JPS5857993B2 - Asphalt coating finishing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for finishing an asphalt coating when an object is coated with asphalt for anticorrosion coating or the like.

BACKGROUND ART It is widely practiced to coat the surfaces of steel materials such as steel pipes and steel tanks, concrete plates, etc. with asphalt to prevent corrosion.

Dip coating or flow coating methods are generally used to coat these objects with asphalt.

In these methods, high-temperature liquid asphalt is applied, so the coating film becomes uneven due to sagging before the asphalt solidifies, so the surface is smoothed with a roll etc. before or after the asphalt solidifies. It is necessary to

In addition, a method of asphalt coating by wrapping a semi-molten asphalt sheet with a cured film on the periphery around a cylinder is disclosed in JP-A-53-119978 and JP-A-54-5.
This is proposed in Publication No. 0574.

In this method as well, since it is necessary to wrap the asphalt sheet around the cylindrical body, it is necessary to crush the lap part before or after solidifying the asphalt to make the surface smooth.

When performing the above-mentioned smoothing treatment after the asphalt has cooled and solidified, equipment that applies a large amount of force for smoothing is required.
Moreover, the workability tends to be complicated.

If this smoothing treatment is performed before the asphalt solidifies, it can be carried out with less force, but the asphalt adheres to the smoothing means, such as rolls, making it difficult to carry out the treatment work.

If it is necessary to wrap a covering material such as vinylon cloth around an asphalt-coated steel pipe, press the covering material between a roller and the asphalt, and smooth the surface at the same time as wrapping the covering material. If this is done, the asphalt will hardly stick to the pressing roller, but it cannot be applied to asphalt-coated steel pipes that do not need to be wrapped with a covering material.

In order to prevent asphalt from adhering to this smoothing roll, the inventors have investigated various materials for the roll, such as applying chrome plating to the surface and experimenting with rolls made of silicone rubber or Teflon. If the asphalt temperature is not sufficiently cooled, for example, the asphalt temperature is 30-40℃.
In the above cases, it is not possible to prevent asphalt from adhering.

An object of the present invention is to provide an asphalt coating that can smooth the asphalt applied to the surface of an object with a small pressure using a roll while the asphalt is not yet solidified, and can also bring the asphalt into close contact with the object. To provide finishing methods.

In the asphalt coating finishing method according to the present invention, a roll whose surface is wetted with an aqueous surfactant solution is pressed onto the surface of the asphalt that has not yet hardened, covering the outer surface of an object, so that the asphalt is uniformly adhered to the object, and the asphalt is This method is characterized by smoothing the surface.

Objects to be coated with asphalt that are subject to the method of the present invention include various objects such as steel pipes, steel materials such as steel tanks, concrete plates, steel pipes, and piles such as concrete columns.

Since asphalt coating is often applied to cylindrical bodies such as steel pipes or concrete cylinders for corrosion prevention or reduction of negative frictional force, the method of the present invention will be described in detail based on the examples.

Example 1 FIGS. 1 and 2 are a schematic side view and a perspective view, respectively, showing an example of an apparatus for applying the method of the present invention to an asphalt-coated steel pipe.

In the drawings, reference numeral 1 denotes a steel pipe rotating in the direction of the arrow, and a semi-molten asphalt sheet 2 with a hardened film formed on the periphery is wrapped around the steel pipe 1.

3 indicates the covered asphalt, and 4 indicates the lap portion of the sheet 2.

Reference numeral 7 denotes a presser roll, which is brought into pressure contact with the coated asphalt surface and rotates in the direction of the arrow.

Therefore, the press roll 7 crushes the ridges of the lap portion 4 to smooth the surface, and also presses the entire asphalt coating 3 to bring the asphalt coating 3 into close contact with the steel pipe 1.

The surface of the presser roll 7 is wetted with a surfactant solution 6 from the supply pipe 5.

When water is merely sprinkled on the surface of the roll 7, the water is repelled and asphalt adheres to the non-wet portions of the roll 7.

When the surfactant solution 6 is sprinkled on the surface of the roll 7, the entire surface of the roll 7 becomes wet and no asphalt adheres to it.

The present inventor discovered that in order to prevent asphalt from adhering to the roll 7, it is sufficient to keep the roll surface constantly wet.

Furthermore, we have found that a liquid that dissolves asphalt is not suitable as an asphalt adhesion inhibitor, and that a surfactant solution is suitable.

A surfactant solution concentration of 1% or less is sufficient.

In the illustrated apparatus, a chrome-plated metal roll is used as the presser roll 7, and a small amount of a 0.3% aqueous solution 6 of sodium alkylbenzenesulfonate is continuously sprinkled on the roll surface to keep the roll surface always wet. The asphalt did not stick.

As a comparative example, when plain water was used instead of the surfactant aqueous solution, the roll surface repelled water and asphalt adhered to the roll.

Example 2 Instead of Example 1, a hard rubber roll was used as the presser roll 7, and a 0.2% aqueous solution of sodium alkylbenzenesulfonate was used as the asphalt adhesion prevention liquid. As in Example 1, asphalt adhesion was prevented. It did not occur.

Furthermore, when the asphalt adhesion prevention liquid was replaced with water, asphalt adhered as in the previous comparative example.

As described above, when using the aqueous surfactant solution according to the method of the present invention, the entire roll surface is kept wet or completely covered with the squeezing liquid.

It is thought that the aqueous surfactant solution covering the roll surface forms a thin film between the pressing roll and the asphalt during use, and this acts as a release agent to prevent asphalt from adhering.

The type or concentration of the surfactant aqueous solution is selected depending on the material of the presser roll.

According to the method of the present invention, by pre-wetting the entire presser roll with an aqueous surfactant solution, the presser roll can smoothly coat the asphalt before it completely solidifies, regardless of the material of the roll. It has extremely great practical value because it allows uniform adhesion of asphalt and smoothes the outer surface of asphalt.

[Brief explanation of drawings]

FIGS. 1 and 2 are a schematic side view and a perspective view showing an embodiment of an apparatus for applying the method of the present invention to asphalt-coated steel pipes. In the drawing, 1 is a steel pipe, 2 is an asphalt sheet, 3 is
4 is the coated asphalt, 4 is the lap portion of the sheet, 5 is the supply pipe, 6 is the surfactant solution, and 7 is the press roll.

Claims (1)

[Claims] 1. A roll wetted with a surfactant aqueous solution is pressed onto the surface of asphalt that has not yet solidified, covering the outer surface of an object, so that the asphalt is evenly adhered to the object and the asphalt surface is smoothed. Asphalt coating finishing method.