JPS6370246A - Coating and drying method for band-shaped material - Google Patents

Abstract

PURPOSE:To reduce the size of a device and to permit the economization in the quantity of heat and the improvement in a coating stage by cooling an inert gas supplied into an oven and coating chamber successively provided adjacently to each other and recirculating an org. solvent after condensing and recovering said solvent. CONSTITUTION:A band-shaped material 1 on which a coating liquid 4 is coated in the coating chamber 11 is dried in the oven 5 adjacent to said chamber. The inert gas is supplied from an inert gas supplying device 26 through feed ports 9, 12 into both the chambers 11, 5 to dry the band-shaped material while said material is kept run. The gas is discharged from discharge ports 10, 13 and is introduced into a condenser 16 where the combustible org. solvent in the coating liquid is condensed and recovered. The remaining inert gas is introduced into a pipeline of the gas supplying device 26 and is recirculated. The size of the device is thus reduced without requiring diluting air. The quantity of heat is thereby economized and the uniformly coated surface is obtd., by which the recovery rate of the solvent is increased.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention improves the drying process when producing photographic materials, for example, by applying a coating liquid to a long plastic support and drying it. It is something.

[Conventional technology]

Photographic light-sensitive materials and various other products in which various types of lamination or coating are applied to a long support such as a plastic sheet or paper are generally produced by coating the support with a coating liquid in which predetermined components are dissolved or dispersed in an organic solvent. It is produced by drying.

Conventionally, this drying method has generally been carried out by blowing hot air onto the support coated with the coating liquid or by irradiating it with infrared rays. In this drying method,
The solvent vaporized in the oven becomes highly concentrated and explodes, so a large amount of air was supplied into the oven to keep the solvent concentration below about 1/3 of the lower explosive limit.

As a result, in addition to the energy required to evaporate the solvent, thermal energy must be consumed to heat the dilution air and incinerate a large amount of exhaust gas.

In the past, various methods have been proposed to solve this problem, such as installing a heat exchanger to recover the heat generated by incinerating exhaust gas, and changing the solvent from organic solvent to water. .

On the other hand, a method is known in which hot inert gas air is blown into the oven during the drying process to prevent the solvent from exploding and eliminate the need for diluting air (Japanese Patent Publication No. 55-363
In this method, the organic solvent contained in the exhaust gas is removed by cooling and condensation, and the remaining exhaust gas (No. 89) is removed.
This explosion is prevented by circulating an inert gas (inert gas) through the oven.

[Problem that the invention seeks to solve]

In the method of recovering the combustion heat of exhaust gas using a heat exchanger, the heat recovery rate by heat exchange is only about 50 to 60%, and the heat exchanger requires a large capacity, so the equipment cost is high and it is not sufficient. It was not a solution.

In addition, the method of using water as a solvent is unsuitable because the amount of thermal energy consumed increases to evaporate the water.

Drying in an inert gas also sometimes caused problems with coating uniformity.

SUMMARY OF THE INVENTION An object of the present invention is to provide a means for coating and drying a strip, which solves these problems, makes the drying equipment compact, reduces thermal energy consumption, and improves the coating process.

[Means for solving problems]

As a result of intensive studies to achieve this purpose, the inventor of the present invention has developed a method in which coating and drying are both carried out in a room filled with inert gas, and organic solvents are recovered from the exhaust gas discharged from these rooms. By circulating and supplying this material, the present invention was completed based on the discovery of numerous advantages such as making the entire apparatus compact and stably producing strips of highly uniform quality.

That is, in the present invention, when applying a coating liquid containing a flammable organic solvent and drying it while running a belt-shaped support,
A device for applying the coating liquid is installed in a coating chamber, a drying oven is connected to the coating chamber, an inert gas is supplied into the oven and the coating chamber, and the inert gas discharged from these is cooled. coating the strip, characterized in that the organic solvent contained therein is condensed and recovered, and the remaining inert gas is circulated into the oven and the coating chamber;
This relates to a drying method.

There are no particular restrictions on the type of band-shaped product, and it is one in which a coating liquid in which the necessary components are dissolved or dispersed in a flammable organic solvent is applied to a support such as various plastic sheets or paper, depending on the purpose. It is.

An appropriate flammable organic solvent is selected depending on the components to be dissolved or dispersed, and examples thereof include benzene, toluene, alcohol, acetone, methyl acetate, and methylene glycol.

A conventional device may be used for applying the coating liquid. This coating device is installed in a coating chamber formed by a sealed casing in order to maintain an inert gas atmosphere around it. In principle, the coating liquid is prepared outside the coating chamber and supplied to the coating device via piping. In addition, the casing is provided with an inlet and an outlet for the support, an inert gas outlet and an exhaust outlet, etc.
The openings at the inlet and outlet of the support should be kept to a minimum in order to reduce leakage of inert gas. Since the coating liquid has not yet been applied to the support passing through the inlet, it is preferable to provide a pair of rolls or the like to create a sealed structure.

A drying oven is installed in the coating room. This drying oven also has a closed structure, and the openings at the inlet and outlet of the strip are kept to a minimum in order to reduce leakage of inert gas.

The inert gas is a gas that can inhibit combustion in the atmosphere, such as nitrogen gas or carbon dioxide gas. The temperature and air volume of the inert gas blown into the oven are set so that the strip can be dried to a predetermined degree, and are set appropriately by taking into consideration the type of strip, size and running speed, type of organic solvent, etc. It is set so that An infrared heater or the like may also be provided within the oven as an auxiliary heat source.

The purpose of the inert gas blown into the coating chamber is to maintain a constant state of the coating liquid. If the temperature is too low, problems such as precipitation of coating liquid components will occur, while if it is too high, the amount of solvent will evaporate, so the temperature of the inert gas should be set so as to be kept constant in the middle. . It is preferable to reduce the amount of airflow as much as possible within a range that can maintain a constant indoor condition in order to reduce the amount of solvent evaporation. In order to reduce the amount of heat transferred from the oven to the coating chamber, it is desirable to provide a heat insulating mechanism such as a heat insulating material therebetween.

A blower is provided to blow inert gas into the oven and coating chamber, while an exhaust fan is provided to exhaust the inert gas from the oven and coating chamber. It goes without saying that either the blower or the exhaust fan can be omitted depending on the size of the oven or coating chamber.

The gas discharged from the oven and coating chamber contains a high concentration of evaporated organic solvent vapor.

Therefore, the exhaust gas is first cooled to condense the organic solvent vapor and then recovered. This condensation may be carried out using a conventional device for cooling and condensing organic solvent vapor.

The inert gas discharged from the condenser is then circulated within the oven and into the coating chamber. Between the condenser and the oven and between the condenser and the coating chamber, a heater for heating an inert gas, a dust prevention device, the above-mentioned blower, and the like are provided as appropriate.

As can be seen from the above description, the drying apparatus used to carry out the method of the present invention is a substantially closed system, and has an inert gas circulation circuit.

[For production]

In the method of the present invention, the coating device is covered with a casing and coating is performed in an inert gas atmosphere, thereby enabling coating under high concentration vapor of the solvent, reducing evaporation of the solvent, and maintaining constant coating conditions. has been achieved. Further, by performing drying in an inert gas atmosphere, explosion of the evaporated solvent vapor is prevented and a high concentration state in the oven is made possible.

〔Example〕

FIG. 1 is a flow sheet showing an example of a coating and drying apparatus used in the method of the present invention.

As shown in the figure, a strip 1 is unwound from a raw roll 2,
A coating liquid 4 is applied using a known coating device 3 .

Then, it is dried in an oven 5 and wound onto a winding roll 6. The oven 5 is a long-sided sealed type, and has a slit-shaped open lower 7 on both end faces in the longitudinal direction, through which the strip 1 passes.
' is provided. An inert gas outlet 9 and an exhaust outlet 10 are provided on the upper surface of the oven 5.

The coating device 3 is housed in a coating chamber 11 connected to the oven 5. An inert gas outlet 12 and an exhaust outlet 13 are provided on the upper surface of the coating chamber. Further, a sealing device 8 for the pair of rolls is provided between the coating device and the original roll. From the exhaust port 10, the condenser 1 is connected via the exhaust fan 14.
6. Similarly, from the exhaust port 13, the exhaust fan 1
5 to a condenser 16. 17 is a cooler that sends refrigerant to the condenser 16, and 18 is a receiving tank for the condensed solvent. One system of exhaust gas coming out of the condenser is connected to the air outlet 9 via a dust prevention device 19, a heating heater 20, and an air blower 21. Another system is connected to the air outlet 12 via a dust prevention device 22, heater 23, and blower 24. Feedback piping 25 is provided from the oven 5 to the piping between the dust prevention device and the condenser, and by circulating inert gas within the oven, thermal energy is saved. 26 is a gas supply device for replenishing inert gas.

A strip 1 was coated with a coating liquid 4 in which a photosensitive diazo compound, a photopolymerizable composition, etc. were dissolved in acetone using polyethylene terephthalate as a support, and was dried using such an apparatus. The temperature inside the oven was 90° C. and the temperature inside the coating chamber was 30° C., and 95% of the solvent contained in the exhaust gas from the oven 5 and the coating chamber 11 was recovered in the condenser 16. The strips were completely dried, the quality was constant, and operation continued without any particular trouble.

〔Effect of the invention〕

The method of the invention also does not require dilution air, thus making the entire circulation system compact. The coating of the resulting strip is also constant, and a homogeneous product can be stably obtained. Since the organic solvent in the exhaust gas is also recovered from the oven and the coating chamber, the recovery rate of the solvent can be increased. In addition, the recovered solvent can be reused or used for other purposes.

[Brief explanation of the drawing]

FIG. 1 is a flow sheet showing an example of a drying apparatus used in the method of the present invention. DESCRIPTION OF SYMBOLS 1... Band-shaped object, 3... Coating device, 4... Coating liquid, 5
...Oven, 11...Coating chamber, 16...Condenser, 26...Inert gas supply device. Patent Applicant Fuji Film Co., Ltd. Agent Patent Attorney 1) Masahiro Naka (and 1 other person) Prosecution Neyama Masashi (spontaneous) March 30, 1985 Commissioner of the Japan Patent Office Kuro 1) Tono Akihiro 1 Special indication of the case Application No. 61-212772 2 Name of the invention Method for coating and drying a strip 3 Relationship with the case of the person making the amendment Name of patent applicant (520) Fuji Photo Film Co., Ltd. 4 Agent residence Address: 3 Hatchobori, Chuo-ku, Tokyo 104 Chome 21-3-6
Column 6 of Detailed Description of the Invention in Specification No. 67 Contents of amendment (1) Changed “flammability” from line 5 on page 5 of the specification to “combustible”
I am corrected. (2) Add "do" after "heating" in paragraph 7, line 20 of the specification. that's all

Claims (1)

[Claims] When applying and drying a coating liquid containing a flammable organic solvent while running a strip support, a device for applying the coating liquid is installed in a coating chamber, and a drying oven is connected to the coating chamber, An inert gas is supplied into the oven and the coating chamber, the inert gas discharged from these is cooled, the organic solvent contained therein is condensed and recovered, and the remaining inert gas is transferred to the oven and the coating chamber. A method for coating and drying a strip, characterized by circulating the material into a coating chamber.