JP2003025548A - Method and apparatus for drying - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus for effectively drying a printing ink without increasing in length of the apparatus without bringing about a register fault due to a thermal expansion or contraction of a web. SOLUTION: The apparatus 11 for drying the web W obtained by printing a printing ink on a base comprises a nozzle 23 for blowing a hot air to a printing surface of the web W running in a drying furnace R1 for blowing the hot air, a nozzle for blowing a cold air to a rear surface of the web W in a drying furnace R2 for blowing the cold air in such a manner that a temperature of the cold air is 40 deg.C or lower or lower by 20 deg.C or more than the temperature of the hot air. The method for drying uses the apparatus 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for drying an oil-based or water-based ink printed or applied on a substrate for printing or coating and a device therefor, and particularly to a gravure printing machine, an offset printing machine and a coating machine. And a drying method for the same.

[0002]

2. Description of the Related Art Conventionally, a hot air drying system has been the mainstream as a drying device used in a printing machine including multicolor printing.
This hot air drying method is a method in which hot air is blown from the nozzles onto the printing surface to dry the printing ink while the web is running with a plurality of guide rolls or floating.

Further, in the above hot air drying system, when performing high-speed printing or printing ink having poor drying properties, the hot air temperature is increased or the drying oven length of the device itself is extended to improve the drying efficiency. Had been improved.

However, when the drying temperature is raised, expansion and contraction occur depending on the characteristics of the printed web, and in the case of multicolor printing, there is a problem that the registration becomes unstable. That is, this registration is performed, for example, as shown in FIG. 1, when the second color is printed after the first color is printed, the register of the first color is detected by the register detector 31, and the operation of the compensator 32 detects the second color. The printing registration position is aligned, and the same operation is repeated to perform multicolor printing. However, if the web is remarkably expanded or contracted due to high temperature drying, the operation of the compensator 32 cannot follow and the registration error occurs. Become.

Further, in the case of improving the drying efficiency by lengthening the oven length of the drying device itself and increasing the drying time, the size of the device becomes large and the workability deteriorates, and the loss during web switching increases. There is also a problem that the traveling of the web becomes unstable.

[0006]

SUMMARY OF THE INVENTION The present invention is intended to solve the problems of the prior art, which is to solve the problems of printing ink or printing ink without causing misregistration of printing due to thermal expansion and contraction of the web. It is an object of the present invention to provide a drying method and an apparatus for effectively drying a coating solution without increasing the size of the apparatus.

[0007]

In order to achieve the above object in the present invention, first, in the invention of claim 1, a method for drying a web in which a printing ink or a coating liquid is printed or applied on a substrate is used. Thus, the drying method is characterized in that hot air is blown to the printing or coating surface of the web running in the drying oven, and cold air is blown to the back surface of the web.

Further, in the invention of claim 2, the temperature of the cold air blown to the back surface of the web is 40 ° C. or lower, or the temperature of the cold air blown to the back surface of the web is blown to the printing or coating surface of the web. The drying method according to claim 1, wherein the temperature is low with respect to the temperature of the hot air and the difference is 20 ° C or more.

According to a third aspect of the present invention, there is provided a web drying device in which a printing ink or a coating liquid is printed or applied on a substrate, and hot air is blown to the printing or application surface of the web running in the drying oven. The drying device is characterized in that a nozzle for blowing is provided and a nozzle for blowing cold air is provided on the back surface of the web.

Further, in the invention of claim 4, the temperature of the cold air blown to the back surface of the web is 40 ° C. or lower, or the temperature of the cold air blown to the back surface of the web is applied to the printing or coating surface of the web. The drying apparatus according to claim 3, wherein the temperature is low with respect to the temperature of the hot air to be blown and the difference is 20 ° C. or more.

According to the above-described drying method and apparatus of the present invention, hot air is blown onto the printing or coating surface of the web to dry the printing ink or the coating liquid, and cold air is blown from the back surface of the web, thereby heating the substrate. The expansion and contraction of the material can be suppressed, and even if the hot air temperature is raised, defective registration and dimensional defects do not occur, there is no need to lengthen the oven length of the drying device, and the web is printed or sprayed on the coated and backside. By giving a temperature difference to the air, the printing or coating surface side where hot air is blown becomes an environment where dew condensation occurs, and the printing or coating surface is less likely to cause the ink or coating liquid to peel, and the inside of the ink or coating liquid layer It is possible to provide a drying method and apparatus capable of improving the drying efficiency by drying without holding the solvent in the.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a schematic side view of a gravure printing machine as an example in which a drying device 11 according to the present invention is attached, and FIG. 2 shows a drying device 11 installed for each printing unit, and inside the drying device 11 using a plurality of guide rolls. The printing surface drying furnace R1 and the back surface cooling furnace R2 are respectively provided on the front and back sides of the web W traveling in the direction.

As the drying device 11 of the present invention, as shown in the enlarged schematic view of FIG. 2, the printing surface drying furnace R1 has a plurality of nozzles 21 for blowing hot air to the printing surface of the traveling web W and a post-spraying nozzle. The exhaust port 22 is provided for discharging hot air containing the volatile solvent.

The backside cooling furnace R2 shown in FIG. 2 is provided with a plurality of nozzles 23 for blowing cold air between the guide rolls and an exhaust port 24 for discharging the cold air after blowing in order to cool the backside of the web W. ing.

Further, the drying oven R of the drying device 11 shown in FIG.
As for the hot air supplied to No. 1, the outside air sucked from the air supply fan 12 becomes hot air in the heating heat exchanger 14 of each printing unit, and is supplied to the drying furnace R1. The hot air supplied to the drying furnace R1 is blown from the nozzle 21 onto the printing surface of the web W, the solvent of the printing ink is volatilized, and the printing surface is dried.
The hot air containing the solvent is exhausted from the exhaust port 22 and exhausted to the outside air by the exhaust fan 13.

The heating heat exchanger 14 for producing the hot air may be steam, gas, an electric heater, or the like, but is not particularly limited as long as it produces heat at room temperature or higher.

On the other hand, the drying furnace R of the drying device 11 shown in FIG.
As for the cool air supplied to 2, the outside air sucked from the air supply fan 12 becomes cool air in the cooling heat exchanger 15 of each printing unit and is supplied to the drying furnace R2. The cold air supplied to the drying furnace R2 is blown from the nozzle 23 to the back surface of the web W, and the heat transferred to the web W by the nozzle 21 is taken away, and the expansion and contraction of the web is suppressed. Further, the cold air after being blown is exhausted from the exhaust port 24 and exhausted to the outside air from the exhaust fan 13.

The cooling heat exchanger 15 for producing the cold air has a cooling coil or the like, but it is not particularly limited as long as it produces air at room temperature or lower.

The shape of the nozzle 21 of the hot air supplied to the drying furnace R1 may be any type such as a slit type or a perforated plate type according to the thickness of the ink to be dried and the volatilization rate of the solvent.

As shown in FIG. 3, the shape of the nozzle 23 for the cold air supplied to the drying furnace R2 is adjusted by the damper 16 so that the traveling web W does not flutter with the cold air blown. If desired, the nozzle 21 may have the same shape as that of the nozzle 21. However, if it is desired to increase the air volume, a slit-shaped nozzle shape is preferable, as shown in FIG.

Regarding the arrangement of the above nozzles, when viewed from a general drying mechanism, in the first half of drying, the solvent evaporates rapidly after the temperature evaporates to the temperature at which the solvent evaporates.
The nozzles 23 of the drying furnace R2 for blowing cool air from the back surface of the web W may be installed between the guide rolls as shown in FIG. 2, but are installed only in the latter half of the drying process in consideration of the drying efficiency. You may do it.

When the ink film thickness of the web is thick or the ink has poor drying properties, an auxiliary device such as a far-infrared, mid-infrared or near-infrared heater, which is effective for heating the inside of the ink film, is used for drying the printing surface of the web. For heating, it may be installed between the nozzles 21 of hot air or built in the nozzles 21 and used together with hot air.

Further, in the case of containing water in the solvent of the printing ink or in the case of a product which does not like moisture, a drying method of blowing hot air heated with a low dew point is preferable. The means for supplying low dew point air also uses a dehumidifier, and the dehumidifier has a cooling type, a compression type, an absorption type, an adsorption type, a hollow fiber membrane separation type, and can supply air with a low dew point. Anything will do. The dew point is 10 ° C or lower, preferably 0 ° C to
-100 ° C is preferable.

[0024]

〔test conditions〕

・ Substrate: 25 μm OPP film (manufactured by Tohcello Co., Ltd.)
U-1) ・ Printing ink: Acqua Ecole (made by Toyo Ink Mfg. Co., Ltd.
Water-based gravure ink) -Printing method: Gravure printing (two-color printing) -Printing plate: Helio 80 lines / cm Stylus angle 12
0 degree (common for 2 colors) ・ Drying unit length: 2 m ・ Printing speed: 60 m / min ・ Printing surface hot air temperature: 50 ℃, 60 ℃, 70 ℃, 80 ℃,
90 ℃ ・ Cold back air temperature: 20 ℃ ・ Dry air volume: 25m ³ / min ・ Environmental temperature: temperature 24 ℃, humidity: 55% The pitch is measured and the misalignment distance is 0.2 m
m or less, substrate pitch is 600.0 ± 0.2 m in flow direction
m, and 1000.0 ± 0.2 mm in the width direction were passed (◯). The results are shown in Table 1.

Comparative Example 1 A coated sheet was prepared in the same manner as in Example 1 except that the backside cool air was not used, and the obtained sheet was evaluated in the same manner as in Example 1 and the results were obtained. Is shown in Table 1.

[0026]

[Table 1]

From Table 1 above, the difference from the hot air from the front side of the surface printed with the printing ink at 20 ° C. is 30 ° C.
With the above-mentioned coated sheet to which the cool air was applied, the registration error was 0.2 mm or less and the substrate pitch was ± 0.2 mm or less even if the hot air temperature from the surface was as high as 90 ° C. On the other hand, in the comparative example in which the cold air from the back surface was not used, especially when the hot air from the front surface was 80 ° C. or higher, the register deviation exceeded 0.2 mm and the substrate pitch exceeded ± 0.2 mm. As a result, the elongation of the base material causes a tarmi on the web, which makes it impossible to measure each of them.

[0028]

Since the present invention has the above-mentioned constitution, it has the following effects. That is, according to the drying method and the drying apparatus of the present invention, the back surface of the web printed or applied on the front surface is 40 ° C. or lower, or the temperature is 20 ° C. with respect to the temperature of the hot air blown on the printed or applied surface of the web. By blowing cold air with the above difference, even if hot hot air is blown to dry the printing ink or coating liquid, the quality of the printing register and the size of the substrate will not deteriorate, and therefore the drying oven length It is not necessary to increase the size of the device to take a long time, and the equipment can be made compact.

Therefore, according to the present invention, even if the hot air temperature is raised, defective registration or dimensional defect does not occur, and it is not necessary to lengthen the oven length of the drying device, and the gravure printing or coating can improve the drying efficiency. As a drying method and an apparatus therefor, it exhibits excellent practical effects.

[Brief description of drawings]

FIG. 1 is a schematic side view showing an embodiment of a gravure printing machine equipped with a drying device of the present invention.

FIG. 2 is a schematic explanatory view showing an enlarged embodiment of a drying apparatus of the present invention.

FIG. 3 is a schematic explanatory view showing, in an enlarged manner, an embodiment of a nozzle that constitutes the drying device of the present invention.

FIG. 4 is a schematic explanatory view showing, in an enlarged scale, another embodiment of the nozzle that constitutes the drying device of the present invention.

[Explanation of symbols]

11. Drying device 12: Air supply fan 13 Exhaust fan 14 Heat exchanger for heating 15 ... Heat exchanger for cooling 16: Damper 21 ... hot air nozzle 22 Hot air exhaust port 23 ... Cold air nozzle 24: Cold air exhaust port 31 ... register detector 32 Compensation R1 ... Drying oven for blowing hot air R2 ... Drying oven for blowing cold air W: Web

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F26B 13/10 F26B 13/10 D 21/00 21/00 A 21/10 21/10 A F term (reference) ) 2C020 CA01 CA03 CA09 2H113 AA01 AA05 BA03 BA05 BB08 BB22 BC01 EA02 FA35 FA36 3L113 AA02 AB02 AC02 AC21 AC31 AC45 AC46 AC48 AC52 AC53 BA32 CA08 CB01 CB13 CB21 CB24 DA10 DA14 DA24 4D075 AAZ ABB86 BB86

Claims (4)

[Claims] 1. A method for drying a web on which a substrate is printed or coated with a printing ink or a coating liquid, wherein hot air is blown onto the printed or coated surface of the web running in a drying oven.
A drying method characterized by blowing cold air on the back side of the web. 2. The temperature of the cold air blown to the back surface of the web is 40 ° C. or lower, or the temperature of the cold air blown to the back surface of the web is lower than the temperature of the hot air blown to the printing or application surface of the web. The method according to claim 1, wherein the difference is 20 ° C or more. 3. A web drying device in which a printing ink or a coating liquid is printed or applied on a base material, wherein a nozzle for blowing hot air is provided on the printing or application surface of the web running in a drying oven, A drying device characterized in that a nozzle for blowing cold air is provided on the back surface. 4. The temperature of the cold air blown to the back surface of the web is 40 ° C. or lower, or the temperature of the cold air blown to the back surface of the web is lower than the temperature of the hot air blown to the printing or application surface of the web. The drying apparatus according to claim 3, wherein the difference is 20 ° C or more.