JPH0525738Y2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The invention involves applying a radical-reactive ultraviolet curing paint to the outer peripheral surface of a metal tube or rod (hereinafter collectively referred to as metal tube). This invention relates to a metal rust prevention treatment device that cures a coating film by irradiating it with ultraviolet rays. More specifically, the present invention relates to a metal rust prevention treatment device using an ultraviolet curable resin that can maintain a low atmospheric oxygen concentration during ultraviolet irradiation.

(Conventional technology) Ultraviolet curable paints (1) cure in seconds without the need for heating, and (2) have almost no volatile components and are almost 100% coating components, so they pose problems of air pollution. Furthermore, (3) equipment costs are relatively low and work can be done in a small space. In addition to this advantage, it has a large rust-preventing effect when applied to the surface of steel materials, so recently it has come to be applied not only to steel plates but also to the outer peripheral surfaces of steel pipes, bars, etc.

However, when a radical-reactive UV-curable paint film is cured in the air, the reactive radicals generated by UV irradiation react with oxygen, producing highly polar substances such as peroxides and curing. The water absorption and water permeability of the coating surface layer (approximately 10 μm) are relatively large, and the hardening of the surface exposed to the atmosphere is generally delayed compared to the internal hardening, resulting in a decrease in the rust prevention properties of the coating, and metal The problem was that a sufficient rust prevention effect could not be obtained as a rust prevention treatment.

It is known that such a decrease in the antirust effect on the surface of the coating can be prevented by performing the irradiation in an inert gas atmosphere. For example, JP-A-63-
Publication No. 214375 describes that the ultraviolet irradiation is performed at different oxygen concentrations.
A method is disclosed in which the inertness of 0.5vo1% or less is carried out in an inert atmosphere.

Various proposals have been made regarding methods and devices for performing ultraviolet irradiation in an inert gas atmosphere. For example, in Japanese Patent Application Laid-Open No. 58-101765, a metal tube whose outer circumferential surface is coated with an ultraviolet curable paint is moved through a quartz tube that is tightly filled with inert gas between the metal tube and the metal tube. A method is disclosed in which the quartz tube is cured by irradiation with ultraviolet light from outside the quartz tube.

(Problem that the invention aims to solve) Painting metal pipes with UV-curable paint usually involves two methods: one is a painting room where the UV-curable paint is sprayed onto the outer surface of the metal pipe, and the other is where the paint film is cured by irradiating UV light. This is carried out by using a device consisting of an irradiation chamber and passing the metal tube sequentially through the coating chamber and the irradiation chamber while being moved by conveyance rollers. Adjustment of the thickness of the coating film is carried out using a squeeze board or the like installed on the exit side of the coating area in the coating chamber. At that time, if the uncured coating film, especially the uncured coating film whose thickness has been adjusted by the ironing plate, comes into contact with the conveying roller, scratches will be generated on the coating film, making the rust prevention treatment uncertain. Therefore, there are usually no conveyor rollers between the squeeze plate and the exit of the irradiation chamber, but in that case, it is unavoidable that the metal tube vibrates during movement, and the maximum amplitude is ±2.5mm.
Since there is some degree of vibration, if the ironing board is fixed, there will be large variations in the film thickness after the coating film is adjusted.

Conventionally, by attaching the stripping board to the wall of the painting room with springs, the stripping board follows this vibration and suppresses variations in film thickness.

However, when the irradiation chamber is sealed for irradiation in an inert gas atmosphere, it is necessary to connect the irradiation plate to the entrance of the irradiation chamber, and this connection restricts the movement of the irradiation plate and prevents the metal tube from vibrating. It was found that the variation in film thickness became large due to insufficient tracking. For example, for a required film thickness of 12 μm, ±
Very large variations in film thickness of about 10 μm were observed, and there were cases in which a sufficient rust prevention effect could not be obtained.

The purpose of this invention is to reduce ultraviolet irradiation to oxygen concentration in order to prevent the deterioration of the rust prevention effect on the coating surface.
An object of the present invention is to provide a rust prevention treatment device for metal pipes using an ultraviolet curable resin, which can be carried out in an inert gas atmosphere of 0.5Vo1% or less and can reduce variations in film thickness.

(Means for Solving the Problems) As a result of studies to achieve the above object, the inventors of the present invention have determined that by configuring the connecting part between the scrubbing board in the painting chamber and the irradiation chamber with bellows, this connecting part can be moved. The present invention was completed by discovering that the vibration of the squeeze plate that follows the vibration of the metal tube inside is not hindered, and as a result, it is possible to suppress variations in film thickness.

The gist of this invention is that it consists of a coating chamber where radical-reactive ultraviolet curable paint is applied to the outer circumferential surface of a metal tube or rod, and an irradiation chamber where ultraviolet rays are irradiated to cure the coating film. A metal rust prevention treatment device using an ultraviolet curable resin for a metal tube or rod, the outer circumferential surface of the metal tube or rod being swingably disposed toward the outlet side from the coating area in the painting chamber. An ironing plate having an opening formed of an elastic material having a shape that fits tightly, one end of which is located inside the painting chamber, and the other end of which is connected to the entrance side end surface of the irradiation chamber to connect the two. , a connecting sleeve at least partially constituted by a bellows; a sealing material provided at the exit side opening of the irradiation chamber to substantially prevent air from entering during irradiation; and an inert gas supply pipe leading into the irradiation chamber. 12
A metal rust prevention treatment apparatus using an ultraviolet curable resin, further comprising the following.

(Operation) The device of the present invention will be explained with reference to the attached drawings.

As shown in FIGS. 1 and 2, the apparatus of the present invention is comprised of a coating chamber 1, an irradiation chamber 2, and a bellows-type connecting sleeve 3 connecting the two as main components.

The cross-sectional shape of the metal tube, which is the object to be coated that can be treated with the apparatus of the present invention, may be circular, polygonal, oval, etc., and is not limited to a tube, but may be a rod.

The metal tube 4, which is the object to be treated, first enters the coating chamber 1 while moving on conveyance rollers 5. Painting room 1
Inside, an ultraviolet curable paint is sprayed from a plurality of paint nozzles 6 arranged around the metal tube 4 and applied to the outer circumferential surface of the metal tube 4 while it is moving. The metal tube 4 to which the paint is applied passes through an opening in a scrubbing plate 7 provided on the exit side from the application area in the painting chamber, and the film thickness is controlled by removing excess paint.
The squeezing plate 7 has an opening shaped to fit closely to the outer peripheral surface of the metal tube (for example, if the metal tube is circular, a circular hole with a diameter slightly smaller than the outer diameter of the metal tube). The periphery is made of an elastic material such as rubber. The film thickness is adjusted by changing the dimensions of the opening of this squeezing plate 7.

The scrubbing board 7 is swingably supported on the wall surface of the painting room by springs 8 attached to the four corners, for example. This ensures the ability of the wiping board to follow the vibrating metal tube, and suppresses variations in coating film thickness.

As mentioned above, the squeeze board is made of an elastic material, usually rubber, at least around the opening through which the metal pipe passes. In the example shown in FIG. 1, the entire squeeze plate is made of rubber, and a supporting plate made of a rigid material is attached to the outer periphery for reinforcement. In the squeezing board shown in FIG. 2, squeezing rubber 9 is provided only around the opening. The rubber preferably has both solvent resistance and abrasion resistance, and specific examples include ethylene propylene rubber (EPR) and ethylene propylene terpolymer rubber (EPT).

The metal tube 4 leaves the coating chamber 1 through the squeeze plate 7, and then proceeds to the irradiation chamber 2 to be irradiated with ultraviolet light. In the device of the present invention, the squeeze plate 7 of the coating chamber 1 is connected to the inlet end face of the irradiation chamber 2 by a connecting sleeve 3 at least partially made of a rosette. One end of this rosette is located inside the coating chamber and connected to the squeeze plate, and the other end is connected to the inlet end face of the irradiation chamber. The material of the rosette is not particularly limited, and it may be made of rubber similar to that used for the squeeze plate, or metal. By surrounding the metal tube leaving the squeeze plate with a connecting sleeve made of a rosette and connecting both ends to the squeeze plate and the inlet end face of the irradiation chamber, respectively, it is possible to prevent air from flowing into the irradiation chamber and maintain an inert gas atmosphere. Moreover, by using the rosette, the connecting part does not hinder the oscillation of the squeeze plate, so that the squeeze plate can be maintained to follow the metal tube, and the variation in coating thickness is suppressed. For this purpose, it is preferable that the entire connecting sleeve 3 is made of rosettes, but a certain degree of effect can be obtained even if only a portion of the connecting sleeve is made of rosettes.

In the irradiation chamber 2, the metal tube is irradiated with ultraviolet rays generated by an ultraviolet lamp 10 to cure the coating film.
The irradiation time and irradiation distance are selected so that the coating film is sufficiently cured within the irradiation chamber. The UV lamp can be any conventional lamp, such as a high pressure mercury lamp.

A seal member 11 is also provided at the exit side opening of the irradiation chamber 2 to substantially prevent air from entering during irradiation.
This sealing member may have a structure similar to that of the squeezing plate 7, as shown in FIG. An inert gas (eg, nitrogen gas) is supplied into the irradiation chamber through an inert gas supply pipe 12 that communicates with the irradiation chamber.
The inside of the irradiation chamber is maintained in a substantially airtight state by the arrangement of the squeeze plate 7, the bellows type connection sleeve 3, and the outlet side seal member 11, and the inert gas supply pipe 1
By supplying inert gas from 2, the oxygen concentration can be reduced.
A low oxygen inert gas atmosphere of 0.5VO1% or less can be easily maintained. Furthermore, since the ultraviolet irradiation is performed in a closed space, leakage of ultraviolet light to the outside of the painting room can be prevented, and deterioration of the paint inside the painting can be prevented.

Inside the irradiation chamber 2, materials that can transmit ultraviolet light (e.g. , quartz) may be arranged. This mantle tube has a length that reaches the entire length of the irradiation chamber, and is airtightly fixed to both ends of the irradiation chamber. In this case, the inert gas atmosphere is not maintained throughout the irradiation chamber, but only in the space between the jacket tube and the metal tube.

As the metal tube moves within the irradiation chamber, some atmospheric oxygen may be brought into the irradiation chamber, causing the oxygen concentration within the irradiation chamber to fluctuate. To deal with this, an oxygen concentration detector (not shown) is provided in the irradiation chamber (inside the mantle tube if the mantle tube 13 is installed), and the flow rate of the inert gas is adjusted according to the detected oxygen concentration. By doing so, the oxygen concentration in the irradiation chamber atmosphere can always be maintained at a low concentration (eg, 0.5vo1% or less).

While the metal tube is passing through the irradiation chamber, the interior of the irradiation chamber is maintained in a substantially sealed state as described above, but when the metal tube passes through the irradiation device at the start and end of operation, Otherwise, air will enter the irradiation chamber. Intrusion of atmospheric air in such cases can be prevented by providing a nitrogen curtain at the entrance and exit of the irradiation device.

As mentioned above, in order to avoid damage to the uncured coating film, as shown in the figure, the metal tube passing through the irradiation chamber is supported by conveyor rollers 5 provided in front of the irradiation plate and outside the exit of the irradiation chamber, and the irradiation chamber is It is preferable that no conveyance rollers be present from the plate to the exit of the irradiation chamber.
By increasing the distance between the conveying rollers in this way, the metal tube vibrates, and if the stripping board cannot follow this vibration, significant variations in coating film thickness will occur.However, as already explained in the device of the present invention,
By using a bellows type connecting sleeve, this variation in film thickness can be suppressed.

Example Using the device of the present invention shown in the attached drawings,
mm steel pipe was treated with anti-corrosion treatment using ultraviolet curing paint.

The cleaning board in the painting room is made of EPT rubber with a hole diameter of 58.
It had a circular opening of mm. The paint is
An epoxy resin-based ultraviolet curing paint (UV Coat, manufactured by Nippon Paint Co., Ltd.) was used. The 100cm long irradiation chamber is equipped with eight 120W/cm high-pressure mercury lamps at a distance of 100mm from the outside of the steel tube.A quartz tube with an inner diameter of 150mm is placed inside the chamber, and a nitrogen atmosphere is introduced into the quartz tube. was held at The distance between the squeeze board and the irradiation chamber is approximately 350 mm, and the connecting sleeve that connects them is the same as above, as shown in Figure 2.
EPT rubber bellows (maximum external diameter 160 mm, wall thickness 1
mm). As shown in Figure 1, the conveyance rollers are installed in front of the application chamber entrance, in front of the stripping board, and at the exit of the irradiation chamber, and the distance between the conveyance rollers from this side of the stripping board to the exit of the irradiation chamber is 150 mm. It was hot.

While moving the above steel pipe at a speed of 60m/min,
Paint was applied and cured. By purging the irradiation chamber with nitrogen before starting coating and supplying nitrogen gas at a flow rate of 10/min during ultraviolet irradiation, we were able to maintain the oxygen concentration in the irradiation chamber at 0.5vo1% or less. The maximum amplitude of vibration of the steel pipe measured during the rust prevention treatment of this steel pipe was ±2.5 mm. When the coating film thickness of the obtained painted steel pipe was measured over the entire circumference,
It was 12μm±4μm.

For comparison, a steel pipe was coated and cured under the same conditions by replacing the above-mentioned bellows with a cylinder with a wall thickness of 1 mm made of the same material as the connecting sleeve, and the coating film thickness was as follows.
It was 12±10 μm. That is, by using the apparatus of the present invention, the variation in film thickness could be suppressed to less than half.

(Effects of the invention) According to the device of the invention, ultraviolet irradiation during curing of the ultraviolet curable paint applied to the outer circumferential surface of a metal tube can be performed at a low oxygen concentration (0.5vo1
% or less) in an inert gas atmosphere, and it is also possible to significantly reduce variations in coating film thickness, which could not be solved in the past.

As a result, the curing reaction on the surface layer of the film is delayed, which was observed in the case of conventional irradiation in the atmosphere, and the water absorption and
Increase in water permeability is prevented, and the rust prevention ability of the obtained cured film is significantly improved. In addition, because there is little variation in coating film thickness, there is no unevenness in the rust prevention treatment effect.
A stable product can be obtained.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the structure of the device of the present invention, and FIG. 2 is a partially cutaway perspective view showing the structure of the device of the present invention. 1... Painting room, 2... Irradiation room, 3... Bellows (connection sleeve), 4... Metal tube, 6... Painting nozzle, 7... Shigo board, 10... Irradiation lamp, 11
... Seal member, 13 ... Quartz tube.

Claims (1)

[Scope of Claim for Utility Model Registration] Consisting of a coating room 1 in which a radical-reactive ultraviolet curable paint is applied to the outer peripheral surface of a metal tube or rod 4, and an irradiation room 2 in which the coating film is cured by irradiating ultraviolet rays. , a metal rust prevention treatment device using an ultraviolet curable resin for a metal tube or rod that passes through the interior, the metal tube or rod being swingably disposed toward the outlet side from the coating area in the painting chamber. A stripping plate 7 having an opening made of an elastic material shaped to fit closely to the outer peripheral surface of the body; one end of the stripping plate located inside the painting chamber, and the other end connected to the entrance side end surface of the irradiation chamber. a connecting sleeve 3 that is at least partially made of a bellows and connects the two; a sealing material 11 that is provided at the exit side opening of the irradiation chamber and that substantially prevents air from entering during irradiation; Inert gas supply pipe 12 leading to
A metal rust prevention treatment device using an ultraviolet curable resin, further comprising the following.