JP2807077B2 - Prevention system for fume adhesion in the drying oven of painted coil material - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a continuous coating system for coil materials, and more particularly, to fume adhesion prevention in dry baking after continuous coating of coil materials such as cans and lids. About the system.

(Prior art and problems to be solved) Aluminum materials and the like are used as materials for various cans and lids, but they are painted before being formed into three-piece can bodies and lids. .

Conventionally, in this coating, a coating material is applied to a sheet material and then baked with hot air in a drying furnace. In the case of coating on both sides of the sheet material, one side is coated and dried, and then the other side is coated and dried in the same manner.

However, in the case of a sheet material, since it is held and processed for each sheet, it takes a long time for drying and baking after coating, and there is a disadvantage that production efficiency is poor.

For this reason, recently, a method in which a coil material is used as a treatment material and one or both surfaces thereof are continuously coated and dried and baked has been adopted, and improvement in productivity is expected.

However, in the case of continuous coating, high temperatures (eg, 260
-285 ° C) and drying for a short time (eg, 20-17 seconds) is essential. However, since the drying temperature is high, the solvent of the paint evaporates and fumes are generated. When a large amount of low-molecular components volatilized) is generated, it deposits and deposits on the inner wall of the drying furnace, the duct in the furnace, and the outer periphery of the nozzle, and finally the attached fume peels off in a thin film form, so-called small paint particles. As a result, it fell on the coil, and there was a problem that the painted surface was stained.

In order to solve this problem, fumes adhering to the inner wall of the drying oven, the duct in the oven, and the outer periphery of the nozzle may be removed periodically, for example, two to three times a week. There is a problem that the work is difficult and requires a lot of manpower and cost.

In addition, if an open system is used that exhausts the hot air discharged for drying and discards it into the atmosphere, and always supplies new hot air into the furnace, the fume concentration will decrease, and the fume concentration will decrease. Almost no fume deposits are deposited, but exhaust treatment is costly and uneconomical.

On the other hand, if a closed system that circulates and uses the discharged hot air used for drying is used, the cost of exhaust processing is relatively low and it is economically advantageous, but when this exhaust hot air is supplied to the nozzle, fumes are included. Fumes on the inner walls of the drying furnace
As before, a fume removing operation is required, which increases the cost. Alternatively, an expensive combustion device is required to completely burn the exhaust hot air and remove most of the fume, which also increases the cost.

An object of the present invention is to solve the above-mentioned disadvantages of the prior art and to provide a system capable of preventing fume adhesion at a low cost in a drying furnace for a coated coil material.

(Means for Solving the Problems) In order to solve the above problems, the present inventor has obtained a coil material having a high quality painted surface which can reduce the amount of fume deposition at a low cost for a closed system that circulates and uses hot air. We conducted intensive research on possible measures.

As a result, there is a characteristic peculiar to fume generation development in a drying furnace, there is a solvent evaporation zone and a fume generation zone following this in the furnace, and the latter fume generation zone has
There is a zone where light fumes are generated and a zone where heavy fumes are generated.Furthermore, light fume does not easily adhere to the drying furnace inner wall, but heavy fume adheres to the furnace inner wall. It turned out to be easy.

Therefore, the present invention has been made as a result of further research on a method of reducing the amount of the heavy fume attached to the inner wall of the furnace so as not to fall on the coil.

That is, according to the present invention, when the coating material is continuously applied to the coil material and then dried in a drying furnace at a high temperature for a short time and baked, the inside of the drying furnace is divided into a solvent evaporation zone and a fume generation zone. In the fume generation zone where hot air is circulated in a closed system, the amount of air replaced is increased from the amount of air replaced in the solvent evaporation zone to reduce fume concentration and reduce the amount of fume adhering to the furnace inner wall in the fume generation zone. The present invention provides a method for preventing fume adhesion in a drying oven of a coated coil material, which is characterized by leveling.

Another aspect of the present invention is a system in which a coating material is continuously applied to a coil material and then dried in a drying furnace at a high temperature for a short time and baked. It is divided into an evaporation zone and a fume generation zone, the supply and discharge of hot air to the nozzle in the fume generation zone is a closed system, and in this system, the replacement amount of air in the fume generation zone is calculated based on the replacement amount of air in the solvent evaporation zone. A fume concentration control system that reduces fume concentration and reduces the amount of fume adhering to the furnace inner wall in the fume generation zone to a low level. The gist of the device is as follows.

 Hereinafter, the present invention will be described in more detail.

(Operation) As described above, in the case of continuous coating of the coil material, there are a solvent evaporation zone and a fume generation zone in the drying furnace, and the fume generation zone includes a zone where light fume is generated and a fume zone for heavy. There is a zone in which fumes are generated, and heavy fume easily adheres to the inner wall of the furnace. Therefore, if the amount of the fume is reduced to a level that causes no actual harm, it is possible to prevent the fume from falling onto the coil.

The fume generation and adhesion situation will be described with reference to an example of a drying furnace including eight zones shown in FIG.
As shown in FIG. 2, no fume was observed in zones No. 1 to No. 3 and fume was adhered in zones No. 4 to No. 8, especially in zones No. 5 and No. 6. Many. This is because the solvent is blown off in the first half (No. 1 to No. 3 zone) of the drying oven, and fumes are generated and adhered in the baking process in the second half (No. 4 to No. 8 zone). Moreover, in the fume generation zone, there are light fume generation zones that do not easily adhere to the furnace inner wall and heavy fume generation zones that easily adhere to the furnace inner wall, and a large amount of light components is generated in the first half of the fume generation zone. However, in the second half (especially in zones No. 5 and No. 6), a lot of heavy components are generated.

In the present invention, based on the investigation result of the fume generation and adhesion phenomenon, as a means for mainly reducing the amount of fume adhesion of the heavy component, the air replacement amount (No. (Intake and discharge).

That is, when the amount of air exchange in this zone is increased, the fume mixing ratio is reduced, so that the fume concentration is reduced and the fume adhesion amount in the fume generation zone can be leveled to a low level. For example, if the intake and exhaust volume is 400 Nm ³
When the fume amount is increased from 800 Nm ³ / min to 800 Nm ³ / min, the amount of fume deposition can be substantially reduced to a target value (eg, 15 mg / dm ² or less per week), and fume falling onto the coil can be almost prevented.

Furthermore, if a catalytic filter is installed in the circulation system of the process hot air in this zone, the target value of fume deposition (10 mg / dm ² or less per week) can always be stably secured, and the fume falling onto the coil can be completely prevented. Can be prevented. The catalytic filter may be a catalyst capable of converting heavy fumes into light fumes, such as a platinum catalyst filter.

Of course, such an effect can be similarly obtained when the number of zones of the drying furnace is reduced or increased, or similarly obtained when the ultimate temperature or temperature distribution in the drying furnace is changed from that shown in the drawing. .

The hot air supply / discharge system in the solvent evaporation zone may be designed in the same manner as in the related art, and a closed system is usually used.

Next, the present invention will be described in more detail by showing examples.

(Example 1) This example is an example in which the air volume in the fume generation zone is increased.

In FIG. 3, the drying furnace 1 is composed of eight zones,
In each zone, eight sets of nozzles are arranged in a staggered manner. In these zones, zones No. 1 to No. 4 are classified as solvent evaporation zones, and zones No. 5 to No. 8 are classified as fume generation zones.

The nozzles in each zone have the structure shown in FIG. 4, and hot air is supplied to the nozzles 10 arranged vertically and in a staggered manner, and are surrounded by partitions 11 provided on both sides of the eight nozzles. Air is taken in from the outlet 12 facing the space. Of course, the number of nozzles may be any number. In the figure, 13 is a hot air fan.

The fume generation zone is a closed system provided with at least the heat exchanger 2 and the temperature and air volume control device 3, and may be provided with a constant displacement device 4 and a catalytic insinator 5 as necessary. As the catalyst of the catalytic insinator, a catalyst having a low operating temperature of, for example, 450 ° C. may be used, and palladium or the like can be used.

The temperature and air volume control device 3 controls the air volume in each zone, as well as controlling the temperature (coil temperature) in the drying oven so as to have a predetermined temperature distribution according to the baking conditions. is there.

On the other hand, the solvent generation zone is a closed system provided with a heat exchanger 6 and a direct combustion type insinator 7 (eg, operating temperature of 700 ° C.), and may be provided with a constant displacement device 4. Although not shown, it goes without saying that the temperature inside the furnace in this zone is controlled by a temperature control device, and the above-mentioned temperature air volume control device 3 may be used for that purpose.

A fume adhesion test on the inner wall of the furnace was performed for one week by using such a drying furnace control system. The results are shown in FIG.

In the conventional example, the air volume is 400 Nm ³ / min in each zone. In the No. 5 and No. 6 zones, the fume adhesion amount is large, but in this example, the air volume in the zone where the fume generation is large is 40%.
When the control is increased, it can be seen that the fume adhesion amount in the No. 5 and No. 6 zones is reduced, and the fume adhesion amount is leveled in all the zones. If the fume adhesion amount is as low as this, the operation of removing the fume from the furnace inner wall may be performed once a week.

(Example 2) This example is an example in which a platinum catalyst filter is provided in the circulation system of the process hot air in the fume generation zone in Example 1.

As shown in FIG. 5, the catalyst filter 14
The structure is shown in FIG.

FIG. 7 shows the result of one week of the fume adhesion test performed on the inner wall of the furnace in the same manner as in Example 1.

It can be seen from the figure that the fume adhesion amount leveled low in Example 1 is further reduced, and that the fume adhesion amount of 10 mg / dm ² can be stably achieved. As a result, it was possible to completely prevent the fume from falling onto the coil without performing the fume removing operation on the inner wall of the furnace for at least one week.

It is needless to say that the present invention can be applied to continuous coating of coils of various materials, and that single-sided continuous coating is also possible.

(Effects of the Invention) As described in detail above, according to the present invention, it is possible to reduce the amount of fume adhering to the inner wall of the drying furnace during continuous coating of the coil material. The advantages of coating can be fully exhibited and a high quality coated coil material can be provided at low cost. In addition, since it is a closed system, it is economical.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a continuous coating facility, FIG. 2 is a diagram illustrating an example of a situation of solvent evaporation and fume generation and adhesion in a drying furnace, and FIG. 3 is a configuration of a fume adhesion prevention system according to an embodiment of the present invention. FIGS. 4 and 5 are cross-sectional views illustrating the structure of the nozzle portion, FIG. 6 is a partial cross-sectional view illustrating a state in which a catalyst filter is provided in the nozzle, and FIG. 7 is obtained in the embodiment. It is a figure which shows the fume adhesion | attachment state to the furnace wall which fell. DESCRIPTION OF SYMBOLS 1 ... Drying furnace, 2, 6 ... Heat exchanger, 3 ... Temperature air volume control device, 4 ... Constant displacement device, 5 ... Catalyst type insinator, 7 ... Direct combustion type insinator, 10 ... …nozzle,
14 ... Catalyst filter.

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masatoshi Yamamoto 6-4-1 Wakabadai, Shiroyama-cho, Tsukui-gun, Kanagawa Prefecture (56) References JP-A-55-155763 (JP, A) (58) Fields investigated (Int) .Cl. ⁶ , DB name) B05C 9/14 B05D 3/02 B01D 53/36 F26B 13/10 B05C 15/00

Claims (5)

(57) [Claims] When a coating material is continuously applied to a coil material and then dried in a drying furnace at a high temperature and in a short time for baking, the inside of the drying furnace is divided into a solvent evaporation zone and a fume generation zone. In the fume generation zone where hot air is circulated in a closed system, the air replacement amount is increased from the air replacement amount in the solvent evaporation zone to reduce the fume concentration, and the fume adhesion amount to the furnace inner wall in the fume generation zone is reduced. A method for preventing fume adhesion in a drying oven of a coated coil material, characterized by leveling. 2. The method according to claim 1, wherein a fume deposition amount is reduced by using a catalyst filter in a circulation system of the process hot air in the fume generation zone. 3. A system in which a coating material is continuously applied to a coil material and then dried in a drying furnace at a high temperature in a short time and baked. It is divided into a fume generation zone, and the supply and discharge of hot air to the nozzles in the fume generation zone is a closed system, and, in this system, the air replacement amount in the fume generation zone is larger than the air replacement amount in the solvent evaporation zone. An apparatus for preventing fume adhesion in a drying oven for a coated coil material, comprising a temperature air volume control device for reducing fume concentration and leveling out fume adhesion to a furnace inner wall in a fume generation zone to a low level. 4. The apparatus according to claim 3, wherein a catalyst filter is used in a circulation system of the process hot air in the fume generation zone. 5. The apparatus according to claim 3, wherein a catalytic-type insinator is provided in a hot air supply / discharge system in the fume generation zone.