JP5525293B2 - Drying apparatus and drying method, and image forming apparatus and image forming method using the same - Google Patents

Description

  The present invention relates to a drying apparatus and a drying method, and an image forming apparatus and an image forming method using the same, and in particular, a drying apparatus and a drying method capable of obtaining a good conveyance state without impairing drying properties, and the use thereof. The present invention relates to an image forming apparatus and an image forming method.

  In general, as a general-purpose image forming apparatus, an ink jet recording apparatus that forms a desired image by ejecting ink droplets from an ink jet head onto a recording medium is widely used. When water-based ink is used in an ink jet recording apparatus, deformation of the recording medium has occurred due to breaking of hydrogen bonds of cellulose and recombination of hydrogen bonds by drying. In order to prevent such deformation as much as possible, the ink jet method requires drying as soon as possible as compared with other printing methods such as offset printing.

  There are two types of drying methods: drying by contact with a heat source and drying by non-contact. Examples of non-contact drying include drying by hot air (drying air). In the case of drying with hot air, there is a problem that if the air volume is too large, the paper flutters, and the transportability deteriorates such as bending or scratching. However, when the air volume is lowered, there is a problem that the atmosphere cannot be replaced and drying is difficult to proceed.

  As a method for stabilizing the transportability of the recording medium, the following Patent Document 1 describes the recording surface of the recording medium and one surface of the recording head in order to stabilize the transporting posture of the recording medium and to obtain an optimum state for image recording. An ink jet printer having posture stabilization means for adjusting the distance is described. Further, in Patent Document 2, when the printing screen of the paper is dried by the blower, the paper is prevented from flapping by the wind pressure, and the wind hitting the paper rises to the upstream side through the paper feed. And a drying method and apparatus for preventing the influence of wind on the printed part.

JP 2004-123250 A Japanese Patent Laid-Open No. 2004-106346

  However, the ink jet printer described in Patent Document 1 stabilizes conveyance during image recording, and has not been studied for drying. In addition, the drying method described in Patent Document 2 is intended to prevent the transportability and the quality of the formed image from being deteriorated, and has not been studied for compatibility between the dryness and the transportability.

  The present invention has been made in view of such circumstances, and by controlling the drying means due to the difference in rigidity of the recording medium, a drying apparatus capable of maintaining good transportability while maintaining dryness, and A drying method, an image forming apparatus using these, and an image forming method are provided.

According to a first aspect of the present invention, in order to achieve the above-mentioned object, there are provided a conveying means for carrying a recording medium on which an image is formed on a conveying medium, and a recording medium on which the image conveyed by the conveying means is formed. The rigidity of the recording medium is determined by the blowing means for blowing the drying air on the image forming surface, the drying air heating means for heating the drying air, the first heating means for heating the transport medium, and the rigidity of the recording medium. And control means for controlling the air volume of the dry air so as to lower the air volume of the dry air when the air flow is low , the control means reduces the amount of heat ΔQ _air that is reduced because the air volume of the dry air is reduced , A drying apparatus characterized in that the temperature rise ΔT is obtained by the following equation (4) by compensating for the heat quantity ΔQ _con obtained by the temperature rise ΔT of the transport medium .
The heat transfer coefficient of the transport medium is hs [W / (m ² · K)], the temperature of the transport medium is T _con [° C.], and the temperature of the transport medium before the air volume of the drying air is reduced is T _type [° C.]. ΔQ _con = hs (T _con −T _type ) = hs · ΔT, the temperature of the drying air is T [° C.], the air volume of the drying air before the change is w ₁ [m ³ / min], and after the change Assuming that the dry air volume difference ΔQ _air (T; w ₁ , w ₂ ) when the air volume of the dry wind is w ₂ [m ³ / min] ,
ΔT = ΔQ _air (T; w ₁ , w ₂ ) / hs (4)

According to the first aspect, when the rigidity of the recording medium is low due to the rigidity of the recording medium, the air volume of the drying air is controlled so as to reduce the air volume of the drying air. Since it can be prevented from being attached or broken, the transportability of the recording medium can be improved.
In addition, since the temperature of the transport medium is controlled by the air volume of the drying air, heating from the transport medium, which is a contact-type drying method, can be controlled according to the drying condition by the dry air, and the drying can be performed efficiently. It can be carried out.
Further, since the amount of heat reduced by lowering the air volume of the drying air is compensated by increasing the temperature of the transport medium, drying can be performed without impairing the drying property.

In a second aspect according to claim 1, wherein, when the rigidity of the recording medium is not more than 3 mN · m, characterized by stopping the blowing of the drying air.

  When the rigidity of the recording medium is 3 mN · m or less, the recording medium flutters when blowing dry air, so it is preferable to stop blowing the dry air. Note that it is preferable to compensate for the amount of heat lost by stopping the drying air blowing by heating the conveyance medium.

A third aspect of the present invention is characterized in that in the first or second aspect , the recording medium further comprises a second heating means for heating the recording medium in a non-contact manner.

According to the third aspect , since the second heating means for heating the recording medium in a non-contact manner is provided separately from the air blowing means, the second heating means is used when the air volume of the drying air is reduced. By drying, a decrease in drying performance can be suppressed.

According to a fourth aspect of the present invention, in order to achieve the above object, the image forming means for forming an image by ejecting ink onto the surface of the recording medium, and the drying according to any one of the first to third aspects. And an image forming apparatus comprising the apparatus.

According to the fourth aspect , since the drying apparatus is provided, it is possible to provide an image forming apparatus that is capable of forming an image that is not bent or bent in the recording medium and that has good drying properties.

According to a fifth aspect of the present invention, in order to achieve the above object, a transporting step of transporting a recording medium on which an image is formed is transported on a transporting medium, a drying air heating step of heating a drying air sprayed on the recording medium, When the rigidity of the recording medium is low due to the blowing process of blowing the drying air onto the image forming surface of the recording medium on which the image is formed, the first heating process of heating the transport medium, and the rigidity of the recording medium Includes a control step of controlling the air volume of the dry air so as to reduce the air volume of the dry air in the air blowing step, and the control step reduces the amount of heat ΔQ _air that is reduced because the air volume of the dry air is reduced. Is provided by providing a heat quantity ΔQ _con obtained by the temperature increase ΔT of the transport medium, and the drying method is characterized in that the temperature increase ΔT is obtained by the following equation (4) .
The heat transfer coefficient of the transport medium is hs [W / (m ² · K)], the temperature of the transport medium is T _con [° C.], and the temperature of the transport medium before the air volume of the drying air is reduced is T _type [° C.]. ΔQ _con = hs (T _con −T _type ) = hs · ΔT, the temperature of the drying air is T [° C.], the air volume of the drying air before the change is w ₁ [m ³ / min], and after the change Assuming that the dry air volume difference ΔQ _air (T; w ₁ , w ₂ ) when the air volume of the dry wind is w ₂ [m ³ / min] ,
ΔT = ΔQ _air (T; w ₁ , w ₂ ) / hs (4)

A sixth aspect of the present invention is characterized in that, in the fifth aspect , the control step stops the blowing of the dry air when the rigidity of the recording medium is 3 mN · m or less.

According to a seventh aspect of the present invention, in order to achieve the above-mentioned object, an image forming process for forming an image by ejecting ink onto the surface of a recording medium, and the recording medium on which the image is formed is carried on a conveying medium. A conveying step for heating, a drying air heating step for heating the drying air blown to the recording medium, a blowing step for blowing the drying air on the image forming surface of the recording medium on which the image is formed, and heating the conveying medium. A control step of controlling the air volume of the drying air so as to lower the air volume of the drying air in the air blowing step when the rigidity of the recording medium is low due to the rigidity of the recording medium and the first heating step ; The control step compensates for the amount of heat ΔQ _air that decreases because the amount of dry air is reduced by providing the amount of heat ΔQ _con obtained by the temperature increase ΔT of the transport medium, and compensates for the temperature increase ΔT. There is provided an image forming method characterized by being obtained by the following equation (4) .
The heat transfer coefficient of the transport medium is hs [W / (m ² · K)], the temperature of the transport medium is T _con [° C.], and the temperature of the transport medium before the air volume of the drying air is reduced is T _type [° C.]. ΔQ _con = hs (T _con −T _type ) = hs · ΔT, the temperature of the drying air is T [° C.], the air volume of the drying air before the change is w ₁ [m ³ / min], and after the change Assuming that the dry air volume difference ΔQ _air (T; w ₁ , w ₂ ) when the air volume of the dry wind is w ₂ [m ³ / min] ,
ΔT = ΔQ _air (T; w ₁ , w ₂ ) / hs (4)

Claims 5 and 6 are developed by using the drying apparatus described above as a drying method, and Claim 7 is developed by using the image forming apparatus described above as an image forming method. According to claims 5 , 6 and 7 , the same effect as described above can be obtained.

  According to the drying apparatus and the drying method of the present invention, and the image forming apparatus and the image forming method using them, the air volume of the drying air is adjusted by the rigidity of the recording medium, so that the fluttering of the recording medium can be suppressed. In addition, the transportability of the recording medium can be improved.

1 is a configuration diagram schematically showing an ink jet recording apparatus in which a drying apparatus according to the present invention is incorporated. It is a list of variables used for calculation of the set temperature of the transport medium. It is a list of the constants used for calculation of the preset temperature of a conveyance medium. It is a table | surface figure which shows the calorie | heat amount which a conveyance medium gives a recording medium. It is a table | surface figure of the calorie | heat amount which a dry wind gives to a recording medium. It is a principal block diagram showing the system configuration of the ink jet recording apparatus. It is a table | surface figure which shows the result of an Example.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of a drying apparatus and a drying method according to the present invention, and an image forming apparatus and an image forming method using the drying apparatus according to the invention will be described. In the following embodiments, an inkjet recording apparatus will be described as an example of an image forming apparatus. However, the present invention is not limited to this, and any apparatus that forms an image on a recording medium and dries can be used. can do. Further, the conveyance is not limited to drum conveyance, and can be used for belt conveyance.

[Overall configuration of inkjet recording apparatus]
First, the overall configuration of an ink jet recording apparatus to which a drying apparatus according to the present invention is applied will be described.

  FIG. 1 is a configuration diagram schematically showing an inkjet recording apparatus 1 according to the present embodiment. An inkjet recording apparatus 1 shown in FIG. 1 is an apparatus that forms an image on a recording surface of a recording medium 22, and mainly includes a paper feeding unit 10, a processing liquid application unit 12, a drawing unit 14, a drying unit 16, a fixing unit 18, and a discharge unit. 20. A recording medium 22 (sheets) is stacked on the paper supply unit 10, and the recording medium 22 is sent from the paper supply unit 10 to the treatment liquid application unit 12, and the treatment liquid application unit 12 processes the treatment liquid on the recording surface. Is applied to the recording surface by the drawing unit 14. The recording medium 22 to which ink has been applied is transported by the discharge unit 20 after the moisture is dried by the drying unit 16 and the image is fastened by the fixing unit 18.

  Intermediate conveyance units (transfer cylinders) 24, 26, and 28 are provided between the respective units, and the recording medium 22 is transferred by the intermediate conveyance units 24, 26, and 28. That is, a first intermediate transport unit 24 is provided between the processing liquid application unit 12 and the drawing unit 14, and the recording medium from the processing liquid application unit 12 to the drawing unit 14 by the first intermediate transport unit 24. 22 delivery is performed. Similarly, a second intermediate transport unit 26 is provided between the drawing unit 14 and the drying unit 16. The recording medium 22 is transferred from the drawing unit 14 to the drying unit 16 by the second intermediate transport unit 26. Is done. Further, a third intermediate transport unit 28 is provided between the drying unit 16 and the fixing unit 18, and the third intermediate transport unit 28 transfers the recording medium 22 from the drying unit 16 to the fixing unit 18. Done.

  Hereinafter, each unit of the inkjet recording apparatus 1 (the paper feeding unit 10, the processing liquid applying unit 12, the drawing unit 14, the drying unit 16, the fixing unit 18, the discharging unit 20, the first to third intermediate conveying units 24, 26, and 28). ) Will be described.

(Paper Feeder)
The paper feed unit 10 is a mechanism that supplies the recording medium 22 to the drawing unit 14. The paper feed unit 10 is provided with a paper feed tray 50, and the recording medium 22 is fed from the paper feed tray 50 to the processing liquid application unit 12 one by one.

(Processing liquid application part)
The processing liquid application unit 12 is a mechanism that applies the processing liquid to the recording surface of the recording medium 22. The treatment liquid includes a color material aggregating agent that agglomerates or deposits the color material (pigment) in the ink applied by the drawing unit 14, and the ink comes into contact with the color material when the treatment liquid comes into contact with the ink. Separation from the solvent is facilitated. A more detailed description of the treatment liquid will be described later.

  As shown in FIG. 1, the treatment liquid application unit 12 includes a transfer drum 52, a treatment liquid drum 54, a treatment liquid application device 56, an IR heater 58, and a hot air blowing nozzle 60. The transfer drum 52 is disposed between the paper feed tray 50 of the paper feed unit 10 and the processing liquid drum 54 and includes a claw-shaped holding means (such as a gripper) on the outer peripheral surface thereof. Is driven to rotate. The recording medium 22 fed from the paper feed unit 10 is received by the transfer drum 52 and transferred to the processing liquid drum 54.

  The treatment liquid drum 54 is a drum that holds and rotates the recording medium 22 and is driven to rotate. Further, the processing liquid drum 54 includes a claw-shaped holding means 55 on the outer peripheral surface thereof, and the holding means 55 can hold the tip of the recording medium 22. The recording medium 22 is rotated and conveyed by rotating the processing liquid drum 54 with the tip held by the holding means 55. A processing liquid coating device (corresponding to a coating device) 56, an IR heater 58, and a hot air blowing nozzle 60 are provided outside the processing liquid drum 54 so as to face the peripheral surface thereof. The treatment liquid coating device 56, the IR heater 58, and the hot air blowing nozzle 60 are sequentially arranged from the upstream side in the rotation direction of the treatment liquid drum 54 (counterclockwise direction in FIG. 1). The processing liquid is applied to the recording surface by the processing liquid application device 56. The film thickness of the treatment liquid is desirably sufficiently smaller than the droplet diameter of ink ejected from the inkjet heads 72M, 72K, 72C, 72Y of the drawing unit 14. For example, when the ink droplet ejection amount is 2 pl, the average droplet diameter is 15.6 μm. At this time, when the film thickness of the processing liquid is large, the ink dots float in the processing liquid without contacting the surface of the recording medium 22. Therefore, in order to obtain a landing dot diameter of 30 μm or more when the ink droplet ejection amount is 2 pl, it is desirable that the film thickness of the treatment liquid is 3 μm or less.

The recording medium 22 coated with the treatment liquid by the treatment liquid application device 56 is conveyed to the positions of the IR heater 58 and the hot air blowing nozzle 60. The IR heater 58 is controlled to a high temperature (for example, 180 ° C.), and the hot air blowing nozzle 60 blows the high temperature (for example, 70 ° C.) warm air toward the recording medium 22 at a constant air volume (for example, 9 m ³ / min). Composed. By the heating by the IR heater 58 and the hot air blowing nozzle 60, water in the solvent of the processing liquid is evaporated, and a thin film layer of the processing liquid is formed on the recording surface. By thinning the treatment liquid in this way, the dots of ink that are ejected by the drawing unit 14 come into contact with the recording surface of the recording medium 22 to obtain the required dot diameter, and the thinned treatment liquid component Reacts with the colorant to cause aggregation of the coloring material, and an effect of fixing to the recording surface of the recording medium 22 is easily obtained. The processing liquid drum 54 may be controlled to a predetermined temperature (for example, 50 ° C.).

(Drawing part)
As shown in FIG. 1, the drawing unit 14 includes a drawing drum 70 and ink jet heads 72M, 72K, 72C, and 72Y that are disposed in proximity to a position facing the outer peripheral surface of the drawing drum 70. The inkjet heads 72M, 72K, 72C, and 72Y correspond to inks of four colors, magenta (M), black (K), cyan (C), and yellow (Y), and are upstream in the rotation direction of the drawing drum 70. Arranged in order from the side.

  The drawing drum 70 is a drum that holds the recording medium 22 on its outer peripheral surface and rotates and conveys the recording medium 22 and is driven to rotate. Further, the drawing drum 70 includes a claw-shaped holding unit 71 on the outer peripheral surface thereof, and the holding unit 71 can hold the leading end of the recording medium 22. The recording medium 22 is rotated and conveyed by rotating the drawing drum 70 with the leading end held by the holding means 71. At this time, the recording medium 22 is transported so that the recording surface faces outward, and ink is applied to the recording surface from the inkjet heads 72M, 72K, 72C, 72Y.

  The inkjet heads 72M, 72K, 72C, and 72Y are full-line inkjet recording heads (inkjet heads) each having a length corresponding to the maximum width of the image forming area in the recording medium 22, and the ink ejection surfaces thereof are arranged on the ink ejection surface. Is formed with a nozzle row in which a plurality of nozzles for ink ejection are arranged over the entire width of the image forming area. Each inkjet head 72M, 72K, 72C, 72Y is fixedly installed so as to extend in a direction orthogonal to the conveyance direction of the recording medium 22 (the rotation direction of the drawing drum 70).

  Corresponding color ink cassettes are attached to each of the inkjet heads 72M, 72K, 72C, 72Y. The ink droplets are ejected from the inkjet heads 72M, 72K, 72C, 72Y toward the recording surface of the recording medium 22 held on the outer peripheral surface of the drawing drum 70. As a result, the ink comes into contact with the treatment liquid applied to the recording surface in advance by the treatment liquid application unit 12, and the color material (pigment) dispersed in the ink is aggregated to form a color material aggregate. Thereby, the color material flow on the recording medium 22 is prevented, and an image is formed on the recording surface of the recording medium 22. At that time, since the drawing drum 70 of the drawing unit 14 is structurally separated from the processing liquid drum 54 of the processing liquid applying unit 12, the processing liquid may adhere to the ink jet heads 72M, 72K, 72C, 72Y. In addition, the cause of ink ejection failure can be reduced.

  In addition, as an example of the reaction between the ink and the treatment liquid, using a mechanism in which an acid is contained in the treatment liquid and the pigment dispersion is destroyed and aggregated by lowering the pH, the color material bleeds, the color mixture between the inks of each color, and the liquid upon landing of the ink droplet It is conceivable to avoid droplet ejection interference due to coalescence.

  In addition, the droplet ejection timing of each of the inkjet heads 72M, 72K, 72C, 72Y is synchronized with an encoder that detects the rotational speed disposed on the drawing drum 70. Thereby, the landing position can be determined with high accuracy. Further, the fluctuation of the speed due to the fluctuation of the drawing drum 70 or the like is learned in advance, and the droplet ejection timing obtained by the encoder 91 is corrected to obtain the fluctuation of the drawing drum 70, the accuracy of the rotation axis, and the speed of the outer peripheral surface of the drawing drum 70. Irregular droplet ejection can be reduced without depending on it.

  Furthermore, maintenance operations such as cleaning the nozzle surfaces of each of the inkjet heads 72M, 72K, 72C, and 72Y and discharging the thickened ink may be performed by retracting the head unit from the drawing drum 70.

  In this example, the configuration of CMYK standard colors (four colors) is illustrated, but the combination of ink colors and the number of colors is not limited to this embodiment, and light ink, dark ink, and special colors are used as necessary. Ink may be added. For example, it is possible to add an inkjet head that discharges light-colored ink such as light cyan and light magenta, and the arrangement order of the color heads is not particularly limited.

(Drying part)
The drying unit 16 is a step of drying moisture contained in the solvent separated by the color material aggregating action. The drying drum 76 and a first IR heater disposed at a position facing the outer peripheral surface of the drying drum 76. 78, a hot air jet nozzle 80, and a second IR heater 82. The first IR heater 78 is provided upstream of the hot air jet nozzle 80 in the rotation direction of the drying drum 76 (counterclockwise direction in FIG. 1), and the second IR heater 82 is jetted of hot air. Provided downstream of the nozzle 80. Further, the outer peripheral surface of the drying drum 76 is heated by a heating means (not shown), and when the recording medium 22 is conveyed by the drying drum 76, drying is performed by contacting the drying drum 76.

  The drying drum 76 is a drum that holds and rotates the recording medium 22 on its outer peripheral surface, and the rotation of the drying drum 76 is controlled by a motor driver (not shown). The recording medium 22 is rotated and conveyed by rotating the drying drum 76 with the tip held by the holding unit 77. At that time, the recording medium 22 is conveyed so that the image forming surface faces outward, and the recording surface 22 is dried by heating the outer peripheral surfaces of the IR heaters 78 and 82, the hot air jet nozzle 80 and the drying drum 76. Is done.

  The hot air jet nozzle 80 includes a dry air heating means so as to blow hot air controlled at a predetermined temperature (for example, 50 ° C. to 75 ° C.) toward the recording medium 22 with a constant air volume, and an IR heater 78, Each 82 is controlled to a predetermined temperature (for example, 180 ° C.). By these hot air jet nozzles 80 and IR heaters 78 and 82, moisture contained in the image forming surface of the recording medium 22 held on the drying drum 76 is evaporated, and a drying process is performed. At that time, since the drying drum 76 of the drying unit 16 is structurally separated from the drawing drum 70 of the drawing unit 14, in the inkjet heads 72 </ b> M, 72 </ b> K, 72 </ b> C, 72 </ b> Y, the head meniscus portion is dried by thermal drying. Ink ejection failure can be reduced. Moreover, there is a degree of freedom in setting the temperature of the drying unit 16, and an optimal drying temperature can be set.

  In FIG. 1, the hot air ejection nozzle 80 is provided so that the drying air is perpendicular to the conveyance direction of the recording medium 22. Preferably, the angle at which the drying air hits the recording medium 22 is set to It is preferable that the angle formed by the wind direction and the tangent of the point where the dry air hits the recording medium 22 is 15 °. Further, the hot air ejection nozzle 80 is provided so as to be approximately the same length as the width of the recording medium 22, and is installed by arranging a plurality of hot air ejection nozzles 80 in the width direction of the recording medium 22. You can also. Further, the recording medium 22 can be installed in a plurality of rows in the conveyance direction. For example, a total of 32 hot-air ejection nozzles can be provided by arranging 8 lines / row in the width direction of the recording medium 22 and installing 4 lines.

  The evaporated water may be discharged out of the apparatus together with air by a discharge means (not shown). Further, the recovered air may be cooled by a cooler (radiator) or the like and recovered as a liquid.

  Moreover, it is preferable that the outer periphery of the drying drum 76 is controlled to a predetermined temperature. By heating from the back surface of the recording medium 22, the amount of heat lost when the amount of drying air from the hot air jet nozzle 80 is reduced is compensated by the amount of heat heated from the drying drum 76, thereby drying the recording medium 22. Sex can be maintained. Further, it is possible to prevent image destruction during fixing. Examples of the heating means for heating the outer peripheral surface of the drying drum 76 include a method in which a heater is provided inside the drying drum 76 and the heater is heated. Further, at a position facing the outer peripheral surface of the drying drum 76, the drying drum 76 is disposed on the side where the recording medium 22 is not transported (the side where the IR heaters 78 and 82 and the hot air jet nozzle 80 are not installed in FIG. 1). Heating can also be performed by providing a heater for heating the outer peripheral surface of the gas and a hot air jet nozzle. Also, for drying the recording medium 22. It is also possible to heat the drying drum 76 using the IR heaters 78 and 82 and the hot air jet nozzle 80 when the recording medium 22 is not conveyed.

  The range of the surface temperature of the drying drum 76 is preferably 50 ° C. or higher, more preferably 60 ° C. or higher. The upper limit is not particularly limited, but is preferably 80 ° C. or lower from the viewpoint of safety of maintenance work such as cleaning ink adhering to the surface of the drying drum 76 (preventing burns due to high temperature).

  In the present invention, by controlling the air volume and temperature of the drying air and the temperature of the outer peripheral surface of the drying drum 76 according to the rigidity of the recording medium, both the transportability and the drying performance of the recording medium are achieved. If the recording medium is low in rigidity, if the drying air is blown on the recording medium, the recording medium flutters, breaks or is damaged, and the transportability deteriorates. Therefore, the air volume of the drying air is adjusted according to the rigidity of the recording medium. When the rigidity of the recording medium is low, the recording medium fluttering is suppressed by reducing the amount of dry air. When the rigidity of the recording medium is 3 mN · m or less, it is preferable to stop the drying air blowing.

When the air volume of the drying air is reduced, the amount of heat (ΔQ _air ) that falls due to the reduction of the air volume is converted to the energy (ΔQ _con ) obtained by the temperature of the drying _air or the temperature increase (ΔT _con ) of the outer peripheral surface of the drying drum 76. )

  The set temperature of the outer peripheral surface of the drying drum 76 can be calculated by the following method, for example.

  2 and 3 show a list of variables and constants used in the calculation. It is calculated assuming that the temperature of the recording medium before heating (after image formation) is 25 ° C. and the temperature of the drying air is 75 ° C.

FIG. 4 shows the temperature of the drying drum (conveyance medium) and the amount of heat given to the recording medium by the drying drum. This time, when the temperature of the outer peripheral surface of the drying drum is based on 60 ° C., the temperature of the drying drum is No. When the temperature is 1-1 to 1-4, the heat quantity of ΔQ _con (T _con ; 60) can be obtained from the following formulas (1) and (2).

_{Q con = h s × (T} con -T 0) ··· formula (1)
ΔQ _con (ΔT) = ΔQ _con (T _con ; 60)
_{= Q con (T) -Q con} (type)
_{= Q con (T) -Q con} (60) ··· Equation (2) (type = 60 ℃ )
Next, FIG. 5 shows the amount of heat given by the drying air. The amount of heat Q _air (75; w) given by the drying air shown in FIG. 5 can be obtained by experiments. The temperature of the drying air was set to 75 ° C., and the hot air jet nozzles were set as described above in the case where a total of 32 hot air jet nozzles were installed, 4 in 8 rows / row. Since the air volume of each hot-air ejection nozzle is 2 [m ³ / min], the experiment was conducted in the case of blowing a maximum of 64 [m ³ / min].

From FIG. In 2-1, the air volume is 64 [m ³ / min] and Q _air (75; 64) is 2400 [W / m ² ], and as the air volume becomes weaker, the relationship between the _air volume w and the heat quantity Q _air (75; w) is The _{reason why} the value of heat quantity Q _air (75; w) becomes small is not proportional, and it is considered that heat exchange is not successful and drying is difficult because the air volume is weakened. On the contrary, in this test, the maximum air volume is 64 [m ³ / min]. However, it is considered that the air volume is further increased to facilitate drying.

In the present invention, as described above, the amount of heat ΔQ _air (75; 64, w) that falls due to the reduction in the air volume is obtained by the energy ΔQ _con (T _con ; 60) obtained by the temperature increase of the outer peripheral surface of the drying drum 76. compensate. Therefore, −ΔQ _air (75; 64, w) = ΔQ _con (T _con ; 60) = h _s × ΔT _con is obtained from the equation (2), and the temperature rise ΔT _con of the outer peripheral surface of the drying drum 76 is determined. To do. From the above, the temperature rise value of the drying drum 76 can be obtained by the following formula (3).

ΔT _con = ΔQ _air (75; 64, w) / h _s Formula (3)
FIG. 5 shows ΔT _con obtained from Equation (3) and the numerical values of FIGS. 4 and 5. From FIG. 5, for example, in order to realize the same amount of heat (dry amount) as the temperature of the drying drum 76 at 60 [° C.] and the air volume of 64 [m ³ / min] with an air volume of 0 [m ³ / min], the temperature is It can be confirmed that it is necessary to carry out at 82 [° C.] increased by 22 [° C.] from type (60 [° C.] in this example).

(Fixing part)
The fixing unit 18 includes a fixing drum 84, a halogen heater 86, a fixing roller 88, and an inline sensor 90. Like the processing liquid drum 54, the fixing drum 84 includes a claw-shaped holding unit (gripper) 85 on its outer peripheral surface, and the holding unit 85 can hold the leading end of the recording medium 22.

  With the rotation of the fixing drum 84, the recording medium 22 is conveyed with the recording surface facing outward. The recording surface is preheated by the halogen heater 86, fixed by the fixing roller 88, and by the inline sensor 90. Inspection is performed.

  The halogen heater 86 is controlled to a predetermined temperature (for example, 180 ° C.). Thereby, preheating of the recording medium 22 is performed.

  The fixing roller 88 is a roller member that heats and pressurizes the dried ink to weld the self-dispersing thermoplastic resin fine particles in the ink to form a film of the ink, and heats and pressurizes the recording medium 22. Composed. Specifically, the fixing roller 88 is disposed so as to be in pressure contact with the fixing drum 84, and constitutes a nip roller with the fixing drum 84. As a result, the recording medium 22 is sandwiched between the fixing roller 88 and the fixing drum 84 and nipped at a predetermined nip pressure (for example, 0.15 MPa), and a fixing process is performed.

  The fixing roller 88 is configured by a heating roller in which a halogen lamp is incorporated in a metal pipe such as aluminum having good thermal conductivity, and is controlled to a predetermined temperature (for example, 60 to 80 ° C.). By heating the recording medium 22 with this heating roller, thermal energy equal to or higher than the Tg temperature (glass transition temperature) of the thermoplastic resin fine particles contained in the ink is applied, and the thermoplastic resin fine particles are melted. Thereby, pressing and fixing are performed on the unevenness of the recording medium 22, and the unevenness on the surface of the image is leveled to obtain glossiness.

  In the embodiment of FIG. 1, only one fixing roller 88 is provided. However, a configuration in which a plurality of fixing rollers 88 are provided may be employed depending on the thickness of the image layer and the Tg characteristics of the thermoplastic resin fine particles.

  On the other hand, the in-line sensor 90 is a measuring unit for measuring a check pattern, a moisture content, a surface temperature, a glossiness, and the like for an image fixed on the recording medium 22, and a CCD line sensor or the like is applied.

  According to the fixing unit 18 configured as described above, the thermoplastic resin fine particles in the thin image layer formed by the drying unit 16 are heated and pressurized by the fixing roller 88 and melted. Can be fixed and fixed. Further, by setting the surface temperature of the fixing drum 84 to 50 ° C. or higher, drying is promoted by heating the recording medium 22 held on the outer peripheral surface of the fixing drum 84 from the back surface, and image destruction during fixing is prevented. In addition, the image intensity can be increased by the effect of increasing the image temperature.

  In addition, when a UV curable monomer is contained in the ink, after the water is sufficiently volatilized in the drying part, the UV curable monomer is irradiated with UV at the fixing part equipped with a UV lamp. Can be cured and polymerized to improve the image strength.

  As the UV lamp, various ultraviolet light sources such as a metal halide lamp, a high-pressure mercury lamp, a black light, a cold cathode lamp, and a UV-LED can be used.

The peak wavelength of the ultraviolet light irradiated by the ultraviolet light source is preferably 200 to 600 nm, more preferably 300 to 450 nm, and still more preferably 350 to 450 nm, although it depends on the absorption characteristics of the ink composition. The irradiation energy of the ultraviolet light source is preferably 2000 mJ / cm ² or less, more preferably from 10 to 2000 mJ / cm ^2, more preferably from 20~1000mJ / cm ^2, particularly preferably 50 to 800 mJ / cm ² . Moreover, it is appropriate to irradiate the recording surface of the recording medium with ultraviolet rays for 0.01 to 10 seconds, more preferably for 0.1 to 2 seconds.

(Discharge part)
As shown in FIG. 1, a discharge unit 20 is provided following the fixing unit 18. The discharge unit 20 includes a discharge tray 92, and a transfer drum 94, a conveyance belt 96, and a tension roller 98 are provided between the discharge tray 92 and the fixing drum 84 of the fixing unit 18 so as to be in contact therewith. It has been. The recording medium 22 is sent to the transport belt 96 by the transfer drum 94 and discharged to the discharge tray 92.

(Intermediate transport section)
Next, the structure of the first intermediate transport unit 24 will be described. Note that the second intermediate conveyance unit 26 and the third intermediate conveyance unit 28 have the same configuration as the first intermediate conveyance unit 24, and a description thereof will be omitted.

  The first intermediate transport unit 24 includes an intermediate transport body 30. The intermediate conveyance body 30 is a drum for receiving the recording medium 22 from the preceding drum, rotating and conveying it to the subsequent drum, and is rotatably attached. Further, the intermediate transport body 30 is rotated by a motor (not shown).

  Claw-shaped holding means are provided at 90 ° intervals on the outer peripheral surface of the intermediate conveyance body 30. The holding unit rotates while drawing a circular locus, and the tip of the recording medium 22 is held by the operation of the holding unit. Accordingly, the recording medium 22 can be rotated and conveyed by rotating the intermediate conveyance body 30 with the holding means holding the tip of the recording medium 22. The recording surface of the recording medium may be conveyed in a non-contact manner by providing a plurality of air outlets on the surface of the intermediate carrier 30 and blowing out air from the air outlets.

  The recording medium 22 transported by the first intermediate transport unit 24 is transferred to the subsequent drum (that is, the drawing drum 70). At this time, the recording medium 22 is delivered by synchronizing the holding means of the intermediate transport unit 24 and the holding means of the drawing unit 14. The transferred recording medium 22 is held and drawn by the drawing drum 70.

(Description of control system)
FIG. 6 is a principal block diagram showing the system configuration of the inkjet recording apparatus 1. The ink jet recording apparatus 1 includes a communication interface 120, a system controller 122, a print controller 124, a treatment liquid application controller 126, a first intermediate transport controller 128, a head driver 130, a second intermediate transport controller 132, and a drying controller 134. A third intermediate conveyance control unit 136, a fixing control unit 138, an inline sensor 90, an encoder 91, a motor driver 142, a memory 144, a heater driver 146, an image buffer memory 148, and the like.

  The communication interface 120 is an interface unit that receives image data sent from the host computer 150. As the communication interface 120, a serial interface such as USB (Universal Serial Bus), IEEE 1394, Ethernet (registered trademark), a wireless network, or a parallel interface such as Centronics can be applied. In this part, a buffer memory (not shown) for speeding up communication may be mounted. Image data sent from the host computer 150 is taken into the inkjet recording apparatus 1 via the communication interface 120 and temporarily stored in the memory 144.

  The system controller 122 includes a central processing unit (CPU) and its peripheral circuits, and functions as a control device that controls the entire inkjet recording apparatus 1 according to a predetermined program, and also functions as an arithmetic device that performs various calculations. . That is, the system controller 122 includes the communication interface 120, the treatment liquid application controller 126, the first intermediate transport controller 128, the head driver 130, the second intermediate transport controller 132, the drying controller 134, and the third intermediate transport controller 136. , Fixing control unit 138, memory 144, motor driver 142, heater driver 146, etc., to control communication with host computer 150, read / write control of memory 144, etc. A control signal for controlling 154 is generated.

  The memory 144 is a storage unit that temporarily stores an image input via the communication interface 120, and data is read and written through the system controller 122. The memory 144 is not limited to a memory made of a semiconductor element, and a magnetic medium such as a hard disk may be used.

  The ROM 145 stores programs executed by the CPU of the system controller 122 and various data necessary for control. The ROM 145 may be a non-rewritable storage unit, or may be a rewritable storage unit such as an EEPROM. The memory 144 is used as a temporary storage area for image data, and is also used as a program development area and a calculation work area for the CPU.

  The motor driver 142 is a driver that drives the motor 152 in accordance with an instruction from the system controller 122. In FIG. 6, a motor 152 disposed in each part in the apparatus is represented by reference numeral 152. For example, the motor 152 shown in FIG. 6 includes a motor that drives the rotation of the transfer drum 52, the treatment liquid drum 54, the drawing drum 70, the drying drum 76, the fixing drum 84, the transfer drum 94, and the like of FIG. 72M, 72Y, 72K head unit retraction mechanism motors, and the like are included.

  The heater driver 146 is a driver that drives the heater 154 in accordance with an instruction from the system controller 122. In FIG. 6, a plurality of heaters provided in the ink jet recording apparatus 1 are represented by reference numeral 154 as a representative. For example, the heater 154 shown in FIG. 6 includes a preheater (not shown) for heating the recording medium 22 to an appropriate temperature in the paper supply unit 10 in advance.

  The print control unit 124 has a signal processing function for performing various processes and corrections for generating a print control signal from the image data in the memory 144 under the control of the system controller 122, and the generated print. It is a control unit that supplies data (dot data) to the head driver 130. Necessary signal processing is performed in the print control unit 124, and the ejection amount and ejection timing of the ink droplets of the inkjet head 100 are controlled via the head driver 130 based on the image data. Thereby, a desired dot size and dot arrangement are realized.

  The print control unit 124 includes an image buffer memory 148, and image data, parameters, and other data are temporarily stored in the image buffer memory 148 when image data is processed in the print control unit 124. In FIG. 6, the image buffer memory 148 is shown in a mode associated with the print control unit 124, but it can also be used as the memory 144. Also possible is an aspect in which the print control unit 124 and the system controller 122 are integrated to form a single processor.

  An outline of the flow of processing from image input to print output is as follows. Image data to be printed is input from the outside via the communication interface 120 and stored in the memory 144. At this stage, for example, RGB image data is stored in the memory 144.

  In the inkjet recording apparatus 1, a pseudo continuous tone image is formed by changing the droplet ejection density and dot size of fine dots with ink (coloring material) to the human eye. It is necessary to convert to a dot pattern that reproduces the gradation (shading of the image) as faithfully as possible. Therefore, the original image (RGB) data stored in the memory 144 is sent to the print control unit 124 via the system controller 122, and the print control unit 124 performs halftoning processing using a threshold matrix, an error diffusion method, or the like. Is converted into dot data for each ink color.

  That is, the print control unit 124 performs a process of converting the input RGB image data into dot data of four colors K, C, M, and Y. Thus, the dot data generated by the print control unit 124 is stored in the image buffer memory 148.

  The head driver 130 is a drive signal for driving the actuator 116 corresponding to each nozzle 102 of the inkjet head 100 based on print data (that is, dot data stored in the image buffer memory 148) given from the print control unit 124. Is output. The head driver 130 may include a feedback control system for keeping the head driving condition constant.

  When the drive signal output from the head driver 130 is applied to the inkjet head 100, ink is ejected from the corresponding nozzle 102. An image is formed on the recording medium 22 by controlling the ink ejection from the inkjet head 100 while conveying the recording medium 22 at a predetermined speed.

  Further, the system controller 122 controls the processing liquid application control unit 126, the first intermediate conveyance control unit 128, the second intermediate conveyance control unit 132, the drying control unit 134, the third intermediate conveyance control unit 136, and the fixing control unit 138. .

  The treatment liquid application control unit 126 controls the operation of the treatment liquid application device 56 of the treatment liquid application unit 12 in accordance with an instruction from the system controller 122.

  The drying controller 134 heats the outer peripheral surfaces of the first IR heater 78, the hot air jet nozzle 80, the second IR heater 82, and the drying drum 76 of the drying unit 16 in accordance with instructions from the system controller 122. The operation of the heating means 83 is controlled. In the hot air jet nozzle 80 and the heating unit 83, the air volume and temperature of the drying air and the temperature of the outer peripheral surface of the drying drum by the heating unit are controlled by the rigidity of the recording medium. By recording in the ROM 145 the drying conditions in the drying section 16 for the rigidity depending on the type of the recording medium and the measured value of the amount of heat given by the hot air, and directly inputting the type of the recording medium 22 to be used by a personal computer (not shown). Control can also be performed.

  The first intermediate conveyance control unit 128 controls the operation of the intermediate conveyance body 30 of the first intermediate conveyance unit 24 in accordance with an instruction from the system controller 122. Specifically, in the intermediate transport body 30, the rotational drive of the intermediate transport body 30 itself, the rotation of the holding means provided in the intermediate transport body 30, and the like are controlled. The second intermediate transfer control unit 132 and the third intermediate transfer control unit 136 also perform the same control as the first intermediate transfer control unit 128.

[ink]
In the ink used in the practice of the present invention, a water-based pigment ink containing a pigment which is a coloring material (coloring agent) or thermoplastic resin fine particles is used as a solvent-insoluble material.

  The concentration of the solvent-insoluble material is preferably 1 wt% or more and 20 wt% or less considering a viscosity of 20 mPa · s or less suitable for ejection. More preferably, the pigment concentration is 4 wt% or more in order to obtain the optical density of the image.

  The surface tension of the ink is preferably 20 mN / m or more and 40 mN / m or less in consideration of ejection stability.

  The color material used in the ink can be a pigment or a mixture of a dye and a pigment. From the viewpoint of aggregability at the time of contact with the treatment liquid, a pigment in a dispersed state in the ink is preferable because it aggregates more effectively. Among the pigments, a pigment dispersed by a dispersant, a self-dispersing pigment, a pigment whose surface is coated with a resin (microcapsule pigment), and a polymer graft pigment are particularly preferable. From the viewpoint of pigment aggregation, a form modified with a carboxyl group having a low dissociation degree is more preferable.

  In the colored ink liquid used in the present invention, it is preferable to add thermoplastic resin fine particles not containing a colorant as a component that reacts with the treatment liquid. The thermoplastic resin fine particles can enhance the thickening and aggregating effects of the ink by reaction with the treatment liquid, and can improve the image quality. In particular, a highly safe ink can be obtained by incorporating anionic thermoplastic fine particles into the ink.

  By using the thermoplastic resin fine particles that react with the treatment liquid and cause thickening and aggregating action in the ink, the quality of the image can be improved, and at the same time, depending on the type of the thermoplastic resin fine particles, the thermoplastic resin fine particles A film is formed on the recording medium, and it has the effect of improving the abrasion resistance and water resistance of the image.

  The dispersion method in the polymer ink is not limited to emulsion, and it may be dissolved or exist in a colloidal dispersion state.

  The thermoplastic resin fine particles may be obtained by dispersing thermoplastic resin fine particles using an emulsifier, or may be dispersed without using an emulsifier. As the emulsifier, a low molecular weight surfactant is usually used, but a high molecular weight surfactant can also be used as an emulsifier. It is also preferable to use capsule-type thermoplastic resin fine particles (core / shell type thermoplastic resin fine particles having different compositions at the center and outer edge of the particle) whose outer shell is made of acrylic acid, methacrylic acid or the like.

  Examples of the resin component added to the ink as the thermoplastic resin fine particles include acrylic resins, vinyl acetate resins, styrene-butadiene resins, vinyl chloride resins, acrylic-styrene resins, butadiene resins, styrene resins, and the like. It is done.

  From the viewpoint of imparting high-speed cohesiveness to the thermoplastic resin fine particles, those having a carboxylic acid group with a low degree of dissociation are more preferable. Since the carboxylic acid group is easily affected by pH change, the dispersion state is easily changed and the cohesiveness is high.

  The change of the dispersion state with respect to the pH change of the thermoplastic resin fine particles can be adjusted by the content ratio of the constituent component in the thermoplastic resin fine particles having a carboxylic acid group such as an acrylate ester, and the anionic property used as the dispersant It can also be adjusted by a surfactant.

  The resin component of the thermoplastic resin fine particles is preferably a polymer having both a hydrophilic portion and a hydrophobic portion. By having the hydrophobic part, the hydrophobic part is oriented inside the thermoplastic resin fine particles, the hydrophilic part is efficiently oriented outside, and the change in the dispersion state with respect to the pH change of the liquid is more effective, Aggregation is performed more efficiently.

  Further, two or more kinds of thermoplastic resin fine particles may be mixed and contained in the ink.

  As the pH adjuster added to the ink of the present invention, an organic base or an inorganic alkali base can be used as a neutralizing agent. The pH adjusting agent is preferably added so that the inkjet ink has a pH of 6 to 10 for the purpose of improving the storage stability of the inkjet ink.

  The ink of the present invention preferably contains a water-soluble organic solvent for the purpose of preventing clogging of the nozzles of the inkjet head due to drying. Such water-soluble organic solvents include wetting agents and penetrants.

  Examples of the water-soluble organic solvent include polyhydric alcohols, polyhydric alcohol derivatives, nitrogen-containing solvents, alcohols, sulfur-containing solvents and the like, as in the case of the treatment liquid.

  In addition, surfactants, pH buffers, antioxidants, fungicides, viscosity modifiers, conductive agents, ultraviolet absorbers, and the like can be added as necessary.

  In addition, the UV curable monomer is contained in the ink so that moisture is sufficiently volatilized in the drying unit, and then the image is irradiated with UV in the fixing unit equipped with the UV irradiation lamp. Can be cured and polymerized to improve the image strength.

  In addition, the UV curable monomer is contained in the ink so that moisture is sufficiently volatilized in the drying unit, and then the image is irradiated with UV in the fixing unit equipped with the UV irradiation lamp. Can be cured and polymerized to improve the image strength.

  The UV curable monomer has a function of causing polymerization or a crosslinking reaction by an initiating species such as a radical generated from a polymerization initiator or the like, and curing a composition containing these.

  As the UV curable monomer, a polymerizable or crosslinkable material that causes a known polymerization or crosslinking reaction such as a radical polymerization reaction or a dimerization reaction can be applied. For example, an addition polymerizable compound having at least one ethylenically unsaturated double bond, a polymer compound having a maleimide group in the side chain, a cinnamyl group having a photodimerizable unsaturated double bond adjacent to the aromatic nucleus, Examples thereof include a polymer compound having a cinnamylidene group or a chalcone group in the side chain. Among these, an addition polymerizable compound having at least one ethylenically unsaturated double bond is more preferable, and from a compound (monofunctional or polyfunctional compound) having at least one terminal ethylenically unsaturated bond, more preferably two or more. It is particularly preferred that it is selected. Specifically, it can be appropriately selected from those widely known in the industrial field according to the present invention. For example, monomers, prepolymers (that is, dimers, trimers, and oligomers) and mixtures thereof, and those Those having a chemical form such as a copolymer of

  A UV curable monomer may be used individually by 1 type, and may be used in combination of 2 or more type.

  As the UV curable monomer that can be used in the present invention, it is particularly preferable to use various known radical polymerizable monomers that cause a polymerization reaction by an initiating species generated from a radical initiator.

Examples of the radical polymerizable monomer include (meth) acrylates, (meth) acrylamides, aromatic vinyls, vinyl ethers, and compounds having an internal double bond (such as maleic acid). Here, “(meth) acrylate” refers to both and / or “acrylate” and “methacrylate”, and “(meth) acryl” refers to both and / or “acryl” and “methacryl”.

[Treatment solution]
The treatment liquid contains at least an aggregating agent for aggregating the components in the ink composition described above, and can be configured using other components as necessary. By using the treatment liquid together with the ink composition, it is possible to increase the speed of ink jet recording, and an image with excellent density and resolution can be obtained even when recording at high speed (for example, reproducibility of fine lines and fine portions). Further, by improving the prescription of the treatment liquid and the ink composition, the strength of the formed image itself can be increased, and the durability of the image by high-pressure air blowing can be reinforced.

  The aggregating agent may be a compound capable of changing the pH of the ink composition, a polyvalent metal salt, or polyallylamines. In the present invention, from the viewpoint of cohesiveness of the ink composition, a compound capable of changing the pH of the ink composition is preferable, and a compound capable of lowering the pH of the ink composition is more preferable.

  In the present invention, it is preferable to select a flocculant that can quickly separate the solid component and the sediment component (liquid component) after aggregation, or can make the aggregate itself rigid. Such a flocculant is preferably an organic acid, more preferably a divalent or higher valent organic acid, and particularly preferably a divalent or higher valent acid substance. The divalent or higher organic acid is preferably an organic acid having a first pKa of 3.5 or less, more preferably an organic acid of 3.0 or less. Specific examples include phosphoric acid, oxalic acid, malonic acid, citric acid and the like.

  A flocculant can be used individually by 1 type or in mixture of 2 or more types.

  The content of the flocculant for aggregating the ink composition in the treatment liquid is preferably 1 to 50% by mass, more preferably 3 to 45% by mass, and still more preferably 5 to 40% by mass.

  The treatment liquid can further contain other additives as other components within a range not impairing the effects of the present invention. Other additives include, for example, anti-drying agents (wetting agents), anti-fading agents, emulsion stabilizers, penetration enhancers, UV absorbers, preservatives, anti-fungal agents, pH adjusters, surface tension adjusters, anti-foaming agents. Well-known additives, such as a foaming agent, a viscosity modifier, a dispersing agent, a dispersion stabilizer, a rust preventive agent, a chelating agent, are mentioned.

<Recording medium>
The inkjet recording method of the present invention records an image on a recording medium.

  The recording medium is not particularly limited, and general printing paper mainly composed of cellulose, such as so-called high-quality paper, coated paper, and art paper, used for general offset printing and the like can be used. General printing paper mainly composed of cellulose is relatively slow in ink absorption and drying in image recording by a general ink jet method using water-based ink, and color material movement is likely to occur after droplet ejection, and image quality is likely to deteriorate. However, according to the ink jet recording method of the present invention, it is possible to record a high-quality image excellent in color density and hue by suppressing the movement of the color material.

  Among the recording media, so-called coated paper used for general offset printing is preferable. The coated paper is obtained by applying a coating material to the surface of high-quality paper, neutral paper, or the like that is mainly surface-treated with cellulose as a main component and is not surface-treated. The coated paper tends to cause quality problems such as image gloss and scratch resistance in image formation by ordinary aqueous inkjet, but in the inkjet recording method of the present invention, gloss unevenness is suppressed and gloss and resistance are reduced. An image having good rubbing properties can be obtained. In particular, a coated paper having a base paper and a coat layer containing an inorganic pigment is preferably used, and a coated paper having a base paper and a coat layer containing kaolin and / or calcium bicarbonate is more preferably used. Specifically, art paper, coated paper, lightweight coated paper, or finely coated paper is more preferable.

[Example]
EXAMPLES Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited thereto.

An image was formed using the image forming apparatus shown in FIG. 1, and the transportability and drying property were evaluated. As the blowing means, eight fans were arranged in one row in the width direction of the recording medium, and drying was performed using a total of 32 fans in four rows. In addition, the drying air temperature was 75 ° C. , and the recording medium was tested using five types of rigid recording media as shown in FIG. Based on the air volume of 64 m ³ / min and the body temperature of 60 ° C., the amount of heat that is insufficient by dropping the air volume is increased by the temperature of ΔT _con described in FIG. 5 and the temperature of the conveying medium (the outer peripheral surface of the drying drum) is increased. And tested. The results are shown in FIG. Further, the transportability and drying property in FIG. 7 were evaluated according to the following criteria.
<Transportability>
○ ・ ・ ・ Good △ ・ ・ ・ Partial, poor transport ×× Transfer failure <Drying>
○: Good Δ: Partially defective drying ×: Drying failure In this example, the evaluation was “◯” within the allowable range, and “Δ” or lower was out of the allowable range.

  As shown in FIG. 7, in Test Examples 3 to 5 using a recording medium with high rigidity, the transportability was good even when the air volume was increased, and the drying property was good even when the cylinder temperature was low. On the other hand, in a recording medium with low rigidity, when the air volume is high, the transportability is poor (Test Examples 1 and 2), and when the drum temperature is low, the drying property is poor (Test Examples 10 and 11). Also, in Test Examples 6 and 7 in which the air volume was lowered and the body temperature was raised, there was some poor transportability. As in Test Examples 8 and 9, the drying air was stopped, and the energy reduced by that amount was compensated from the drum temperature (contact recording means), thereby making it possible to achieve both dryness and transportability.

  DESCRIPTION OF SYMBOLS 1 ... Inkjet recording apparatus, 10 ... Paper feed part, 12 ... Processing liquid provision part, 14 ... Drawing part, 16 ... Drying part, 18 ... Fixing part, 20 ... Discharge part, 22 ... Recording medium, 24 ... 1st middle Conveying section, 26 ... second intermediate conveying section, 28 ... third intermediate conveying section, 30 ... intermediate conveying body, 55, 71, 77, 85 ... holding means, 70 ... drawing drum, 72M, 72C, 72Y, 72K Ink head, 76 ... Drying drum, 78 ... First IR heater, 80 ... Hot air jet nozzle, 82 ... Second IR heater, 83 ... Heating means, 84 ... Fixing drum, 88 ... UV lamp

Claims (7)

Conveying means for carrying the recording medium on which the image is formed on the conveying medium;
A blower that blows dry air on the image forming surface of the recording medium on which the image conveyed by the conveying unit is formed;
A drying air heating means for heating the drying air;
First heating means for heating the carrier medium;
Control means for controlling the air volume of the drying air so as to lower the air volume of the drying air when the rigidity of the recording medium is low due to the rigidity of the recording medium ,
The control means compensates for the amount of heat ΔQ _air that decreases because the amount of dry air is reduced by giving the amount of heat ΔQ _con obtained by the temperature increase ΔT of the transport medium ,
The drying apparatus characterized in that the temperature rise ΔT is obtained by the following equation (4) .
The heat transfer coefficient of the transport medium is hs [W / (m ² · K)], the temperature of the transport medium is T _con [° C.], and the temperature of the transport medium before the air volume of the drying air is reduced is T _type [° C.]. ΔQ _con = hs (T _con −T _type ) = hs · ΔT,
The drying air temperature when the temperature of the drying air is T [° C.], the air volume of the drying air before the change is w ₁ [m ³ / min], and the air volume of the drying air after the change is w ₂ [m ³ / min]. Assuming that the calorific difference ΔQ _air (T; w ₁ , w ₂ ),
ΔT = ΔQ _air (T; w ₁ , w ₂ ) / hs (4) Wherein, when the rigidity of the recording medium is not more than 3 mN · m, drying apparatus according to claim 1, characterized in that stopping the blowing of the drying air. Drying apparatus according to claim 1 or 2, characterized in that it comprises a second heating means for heating the recording medium in a non-contact manner. Image forming means for depositing ink on the surface of the recording medium to form an image;
An image forming apparatus comprising the, a drying device according to 3 any one of the claims 1. A transport step of transporting a recording medium on which an image is formed on a transport medium;
A drying air heating step for heating the drying air blown onto the recording medium;
An air blowing step of blowing the dry air on an image forming surface of the recording medium on which the image is formed;
A first heating step for heating the carrier medium;
A control step of controlling the air volume of the drying air so as to lower the air volume of the drying air in the air blowing process when the rigidity of the recording medium is low due to the rigidity of the recording medium,
In the control step, the amount of heat ΔQ _air that decreases because the amount of dry air is reduced is compensated by giving the amount of heat ΔQ _con obtained by the temperature increase ΔT of the transport medium ,
The drying method characterized in that the temperature increase ΔT is obtained by the following equation (4) .
The heat transfer coefficient of the transport medium is hs [W / (m ² · K)], the temperature of the transport medium is T _con [° C.], and the temperature of the transport medium before the air volume of the drying air is reduced is T _type [° C.]. ΔQ _con = hs (T _con −T _type ) = hs · ΔT,
The drying air temperature when the temperature of the drying air is T [° C.], the air volume of the drying air before the change is w ₁ [m ³ / min], and the air volume of the drying air after the change is w ₂ [m ³ / min]. Assuming that the calorific difference ΔQ _air (T; w ₁ , w ₂ ),
ΔT = ΔQ _air (T; w ₁ , w ₂ ) / hs (4) 6. The drying method according to claim 5 , wherein the control step stops the blowing of the drying air when the rigidity of the recording medium is 3 mN · m or less. An image forming step of forming an image by ejecting ink onto the surface of the recording medium; and
A transport step of transporting the recording medium on which the image is formed on a transport medium;
A drying air heating step for heating the drying air blown onto the recording medium;
An air blowing step of blowing the dry air on an image forming surface of the recording medium on which the image is formed;
A first heating step for heating the carrier medium;
A control step of controlling the air volume of the drying air so as to lower the air volume of the drying air in the air blowing process when the rigidity of the recording medium is low due to the rigidity of the recording medium ,
In the control step, the amount of heat ΔQ _air that decreases because the amount of dry air is reduced is compensated by giving the amount of heat ΔQ _con obtained by the temperature increase ΔT of the transport medium ,
An image forming method, wherein the temperature rise ΔT is obtained by the following equation (4) .
The heat transfer coefficient of the transport medium is hs [W / (m ² · K)], the temperature of the transport medium is T _con [° C.], and the temperature of the transport medium before the air volume of the drying air is reduced is T _type [° C.]. ΔQ _con = hs (T _con −T _type ) = hs · ΔT,
The drying air temperature when the temperature of the drying air is T [° C.], the air volume of the drying air before the change is w ₁ [m ³ / min], and the air volume of the drying air after the change is w ₂ [m ³ / min]. Assuming that the calorific difference ΔQ _air (T; w ₁ , w ₂ ),
ΔT = ΔQ _air (T; w ₁ , w ₂ ) / hs (4)

Images