JP2014238191A - Drier and printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce printing cost by quickly drying, with inexpensive constitution, paint like ink applied to an inexpensive base material inferior in water absorption.SOLUTION: A drier includes a heat roll 7 rolling in contact with a back face 3b of a roll base paper 3 conveyed and heating the base paper 3 to which ink has been applied, first hot wind blowing means 8 blowing hot wind onto a front face 3a of the roll base paper 3 conveyed in contact with the heat roll 7, and second hot wind blowing means 9 arranged downstream of the first hot wind blowing means 8 in a conveyance direction of the base paper 3 and blowing onto the roll base paper 3 conveyed hot wind higher in the temperature than that from the first hot wind blowing means 8.

Description

  The present invention relates to a drying device that dries the paint on the surface of a substrate such as paper to which a paint such as ink is applied, and a printing device such as an ink jet printer including the drying device.

  As this type of drying device, a paint is applied to a long base material by printing or the like, and then the base material is wrapped around a rotating drying drum and conveyed around the circumference of the drying drum. There is one in which hot air is blown from a disposed hot air blower to dry it (see, for example, Patent Document 1).

JP 2001-141365 A

  However, the above Patent Document 1 does not specifically disclose the base material, printing ink, and the like. For example, in order to reduce the printing cost when applied to a printing apparatus such as an inkjet printer, The base material is not high-quality paper or special paper with high water absorption of ink, but cheap plain paper with low water absorption of ink. It is cheaper and safer than UV (ultraviolet curable) ink. There is no disclosure of a specific configuration for increasing the printing speed by using the above ink.

  In order to increase the printing speed as described above, it is conceivable to increase the temperature of the drying drum and the hot air of the hot air blower of Patent Document 1; Moisture contained in plain paper as a base material bumps up, and the printed surface becomes rough, resulting in poor quality.

  On the other hand, water-based ink, which is a paint, contains a high-boiling solvent having a boiling point higher than that of water. When printing on plain paper having low water absorption, it is necessary to evaporate the high-boiling solvent and dry it. is there. However, when the temperature of the drying drum and the hot air of the hot air blower of Patent Document 1 are increased in order to evaporate the high boiling point solvent, bumping due to moisture occurs as described above.

  As described above, in the conventional technology such as Patent Document 1, it is possible to perform high-speed printing by using a base material such as plain paper having low water absorption while preventing bumping of moisture contained in paint such as ink. Have difficulty.

  The present invention has been made paying attention to such a situation, and reduces the printing cost by drying a paint such as ink applied to an inexpensive base material having low water absorption at a high speed with an inexpensive configuration. It aims to plan.

  In order to achieve the above object, the present invention is configured as follows.

(1) The drying device of the present invention is a drying device for drying a paint applied to the surface of a substrate,
Rotating while contacting the back surface of the substrate to be conveyed, a heat roll for heating the substrate,
First hot air blowing means for blowing hot air on the surface of the base material conveyed while being in contact with the hot roll;
A second hot air blowing means that is provided downstream of the first hot air blowing means in the conveying direction of the base material and blows hot air having a temperature higher than that of the first hot air blowing means to the conveyed substrate; Is provided.

  According to the present invention, by appropriately setting each temperature of the hot roll, the hot air of the first hot air blowing means, and the hot air of the second hot air blowing means, the solvent having the lowest boiling point among the solvents contained in the paint, For example, water and high-boiling solvent can be evaporated and dried while preventing bumping due to moisture in the case of water-based ink, and in particular, the heating temperature by the hot roll and the heating temperature by the hot air of the first hot air blowing means are compared. The boiling point contained in the paint is set to a relatively low value by setting the heating temperature of the second hot air blowing means to a relatively high temperature while preventing the bumping due to the moisture contained in the paint. The solvent can be evaporated and dried.

  As a result, the coating cost applied to an inexpensive base material with low water absorption can be dried at a high speed with a relatively simple configuration of the hot roll and the first and second hot air blowing means, thereby reducing the printing cost. .

  (2) In a preferred embodiment of the present invention, the second hot air blowing means blows the high-temperature hot air onto the surface of the base material conveyed while being in contact with the hot roll.

  According to this embodiment, since hot hot air is blown to the surface of the substrate conveyed while being in contact with the hot roll, high temperature hot air is applied to the surface of the substrate conveyed in a state of being peeled from the hot roll. Compared with the case of blowing air, the high boiling point solvent can be reliably evaporated and dried.

  (3) In another embodiment of the present invention, the base material is roll-shaped paper or film, and the paint is water-based ink ejected on the surface of the base material.

  According to this embodiment, even if the base material is an inexpensive roll-like plain paper or film with low water absorption, the water is evaporated while preventing bumping due to the water contained in the water-based ink. The high boiling point solvent contained in can be evaporated and dried.

  Accordingly, it is possible to reduce the printing cost by drying the water-based ink applied to inexpensive plain paper or film having low water absorption at a high speed with a relatively simple configuration.

  (4) In the embodiment of (3) above, the temperature of the hot air blown by the second hot air blowing means may be equal to or higher than the boiling point of the high boiling point solvent contained in the aqueous ink.

  According to this embodiment, since the second hot air blowing means blows hot air having a temperature higher than the boiling point of the high boiling point solvent, the high boiling point solvent contained in the water-based ink can be reliably evaporated and dried.

  (5) In another embodiment of the present invention, the surface temperature of the hot roll may be equal to or lower than the boiling point of the solvent having the lowest boiling point among the solvents contained in the paint.

  According to this embodiment, since the surface temperature of the hot roll with which the back surface of the substrate to be conveyed contacts is equal to or lower than the boiling point of the solvent having the lowest boiling point among the solvents included in the coating material, the highest boiling point included in the coating material is set. It is possible to effectively prevent bumping due to moisture of a low solvent, for example, water-based ink.

  (6) In another embodiment of the present invention, the surface temperature of the hot roll is equal to or lower than the temperature of hot air blown by the first hot air blowing means.

 According to this embodiment, since the surface temperature of the hot roll contacted with the back surface of the substrate to be conveyed is equal to or lower than the temperature of the hot air blown by the first hot air blowing means, bumping due to moisture contained in the paint is effectively prevented. Can be prevented.

  (7) In still another embodiment of the present invention, the surface temperature of the hot roll is 80 ° C. or less.

  According to this embodiment, since the surface temperature of the hot roll with which the back surface of the substrate to be conveyed is 80 ° C. or less, bumping due to moisture contained in the paint can be more effectively prevented.

  (8) In another embodiment of the present invention, the temperature of the hot air blown by the second hot air blowing means is equal to or higher than the boiling point of the solvent having the highest boiling point among the solvents contained in the paint.

  According to this embodiment, since the temperature of the hot air blown by the second hot air blowing means is equal to or higher than the boiling point of the solvent having the highest boiling point contained in the paint, the high boiling point solvent contained in the paint is sufficiently evaporated and dried. be able to.

  (9) In still another embodiment of the present invention, the conveyance speed of the substrate is 25 m / min or more.

  According to this embodiment, the coating material can be dried while the substrate is conveyed at a conveying speed of 25 m / min or more.

  (10) The printing apparatus of the present invention is a drying unit according to any one of (1) to (9), wherein a printing unit that discharges and prints ink on a substrate, and the printed substrate is dried. Device.

  According to the present invention, ink applied to an inexpensive base material having low water absorption can be dried at a high speed with a relatively simple configuration, thereby reducing the printing cost.

  According to the present invention, the coating material applied to the substrate is dried by heating the substrate with the hot roll, the hot air from the first hot air blowing unit, and the hot air from the second hot air blowing unit. And the heating temperature by the hot air of the first hot air blowing means is set to be relatively low, the moisture is evaporated while preventing the bumping due to the water contained in the paint, and the heating temperature of the second hot air blowing means by the high temperature hot air is set. It can be set relatively high, and the high boiling point solvent contained in the paint can be evaporated and dried.

  As a result, the coating cost applied to an inexpensive base material with low water absorption can be dried at a high speed with a relatively simple configuration of the hot roll and the first and second hot air blowing means, thereby reducing the printing cost. .

1 is a schematic configuration diagram of a printing apparatus according to an embodiment of the present invention. It is a schematic block diagram of the drying part of FIG. It is a figure which shows the temperature measurement position of the base paper in a heat roll. It is a figure which shows the temperature measurement position of a base paper at the time of spraying high temperature hot air in the state which sprinkled the base paper conveyed. It is a figure which shows the temperature measurement position of a base paper at the time of spraying a hot hot air in the state which peeled the base paper conveyed from a heat roll. It is a figure which shows the temperature measurement position of the heat roll by a hot hot air. It is a figure which shows the temperature measurement result of FIG. It is a figure which shows schematic structure of the drying part of other embodiment of this invention. It is a figure which shows schematic structure of the drying part of other embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is an ink jet printer as a printing apparatus according to an embodiment of the present invention.

  The inkjet printer 1 is a so-called business printer, and includes a printing unit 4 that performs printing on a roll-shaped base paper 3 sent from a feeding unit 2, a drying unit 5 that dries ink printed on the base paper 3, and And a winding unit 6 for winding the base paper 3 that has been dried into a roll.

  The base paper 3 is an inexpensive plain paper, not a high-quality paper or a dedicated paper for an inkjet printer. Here, the plain paper refers to a medium for printing excluding a medium for printing manufactured or adjusted for an ink jet printer, and specifically used for offset printing, gravure printing, and convex rotary printing. It refers to the printed medium that is printed. More specifically, not only paper media such as coated paper, art paper, and cast coated paper, but also media for printing that are not classified as “paper”, such as resin films typified by synthetic paper and PET film, are included. Such plain paper generally has poor hygroscopicity as compared with dedicated paper for inkjet printers, and thus ink is likely to bleed.

  The printing unit 4 performs printing by ejecting water-based ink from an inkjet head (not shown) onto the surface of the base paper 3 conveyed from the feeding unit 2. Water-based inks are cheaper than UV (ultraviolet curable) inks, are safe, and are suitable for printing for food applications.

  The drying unit 5 dries the ink dots on the base paper 3 on which the ink has been ejected as described later.

  FIG. 2 is a diagram showing a schematic configuration of the drying unit 5 of FIG.

  The drying unit 5 of this embodiment is configured by a drying device according to an embodiment of the present invention. The drying unit 5 includes a heat roll 7 around which the base paper 3 conveyed from the printing unit 4 is wound, and first and first air blows hot air on the surface 3 a of the base paper 3 so as to face the outer peripheral surface of the heat roll 7. Two hot-air blowers 8 and 9 and support rollers 10 to 14 for changing the transport path of the base paper 3 are provided.

  The heat roll 7 is driven by a driving device (not shown) and rotates in the direction of the arrow A together with the conveyed base paper 3. The heat roll 7 has a cylindrical shape, and a heat medium flow path (not shown) is formed therein, and the surface temperature of the heat roll 7 is made relatively low by circulating a heat medium such as oil. It is said.

  The back surface 3b of the base paper 3 to be conveyed comes into contact with the heat roll 7 and is heated to mainly evaporate the ink moisture.

  The first hot air blower 8 blows dry air onto the surface 3 a of the base paper 3 that is wound around the hot roll 7 and conveyed to dry the ink, and is a circle facing the outer peripheral surface of the hot roll 7. It has an arcuate facing surface. A plurality of jet outlets 8a for jetting hot air are formed along the facing surface.

  The second hot air blower 9 is disposed downstream of the first hot air blower 8 in the conveyance direction of the base paper 3, and is wound on the surface 3 a of the base paper 3 that is wound around the hot roll 7 and conveyed from the first hot air blower 8. Also, high-temperature hot air is blown to dry the ink, and an arc-shaped facing surface facing the outer peripheral surface of the heat roll 7 is provided. A plurality of jet outlets 9a for jetting hot air are formed along the facing surface.

  Compared to the second hot air blower 9, the first hot air blower 8 has an arcuate opposing surface surrounding the hot roll 7, that is, a region where hot air is ejected, and is approximately 1 in the circumference of the hot roll 7. Opposing across / 2. In addition, the length of the area | region which ejects the hot air of the 1st, 2nd hot air blowers 8 and 9 should just be suitably set according to the temperature of a hot air, a conveyance speed, etc. not only in the example of FIG.

  The heat roll 7 mainly evaporates the water contained in the ink and the base paper 3, but in order to evaporate the water without bumping, the surface temperature is a solvent contained in the water-based ink that is a paint. Among these, it is preferable that it is below the boiling point of water which is a solvent with a low boiling point. For example, it is 90 ° C. or lower, preferably 80 ° C. or lower, more preferably 70 ° C. or lower. The lower limit value of the surface temperature of the hot roll 7 is 50 ° C, preferably 60 ° C.

  Here, the surface temperature of the hot roll 7 refers to a state in which the hot roll 7 and the first and second hot air blowers 8 and 9 are sprayed with hot air while the base paper 3 is being transported to perform the drying process. This is the temperature measured with a contact-type thermometer embedded near the surface.

  The 1st hot air blower 8 evaporates the water | moisture content mainly contained in ink and the base paper 3 with the hot roll 7, Comprising: A comparatively low temperature hot air, for example, 50 to 150 degreeC, Preferably, it is 70 to Hot air in a temperature range of 100 ° C. is blown onto the surface 3a of the conveyed base paper 3.

  The wind speed of the hot air of the first hot air blower 8 is 10 m / s to 40 m / s, preferably 20 m / s to 30 m / s.

  The second hot air blower 9 that blows hot air that is hotter than the hot air of the first hot air blower 8 mainly evaporates a high-boiling solvent having a boiling point higher than that of water contained in the ink. Accordingly, the temperature is preferably higher than the boiling point of the solvent having the highest boiling point among the solvents contained in the ink. For example, hot air in a temperature range of 150 ° C. to 250 ° C., preferably 200 ° C. to 230 ° C. is blown onto the surface 3a of the base paper 3 being conveyed.

  The wind speed of the hot air of the second hot air blower 9 is 20 m / s to 70 m / s, preferably 40 m / s to 60 m / s.

  The conveying speed of the base paper 3 heated by the hot roll 7 and the first and second hot air blowers 8 and 9 is 25 m / min or more, preferably 30 m / min or more, more preferably 40 m / min or more, and still more preferably 50 / More than a minute.

  In this embodiment, the base paper 3 is heated from the back surface 3b side while being wound on a relatively low temperature hot roll 7 and conveyed, and on the front surface 3a side, first, the first hot air blower 8 compares the heat. Low temperature hot air is blown, ink applied to the surface 3a of the base paper 3 and water contained in the base paper 3 are evaporated without bumping, and further hot hot air is blown by the second hot air blower 9. Thus, the high boiling point solvent contained in the ink can be evaporated and dried.

  Next, an experiment conducted for evaluating the relationship between the surface temperature of the hot roll 7 and bumping due to moisture will be described.

In this experiment, as shown in FIG. 3, the surface temperature of the hot roll 7 is varied without blowing hot air, and the magenta ink is manually applied at the application position Pc before the base paper 3 is wound around the hot roll 7. It was applied with. Cast base tack paper, which is plain paper, was used as the base paper 3, and the amount of ink applied was 28 g / m ² . The first position P1 before the contact position Pt where the base paper 3 comes into contact with the heat roll 7 rotating in the direction of the arrow A and the contact position Pt as the origin (0 mm), and from the contact position Pt, the heat roll 7 A second position P2 of 343 mm along the circumference, a third position P3 of 1029 mm along the circumference of the heat roll 7 from the contact position Pt, and the circumference of the heat roll 7 from the contact position Pt At a fourth position P4 of 1715 mm and a fifth position P5 of 2401 mm along the circumference of the heat roll 7 from the contact position Pt, the temperature of the plain portion where the ink is not applied to the surface 3a of the base paper 3, And the temperature of the coating-film part in which the ink was apply | coated was each measured using the non-contact-type thermometer. Moreover, the presence or absence of bumping (foaming) of the coating film during drying was visually determined. The separation position Pr of the base paper 3 from the heat roll 7 was 2720 mm along the circumference of the heat roll 7 from the contact position Pt.

  Table 1 below shows the experimental results.

  As shown in Table 1, the experiment No. 1-4 were performed. In this experiment No. In 1-4, the actual measurement temperature of the surface of the hot roll 7 was 63 degreeC, 70 degreeC, 81 degreeC, and 91 degreeC. Each experiment No. In 1-4, the conveyance speed of the base paper 3 was 50 m / min and 30 m / min.

  As shown in Table 1, the surface temperature of the hot roll 7 is 63 ° C and 70 ° C. In Nos. 1 and 2, bumping was not recognized at any conveying speed, and it was good (◯).

  On the other hand, in Experiment No. 1 in which the surface temperature of the heat roll 7 is 81 ° C. 3, when the conveyance speed is 50 m / min, bumping occurs near the third position P3 of 1029 mm along the circumference of the heat roll 7 from the contact position Pt, and when the conveyance speed is 30 m / min. Then, bumping occurred in the vicinity of the first position P1 of 343 mm along the circumference of the heat roll 7 from the contact position Pt, resulting in printing failure (x).

  In addition, Experiment No. in which the surface temperature of the heat roll 7 is 91 ° C. 4, bumping occurred near the first position P1 of 343 mm along the circumference of the heat roll 7 from the contact position Pt, regardless of whether the conveyance speed was 50 m / min or 30 m / min, and printing failure (× )

  Thus, if the surface temperature of the heat roll 7 is too high, bumping due to moisture contained in the ink or the base paper 3 occurs, and therefore the surface temperature of the heat roll 7 is set to a relatively low temperature in order to prevent bumping. You will find that you need to.

  Next, the experiment conducted in order to evaluate the relationship between the temperature of the hot air of the 2nd hot air blower 9 and a dry state is demonstrated.

In this experiment, as shown in FIG. 4, the base paper 3 was blowing hot air at different temperatures by the second hot air blower 9 ₁ over a heat roll 7 wound. The magenta ink was manually applied at the application position Pc before the base paper 3 was wound around the heat roll 7. Cast coat tack paper was used as the base paper 3, and the amount of ink applied was 28 g / m ² . Sheet 3, the first position P1 immediately before the contact position Pt in contact with the heat roll 7 rotating in the arrow A direction, the the first hot air blower ₈₁ in the vicinity of the end of the region where the low-temperature hot air is blown and second position P2, was measured paper temperature respectively the third position P3 of the area hot air high temperature from the second hot air blower 9 ₁ is sprayed.

In the first hot air blower _81, the blowing hot air over to the position of 1030mm along the circumference of the heat roll 7 from the contact position Pt only, in the second hot air blower 9 _1, along the circumference of the heat roll 7 Hot air was blown over 390 mm.

Further, in order to evaluate the relationship between the hot air of the second hot air blower 9 and the heating by the hot roll 7, the second hot air blower is peeled off from the hot roll 7 as shown in FIG. the case where blowing hot air from 9 ₁ to measure the paper surface temperature of the sheet 3, respectively said at each measurement point P1 to P3.

  In addition, the presence or absence of bumping of the coating film during drying was visually determined, and the dry state was determined by rubbing the printed portion of the base paper 3 with a finger and by set-off.

  Table 2 below shows the experimental results.

In the upper column of Table 2, and the presence or absence of contact refers to the presence or absence of contact between the sheet 3 and the heat roll 7 blowing hot air by the second hot air blower 9 _1, contact "present", as shown in FIG. 4 to refers to a state with respect to base paper 3 conveyed in contact with the heat roll 7 are blowing hot air from the second hot air blower 9 _1, contact "no", as shown in FIG. 5, the heat roll 7 It refers to a state in which blowing hot air from the second hot air blower 9 ₁ for sheet 3 being conveyed is separated from. Also, the hot air [1], the hot air by the first hot air blower _81, the hot air [2] refers to the hot air by the second hot air blower _{9 1.}

As shown in FIG. In 1, the wind speed of the second hot air blower _{9 1} by hot air (hot air [2]) and 20m / s, 60m / s, the temperature, 80 ° C., and 227 ° C., the conveying speed 20 m / min, 30 m / Minutes. The first hot air by a hot air blower _{8 1} (hot air [1]) is one of the Experiment No. 1 to 3 also had a wind speed of 20 m / s and a temperature of 80 ° C.

  The surface temperature of the heat roll 7 is approximately the same 70 ° C. 1 and 2 are 70 ° C. 3 was 71 degreeC.

Velocity of the second hot air blower _{9 1} of hot air (hot air [2]), the Experiment No. 1 is 20 m / s, Experiment No. 2 and 3 were 60 m / s. Temperature of the second hot air blower _{9 1} of hot air (hot air [2]), the Experiment No. 1 is 80 ° C., Experiment No. 2 is 227 ° C., Experiment No. 3 was 230 degreeC.

  The conveyance speed of the base paper 3 is the same as that in Experiment No. 1 is 20 m / min. 2 and 3 were 30 m / s.

As shown in Table 2, in the state in which the base paper 3 was brought into contact with the hot roll 7, an experiment No. ₁ was sprayed with 80 ° C. hot air from the second hot air blower 91. In No. 1, bumping did not occur (O), but when the printed portion of the base paper 3 was rubbed with a finger, ink was removed (XX), set-off occurred (XX), and it was not dried at all. In this experiment No. In No. 1, the temperature on the paper surface was not measured at each of the positions P1, P2, and P3 because it was not dry at all.

In this experiment No. For one, in the state in which the heat roll 7 is brought into contact with sheet 3, the experiment was blowing hot air in the second hot air blower 9 ₁ from 227 ° C. No. In No. 2, there is no bumping (O), no ink is removed even if the printed portion of the base paper 3 is rubbed with a finger (O), no set-off occurs (O), and it is sufficiently dry It was.

On the other hand, in the state where the base paper 3 was peeled off from the hot roll 7, an experiment No. _{1 in which} hot air of 230 ° C. from the second hot air blower 91 was blown. In No. 3, bumping did not occur (O), but when the printed portion of the base paper 3 was rubbed with a finger, ink was removed (X) and set-off occurred (X). Although it was dry compared with 1, it was insufficiently dried.

Thus the hot air by the second hot air blower 9 _1, in order to dry skipping a high boiling point solvent, it can be seen that it is necessary to high temperature. Experiment No. Since the boiling point of the solvent having the highest boiling point among the high boiling point solvents contained in the inks 1 to 3 is considered to be 180 to 200 ° C., good drying at 200 ° C. or higher higher than the boiling point. It is thought that the state was obtained.

Furthermore, the high temperature of the hot air by the second hot air blower 9 _1, the heat roll 7 is brought into contact with the base paper 3, heating the sheet 3 from the back side, seen to be effective in causing sufficiently dried.

  As described above, moisture is evaporated while preventing bumping by the low-temperature hot roll 7, and the high boiling point solvent is evaporated and dried by the high-temperature hot air from the second hot-air blower 9. Instead of blowing hot air having different temperatures depending on the hot air blowers 8 and 9, it is conceivable to blow only hot hot air from a single hot air blower.

  However, it is not easy to maintain the temperature of the hot roll 7 at a low temperature in a configuration in which only high-temperature hot air is blown by a single hot air blower.

As shown in FIG. 6, without applying winding sheet 3, is rotated only heat roll 7, the surface temperature of the measuring position P of the thermal roller 7 when blowing hot air at 230 ° C. by the second hot air blower 9 ₁ in conjunction with measuring and second hot air blower 9 ₁ of hot air temperature furnace, a heat medium circulating in the heat roll 7 oil temperature was measured. The length of the area sprayed a second hot air hot air blowers 9 ₁ is 390mm along the circumference of the heat roll 7, which is about 13% of the total circumference of the heat roll 7.

  FIG. 7 is a diagram showing the measurement results, in which the horizontal axis corresponds to the elapsed time, the left vertical axis corresponds to the temperature of the heat roll and the heat medium, and the right vertical axis corresponds to the temperature of the hot air.

  As shown in FIG. 7, the surface temperature of the heat roll 7 and the temperature of the heat medium gradually increase with the passage of time, and after about one and a half hours, the surface temperature of the heat roll 7 increases by about 6 ° C. However, the temperature of the heating medium increased by about 4 ° C.

  In this way, the surface temperature of the hot roll 7 rises only by blowing hot hot air over about 13% of the entire circumference of the hot roll 7, so that the surface temperature of the hot roll 7 is set to prevent bumping. In order to keep it low, it is necessary to provide a large cooling capacity and to control the temperature of the heat medium. As a result, the configuration becomes complicated, the size increases, and the cost increases.

  Therefore, in order to reduce the size of the apparatus and reduce the cost, the first hot air blower 8 blows hot air at a relatively low temperature onto the hot roll 7 in order to maintain the temperature of the hot roll 7 at a low temperature. It is valid.

In the above-described embodiment, the second hot air blower 9 blows hot hot air on the base paper 3 wound around the hot roll 7, but as another embodiment of the present invention, FIG. 8 or FIG. as shown in 9, the sheet 3 while peeled from the heat roll 7 may be a second hot air blower 9 _2, 9 ₃ to blowing hot hot air. In this case, hot hot air is blown to at least one of the front surface 3a side and the back surface 3b side of the base paper 3. However, as described above, since the drying efficiency is higher when the hot roll is used in combination than when the hot air [2] is simply blown, the second hot air blower 9 ₂ with the base paper 3 peeled from the hot roll 7 is used. , when spraying high-temperature hot air from 9 _3, increasing the velocity of the second hot air blower 9 _2, 9 _3, raising the temperature, it is desirable to perform additional means such as a longer spraying time.

  The above-described embodiment in which high-temperature hot air is blown from the second hot air blower 9 to the base paper 3 wound around the hot roll 7 without requiring such additional means is in contact with the hot roll 7. Therefore, the heating temperature of the base paper 3 is stabilized, and the base paper 3 can be efficiently dried by reliably evaporating the high boiling point solvent.

  In the above-described embodiment, hot air is blown by the two first and second hot air blowers 8 and 9, but a hot air blower may be further added.

  In the above-described embodiment, the case of printing on plain paper having low water absorption has been described. As already mentioned, plain paper includes film. When a film is used as the base material, the surface temperature of the heat roll 7 is relatively low. Therefore, by winding the film around the heat roll 7 having a relatively low temperature, an increase in the temperature of the film is suppressed. It is possible to effectively prevent the deformation.

  In the above-described embodiment, the heat roll 7 has a required heating temperature by circulating a heat medium therein, but a heater or the like may be provided inside to provide the required heating temperature.

1 Inkjet printer 3 Base paper (base material)
4 Printing part 5 Drying part 7 Heat roll 8 1st hot air blower (1st hot air blowing means)
9 Second hot air blower (second hot air blower)

Claims (10)

A drying device for drying a paint applied to the surface of a substrate,
Rotating while contacting the back surface of the substrate to be conveyed, a heat roll for heating the substrate,
First hot air blowing means for blowing hot air on the surface of the base material conveyed while being in contact with the hot roll;
A second hot air blowing means that is provided downstream of the first hot air blowing means in the conveying direction of the base material and blows hot air having a temperature higher than that of the first hot air blowing means to the conveyed substrate; ,
A drying apparatus comprising: The second hot air blowing means blows the high-temperature hot air to the surface of the base material conveyed while being in contact with the hot roll.
The drying apparatus according to claim 1. The base material is roll-shaped paper or film, and the paint is water-based ink ejected on the surface of the base material.
The drying apparatus according to claim 1 or 2. The temperature of the hot air blown by the second hot air blowing means is equal to or higher than the boiling point of the high boiling point solvent contained in the aqueous ink;
The drying apparatus according to claim 3. The surface temperature of the hot roll is not higher than the boiling point of the solvent having the lowest boiling point among the solvents contained in the paint,
The drying apparatus according to any one of claims 1 to 4. The surface temperature of the hot roll is equal to or lower than the temperature of hot air blown by the first hot air blowing means.
The drying device according to any one of claims 1 to 5. The surface temperature of the heat roll is 80 ° C. or less.
The drying apparatus according to any one of claims 1 to 6. The temperature of the hot air blown by the second hot air blowing means is equal to or higher than the boiling point of the solvent having the highest boiling point among the solvents contained in the paint.
The drying apparatus according to any one of claims 1 to 7. The conveyance speed of the base material is 25 m / min or more.
The drying apparatus according to any one of claims 1 to 8. A printing unit that discharges and prints ink on a substrate;
The drying apparatus according to any one of claims 1 to 9, which dries a printed substrate.
A printing apparatus characterized by that.

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