ink layer,
A light irradiation unit that cures the first ink layer by irradiating the first ink layer formed on the transfer member with light before forming the second ink layer.
By bringing the uncured second ink layer superimposed on the cured first ink layer into contact with the print target, the first ink layer and the second ink layer are transferred from the transfer member to the print target. Equipped with a transfer part to
The transfer member is a roller that rotates in a predetermined rotation direction.
The ink ejection unit forms the first ink layer by the inkjet head, and is superimposed on the first ink layer that has returned to a position facing the inkjet head as the transfer member rotates. A printing device that forms an ink layer with the inkjet head. Transfer member and
By ejecting a photocurable ink that is cured by irradiation with light to the transfer member by an inkjet method, a first ink layer is formed on the transfer member and a second ink layer is formed by superimposing the first ink layer on the transfer member. Ink ejection part and
A light irradiation unit that cures the first ink layer by irradiating the first ink layer that faces the transfer member and is formed on the transfer member with light before the formation of the second ink layer.
By bringing the uncured second ink layer superimposed on the cured first ink layer into contact with the print target, the first ink layer and the second ink layer are transferred from the transfer member to the print target. With the transfer part
With
The light irradiation unit is a printing device that turns off the light after the first ink layer is cured and before the formation of the second ink layer is started.