JP2010253727A - Inkjet recorder and inkjet recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simultaneously suppress void of image resulting from the remaining of ink in an intermediate transfer body and distortion of image caused at the time of transfer in an inkjet recorder with the intermediate transfer body. <P>SOLUTION: In a transfer process, the condition of ink having contacted with a recording medium is maintained for a fixed time after pressing. Then, after partially releasing by sagging the recording medium in a partial release unit, the intermediate transfer body is released from the recording medium. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an ink jet recording apparatus that performs recording by discharging ink, and particularly relates to an ink jet recording apparatus having a transfer unit using an intermediate transfer member.

  In recent years, an inkjet image forming apparatus using an inkjet discharge device has been studied for industrial use, and one of such applications is expected to be applied to the printing field. A plate necessary for a conventional printing method such as offset printing is not necessary for an ink jet recording method. Furthermore, since no lead time is required, a desired printed matter can be obtained immediately. For this reason, it has been attracting attention as a printing technology suitable for the needs of the times, such as multi-variety, small lot, and quick delivery.

  In this ink jet recording system, a characteristic image quality deterioration phenomenon such as bleeding and beading occurs. The bleeding phenomenon is caused when ink is directly applied to printing paper with high surface smoothness using an ink jet device, and the ink does not absorb completely on the paper and remains on the surface. It is a phenomenon that ends up. The beading phenomenon is a phenomenon in which the ink droplets that have landed first are attracted to the ink droplets that have landed later, and may cause degradation in image formation quality and poor drying.

  In order to reduce such a phenomenon of deteriorating image quality, a transfer type recording method has been proposed. In this recording method, an ink is formed on an intermediate transfer member by an ink jet recording method to form an ink image, and the ink image on the intermediate transfer member is thickened by drying the ink or the solvent of the ink image is removed. Concentrate the ink. Thereafter, the ink image is transferred from the intermediate transfer member onto the recording medium. Thereby, the above-mentioned bleeding phenomenon and beating phenomenon can be suppressed.

  Here, in the conventional transfer process, the intermediate transfer member and the recording medium are simultaneously pressed and peeled. The configuration is shown in FIG. Reference numeral 1 denotes a transfer belt as an intermediate transfer member, 6 denotes a recording medium, 7 denotes a pressure roller, and 13 denotes a transfer roller. The transfer belt 1 is conveyed in the direction of arrow 21 and the recording medium 6 is conveyed in the direction of arrow 22.

  At this time, the ink transferred from the intermediate transfer member to the recording medium is not in a completely dry state but contains a very small amount of solvent, and it is considered that the cohesive force of the ink is weak. If the intermediate transfer member and the recording medium are pressed and peeled at the same time in this state, the ink remains on the intermediate transfer member without being transferred to the recording medium, and the image on the recording medium is whitened. End up.

  In order to solve the problem of ink white spots, ink transfer performance is achieved by providing a difference in the rotation speed of the transfer roller that presses the intermediate transfer member and the recording medium at the time of ink transfer to cause slippage. There is known a method for improving the above (see Patent Document 1).

JP-A-6-155725

  However, in Patent Document 1, if there is a speed difference between the rotation speeds of the transfer rollers that press the intermediate transfer member and the recording medium, the ink image formed on the intermediate transfer member is not recorded at the correct position on the recording medium. It will occur. This will be described below.

  FIG. 2 is a schematic diagram showing the transfer belt 1, the recording medium 6, and the ink 15 which are intermediate transfer members. These have a structure sandwiched between two upper and lower rollers 7 and 13. Immediately before the transfer, the ink 15 and the recording medium 6 are not adhered and are in a separated state. In general, a material having high elasticity is used for the transfer belt to improve transfer performance, and at the time of transfer, the ink sandwiched between the recording medium and the transfer belt is crushed by a roller as shown in the figure. At this time, if slip is generated by changing the rotation speed of the roller, shearing force is applied in various directions of the ink, the ink is easily separated from the transfer belt, and white spots can be suppressed. On the other hand, because the transfer speeds of the transfer belt and the recording medium are different, the recording medium greatly deviates from the position of the transfer belt before the ink image is copied to the correct position on the recording medium. It occurs. This causes a problem that the image is distorted. In particular, the effect appears remarkably during high-speed transfer and fine image transfer.

  The present invention has been made in view of the above-described technical background, and suppresses white spots in a recorded image due to ink remaining on the intermediate transfer member and distortion of the recorded image that occurs during transfer at the same time. An object is to provide a recorded image.

  In order to solve such problems, the present invention provides an ink jet recording apparatus that transfers an ink image formed on an intermediate transfer member to a recording medium by a recording head, and the ink image formed on the intermediate transfer member is recorded on the recording medium. A contact means for contacting the medium, and a portion for partially peeling the ink image formed on the intermediate transfer body after contacting the intermediate transfer body and the recording medium by the contact means It has a peeling means and a peeling means for peeling off the recording medium and the intermediate transfer member after partial peeling is caused by the partial peeling means.

  According to the present invention, distortion of an image transferred to a recording medium is reduced, stable transfer with little transfer residue is enabled, and a high-quality recorded image is formed.

It is a schematic diagram of the example with which the conventional crimping | compression-bonding process and peeling process are continuing. FIG. 4 is a schematic diagram showing a relationship among ink, a recording medium, and an intermediate transfer member. 1 is a schematic cross-sectional view of a recording apparatus according to a first embodiment. FIG. 3 is a schematic cross-sectional view of a pressure bonding unit and a peeling unit of the recording apparatus. FIG. 3 is a schematic diagram of a recording medium, an intermediate transfer member, and an ink aggregate in a holding process. It is the time dependence of F1 and F2 in a holding process. It is typical sectional drawing in the case of using a pair of roller in a partial peeling process. It is a schematic diagram of the ink aggregate in a partial peeling process. FIG. 6 is a schematic diagram when the recording medium is bent. It is a stress schematic diagram when a crack arises in the ink aggregate. It is a schematic diagram of the ink aggregate in a partial peeling process. It is typical sectional drawing in the case of using an ultrasonic device in a partial peeling process. It is a schematic diagram of the ink aggregate for demonstrating a partial peeling process. It is a schematic diagram of an ink aggregate. It is a schematic diagram of the recording medium in a partial peeling process.

(First embodiment)
FIG. 3 is a schematic cross-sectional view of the recording apparatus in the present embodiment. Reference numeral 1 denotes a transfer belt as an intermediate transfer member, and has an ink releasable surface layer 2. The transfer belt 1 is stretched around four belt conveyance rollers 10, 11, 12, and 13, and any one of these conveyance rollers is rotationally driven by a belt driving device (not shown), so that the direction of arrow 21 is reached. It is conveyed to. The conveying roller 13 is opposed to the pressure roller 7 to form a pressure bonding unit 14. This pressure bonding unit 14 is also used as a pressure roller for bringing the ink image formed on the intermediate transfer body into contact with the recording medium, and has a heater inside the roller to give a stable temperature during transfer. ing. Around the transfer belt 1, the reaction liquid applying unit 3, the ink jet recording unit 5, the pressure bonding unit 14, and the partial peeling unit 8 are arranged in order from the upstream side to the downstream side in the conveyance direction (arrow 21 direction) of the transfer belt 1. A recording medium peeling unit 9 is arranged. In the present embodiment, the partial peeling unit 8 as the partial peeling means is installed between the pressure bonding unit 14 as the pressure bonding means and the recording medium peeling unit 9 as the peeling means, and is separated from the pressure bonding unit 14 by a certain distance. Has been.

  First, the reaction solution 4 is applied by the reaction solution applying unit 3 to the surface layer 2 on the transfer belt 1 that is an intermediate transfer member. Thereafter, ink is ejected from the recording head in the ink jet recording unit 5 on the surface layer 2 to form an image (mirror inverted image of the target image). At this time, the ejected ink comes into contact with the reaction liquid on the surface layer 2 and an agglomeration reaction occurs instantaneously. Due to this reaction, the fluidity of the color material is lowered, so that the disturbance of the ink image on the transfer belt 1 is suppressed. The formed ink image is pressure-bonded to the recording medium 6 in a pressure-bonding process in the pressure-bonding unit 14. Then, while maintaining the state in which the ink image is in contact with the recording medium 6 (holding step 16), the ink image passes through a partial peeling unit 8 which is a partial peeling step described later. And it is conveyed to the recording medium peeling unit 9, and the recording medium 6 and the transfer belt 1 isolate | separate in the recording medium peeling unit 9 which is a peeling process. Hereinafter, these will be described in more detail.

<Reaction liquid unit>
The reaction solution 4 used in the reaction solution application unit 3 is appropriately selected depending on the type of ink used for image formation. For example, it is effective to use a polymer flocculant for dye inks, and it is effective to use metal ions or organic acids for pigment inks in which fine particles are dispersed. Furthermore, when a metal ion is used in combination with a polymer flocculant as an image fixing component for the dye ink, a pigment having the same color as the dye is mixed in the ink, or the white or It is preferable to mix transparent fine particles.

  In order to improve the fastness of the finally formed image, a water-soluble resin or a water-soluble crosslinking agent can be added. The material used is not limited as long as it can coexist with the reaction solution components. As the water-soluble resin, it is preferable to add PVA, PVP or the like. As the water-soluble crosslinking agent, oxazoline or carbodiimide having a low reactivity is preferably used in terms of stability of the reaction solution.

  The means for applying the reaction liquid is not particularly limited, and those by contact coating such as wire bar coating, and those by non-contact coating such as spray coating or droplet application by an ink jet recording head can be used. Although the range of application is limited, even if the coating is performed by spin coating, pulling up coating, coating with an air knife, etc., it can be used without problems in terms of characteristics. Moreover, you may use combining those application means suitably.

<Inkjet recording unit>
As described above, in the ink jet recording unit 5, ink is ejected from the recording head (not shown) to the surface layer 2 of the transfer belt, which is an intermediate transfer member, and an ink image is formed. Although there is no restriction | limiting in particular about the ink used here, Generally the water-system ink which used dye and a pigment is used suitably. In particular, the water-based pigment ink is suitable when a metal salt or an organic acid is used for the reaction liquid. The pigment is not limited in form, and for example, any of self-dispersion type, resin dispersion type, microcapsule type and the like can be used. As the pigment dispersant used in this case, a water-soluble dispersion resin having a weight average molecular weight of about 1,000 to 15,000 can be preferably used. In order to improve the fastness of the finally formed image, a water-soluble resin or a water-soluble crosslinking agent can be added.

  Here, in FIG. 4, the typical sectional drawing of the crimping | compression-bonding unit 14, the peeling unit 9, and the partial peeling unit 8 in this embodiment is shown. As described above, the partial peeling unit 8 is separated from the crimping unit 14 and has a holding step 16 therebetween.

<Crimping process>
In the present embodiment, as described above, the crimping unit 14 includes the transport roller 13 and the pressure roller 7 for driving the transfer belt. An ink image on the transfer belt 1 is transferred to the surface of the recording medium 6 by pressing the recording medium 6 against the transfer belt 1 with a pressure roller 7. The pressure roller 7 is disposed so as to allow the recording medium 6 to pass through the nip portion between the pressure belt 1 and the pressure roller 7 and can be formed by a rubber roller, a metal roller, or the like. In the present embodiment, the pressure-bonding step is pressed by the pressure roller 7 with a linear load of 10 kg / cm ² , but any contact means may be used as long as the ink image on the intermediate transfer member and the recording medium come into contact with each other, and the pressure is not limited to this. is not. Furthermore, if it is a contact process in which the recording medium 6 is brought into contact with the transfer belt 1 by the pressure roller 7, the transport roller 13 does not need to face the pressure roller 7.

<Holding process>
Next, the holding step 16 will be described with reference to FIG. The holding step is a step until the transfer belt 1 and the recording medium 6 that are in contact with each other by the pressure bonding unit 14 reach the partial peeling unit 8. In the holding step 16, it is sufficient that the recording medium and the ink image, and the ink image and the transfer belt surface are in contact with each other, and only the conveyance is performed in a state where no pressure is applied.

  In general, since the recording medium has higher solvent absorbability than the intermediate transfer member, the solvent remaining in a minute amount in the ink aggregate is preferentially absorbed by the recording medium during the holding step. At this time, the adhesion force F1 at the interface between the recording medium 6 and the ink aggregate 15 is defined as the adhesion force F2 at the interface between the surface layer 2 of the transfer belt and the ink aggregate 15, and the aggregation force F3 of the ink aggregate. These forces increase with decreasing amount of solvent in the ink.

  FIG. 6 shows the relationship between time and F1 and F2. The relationship between F1 and F2 varies depending on the type of the intermediate transfer member, ink, and recording medium, but the adhesion forces F1 and F2 that were similar at the time of pressure bonding are then increased as the solvent is absorbed by the recording medium. However, F1 rises rapidly.

  As shown in FIG. 1 as a conventional example, when the pressure bonding step and the peeling step are continuously present and the holding step is not provided, a large amount of solvent remains in the soft ink aggregate. That is, since the agglomeration force F3 of the ink aggregate is weak and the separation is performed in a state where the adhesion forces F1 and F2 are not different, the place where the ink aggregate is cracked is not easily limited, and the ink on the intermediate transfer body is not limited. Aggregates tend to remain.

  On the other hand, as in this embodiment, the pressure bonding step and the peeling step are separated, and the ink aggregate is held for a certain period of time with the structure sandwiched between the recording medium and the intermediate transfer member, so that the cohesive force F3 is greater than that during pressure bonding. Further, the contact force F1 becomes relatively larger than the contact force F2. Therefore, when the intermediate transfer member and the recording medium are subsequently peeled off, the place where the ink aggregate is cracked is easily limited to the interface between the intermediate transfer member and the recording medium, so that the ink aggregate can easily move to the recording medium. Become. In an ink jet discharge device in which the ink aggregate is transferred to the recording medium from the intermediate transfer member in a semi-dry state containing a solvent such as moisture, this embodiment having a holding step is a very effective transfer unit. it is conceivable that.

  The distance and time required for the holding step may be appropriately set according to the speed of the transfer belt, the concentration and composition of the ink solvent, and the temperature and humidity of the environment. Considering the time for the semi-dried ink to permeate and fix the recording medium, the time required from the pressure bonding process to the partial peeling process may be 1 second or more at room temperature and normal pressure. preferable. Further, in order to obtain stable fixing, it is preferably 3 seconds or more.

<Partial peeling process>
Next, the partial peeling unit 8 will be described with reference to FIG. The partial peeling unit 8 includes a roller 17 on the transfer belt side and a roller 18 on the recording medium side. In each of the rollers 17 and 18, the width of each roller is equal to or larger than the width of the ink image. Further, the rotation axis is parallel to the plane formed by the ink image and is orthogonal to the transfer belt conveyance direction.

  The ink aggregate 15 sandwiched between the transfer belt 1 as an intermediate transfer member and the recording medium 6 is passed between the pair of rollers. At this time, the rotation speed r1 of the roller 18 on the recording medium side is slower than the rotation speed r2 of the roller 17 on the transfer belt side. Due to the difference in the conveying speed, a pressure F4 is applied to the recording medium side to cause the recording medium 6 to bend. At this time, r1 does not always have to be slower than r2, and the conveyance speed can be appropriately changed according to the deflection amount of the recording medium.

  FIG. 8 shows a schematic diagram in the partial peeling step. In this embodiment, since the crimping process has already passed, the ink image drawn on the transfer belt is copied to the correct position of the recording medium, and there is no gap between the recording medium and the ink aggregate, and between the ink aggregate and the transfer belt. It is in a close contact state. In addition, since the holding process has been performed, the cohesive force of the ink aggregate 15 is greater than that of the semi-dried ink.

  In this state, when the rollers 17 and 18 having different upper and lower conveying speeds are passed to cause deflection on the recording medium 6 side, the ink aggregate 15 in close contact with the recording medium 6 and the surface layer 2 of the transfer belt is obtained. As shown in FIG. 9, it is stretched up and down without leaving the recording medium or the transfer belt. The recording medium 6 sandwiched between a pair of rollers having different rotational speeds receives a press F4 from the back side. This F4 can be decomposed into a force F5 in the parallel direction and a force F6 in the vertical direction with respect to the plane formed by the ink image. A characteristic of the partial peeling unit 8 is this force F5.

  When a force F5 parallel to the plane formed by the ink image is generated on the recording medium 6, the recording medium 6 slightly bends in the direction perpendicular to the plane formed by the ink image (peeling direction). With this slight deflection, the ink aggregate 15 receives stress in the peeling direction. At this time, if the ink aggregate receives a certain force or more, the ink aggregate disperses the received force, and therefore cracks start from the weakest part. As described above, the ink aggregate 15 that has undergone the holding process has the weakest adhesion force F2 at the interface with the surface layer 21 of the transfer belt, and therefore cracks are generated starting from this interface. Accordingly, as shown in FIG. 10, the force F7 is applied to the ink aggregate 15 along with the deflection of the recording medium, and a crack is generated starting from the interface with the surface layer 2 of the transfer belt. In this embodiment, the state in which the ink aggregate is cracked at the interface between the ink aggregate 15 and the surface layer 2 of the transfer belt due to the bending of the recording medium 6 is referred to as partial peeling (micro peeling).

  Here, the force F7 relating to the interface between the ink aggregate and the intermediate transfer member when cracks are generated will be described. F7 is decomposed into a component F8 in the equilibrium direction with respect to the plane formed by the ink image and a component F9 perpendicular to the plane formed by the ink image.

  It is desirable that the sizes of F8 and F9 are such that the ink aggregates do not move greatly due to the application of stress so that the transferred image is not distorted. That is, F9 needs to be such that the ink aggregate does not completely peel from the transfer body.

  Here, partial peeling will be described. The ink aggregate has elasticity having a certain elongation rate k depending on the resin, the solvent species contained, and the like. Due to this elasticity, even if the recording medium is bent, the ink aggregate adheres to both the recording medium and the intermediate transfer belt and does not peel up to a certain amount of elongation. However, if it exceeds a certain amount of elongation, the ink aggregate cannot extend any more, and as described above, peeling occurs at the interface between the ink aggregate having the weakest cohesive force and the transfer belt.

  In general, as shown in FIG. 13A, the ink aggregate does not have a flat structure on one side, but has a non-uniform structure in which the center is thick and becomes thinner toward the end. Therefore, when a force is applied in the direction in which such an ink aggregate extends, partial peeling occurs at the end of the aggregate which is originally low in height and cannot be extended. At this time, assuming that the maximum peel height at which the recording medium can bend is Tmax, Tmax <L1 · k (Tmax: maximum peel height, L1: height of untreated ink aggregate, k: ink cohesion) (Elongation rate of the aggregate) holds.

  The maximum height of the ink aggregate before extending as shown in FIG. 13A has a height L2 at the end of the ink aggregate and a height L1 at the center of the ink aggregate. When this ink aggregate is stretched by the deflection of the recording medium, it can stretch to a certain height as shown in FIG. Assuming that the fully extended heights are L1 'and L2', respectively, the end of the ink aggregate can be extended to L1 '= kL1, and the center of the ink aggregate can be extended to L2' = kL2.

  When the deflection height Tmax is L1 '<Tmax <L2', the central portion is not peeled and the end portion is extended by kL1 or more, so that partial peeling occurs. In the case of L2 '<Tmax, the central portion and the end portion are peeled off, which may cause distortion of the recording medium and distortion of the image, which is not preferable. Therefore, in the partial peeling step, it is desirable to cause a deflection of Tmax <L2 ′.

FIG. 14 shows a detailed view of the ink aggregate before stretching. Since the maximum height L1 of the pre-elongating ink aggregate can be regarded as an arc of a circle,
Lo = Φ (1-cos ( θ 1/2)) / 2sin (θ 1/2)
It can be expressed as. (Lo: maximum height of untreated ink aggregate, θ ₁ : central angle of arc forming ink aggregate, Φ: dot diameter of ink aggregate)
That is,
Tmax <Φ (1-cos ( θ 1/2)) / 2sin (θ 1/2) · k
If it is. Here, since Φ, θ ₁ , and k can be obtained from actual measurement values, it is possible to obtain a height Tmax that can deflect the recording medium to the maximum.

The dot diameters Φ and θ ₁ of the ink aggregate may be obtained by actually measuring the dot diameter of the ink aggregate on the transfer belt. The maximum elongation k of the ink aggregate is a value that varies greatly depending on the ink type and the solvent type. For example, it can be determined from the elongation length of each ink aggregate using a tacking test apparatus.

The maximum displacement amount x between the recording medium and the transfer belt may be obtained from the height Tmax at which the recording medium can be bent to the maximum. FIG. 15 shows a state in which the recording medium is bent by the displacement amount x. The displacement of the recording medium, the recording medium produces a deflection having a height Tmax, the angle theta _2. At this time, the following equation holds.
Displacement _{x = 2Tmax / cos (θ 2} /2) -2Tmax · tan (θ 2/2)
_{= 2Tmax / cos (θ 2/} 2) (1-sin (θ 2/2))
The process of bending the recording medium is a phenomenon that can occur due to a very small displacement. Further, since the recording medium to be bent has flexibility and stiffness, it does not bend greatly. The bending angle θ ₂ of the recording medium may be actually measured, but is generally preferably about 120 °.

  On the other hand, F8 in FIG. 10 is preferably such that the transferred ink does not move significantly. FIG. 11 illustrates the relationship among the recording medium 6, the ink aggregate 15, and the surface layer 2 of the transfer belt. When the recording medium is bent and the ink aggregate is distorted, the aggregated ink may move by a certain distance a. In order to obtain a more stable image and to allow peeling, it is desirable that the ink moving distance a is ½ or less of the average diameter L of one ink aggregate. More preferably, it is 1/3 or less of the average diameter L.

  In general, the recording medium is thinner than the intermediate transfer member and tends to bend. Therefore, by pressing from the back side of the recording medium, the recording medium can be more efficiently bent and partial peeling can be generated.

The roller pressure here does not need to apply a strong pressure and is preferably 1.0 kg / cm ² or less.

  In the present embodiment, the recording medium is deflected by being brought into contact with a roller having a speed difference in a state in which the pressure is not applied so much in the vertical direction. Thereby, partial peeling can be promoted. The rotation axis of the roller is not particularly limited as long as it can cause the recording medium to bend. However, in order not to cause image distortion and paper skew more than necessary, it is preferable to be parallel to the plane formed by the ink image and to be orthogonal to the conveyance direction of the intermediate transfer member.

<Peeling process>
The peeling unit includes a conveyance roller 10 and a recording medium peeling unit 9. In the present embodiment, the recording medium separation unit 9 includes a separation claw, and the separation claw operates according to the conveyance timing of the recording medium 6. The separation claw is driven by a driving device (not shown) to separate the recording medium 6 from the transfer belt 1 and to peel it off.

  As described above, in the transfer process of the present embodiment, the cohesive force of the ink aggregate is increased through the pressure-bonding process and the holding process, and the interface between the intermediate transfer body and the ink image is easily cracked. Then, using a pair of rollers having different rotational speeds, the recording medium and the intermediate transfer member are peeled in the peeling process after the partial peeling process in which the recording medium is bent. By using such a transfer method, the ink image of the intermediate transfer member is transferred to the recording medium without distortion, and further, the remaining of the ink on the intermediate transfer member can be suppressed and the transfer efficiency can be improved.

  In this embodiment, the following experiment was performed and the result was confirmed.

(1) Surface Modification of Transfer Body In this example, a material obtained by coating a silicone rubber (KE12 manufactured by Shin-Etsu Chemical Co., Ltd.) having a rubber hardness of 40 ° to a thickness of 0.2 mm was used as an intermediate transfer body. First, the surface of the intermediate transfer member was subjected to surface modification using the atmospheric pressure plasma processing apparatus 3 (ST-7000 manufactured by Keyence Corporation) under the following conditions.
Processing distance: 5mm
Plasma mode: High
Processing speed: 100mm / sec
Subsequently, a commercially available neutral detergent composed of sodium alkylbenzenesulfonate was immersed in a surfactant aqueous solution diluted with pure water to 3%, washed with water and dried.

(2) Image formation on intermediate transfer member Next, a 5% by mass aqueous solution of a polymer flocculant (C577S manufactured by Mitsui Cytec) is applied to the surface of the intermediate transfer member with a roll coater. Subsequently, a character image that was mirror-reversed using water-based ink was formed on the intermediate transfer member with an inkjet recording unit (nozzle density 1200 dpi (dot / inch; reference value), ejection amount 4 pl, drive frequency 12 kHz). .

(3) Transfer The intermediate transfer body after the above-described series of steps and the surface-coated printing paper (Mitsubishi Paper, N Pearl Coat L, 64.2 g) with low ink absorption are brought into contact with a pressure roller, and the intermediate The ink image formed on the transfer body was pressure bonded (pressure bonding process). About 5 seconds after the press-bonding step, the sample having a layered structure composed of the intermediate transfer member, the ink aggregate, and the recording medium was further passed between rollers having different vertical speeds, thereby causing the recording medium to bend. At this time, the transfer belt side roller speed is 50 mm / s, the recording medium side roller speed is 49 mm / s, and the vertical pressure is 0.5 kg / cm ² . Thereafter, the intermediate transfer member was peeled from the recording medium to obtain a printed recording medium. Residual ink was not observed on the surface of the intermediate transfer member after the transfer, and almost no phenomenon such as whitening of the image on the printed recording medium was observed. Also, even if the next image was received as it was, no effect was seen.

(Comparative Example 1)
In the above (3) transfer step, the intermediate transfer member was peeled off from the recording medium immediately after the pressure-bonding step to obtain a printed recording medium. Residual ink was observed on the surface of the intermediate transfer member after transfer.

(Comparative Example 2)
In the transfer step (3), the recording medium was bent by the partial peeling unit immediately after the pressure-bonding step. Thereafter, the intermediate transfer member was peeled from the recording medium to obtain a printed recording medium. Residual ink was observed on the surface of the intermediate transfer member after transfer.

(Comparative Example 3)
In the transfer step (3) above, the transfer was performed while slipping in the pressing step by controlling the speed of the upper and lower rollers. Residual ink was observed on the surface of the intermediate transfer member after transfer.

(Comparative Example 4)
In the transfer step (3) above, about 5 seconds after the pressure-bonding step, a layered structure sample consisting of an intermediate transfer member, an ink aggregate, and a recording medium is passed between a pair of pressure rollers to record on the intermediate transfer member. The image was crimped (crimping process). Thereafter, the intermediate transfer member was peeled from the recording medium to obtain a printed recording medium. Residual ink was observed on the surface of the intermediate transfer member after transfer.

(Second Embodiment)
In the first embodiment, in the partial peeling unit, the recording medium is bent using a roller and the partial peeling is performed. However, the present embodiment is not limited thereto. As shown in FIG. 12, an ultrasonic oscillator 19 may be used as the partial peeling unit, and partial peeling may be performed by applying ultrasonic vibration from the recording medium side. At this time, a presser 20 may be provided on the intermediate transfer member side in order to suppress distortion of the belt conveyance due to the applied ultrasonic vibration.

  In the present embodiment, the following experiment was performed. In the transfer step, about 5 seconds after the press-bonding step, an ultrasonic oscillator was further applied from the recording medium side to the sample having a layered structure including the intermediate transfer member, the ink aggregate, and the recording medium, thereby causing the recording medium to bend. . Thereafter, the intermediate transfer member was peeled from the recording medium to obtain a printed recording medium. There was almost no residual ink on the surface of the intermediate transfer member after the transfer, and even if the next image was received as it was, no effect was observed.

  Furthermore, the shape of the ultrasonic wave generation terminal is not particularly limited as long as vibration can be applied to the recording medium. For example, pressing F4 is applied to almost all the ink aggregates by arranging the ultrasonic wave generation terminals in a straight line in a direction parallel to the plane formed by the ink image and perpendicular to the transport direction of the intermediate transfer body. be able to.

  As a mechanism for applying F4 from the back side of the recording medium, it is preferable to press continuously or intermittently from the back side of the recording medium toward the recording medium and the intermediate transfer member.

  As described above, in the present embodiment, through the pressure bonding process and the holding process, the cohesive force of the ink aggregate is strengthened, and the interface between the intermediate transfer body and the ink aggregate is easily cracked. Then, after the recording medium is bent using an ultrasonic generator to perform partial peeling, the recording medium and the intermediate transfer member are peeled in a peeling step. By using such a transfer method, the ink image of the intermediate transfer member is transferred to the recording medium without distortion, and further, the remaining of the ink on the intermediate transfer member can be suppressed and the transfer efficiency can be improved.

  In the above-described embodiment, a pair of rollers and ultrasonic generators having different rotational speeds are used as the partial peeling means. However, if the ink image formed on the intermediate transfer member can be partially peeled from the intermediate transfer member. There is no particular limitation. For example, a vibrator that presses and partially peels the recording medium by applying vibration to the recording medium, a wind pressure generator, a sound wave generator, a contact blade that causes partial peeling by causing friction to the recording medium, etc. Is mentioned. As a method of pressing to the recording medium, a terminal for pressing may be brought into direct contact with the back surface of the recording medium, or in the case of a sound wave or the like, it may be given without contact.

  As a method for applying minute vibrations such as ultrasonic waves, a structure in which a terminal for applying vibration to the recording medium side is applied to the ink aggregate held between the intermediate transfer member and the recording medium is desirable. It is necessary to apply a stress at least once to one inkjet ink aggregate and to give a certain amount of change to the recording medium.

  Therefore, in order to perform high-speed and high-quality printing, it is necessary to apply stress to the ink aggregate of several thousand to several tens of thousands of dots per second. Therefore, an ultrasonic generator is suitably used as the vibration generator.

(Other embodiments)
In the recording apparatus of this embodiment, the intermediate transfer member is an endless belt, but may be a drum shape. Although not shown in FIG. 3, for the purpose of evaporating and removing moisture or solvent components in the ink constituting the image on the surface layer 2, the moisture removal promoting device is an inkjet recording unit and the image is recorded on the recording medium. You may install between the means to transfer to. Any known technique such as air blowing, decompression, or contact with an absorbent material can be suitably used for the moisture removal promoting device. For the same purpose, a means for heating the intermediate transfer belt 1 itself may be provided. Further, a fixing unit for fixing the ink image transferred to the recording medium after the ink image transfer may be provided. A cleaning unit for cleaning the surface of the intermediate transfer belt after transferring the ink image may be provided.

  Further, the surface layer 2 of the intermediate transfer member may be formed over the entire circumference of the intermediate transfer member belt 1 or may be divided into a size corresponding to the recording medium 6, for example, about A4 size. In the latter case, by providing a mechanism that can be attached and detached in units of one sheet, the cost and labor of regeneration processing and replacement can be reduced.

  The surface layer 2 of the transfer belt as an intermediate transfer member in this example has a property (release property) that allows the ink image to be easily peeled off on the surface. Silicone rubber is one of the optimum materials for forming the surface layer 2 because of its low surface energy and high peelability. However, the material of the surface layer 2 is not limited to silicone rubber, and any material having preferable releasability and elastic characteristics and excellent transfer rate when transferring an ink image to a recording medium. Good. Further, the layer configuration may be changed as appropriate, for example, the surface layer 2 has a configuration of two or more layers.

DESCRIPTION OF SYMBOLS 1 Transfer belt 2 Surface layer 3 Reaction liquid provision unit 4 Reaction liquid 5 Inkjet recording unit 6 Recording medium 7 Pressure roller 8 Partial peeling unit 9 Recording medium peeling unit 10, 11, 12, 13 Conveyance roller 14 Crimp unit 15 Ink aggregate 16 Holding process 17 Intermediate transfer member side roller 18 Recording medium side roller 19 Ultrasonic transmission terminal 20 Presser 21 Transfer belt conveyance direction 22 Recording medium conveyance direction

Claims (4)

In an ink jet recording apparatus for transferring an ink image formed on an intermediate transfer member by a recording head to a recording medium,
Contact means for bringing the ink image formed on the intermediate transfer member into contact with the recording medium;
A partial peeling means for partially peeling the ink image formed on the intermediate transfer body from the intermediate transfer body after contacting the intermediate transfer body and the recording medium with the contact means;
An ink jet recording apparatus comprising: a peeling unit that peels off the recording medium and the intermediate transfer body after partial peeling is caused by the partial peeling unit.   The partial peeling means is a roller, and the roller contacts the back surface of the recording medium at a speed different from the conveyance speed of the intermediate transfer member, so that the ink image formed on the intermediate transfer member is removed. The ink jet recording apparatus according to claim 1, wherein partial peeling is performed.   The inkjet recording apparatus according to claim 1, wherein the partial peeling unit partially peels the ink image formed on the intermediate transfer member by generating ultrasonic vibration with an ultrasonic oscillator. In an inkjet recording method including a transfer step of transferring an ink image formed on an intermediate transfer member by a recording head to a recording medium,
The transfer step includes a contact step of bringing an ink image formed on the intermediate transfer member into contact with the recording medium, and an ink image formed on the intermediate transfer member after the contact step is partially transferred to the intermediate transfer member. An ink jet recording method comprising: a partial peeling step for peeling off the recording medium; and a peeling step for peeling off the recording medium from the intermediate transfer member from which the ink image has been partially peeled after the partial peeling step.