JPH0880466A - Method for preventing deposition of resin in coating film drying furnace and coating film drying furnace furnished with resin deposition preventive function - Google Patents

Abstract

PURPOSE: To securely prevent the deposition of resin on the inner wall face of a furnace and dry the coating film of a material to be coated by irradiating the inner wall face of the furnace on which resin is liable to deposit with NIR, reflecting the NIR from the inner wall face and projecting the reflected NIR into the material. CONSTITUTION: The periphery of a region on which resin is liable to deposit is irradiated with NIR by means of a unit 12 consisting of an NIR lamp 10 and a reflecting mirror 11 and heated. As a result, the condensation of resin on the region is prevented, and the deposition of resin is infallibly obviated. Further, since the density of the rays of NIR is high and the reflection itself is large, a wall face 13 capable of reflecting NIR toward a material 4 to be coated is formed on the periphery of the region on which resin is liable to deposit. The reflected NIR is effectively utilized to promote the drying of the coating film of the material 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is for preventing vaporized tar components from condensing on the inner wall surface of a furnace and adhering to the inner wall surface of the furnace as tar when drying paints, adhesives, inks and the like. TECHNICAL FIELD The present invention relates to a method for preventing tar adhesion and a coating film drying furnace with a tar adhesion prevention function.

[0002]

2. Description of the Related Art In a coating film drying oven, a paint, an adhesive, and an ink generate a solid element which becomes a resin. The amount of the generated solid element is related to the chemical composition of the resin used.

As an example, regarding the amount of tar generated in painting an automobile body, Masaharu Nishimura, “Painting Engineering 29,
[4], 161 (1949) ”are shown in Table 1.

[0004]

[Table 1]

[0005] The main constituents of tars are low molecular weight or unreacted components contained in resins used in paints, inks, adhesives, etc., used in paints, inks, adhesives, etc. by hot air. In order to make the volatile matter in which a part of the resin is oxidatively decomposed, the one that should originally be used as a two-pack type paint, into a one-pack type from the work, the reactive crosslinking agent should In the case of blocking with a compound and dissociating with heat in a coating film drying furnace to cure and dry, the blocking agent is a vaporized substance or the like.

A typical example of when the blocking agent is vaporized is a blocking agent of a thermally dissociated isocyanate compound found in cationic electrodeposition coatings and the like.

While these components are vaporized and oxidatively polymerized while adhering to the inner wall surface of the furnace or decomposed, they apparently form a dark brown or black brown oil in the form of a plate and are deposited.

The components heated and vaporized in the furnace adhere to low temperature parts such as the entrance and exit of the furnace body and the exhaust duct, and accumulate as oily or plate-like particles, which eventually fall or scatter. This has been a cause of so-called dust defects in the coating film of the object to be coated.

As a countermeasure against this, a method of burning the air in the furnace with an afterburner or cleaning the inside of the furnace at an extremely high frequency to remove the accumulated tar is adopted.

[0010]

However, the method of burning the air in the furnace by the afterburner in order to remove the resin has a problem of increasing fuel consumption.

A method of cleaning the inside of the furnace at high frequency is as follows.
The so-called dirty, bitter, and odorous 3K work not only compels the worker to perform painstaking work, but the powder peeled off during cleaning floats again in the furnace, and after cleaning it adheres to the inner wall of the furnace again, which causes dust defects. It does not necessarily mean that the cleaning effect is high.

Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art, to properly prevent the adhesion of the varnish to the inner wall of the furnace, and to protect the near-infrared rays irradiated to prevent the adhesion of the varnish. It is an object of the present invention to provide a method for preventing tar adhesion in a coating film drying furnace that can be effectively used for drying a coating film of a coating material.

Another object of the present invention is to precisely prevent the adhesion of tar to the inner wall surface of the furnace, and to dry the coating film of the near infrared rays irradiated to prevent the tar from adhering. Another object of the present invention is to provide a coating film drying furnace with a tar-sticking preventing function that can be effectively used.

Further, another object of the present invention is to provide a coating film drying furnace with a tar adhesion preventing function capable of further effectively preventing the adhesion of tar to the inner wall surface of the furnace.

[0015]

In order to achieve the above object, a method for preventing tar adhesion in a coating film drying furnace according to the present invention comprises:
At least irradiate the near-infrared wall surface of the furnace where the tar easily adheres to prevent the tar from adhering to the inside wall of the furnace, and reflect the gold infrared rays from the inside wall of the furnace to coat the reflected near-infrared ray. It is applied to an object and used to dry the coating film.

In order to achieve the above-mentioned object, the coating film drying oven with a function of preventing adhesion of tars of the present invention is provided with a near-infrared lamp for irradiating near-infrared rays on the inner wall surface of the furnace where the tars are likely to adhere, The wall surface is configured to reflect near infrared rays on the object to be coated in the furnace.

Further, in order to achieve the above-mentioned object, the coating film drying furnace with a function of preventing adhesion of tars of the present invention has an inner wall of the furnace body irradiated with the near infrared rays having an inner and outer double wall structure. is there.

[0018]

In the method for preventing tar adhesion in the coating film drying furnace of the present invention, near-infrared rays are irradiated to the furnace inner wall surface where the tar easily adheres, for example, the upper part near the furnace body entrance and exit and the furnace inner wall surface around the exhaust duct.

The near-infrared ray has a wavelength characteristic in which the amount of reflection is large because the near-infrared ray has a large absorption in metal and a large energy density.

Therefore, as described above, the temperature of the surface to be irradiated can be raised quickly by irradiating the inner wall surface of the furnace where the tar is apt to adhere, with the near infrared rays. In general, it is possible to properly prevent the adhesion of tars to the upper part of the furnace body entrance and exit where the temperature tends to be low, the inner wall surface of the furnace around the exhaust duct, and the like.

In the method for preventing tar adhesion in the coating film drying furnace of the present invention, the near infrared rays reflected from the inner wall surface of the furnace are applied to the object to be coated and used for drying the coating film.

Thus, the coating film of the object to be coated can be dried better from the inside by utilizing the reflected light of the near infrared rays irradiated to prevent the adhesion of tar to the inner wall surface of the furnace.

Further, in the coating film drying furnace of the present invention having a function of preventing adhesion of tar, the near-infrared lamp irradiates the inner wall surface of the furnace where the tar easily adheres with near infrared rays to rapidly raise the temperature of the inner wall of the furnace. .

This makes it possible to prevent the adhesion of tars to the inner wall surface of the furnace, and also to reflect near infrared rays from the inner wall surface of the furnace to the object to be coated in the furnace.

As a result, the coating film of the object to be coated can be dried by effectively utilizing the reflected light of the near infrared rays irradiated to prevent the adhesion of tar.

Further, in the coating film drying furnace with the function of preventing adhesion of tars of the present invention, the inner wall of the furnace body irradiated with near infrared rays is
Since the inner and outer double wall structure is used, the effect of raising the temperature of the wall surface can be further enhanced, and it becomes possible to prevent the adhesion of tar to the inner wall surface of the furnace from the initial stage of the operation of the drying furnace.

[0027]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a vertical cross-sectional side view showing an embodiment of a coating film drying furnace with a function of preventing adhesion of tars of the present invention, and FIG. 2 is Z of FIG.
It is a -Z line sectional view.

In the embodiment shown in these figures, the furnace body 1
And a trolley conveyor 2 having a hanger 3 for an object to be coated,
The hot-air generator 5, the hot-air duct 6, the hot-air circulation system, the near-infrared lamp 10, and the reflecting mirror 11 are provided.

As shown in FIG. 1, the furnace body 1 has a furnace body carry-in section A, a furnace body effective section B that follows the furnace body carry-in section A, and a furnace body carry-out section C that further follows the furnace body effective section B.

The furnace body carry-in section A and the furnace body carry-out section C are obliquely downward from the furnace body effective section B for the purpose of preventing the heat in the furnace from flowing out and the atmosphere temperature in the furnace from lowering. The furnace body 1 is formed in a mountain shape as a whole.

Reference numeral 9 in FIG. 1 denotes an exhaust duct, P
1, P2, P3 and P4 indicate points for explaining the action.

The trolley conveyor 2 suspends an article 4 to be coated on a hanger 3, and sends the article 4 to the next step through a furnace body loading section A, a furnace body effective section B, and a furnace body unloading section C. It is mounted to do.

The hot air generator 5 generates hot air and supplies the hot air from the bottom of the furnace body 1 to the effective furnace body B through the hot air duct 6.

The hot air circulation system comprises a circulation duct 7 and a circulation fan 8. The circulation duct 7 sucks a part of the air in the furnace, and the air is forced to the hot air generator 5 through the circulation fan 8. It is circulated and reused.

The near-infrared lamp 10 and the reflecting mirror 11 are constructed as one unit 12.

As the near-infrared lamp 10, for example, a lamp capable of irradiating near-infrared rays having a maximum wavelength peak of about 1.5 μm is used.

The reflecting mirror 11 is a concave mirror made of an aluminum plate, a copper plate, a mirror-finished iron plate or the like, and collects and reflects near infrared rays.

The unit 12 including the near-infrared lamp 10 and the reflecting mirror 11 is located around the P1 and the exhaust duct 9, which is the upper part of the furnace body entrance, which is a portion where the temperature tends to be lower structurally than the atmospheric temperature in the furnace. P2 around the suction port of the circulation duct 7, P4 at the upper part of the outlet of the furnace body
It is provided so as to correspond to the inner wall surface of the furnace where the tar easily adheres.

Then, at least the P1,
The periphery of P2, P3, and P4 is configured as a wall surface 13 capable of reflecting near infrared rays toward the object to be coated 4.

Next, with reference to the operation of the coating film drying furnace having a resin adhesion preventing function, the method for preventing resin adhesion in the coating film drying furnace of the present invention will be described.

In this embodiment, a typical object 4 coated with a cationic electrodeposition coating composition which produces a large amount of resin will be described.

First, hot air is generated by the hot air generator 5,
The hot air is supplied from the bottom of the furnace body effective portion B through the hot air duct 6 to keep the inside of the furnace body 1 at a required temperature.

Further, the near-infrared lamp 10 in the unit 12 of the near-infrared lamp 10 and the reflecting mirror 11 provided in the above P1, P2, P3 and P4 is turned on, and the near-infrared rays are condensed by the reflecting mirror 11 at the same time. , P1 and P
2, P3 and P4 are reflected on the inner wall surface of the furnace,
Near-infrared rays are radiated to the furnace inner wall surfaces of P2, P3 and P4.

The periphery of P1, P2, P3 and P4 is a portion which is usually lower than the temperature of the atmosphere in the furnace due to the structure of the furnace body, but near infrared rays are largely absorbed by the metal and have an energy density. Since it is large, it has a wavelength characteristic of a large amount of reflection, so that by irradiating the near infrared rays, the periphery of P1, P2, P3, and P4 is heated, and the temperature is rapidly raised.

Moreover, the near infrared rays are transmitted to the P1, P2 and P3.
And from the wall surface 13 around P4 toward the article 4 to be described later.

Next, the article 4 coated with the electrodeposition paint is hung on the hanger 3 supported by the trolley conveyor 2, and the article 4 is applied by the trolley conveyor 2 to the furnace body loading section A and the furnace body effective section B. Then, it is sent to the furnace body carry-out section C, the coating film is dried, and then sent from the furnace body carry-out section C to the next step.

As described above, the object to be coated 4 which has been coated with the electrodeposition coating material, hung on the hanger 3 and sent to the furnace body carry-in section A has the furnace body carry-in section A as the trolley conveyor 2 advances.
In the process of passing through, the water content and the solvent content are vaporized from the surface of the coating film.

Next, the article to be coated 4 advances to the effective part B of the furnace body, is heated by hot air, water and solvent components are removed from the warmed coating film, heat conduction is advanced, and the coating film becomes the dissociation temperature of the blocking agent. When the temperature reaches, the blocking agent such as a phenol resin containing an isocyanate compound is dissociated, the reaction of the resin is started, and a coating film is formed.

When the blocking agent is dissociated, the phenol resin and the like are vaporized by heat and mixed in the air in the furnace as a tar component, and the temperature of the atmosphere in the furnace required to keep the air in a vaporized state is higher than that. Part inside the furnace, that is, P1 around the upper part of the furnace body carry-in part A that is not directly heated and is easily affected by outside air, P1 around the exhaust duct 9, P3 around the circulation duct 7, and direct heating There is no part, and the upper part of the furnace body unloading part C, which is easily affected by the outside air, comes in contact with the heat to be deprived of heat, causing dew condensation to form a tar and adhere.

On the other hand, in this embodiment, the P
Near infrared lamp 1 around 1, P2, P3 and P4
Near infrared rays are emitted by the unit 12 of 0 and the reflecting mirror 11 to raise the temperature.

As a result, the P
Condensation of the resin on 1, P2, P3, and P4 can be prevented, and as a result, the adhesion of the resin can be accurately prevented.

Further, since the near infrared rays have a high luminous flux density, the amount of reflection itself is large.

Therefore, in this embodiment, P1, P
2, the periphery of P3 and P4 is a wall surface 13 capable of reflecting near infrared rays toward the object to be coated 4.

As a result, the reflected light of the near infrared rays can be effectively used to accelerate the drying of the coating film of the article to be coated 4.

Further, FIG. 3 is a vertical sectional front view showing another embodiment of the drying furnace of the present invention.

In the embodiment shown in FIG. 3, the above-mentioned P, which is a portion that is structurally lower than the ambient temperature in the furnace, is usually used.
Inner walls around 1, P2, P3, and P4 have a double-wall structure with a lid-shaped reflecting plate 14.

The reflection plate 14 is formed of a metal plate having good heat conduction and a reflection effect, for example, an aluminum plate, a copper plate, a mirror-finished iron plate, or the like.

The thickness of the reflection plate 14 is preferably about 0.5 mm in consideration of heat conduction and workability.

Then, the four corners of the reflection plate 14 are bent by a bender or the like to form a lid, and the lid is fixed to the inner wall of the furnace by welding or the like to reduce the contact area with the inner wall of the furnace and to reflect the light. The amount of heat flowing from the plate 14 to the furnace body can be reduced.

When the reflection plate 14 is irradiated with near infrared rays, the temperature of the reflection plate 14 rapidly rises, and
Since the temperature around 1, P2, P3 and P4 rises above the atmospheric temperature in the furnace and is maintained at that temperature, the temperature of the P1, P tends to be lower than the internal temperature of the furnace as described above.
2, it is possible to effectively eliminate the inconvenience that the tar is condensed and adheres to the periphery of P3 and P4.

Table 2 shows the relationship between the furnace atmosphere temperature and the furnace wall temperature in the hot air heating furnace as the coating film drying furnace, the furnace wall temperature when irradiated with near infrared rays, and the lid-shaped reflection plate 14 attached. The relationship of the temperature of the furnace wall when A 1 kW lamp was used as the near-infrared lamp. In addition, the temperature of the atmosphere in the furnace using only hot air is 120 ° C.

[0063]

[Table 2]

Other configurations and operations of the embodiment shown in FIG. 3 are similar to those of the embodiment shown in FIGS. 1 and 2.

[0065]

According to the above-mentioned invention of claim 1, near-infrared rays are irradiated to at least the inner wall of the furnace where the tar easily adheres to prevent adhesion of the tar to the inner wall of the furnace. Near-infrared rays are reflected from the inner wall surface of the furnace, and the reflected near-infrared rays are applied to an object to be used for drying the coating film.

Therefore, the adhesion of the varnish to the inner wall of the furnace can be accurately prevented, and the near-infrared rays radiated to prevent the adhesion of the varnish are also effectively used for drying the coating film of the coating object. obtain. .

According to the second aspect of the invention, a near-infrared lamp for irradiating near-infrared rays is provided on the inner wall surface of the furnace where the tar is prone to adhere, and the inner wall surface of the furnace is close to the object to be coated in the furnace. Since it is configured to reflect infrared rays, it is possible to accurately prevent the adhesion of tars to the inner wall of the furnace, and the near infrared rays that are irradiated to prevent the adhesion of tars are also used to dry the coating film on the coating object. It can be used effectively.

Further, according to the third aspect of the present invention, since the inner wall of the furnace body irradiated with the near infrared rays has a double-wall structure of inner and outer sides, the adhesion of the tar to the inner wall surface of the furnace is further improved. It can be prevented more effectively.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional side view showing an embodiment of a coating film drying furnace with a tar adhesion preventing function of the present invention.

FIG. 2 is a sectional view taken along line ZZ of FIG.

FIG. 3 is a vertical cross-sectional front view showing another embodiment of the coating film drying furnace with a tar adhesion preventing function of the present invention.

[Explanation of symbols]

 1 ... Furnace main body 2 ... Trolley conveyor 3 ... Hanger 4 ... Coated object 5 ... Hot air generator 6 ... Hot air duct 7 ... Circulation duct 8 ... Circulation fan 10 ... Near infrared lamp 11 ... Reflector 12 ... Near infrared lamp and reflector Unit 13 ... Wall surface that enables reflection of near infrared rays

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[Procedure amendment]

[Submission date] September 28, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0015

[Correction method] Change

[Correction content]

[0015]

In order to achieve the above object, a method for preventing tar adhesion in a coating film drying furnace according to the present invention comprises:
At least irradiate the near-infrared wall on the furnace wall where the tar easily adheres, prevent the tar from adhering to the inside wall of the furnace, and reflect the near-infrared ray from the inside wall of the furnace to coat the reflected near-infrared ray. It is applied to an object and used to dry the coating film.

Claims (3)

[Claims] 1. A near-infrared ray is irradiated onto at least a furnace inner wall surface to which a tar easily adheres to prevent the tar from adhering to the furnace inner wall surface, and a near-infrared ray is reflected from the furnace inner wall surface, and the reflected near-infrared ray is reflected. A method for preventing adhesion of tar in a coating film drying furnace, which comprises applying near-infrared rays to an object to be coated to dry the coating film. 2. A near-infrared lamp for irradiating near-infrared rays is provided on the inner wall surface of the furnace where the tar easily adheres, and the inner wall surface of the furnace is configured to be capable of reflecting the near-infrared ray to an object to be coated in the furnace. A coating film drying furnace with a function to prevent the adhesion of tars. 3. The coating film drying furnace with a tar-sticking preventing function according to claim 2, wherein an inner wall of the furnace body irradiated with the near infrared rays has an inner and outer double wall structure.