JPH09123403A - Drying device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively utilize heat energy by improving drying efficiency without deteriorating printing quality, such as printing register or the like in a multicolor photogravure press. SOLUTION: In addition to a structure wherein hot air is blown against a printing surface of a web W traveling by being guided by a plurality of guide rollers 11 from a plurality of nozzles 12, an auxiliary nozzle 14 blowing hot air against a rear surface of the web W is provided between the guide rollers 11. Besides, the hot air after being blown against the printing surface is sent to the auxiliary nozzle 14. Since printing ink is dried by blowing hot air from both sides of the web W, it is not required that a temperature of hot air is raised, and an air speed of the nozzle is increased. Further, lengthening a length of a furnace of the drying device itself is not required. Therefore, dry efficiency can be improved without deteriorating the printing quality such as printing register or the like. Furthermore, heat energy can be effectively utilized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot air drying type drying device used in a multicolor gravure printing machine.

[0002]

Generally, as a drying device used in a gravure printing machine including multicolor printing, a heating drum system using steam or electric heat, an infrared lamp system, and a hot air drying system are known. Recently, due to regulations such as the Fire Service Law, there are few infrared lamp systems, and the heating drum system is not used much because of the problem of the difference in the diameter of the driving drum and the cost of the device. Equipment is becoming mainstream. This hot air drying method is a method in which hot air is blown from a nozzle onto a printing surface to dry the printing ink while the web is guided and run by a plurality of guide rollers.

In a conventional hot air drying type drying device, when printing an ink having poor drying property or printing at high speed, the hot air temperature is raised, the nozzle wind speed is raised, or the device itself. The drying efficiency is improved by increasing the furnace length. However,
If the drying temperature is too high, the product may not be stretched more than necessary depending on the characteristics of the printed web, and it may not be possible to maintain the specified dimensions of the product or the registration may become unstable in the case of multicolor printing. The problem occurs. Further, if an attempt is made to increase the nozzle wind speed, the noise of the drying device becomes large and the working environment is remarkably lowered, and the running web becomes fluttered to make the registration unstable. In addition, when trying to cope by increasing the furnace length of the device itself and increasing the drying time, the size of the device becomes large and the workability deteriorates, the paper loss at the time of switching increases, or the web travels. This causes problems such as instability, and further increases fan capacity and energy cost.

On the other hand, as a drying device used in the coating device, as shown in FIG. 1, hot air is blown from both sides of the web W running in the dryer 1 without using guide rollers to dry it while floating. The floating method is used and it is known that the drying efficiency is considerably high. However, in this method, the hot air from the hot air generator 2 is blown out from the nozzle 3 in the dryer 1, and the web W is dried while being floated by this blowing air, so that the flap of the web W is large and the running tends to be unstable. . Therefore, when this method is applied to a multi-color gravure printing machine, the print registration becomes unstable, and high-quality gravure printing cannot be realized. Also, the heated air used for drying is blown onto the web W and then exhausted by the exhaust device 4.
Is discharged into the atmosphere. At this time, a few percent of the thermal energy given to the heated air is used for solvent evaporation for drying the ink, but most of it is released to the outside air and is not used.

The present invention has been made in view of the above problems, and an object thereof is to improve the drying efficiency in a multicolor gravure printing machine without lowering the printing quality such as the printing register. Moreover, it is to provide a drying device capable of effectively utilizing heat energy.

[0006]

In order to achieve the above object, the drying apparatus of the present invention dries the printing ink by blowing hot air from a plurality of nozzles onto the printing surface of the web which is guided by a plurality of guide rollers and runs. In a drying device for a multi-color gravure printing machine, a plurality of auxiliary nozzles for blowing hot air on the back surface of the web are installed between the guide rollers, and hot air after being blown on the printing surface is applied to the auxiliary nozzles. It is characterized in that it is configured to send.

In the drying apparatus of the present invention having the above-mentioned structure, the hot air is blown to both the printing surface and the back surface of the web to dry the ink, so that the hot air temperature and the nozzle wind speed are not increased. Further, it becomes possible to improve the drying efficiency without increasing the length of the oven of the drying device. Moreover, thermal energy is effectively used by reusing the hot air blown on the printing surface for drying the back surface of the web.

[0008]

FIG. 2 is a schematic view showing a drying apparatus according to the present invention. The drying apparatus 10 is an impression cylinder 5 as shown.
It is arranged for each printing unit 7 including the plate cylinder 6. FIG.
As also shown in the enlarged view of the main part of FIG. 1, the drying device 10 has a structure in which a printing surface drying hood A and a back surface drying hood B are provided on both sides of the web W which is guided by a plurality of guide rollers 11 and runs. Of these, the printing surface drying hood A is
A plurality of nozzles 12 for blowing hot air onto the printing surface of the traveling web W, and an exhaust port 1 for sucking the hot air after blowing
On the other hand, the backside drying hood B is provided between the guide rollers 11 and has a plurality of auxiliary nozzles 14 for blowing hot air to the backside of the web W, and an exhaust port for sucking the hot air after the blowing. And 15.

In the drying device 10, the air taken in from the outside air is heated by the hot air generator 20 and then supplied to the printing surface drying hood A and blown as hot air air from the nozzle 12 onto the printing surface. Then, the hot air blown on the printing surface is sucked from the exhaust port 13 provided in the printing surface drying hood A, and is sent to the back surface drying hood B through the air blower 21. Here, in order to use the heat energy of the hot air coming out of the printing surface drying hood A in the back surface drying hood B without waste, it is necessary to cover the duct for sending the hot air with a heat insulating material so that the heat does not escape to the outside. There is. In this way, the hot air supplied from the printing surface drying hood A is
It is sprayed from the auxiliary nozzle 14 installed between the guide rollers 11 to the back side of the printing surface. The hot air blown on the back surface is exhausted through the exhaust port 15 provided adjacent to the auxiliary nozzle 14.
It is further sucked and is discharged to the outside air through the exhaust device 22. Reference numeral 23 in the figure denotes a damper provided in the middle of the duct. Further, the auxiliary nozzles 14 for blowing hot air to the back surface of the web W may be all installed between the guide rollers 11 in the drying device 10 as shown in FIG. 3, but the inlet of the drying device 10 in consideration of drying efficiency. Therefore, it may be installed only in the first half.

Auxiliary nozzle 14 provided on the backside drying hood B
When the same shape as that of the nozzle 12 provided on the printing surface drying hood A and hot air is blown from both sides of the web W at the same wind speed, fluttering occurs on the web W, and the registration becomes unstable in multicolor printing. Occurs.
Therefore, the nozzle 12 provided on the printing surface drying hood A
May be any type such as a slit shape or a perforated plate shape, but the auxiliary nozzle 14 provided on the back surface drying hood B is
In order to prevent the traveling web W from being fluttered by the hot air blown, it is necessary to make it slit-shaped and to blow it at an oblique angle to the web W.
From such a point of view, suitable arrangement examples of the combination of the auxiliary nozzle 14 and the exhaust port 15 provided in the back surface drying hood B are shown in FIGS. 4 and 5.

In order to confirm that the drying efficiency is improved by the present invention, as shown in FIG. 6 (a), only the perforated plate nozzle 31 for blowing hot air onto the printing surface of the traveling web W is installed and dried. As shown in FIG. 6B, a comparison test of drying efficiency was performed between the case where a slit nozzle 32 for blowing hot air was further installed on the back surface of the printing surface and the case was dried. Specifically, using a water-soluble gravure ink with poor dryness, setting various hot air temperatures in each drying method, and gradually increasing the printing speed, at which speed the ink will not dry It was compared whether it would adhere to the. That is, the drying efficiencies were compared by looking at the blocking limit speeds corresponding to various hot air temperatures. The test conditions are as follows.

(Test Conditions) Web: Tocello, OPP film “U-1, # 30” (30 μm) Ink: Aqua Ecole (Dainippon Ink, water-soluble gravure ink) Gravure plate: Helio plate 80 lines, 140 ° ∠0 Drying oven length: 600 mm Environment: Air temperature 24 ° C, Humidity 45% Nozzle wind speed: (1) Perforated plate nozzle 30 m / sec, Slit nozzle 27 m / sec (2) Perforated plate nozzle 41 m / sec, Slit nozzle 37 m / sec Hot air Temperature: 50 ℃, 60 ℃, 70 ℃, 80 ℃

FIGS. 7A and 7B are graphs showing the results of comparison tests when the nozzle wind speeds are set as in the above (1) and (2), respectively. The horizontal axis of the graph is the set hot air temperature (° C), and the vertical axis is the blocking limit speed (m /
Represents the case where the perforated plate nozzle 31 alone was used for drying, and the square represents the case where the perforated plate nozzle 31 and the slit nozzle 32 were used together for drying. From this result, it is understood that the drying efficiency is improved by about 10 to 20% by blowing hot air from the back surface at the same time as compared with the case of blowing hot air on the printing surface. In this comparative test, a drying device in which the web travels in the horizontal direction was used, but similar results are obtained even in a drying device in which the web travels in the vertical direction, such as a drying device of a normal gravure printing machine. To be

By the way, as a drying device of the backside spraying combined type, a system as shown in FIGS. 8 and 9 can be considered in addition to the system of the present invention. The one shown in FIG. 8 is one in which hot air is supplied from one hot air generator 20 to the printing surface drying hood A and the back surface drying hood B through different ducts, and the one shown in FIG. Hot air is supplied to the dry hood A and the back surface dry hood B from different hot air generators 20, respectively. In these methods, as shown in Table 1, although the drying ability is improved,
It requires twice as much thermal energy as a conventional dryer. On the other hand, in the drying device of the present invention, since the hot air used for heating the printing surface is used for heating the back surface, the thermal energy used is the same as that of the conventional method and the drying capacity can be improved. .

[0015]

[Table 1]

[0016]

As described above, according to the drying apparatus of the present invention, hot air is blown to the back surface as well as the printing surface of the web to dry the printing ink. Since it is not necessary to raise the nozzle height or increase the nozzle wind speed, and it is not necessary to lengthen the furnace length of the device itself, it is possible to improve the drying efficiency without deteriorating the printing quality such as printing register. Since the hot air after being blown to the printing surface is blown to the back surface, it is possible to effectively utilize the heat energy and improve the production efficiency of the printed matter.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a drying device used in a coating device.

FIG. 2 is a schematic view showing a drying device according to the present invention.

FIG. 3 is an enlarged view of a main part of the drying device shown in FIG.

FIG. 4 is a schematic view showing an arrangement example of nozzles.

FIG. 5 is a schematic view showing another arrangement example of nozzles.

FIG. 6 is a schematic view showing a drying device used in a comparative test for confirming the drying efficiency.

FIG. 7 is a graph showing the results of a comparison test.

FIG. 8 is a schematic view of another drying device compared with the drying device of the present invention.

FIG. 9 is a schematic view of another drying device compared with the drying device of the present invention.

[Explanation of symbols]

 10 Drying device 11 Guide roller A Printing surface drying hood 12 Nozzle 13 Exhaust port B Back side drying hood 14 Nozzle 15 Exhaust port 20 Hot air generator 21 Blower device 22 Ejecting device 23 Damper 31 Perforated plate nozzle 32 Slit nozzle

Claims (1)

[Claims] 1. A drying device for a multi-color gravure printing machine, wherein hot air is blown from a plurality of nozzles onto a printing surface of a web which is guided by a plurality of guide rollers to dry the printing ink, the back surface of the web being provided. A drying apparatus, wherein a plurality of auxiliary nozzles for blowing hot air are installed between the guide rollers, and the hot air after being blown to the printing surface is sent to the auxiliary nozzles.