JP2003112105A - Inert drying apparatus, seal apparatus, drying method, and method for producing image formation material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep the oxygen concentration in an inert drying apparatus at a constant and low level and prevent occurrence of unevenness and irregularity attributed to blow of an inert gas. SOLUTION: The inert drying apparatus comprises a transportation roll for holding the rear face of a coating film and a blowing port for blowing out an insert gas to the coating film side, and in the apparatus, the distance between the blowing port and the coating film face is controlled to 50-400 mm and the blow velocity of the inert gas is controlled to 0.1-10 m/sec.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an inert drying device,
The present invention relates to a sealing device, a drying method, and a method for producing an image-forming material using them, and more particularly to a drying device using an inert gas, a sealing device, a drying method, and a method for producing an image-forming material using them.

[0002]

2. Description of the Related Art Conventionally, a drying means for continuously introducing a coating film containing a solvent into a drying device by a conveying means and evaporating the solvent by heating has been widely used in the industrial field. In such a drying device, generally, a method of drying a coating film containing a solvent in air (air mode) is adopted, but on the other hand, as described in JP-B-55-36389, the atmosphere of the drying device is There is disclosed a so-called inert drying apparatus in which the solvent concentration in the atmosphere is safely increased to the lower limit of the explosion limit or higher by injecting an inert gas such as nitrogen gas to fill it with oxygen and lowering the oxygen concentration.

Although it is advantageous from the viewpoint of solvent recovery to make the solvent concentration above the lower limit of the explosion limit, the inert dryer has an opening through which the coating film is conveyed, which connects the internal atmosphere to the outside air. Therefore, the organic solvent gas may flow out through the opening or the outside air may flow into the drying device, which may affect the working environment, and may cause explosion and combustion.

Japanese Patent Publication No. 8-7025, Japanese Patent Laid-Open No. 11-13
No. 2661 and Japanese Patent Publication No. 59-21656 disclose a sealing device for preventing the above outflow and inflow, but it cannot be said to be sufficient.

On the other hand, when a heated inert gas is sprayed on the coating film, the surface of the coating film is disturbed, the smoothness of the surface is lost, and so-called mottled unevenness occurs. Japanese Unexamined Patent Publication No. 2000-329463 proposes a method of improving the unevenness caused by the wind like the mottled unevenness according to the regulation of the wind speed and the atmospheric temperature applied to the surface of the coating film, but it cannot be said to be sufficient.

[0006]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to maintain the oxygen concentration in an inert dryer at a constant low level and to suppress the occurrence of mottled unevenness due to the blowing of an inert gas. .

[0007]

The above objects of the present invention have been achieved by the following constitutions.

1) In an inert drying apparatus in which the back surface of the coating film is held by a transport roll and the surface of the coating film has an outlet for inert gas, the distance between the outlet and the surface of the coating film is 50 to 4
00 mm, the blowing velocity of the inert gas is 0.1 to 10 m
/ Sec. An inert drying device.

2) The inert drying apparatus as described in 1) above, wherein the most mass% solvent in the coating liquid for coating has a boiling point lower than that of water.

3) A method for producing an image-forming material, which is produced by the inert drying apparatus described in 2) above.

4) In the sealing device for blowing out the inert gas, which is installed in the portion before and after the coating film passes through the inert drying device described in 1) above, the temperature of the inert gas blown out from the inlet sealing device and the temperature before the sealing device. A sealing device, wherein the temperature difference from the environmental temperature is within a difference between the environmental temperature before the sealing device and the temperature inside the inert drying device immediately after the sealing device.

5) The sealing device as described in the above item 4), wherein the most mass% solvent in the coating liquid for coating has a boiling point lower than that of water.

6) A method for producing an image-forming material, characterized in that it is produced by the sealing device described in 5) above.

7) In a drying method in which a second drying device for evaporating the solvent in the coating film is provided after passing through the inert drying device according to the above 1) and then conveying the coating film while folding the coating film in an air atmosphere. A drying method comprising providing an open space between an inert drying device and a second drying device.

8) The drying method according to the above item 7), wherein the most mass% solvent in the coating liquid for coating has a boiling point lower than that of water.

9) A method for producing an image-forming material, characterized in that it is produced by the drying method described in 8) above.

The present invention will be described in detail. In the present invention, the sealing device is a coating film inlet / outlet port of the inert drying device, in order to prevent atmospheric gas in the inert drying device from flowing out, or to prevent atmospheric air from flowing into the drying device. The installed device. The sealing device is installed opposite to the front and back surfaces of the coating film, and is provided with a temperature-controlled inert gas outlet. The outlet is provided in the width direction of the coating film, and the inert gas is uniformly blown out across the width from a slit, a punch plate, a mesh, or the like. Further, the flow rate of the inert gas can be adjusted with a valve or the like so that the blowing speed of the inert gas can be adjusted. Temperature control is performed by passing an inert gas through a heat exchanger such as steam, cold water, or electricity. Further, in order to remove foreign matter of the inert gas, it is also passed through a filter.

It has been found that in the inert drying apparatus of the present invention, the oxygen concentration can be easily maintained by setting the distance between the coating film and the inert gas outlet to be 50 to 400 mm, which distance is preferable. Is 150-300
mm. When the thickness is 150 mm or more, the oxygen concentration can be maintained by a smaller amount of sealing air (inert gas stream blown out by the sealing device installed before and after the inert drying device). Furthermore, this reduced the mottled unevenness due to the seal wind in the coating film.

Further, in the inert drying apparatus of the present invention,
The blowing velocity of the inert gas blown onto the coating film is 0.1
It has been found that when the air velocity is 10 m / sec, it is possible to maintain the oxygen concentration at a lower seal air velocity, and more preferably, the air velocity is 0.1 to 7 m / sec. Further, this reduced the unevenness of the coating film due to the seal wind.

Further, in the present invention, after passing through the inert drying device, the second drying device which conveys the coating film while folding it back in an air atmosphere to evaporate the solvent in the coating film is physically installed in the inert drying device. By providing an open space between the two without directly connecting them, the influence of the change in the internal pressure of the second drying device or the change in the pressure of the outlet of the second drying device on the inert inlet differential pressure is reduced, It became possible to maintain the oxygen concentration at a lower seal wind speed. Furthermore, the fluctuation of the differential pressure change between the inlet seal part and the inside of the dryer is reduced,
The amount of inert gas passing through the sealing device was reduced, and mottled unevenness was improved. Furthermore, it became possible to reduce the amount of seal air flow, and uneven mottle was improved. At the same time, since it is basically impossible for a gas containing a high concentration of solvent to flow from the inert dryer to the second dryer,
It was possible to suppress an increase in the solvent concentration in the atmosphere of the drying apparatus. Further, the amount of residual solvent can be reduced in a short distance by using air instead of inert gas in the second drying device.

Further, in the present invention, the temperature of the sealing air at the inlet is within the range of the environmental temperature before the sealing and the temperature in the inert drying device immediately after the sealing, more preferably the temperature of the sealing wind at the inlet and the temperature before the sealing device. The difference between the environmental temperature before the sealing device and the difference between the environmental temperature before the sealing device and the temperature inside the inert drying device immediately after the sealing device is less than 1/2, more preferably the same as the environmental temperature before the sealing device. In this, the uneven mottle was remarkably reduced.

In the present invention, the solvent species, solute species, and solid species are not limited as long as the solute is dissolved or the solid matter is dispersed in the solvent, and the solid matter is coated and dried on the support. However, a particularly preferable coating liquid that can be used in the present invention is a coating liquid using an organic solvent having a boiling point lower than that of water, such as a photographic light-sensitive material, a heat-developable recording material, an ablation recording material, and a magnetic recording medium. It can be applied to coating liquids for image forming materials (including undercoating liquids, overcoating liquids, backside liquids, etc.).

As the solvent having a boiling point lower than that of water used for the coating liquid, for example, methanol, ethanol, acetone, methyl ethyl ketone, ethyl acetate, tetrahydrofuran,
Acetonitrile etc. are mentioned. Particularly preferable organic solvents include methanol, acetone and methyl ethyl ketone.

From coating to drying, the following process is generally followed. The support unwound from the original roll is sent to a coater to form a coating film. It is preferable to clean the support surface, the back surface, or both surfaces with a web cleaner immediately before coating. If the coating liquid is applied with foreign matter adhered to the coated surface, the foreign matter may enter the coating film, and the desired function may not be obtained, and it may cause streak failure in the application.
If coating is performed with the foreign matter attached to the back surface in a coating form having a back roll, the coating film may be lifted during coating due to the foreign matter, and the locally required coating film thickness may not be obtained. As the web cleaner, an adhesive roll or a spray of clean air is used.

The coating method is not limited in the present invention, and a roll coater such as a double roll coater and a reverse roll coater, a gravure coater, a comma coater, an extrusion die coater and the like can be mentioned.

Generally, the drying of the coating film coated on the support is started immediately after coating on the support by the above coating method. In particular, since the latent heat of vaporization of the organic solvent system is about 1/3 of that of water, it vaporizes violently when the boiling point is low. Therefore, when humans work below the lower limit of explosion of the volatile organic solvent, equipment for supplying and exhausting the solvent evaporated in the coating part is necessary in order to reduce the solvent concentration below the allowable working environment. Also, the drying box is surrounded by a heat insulating panel or the like, and has an entrance for a support that separates it from the coating part.

Although there is a method using infrared rays or microwaves for drying, generally, a means for evaporating the solvent from the coating film by spraying a heated inert gas uniformly on the coating film is generally used. Further, the drying process is formed in a box shape in order to efficiently collect the evaporated solvent and control the drying environment. At this time, one drying box may be used,
By dividing into a plurality of zones, the drying condition of each zone can be selectively changed.

When the coating film is dried by spraying an inert gas, the drying conditions of each zone are as follows: drying temperature, blowing velocity, distance between the inert gas outlet and the coating film, circulating amount of the inert gas, The internal solvent concentration may be mentioned. The inert gas may be supplied to the drying zone through a nozzle or a slit for spraying the coating film, or in combination with another supply port that is less likely to be affected by the air flow to the coating film.

When the coating film is conveyed from the back side while being supported by the supporting rolls in the drying device, the progress of the supporting rolls is 1.
The thickness is generally 00 μm or less, preferably 50 μm or less.

Since the coating film is not dried from the coater to the inside of the drying box, and the foreign matter adhering to the surface adheres to the coating film, the cleanliness of the periphery must be kept high.
The degree of cleanliness in the drying box depends on the characteristics of the product to be manufactured, but it is class 1000 or less, preferably class 100.
The following is preferable.

When the amount of residual solvent in the coating film affects the function of the finished product, it needs to be controlled, and usually a second drying device for applying heat after passing through the drying box is provided. It is desirable to provide a drive roll or a web guide system between the drying box and the second drying device. The drive roll is preferably held by a suction roll from the back side of the dried coating surface.

The transportation of the coating film in the second drying device while folding it back can be carried out by a plurality of rolls, or the coating film may be floated by an air float system and transported.
After the second drying device, it is desirable to provide a drive roll for transporting the coating film and a web guide system for controlling the position of transporting the coating film.

The present invention will be specifically described below with reference to the drawings. 1 is an inert drying device having a sealing device at the entrance and exit of a coating film, which includes claims 1, 4 and 7, and is provided with an open space between the inert drying device and the inert drying device. It is a schematic diagram of a 2nd drying device.

The back roll 2 is attached to the support 0 which runs continuously.
The coating liquid is applied by the die coater 1 through the
After passing through the sealing device 6 that blows out the inert gas installed at the inlet, it enters the inert drying device 4, where it is dried by the inert gas blown from the blowout port (slit nozzle) 7, and then the After passing through the sealing device 6 that blows out the active gas, it is conveyed to the second drying device 5 that is arranged with an open space between it and the inert drying device, and further drying is performed there. The second drying device 5
Is in an air atmosphere.

FIG. 2 is a partially enlarged view of the inert dryer, showing how to measure the blowout port distance.

[0036]

EXAMPLES The present invention will be specifically described below with reference to examples, but the embodiments of the present invention are not limited thereto.

Example 1 A photosensitive layer coating solution and a protective layer coating solution described below were commercially available so that the target wet film thickness of the photosensitive layer coating solution was 90 μm and the target wet film thickness of the protective layer coating solution was 30 μm. The biaxially stretched and heat-fixed 175 μm thick PET film was uniformly coated at a coating speed of 50 m / min by a multi-layer die coater holding the web with a back roll.

As shown in FIG. 1, the back side of this coating film was supported by a web guide roll, and while it was being conveyed, it was conveyed to an inert drying device in a nitrogen atmosphere consisting of three drying zones, and heated air was blown from a blowing port to form a coating film. It was dried by spraying on the surface. The temperature of the drying zone was 70 ° C. in all of the first zone, the second zone and the third zone.

Table 1 shows the results of mottled unevenness and oxygen concentration by changing the distance between the air outlet and the coating surface, the air velocity of the air blow, and the air flow rate of the seal. The sealing air volume was 100% when the air volume was adjusted so that the oxygen concentration was 5% when the outlet distance was 5 mm. The temperature of the inlet seal air is
The temperature was 25 ° C., which was the same as the ambient temperature before the inlet seal.

The mottled unevenness was evaluated by uniformly exposing and heat-developing the obtained coated sample so that the optical density was 1.5, and visually observing the state of occurrence with transmitted light on a Schaukasten. . Regarding the strength of mottled unevenness, 1 is bad and 10 is good in the 10-point evaluation.

(Preparation of Silver Halide Emulsion A) 1.3 kg of inert gelatin and 160 ml of 0.1M potassium bromide were dissolved in 40 L of water to adjust the temperature to 35 ° C. and pH to 3.0, and then silver nitrate 4. 39 L of aqueous solution containing 5 kg and (9
8/2) aqueous solution containing potassium bromide and potassium iodide at a molar ratio of 8/2) and 1 × 10 ⁻⁶ mol of [Ir (NO) Cl ₅ ] salt per mol of silver and 1 part of rhodium chloride salt per mol of silver.
× 10 ^-4 mol was added by the controlled double jet method while maintaining the pAg at 7.7. Thereafter, 4-hydroxy-6-methyl-1,3,3a, 7-tetrazaindene was added, pH was adjusted to 5 with NaOH, the average particle size was 0.06 μm, and the variation coefficient of the projected diameter area was 8%. 10
0) Cubic silver iodobromide grains having an area ratio of 87% were obtained. This emulsion was coagulated and precipitated using a gelatin coagulant, and after desalting, 4.2 g of phenoxyethanol was added, pH 5.9, p
Ag Ag was adjusted to 7.5 to obtain a silver halide emulsion.

Next, to this silver halide emulsion, 3 × 10 ^-2 mol of sodium thiosulfate was added per mol of silver, and 55
The reaction was performed at 60 ° C. for 60 minutes for chemical sensitization. afterwards,
After the temperature of the silver halide emulsion was lowered to room temperature, an antifoggant described later was added, and chemical sensitization was performed with chloroauric acid and inorganic sulfur to prepare a silver halide emulsion A.

(Preparation of Na Behenate Solution) Behenic acid (1.4 kg), arachidic acid (0.42 kg) and stearic acid (0.25 kg) were dissolved in 40 L of pure water at 90 ° C. Then, 4.1 L of 1.5 M sodium hydroxide solution was added while stirring at high speed. Next, add 39 L of concentrated nitric acid, and then 5
After cooling to 5 ° C. and stirring for 30 minutes, a sodium behenate solution was obtained.

(Preparation of Preform Emulsion of Silver Behenate and Silver Halide Emulsion A) 640 g of the above silver halide emulsion A was added to the above Na behenate solution, and the pH was adjusted to 8.1 with sodium hydroxide solution. 1M silver nitrate solution 6.
2 L was added, the mixture was stirred for 20 minutes, and the water-soluble salts were removed by ultrafiltration. The obtained silver behenate had an average particle size of 0.
The particles were 8 μm and had a monodispersity of 8%. After forming the flocs of the dispersion, water was removed, and the resultant was washed with water 6 times and removed, and then dried.

(Preparation of Coating Solution for Photosensitive Layer) A solution of polyvinyl butyral (average molecular weight 3000) in methyl ethyl ketone (17% by mass) was added to the preform emulsion obtained above.
3 kg and 4.5 kg of toluene were gradually added and mixed, and then dispersed at 4000 psi.

Using this dispersion, a photosensitive layer coating solution having the following composition was prepared. Methyl ethyl ketone 70 mass% Photosensitive emulsion dispersion 22.8 mass% Sensitizing dye-1 0.16 mass% Pyridinium bromide perbromide 0.29 mass% Calcium bromide 0.16 mass% Antifoggant-1 0.11. Mass% 2- (4-chlorobenzoyl) benzoic acid 0.87 mass% 2-Mercaptobenzimidazole 1.05 mass% Tribromomethylsulfoquinoline 1.62 mass% A-1 2.82 mass%

[0047]

[Chemical 1]

<Preparation of Coating Solution for Protective Layer> A coating solution for protective layer having the following composition was prepared.

Methyl ethyl ketone 82.7% by mass Cellulose acetate 4.61% by mass Methanol 11.0% by mass Phthalazine 0.50% by mass 4-Methylphthalic acid 0.36% by mass Tetrachlorophthalic acid 0.30% by mass Tetrachlorophthalic acid Anhydrous 0.34% by mass Monodisperse silica matting agent (monodispersity 10%, average particle size 4 μm) 0.14% by mass C ₈ H ₁₇ —C ₆ H ₄ —SO ₃ Na 0.020% by mass

[0050]

[Table 1]

In Experiment 1 (comparison), the mottled unevenness was the worst rank 1. In Experiment 2 (comparison), the sealing air volume was reduced to 25%, and the blocking effect of the sealing device was reduced due to the influence of the dynamic pressure of the air blown from the air outlet on the surface of the support, and the inert dryer Outside air and internal atmosphere come in and out from the support entrance and exit, resulting in an oxygen concentration of 10%, a safe range oxygen concentration of 6% or less to prevent explosion, and a coating length of 100 m
I canceled it. The coated sample was exposed and developed, and mottled unevenness was evaluated. The mottled unevenness was Rank 3 which was slightly improved from Experiment 1 due to the seal air volume being reduced to 25%.

In Experiment 3 (invention), surprisingly,
By increasing the outlet distance, the oxygen concentration was reduced to 5%, which is within the safety range for preventing explosion. Therefore, coating drying was performed up to a coating length of 5000 m. Mottled spots have improved to rank 5.

In Experiment 4 (invention), the oxygen concentration was further reduced to 2% by increasing the outlet distance to 150 mm, and the coating and drying were performed up to the coating length of 5000 m. Mottled spots have improved dramatically to rank 8.

In Experiment 5 (the present invention), the blowing wind speed was set to 7
When it was set to m / sec, the oxygen concentration further decreased to 1.5.
%, And the coating was dried up to a coating length of 5000 m. Mottled spots have improved to rank 9.

In Experiment 6 (invention), when the air outlet distance was set to 300 mm, the oxygen concentration was further reduced to 1.0.
%, And the coating was dried up to a coating length of 5000 m. Mottled spots have improved to rank 10.

In Experiment 7 (invention), the air outlet distance was 400 mm, but the oxygen concentration and mottled unevenness were the same as in Experiment 6.

In Experiment 8 (invention), the seal air volume was set to 10
Coating and drying were carried out up to a coating length of 5000 m in the same manner as in Experiment 6 except that the content was 0%. Although the oxygen concentration was the same as in Experiment 6, the mottled unevenness was reduced to rank 5 due to the influence of the seal airflow at the inlet of the drying device due to the increase of the seal airflow.

In Experiment 9 (comparison), the blowing wind speed was set to 15
Application and drying were performed in the same manner as in Experiment 3 except that m / sec was set. As a result, the oxygen concentration increased to 6.5%, probably due to the effect of increasing the blowing air velocity, and the oxygen concentration in the safe area for suppressing the explosion did not fall below 6%, and coating drying was stopped at a coating length of 100 m. . The coated sample was exposed and developed and evaluated for mottled unevenness. As a result, the mottled unevenness was reduced to rank 3 by increasing the blowing air velocity.

Example 2 Coating and drying were carried out under the same conditions as in Experiment 6 of Example 1 except for the seal air temperature.

[0060]

[Table 2]

Experiment 10 (invention) is Experiment 6 of Example 1.
Under the same conditions as. The mottled spot rank is also reproduced.

In Experiment 11 (invention), when the inlet seal temperature was raised to 35 ° C., mottled unevenness was slightly deteriorated due to the influence of the seal air temperature at the inlet seal portion, and the product was ranked 9, but There was no problem as a level.

In Experiment 12 (comparison), when the inlet seal temperature was set to 50 ° C., the mottled unevenness rank deteriorated to 5.

In Experiment 13 (comparison), when the inlet seal temperature was set to be the same as the drying temperature of 70 ° C., the mottled unevenness rank deteriorated to 3.

Example 3 The following experiment was conducted under the same coating conditions and drying conditions in an inert dryer as in Experiment 6 of Example 1.

The amount of residual solvent was determined by the following method. After coating and drying the sample, cut out an area of 46.3 cm ² , finely chop it to about 5 mm, store it in a dedicated vial bottle, seal it with a septum and an aluminum cap, and then use a Hewlett Packard headspace sampler HP7694 type. Set to.

The gas chromatography (GC) connected to the headspace sampler uses a Hewlett-Packard 5971 type equipped with a hydrogen flame ionization detector (FID) as a detector. The measurement conditions are as follows.

Headspace sampler heating conditions: 120 ° C., 20 minutes GC introduction temperature 150 ° C. Column: J &W's DB-624 Temperature rise: 45 ° C., 3 minutes hold → 100 ° C. (8 ° C./minute) Use to obtain a gas chromatogram. The measurement target solvent is water, methyl ethyl ketone, acetone,
After storing a fixed amount diluted with butanol of each solvent in a vial bottle, residual in the film using the calibration curve prepared using the peak area of the chromatogram obtained by measuring in the same manner as above Obtain the amount of solvent.

[0069]

[Table 3]

Experiment 14 (invention) was carried out in the second drying device as shown in FIG. 1 because the second drying device was not physically connected to the inert drying device and there was an open space. Experiment 6 of Example 1 was performed without being affected by the internal pressure of the device and the indoor pressure at the outlet of the second drying device, and the oxygen concentration was stable.
It was at the same level as.

Experiment 15 (comparison) is shown in FIG. 3, in which the second drying device is in an air atmosphere, but the second drying device is connected to the inert drying device, so that the second drying device is connected to the second drying device.
Due to the influence of the internal pressure of the drying device and the indoor pressure at the outlet of the second drying device, the outside air enters from the entrance and exit of the inert drying device, which is an inert atmosphere, and the oxygen concentration fluctuates beyond the safe area. It was unstable.

Experiment 16 (comparison) is shown in FIG. 4. Experiment 15 is performed because the inside of the second drying apparatus is also in an inert atmosphere.
Although the oxygen concentration did not change so much, the concentration of the solvent in the second drying device increased due to the influence of the atmospheric gas flowing out from the inert drying device, and as a result, the amount of the residual solvent in the coating film increased.

[0073]

According to the present invention, the oxygen concentration in the inert dryer can be kept low and the mottled unevenness can be improved.

[Brief description of drawings]

FIG. 1 is a schematic view of an inert drying device provided with a sealing device and a second drying device arranged with an open space provided between the inert drying device and the inert drying device.

FIG. 2 is a partially enlarged view of an inert drying device.

FIG. 3 is a schematic view of an inert drying device provided with a sealing device and a second drying device in an air atmosphere directly connected to the inert drying device.

FIG. 4 shows an inert drying device provided with a sealing device and a second inert atmosphere directly connected to the inert drying device.
Schematic of the drying device of FIG.

[Explanation of symbols]

0 support 1 die coater 2 back rolls 3 guide rolls 4 Inert dryer 5 Second drying device 6 Sealing device 7 slit nozzle

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03C 1/74 G03C 1/74 351 351 F term (reference) 2H023 EA05 2H123 BC00 3L113 AA02 AB02 AC47 BA28 DA24 4D075 BB24Z BB57Z BB91Z DA04 DB31 DB48 DC27 EA05 EA45 EB01 4F042 AA22 AB00 BA04 BA08 DB01 DB02 DB12 DC00 DD38 ED05

Claims (9)

[Claims] 1. In an inert drying apparatus in which the back surface of a coating film is held by a transport roll and an inert gas outlet is provided on the coating surface side, the distance between the outlet and the coating surface is 50 to 40.
0 mm, the blowing velocity of the inert gas is 0.1-10 m /
An inert drying device characterized by being sec. 2. The inert drying apparatus according to claim 1, wherein the most mass% solvent in the coating film coating liquid has a boiling point lower than that of water. 3. A method for producing an image forming material, which is produced by the inert drying apparatus according to claim 2. 4. A sealing device for blowing out an inert gas, which is installed in a portion before and after the coating film passes through the inert drying device according to claim 1, wherein the temperature of the inert gas blown out from the inlet sealing device and the temperature before the sealing device A sealing device, wherein the temperature difference from the environmental temperature is within a difference between the environmental temperature before the sealing device and the temperature inside the inert drying device immediately after the sealing device. 5. The sealing device according to claim 4, wherein the most mass% solvent in the coating film coating liquid has a boiling point lower than that of water. 6. A method of manufacturing an image forming material, which is manufactured by the sealing device according to claim 5. 7. A drying method in which, after passing through the inert drying apparatus according to claim 1, a second drying apparatus is disposed in which the coating film is conveyed while being folded back in an air atmosphere to evaporate the solvent in the coating film. A drying method comprising providing an open space between an inert drying device and a second drying device. 8. The drying method according to claim 7, wherein the most mass% solvent in the coating liquid for coating has a boiling point lower than that of water. 9. A method for producing an image forming material, which is produced by the drying method according to claim 8.