JP3001331B2 - Method for accelerating primer hardening of heavy corrosion resistant coated steel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for accelerating the hardening of a primer coating of a heavy corrosion-resistant coated steel material.

[0002]

2. Description of the Related Art Among heavy anticorrosion coatings of steel materials, there is a urethane resin coating. In many cases, the urethane resin is coated with a thermosetting resin primer such as an epoxy-based or urethane-based resin after a steel material is subjected to an undercoat treatment, and then the urethane resin is coated after the primer coating is cured. The thermosetting resin primer cures rapidly because the chemical reaction is greatly accelerated by heat. Therefore, depending on the resin at room temperature, the resin does not cure or the curing reaction proceeds, but the curing speed is slow and a sufficient curing period is required, which often impairs coating efficiency in the process. Therefore, a method of heating with a heating furnace, a method of heating with a hot air heater, a method of heating with a sheet heating element, a method of heating with an infrared heater,
And so on. However, it is not possible in terms of quality to heat the steel material with a heating furnace after painting because there is concern about thermal degradation of the primer coating, and it is necessary to heat it before painting, but when the size of the steel material becomes large If the cost becomes enormous, or if the size of the steel material is large, a uniform and sufficient temperature rise cannot be obtained in a short time, the load such as lapping work of the sheet on the steel material is large, and it is not suitable for large steel materials. It seems to be the most effective.
No. 1459 discloses a method for accelerating the curing of a coating film using a heating device that emits infrared rays of 0.72 to 1000 μm.
The simple heating device shown in the method can be used when there is some allowance both in time and space, but it is not necessarily optimal when the primer coating is to be cured in a shorter time in a smaller space. .

[0003]

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to efficiently cure a steel material coated with a thermosetting resin primer in a small space in a short time.

[0004]

Means for Solving the Problems The present inventors have studied the heating effect of an infrared heater and the curing reaction accelerating effect due to the absorption of a coating film. Reached.

That is, according to the present invention, a primer of thermosetting resin is applied to a steel material after a primer treatment such as grit blast, shot blast, sand blast, etc., and then the primer is cured. In the accelerating method, a steel material coated with heavy corrosion protection characterized by heating a primer-coated steel material sequentially or simultaneously with an infrared radiation heating device having a peak at a wavelength of 1 μm or less and an infrared radiation heating device having a peak at a wavelength of 2 to 10 μm. Is a method for accelerating the curing of the primer.

Hereinafter, the method of accelerating the hardening of the primer of the heavy corrosion-resistant coated steel according to the present invention will be specifically described.

FIG. 1 is a diagram showing a coating structure of a heavy corrosion-resistant coated steel material. In the figure, 1 is a steel material, 2 is a thermosetting resin primer layer, and 3 is a urethane resin coating layer. After the steel material 1 is subjected to a base treatment such as grit blast, shot blast, and sand blast, a primer of a thermosetting resin is applied by spraying or the like to form a primer layer 2. Primer layer 2
Is generally about 10 to 100 μm. After the primer layer 2 is cured, the urethane resin coating layer 3 is formed by spraying or the like. If the curing curing time of the primer layer 2 becomes long in the above process, the efficiency is hindered.

FIG. 2 schematically shows an example of the method for accelerating the curing of a coating film according to the present invention. In the figure, 1 is a steel material, 2
Is an infrared radiation heating device having a peak at a wavelength of 1 μm or less, and 5 is an infrared radiation heating device having a peak at a wavelength of 2 to 10 μm.

In the present invention, the thermosetting resin primer layer 2
Before the thermosetting resin primer layer 2 is cured, the steel material 1 formed with the infrared radiation heating device 4 having a peak at a wavelength of 1 μm or less is used together with the infrared radiation heating device 5 having a peak at a wavelength of 2 to 10 μm. Thus, the curing of the thermosetting resin primer layer 2 is promoted. That is, in the drawing, the steel material 1 moves to the right and passes under the infrared radiation heating device 4 having a peak at a wavelength of 1 μm or less, and the infrared radiation heating device 5 having a peak at a wavelength of 2 to 10 μm. The interval from application of the thermosetting resin primer layer 2 to the steel material 1 to promotion of the curing is not particularly limited in the present invention.

In the present invention, the infrared radiation heating device 4 having a peak at a wavelength of 1 μm or less mainly exhibits a heating effect. Therefore, when the thickness of the steel material 1 is relatively thick, 1 μm
Increase the output or increase the number of infrared radiant heaters 4 having a peak at a wavelength of less than m, or increase the number of infrared radiant heaters 4, shorten the gap between the infrared radiant heater and the primer coated steel material, etc. It is desirable to consider it. Conversely, if there is a concern that the thermosetting resin primer layer 2 may be deteriorated at a high temperature, the output of the infrared radiation heating device 4 having a peak at a wavelength of 1 μm or less is reduced or the number thereof is reduced. By increasing the gap between steel and painted steel
It is desirable to consider so as to reduce the heating effect.

The infrared radiation heater 5 having a peak at a wavelength of 2 to 10 μm exhibits a heating effect and the absorption wavelength of a general polymer material is distributed at 2 to 10 μm.
There is a reaction promoting effect by infrared absorption. Therefore, rather than a relatively high temperature, 2-10 μm
It is desirable to increase the output or increase the number of infrared radiation heating devices 5 having a peak at the wavelength.

The proper arrangement of the infrared radiation heating device 4 having a peak at a wavelength of 1 μm or less and the infrared radiation heating device 5 having a peak at a wavelength of 2 to 10 μm generally depends on the properties of the thermosetting resin primer. Typically 1
After sufficiently heating with an infrared radiation heating device 4 having a peak at a wavelength of μm or less, the temperature is maintained by an infrared radiation heating device 5 having a peak at a wavelength of 2 to 10 μm, and curing of the coating film 3 is accelerated by infrared absorption. Is desirably arranged to carry out. The output ratio of the infrared radiation heating device 4 having a peak at a wavelength of 1 μm or less and the infrared radiation heating device 5 having a peak at a wavelength of 2 to 10 μm is as follows.
And the thickness and properties of the thermosetting resin primer layer 2.

[0013]

Embodiments of the present invention will be described below in detail. After cleaning a steel plate (150 mm × 75 mm × 9 mm) by grit blasting, a non-solvent type two-component urethane-based primer was applied to a film thickness of 50 μm to prepare a primer-coated steel plate. 5 to 1 after painting of the primer coated steel
When the primer coating after 0 minutes is not cured, the wavelength is 0.8 μm
Infrared radiation heating device (width 500 mm, output 32 kW / m ² ) with a peak at the peak and infrared radiation heating device (width 500 mm, output 32 kW / m with a peak at a wavelength of 2.4 μm)
² ) are continuously arranged, and the coated steel sheet is moved at a distance of 200 mm from the two infrared radiation heating devices at a moving speed of 0.8.
It was moved at m / min. After 1.3 minutes of treatment, the coating was cured and had a pencil hardness of 6B. The maximum temperature of the primer-coated steel sheet during the treatment was 97 ° C. For comparison, when the primer coated steel sheet is left at room temperature,
The time for the primer coating to reach 6B in pencil hardness is 5.
5 hours. The primer coated steel sheet is
When placed in an oven at ℃, the time required for the primer coating to reach 6B in pencil hardness was 27 minutes.

From the above, it can be seen that the method for accelerating the curing of the primer of the present invention has a very large curing accelerating effect.

Subsequently, two-part solvent-free urethane paint was spray-coated on the primer-coated steel material subjected to the method for accelerating primer hardening of the present invention, and the quality was confirmed. The quality check method is to measure the adhesion of urethane coated steel sheet by pull-off method,
Further, the adhesion after immersion in 3% salt water at 60 ° C. × 60 days was also performed by a pull-off method. As a result, both were 80 kgf /
In the case of cm ² or more, the urethane coating film was cohesive failure, and it was confirmed that the application of the primer curing acceleration method of the present invention did not adversely affect the quality.

[0016]

According to the present invention, a steel material coated with a thermosetting resin primer can be efficiently cured in a small space in a short time.

[Brief description of the drawings]

FIG. 1 is a diagram showing a coating configuration of a heavy-corrosion-coated steel material which is an object of the present invention.

FIG. 2 is a schematic view of one example of a method for accelerating primer hardening of a heavy corrosion resistant coated steel material of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Steel material 2 ... Thermosetting resin primer layer 3 ... Urethane resin coating layer 4 ... Infrared radiation heating device which has a peak in the wavelength of 1 micrometer or less 5 ... Infrared radiation heating device which has a peak in the wavelength of 2-10 micrometers.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshiyuki Kawase 1 Kimitsu, Kimitsu City Nippon Steel Corporation Kimitsu Works Nippon Steel Corrosion Protection Co., Ltd. Kimitsu Works (72) Inventor Fumihiko Chino 1 Kimitsu, Kimitsu City Nippon Steel Corporation Kimitsu Works Inside Nippon Steel Corrosion Protection Co., Ltd. Kimitsu Works (56) References JP-A-55-51459 (JP, A) JP-A-60-232275 (JP, A) JP-A-1 −155969 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B05D 1/00-7/26 B05C 9/14

Claims (1)

(57) [Claims] 1. A method for promoting primer hardening of a heavy corrosion-resistant coated steel material in which a primer of a thermosetting resin is applied to a steel material after a base treatment and the urethane resin is coated with the primer after the primer has hardened, has a peak at a wavelength of 1 μm or less. A method for accelerating primer hardening of a heavy corrosion-resistant coated steel material, comprising heating a primer-coated steel material with an infrared radiation heating device and an infrared radiation heating device having a peak at a wavelength of 2 to 10 μm.