JP6389437B2 - Method for removing waterproof layer using coating film remover - Google Patents

Description

  The present invention relates to a method for removing a waterproof layer and a release agent therefor.

  Steel water tanks and aquariums are widely used to temporarily store industrial water, sewage, drainage, and the like when manufacturing industrial products. The inner surface of steel water tanks and aquariums (hereinafter referred to as “water tanks”) has the purpose of preventing rust and cracking to improve durability and preventing contamination of the contents. Usually, a waterproof layer (lining) is applied.

  As a material used for the waterproof layer, conventionally, a bitumen material that is inexpensive and excellent in corrosion resistance has been used. Bituminous materials have the advantage that they have a strong adsorbing power to steel materials and a high water-stopping performance. Bituminous materials are excellent in long-term durability against water and can be manufactured at low cost.

  Generally, it is not envisaged to remove the waterproof layer of the water tanks, and the water tanks themselves are discarded when they deteriorate over time. Therefore, the necessity for removing the waterproof layer did not occur.

  However, if the wastewater stored in the water tanks has non-degradable toxicity or is contaminated with radioactive substances, the waterproof layer itself is contaminated. For this reason, there are concerns that environmental pollution and health damage will occur after disposal of water tanks, making it difficult to dispose of water tanks themselves. In such a case, it is necessary to remove the waterproof layer by some method.

  Several types of coating film release agents are already known. Patent Document 1 discloses a coating film release agent mainly composed of a dibasic acid ester that can be applied to a tar epoxy resin or the like. Patent Document 2 discloses a coating film release agent mainly composed of dichloromethane.

JP 2006-63106 A JP-A-5-171076

  However, in the coating film peeling method using the coating film peeling agent disclosed in Patent Document 1, it takes about 20 hours for the coating film to be peeled. Further, the peeling work performed with a scraper or the like needs to be performed close to the coating film, but since the softened coating film is in a wet state, care must be taken not to adhere to the operator. Moreover, the coating film peeling method by the coating film peeling agent disclosed in Patent Document 2 is a method in which the film is dissolved and peeled in a state where the coating film is swollen and softened. Since it is in a wet state, care must be taken not to adhere to the worker.

  In view of the above situation, the present invention has been made for the purpose of removing a waterproof layer that has not been assumed to be removed. That is, the subject of this invention is providing the removal method and the removal agent for the waterproof layer which can remove the waterproof layer which has a bitumen material as a main component safely in a short time.

  The present inventors examined an organic solvent that can penetrate and swell into the waterproof layer in a short time as a method for removing the waterproof layer mainly composed of the bituminous material. As a result, it has been found that dichloromethane can permeate and swell into a waterproof layer mainly composed of a bitumen material in a short time, and that dichloromethane is volatilized and hardly remains in a short time. Furthermore, it has been found that the waterproof layer dried after swelling can be peeled off relatively easily unlike conventional knowledge.

  The present invention has been made based on such knowledge. That is, the present invention is a method for removing a waterproof layer mainly composed of a bituminous material, the first step of applying a release agent mainly comprising dichloromethane and containing phenol to the waterproof layer, and the coated surface is dried. And a second step of removing the waterproof layer by performing blasting later.

The present invention is also a release agent for a waterproof layer containing dichloromethane as a main component and phenol, and containing a bitumen material as a main component.
The bitumen material is preferably a tar epoxy resin.

  The method for removing a waterproof layer using the coating film release agent of the present invention can remove the waterproof layer mainly composed of a bitumen material in a short time.

  Embodiments of the present invention will be described in detail below. However, the embodiment described below is an example of the embodiment of the present invention, and the present invention is not limited to these contents, and various modifications can be made within the scope of the gist.

  In the present invention, the waterproof layer is applied to the inner surface of water tanks in order to improve rust prevention and corrosion resistance and to provide long-term durability. In this invention, although the material of the base material of water tanks is not limited, it has aptitude especially for the thing manufactured with the steel-type metal material. Of the water tanks, the type having a flange structure is preferable because the inner surface is opened by removing the flange and the waterproof layer can be easily removed.

  Conventionally, a hydrocarbon-based multicomponent mixed resin such as a bitumen material is used for the waterproof layer provided for the above purpose. The bituminous material is excellent in corrosion resistance and durability, and can be obtained at a low price, so it is suitable for the above purpose. Bituminous materials include natural asphalt, coal tar, petroleum asphalt, pitch and the like, and are not particularly limited.

  The bituminous material can improve durability and handleability as a coating film by mixing with other resins. Examples of other resins mixed with the bitumen material include epoxy resins, urethane resins, and phenol resins. A bitumen material becomes a tar epoxy resin by mixing with an epoxy resin. The present invention is particularly useful for removing a waterproof layer with a tar epoxy resin.

  The release agent of the present invention contains dichloromethane as a main component. Here, the main component means 50% by mass or more. Dichloromethane is also called methylene chloride and has a boiling point as low as 40 ° C., so it volatilizes rapidly even at room temperature and is dried in a relatively short time, for example, about 12 hours. The drying time is shorter when the room temperature is high, such as in summer.

  The content of dichloromethane in the release agent is preferably 60% by mass or more, and more preferably 70% by mass or more. The higher the content, the better the permeability and volatility to the waterproof layer. Moreover, 90 mass% or less is preferable from a viewpoint of application | coating workability | operativity.

  The present inventors have found a phenomenon in which an infinite number of bubbles are formed when a composition containing dichloromethane as a main component is applied to a waterproof layer containing a bitumen material as a main component, and the waterproof layer expands. Furthermore, after the dichloromethane is volatilized and dried, the waterproof layer is physically easily broken and found to be innumerable fragments that can be peeled off from the substrate and removed from the substrate. It was.

The phenomenon that occurs after the release agent mainly composed of dichloromethane is applied to the waterproof layer can be considered as follows.
Dichloromethane is excellent in affinity with the bitumen material, and penetrates into the gaps between the crosslinked resin molecules of the waterproof layer mainly composed of the bitumen material. Thereafter, when the dichloromethane is vaporized, the volume rapidly expands in the gaps between the resin molecules. At this time, due to the dense cross-linking structure of the waterproof layer mainly composed of the bituminous material, the gas of dichloromethane is difficult to escape during expansion. Therefore, innumerable bubbles are generated in the waterproof layer, resulting in a turtle shell-like surface form. Thereafter, the dichloromethane gas escapes from the bubble membrane. Since the bubble film shrinks after the dichloromethane is removed, the film is peeled off from the substrate or the bubbles are broken by the shrinkage force of the film. In addition, since the bubble film maintains a certain shape, the waterproof layer changes to a state in which thin films overlap each other. Therefore, the waterproof layer is easily broken by the physical force of the blast, becomes innumerable pieces, peels off from the base material, and falls off.

  The pH of the release agent of the present invention is generally acidic from the viewpoint of facilitating volatilization or dissolving contaminants. However, the pH of the release agent can be adjusted to neutral in order to suppress rusting of the substrate.

  The release agent of the present invention contains phenol. 5-30 mass% is preferable and, as for content of phenol, 10-25 mass% is more preferable.

  Examples of components of the release agent other than dichloromethane and phenol include organic solvents, surfactants, drying inhibitors, acids, pH adjusters, and the like. Furthermore, in order to facilitate the application with a roller or a brush or the spraying with an airless gun, the viscosity can be adjusted by adding a thickener.

The waterproof layer removing method of the present invention includes the following two steps.
(1) First step of applying a release agent containing dichloromethane as a main component and phenol to the waterproof layer (2) Second step of removing the waterproof layer by blasting after the coated surface is dried. Will be described.

(First step)
In the first step, a release agent containing dichloromethane as a main component and containing phenol is applied to the waterproof layer to swell the waterproof layer.

  The amount of the release agent applied to the waterproof layer can be appropriately set according to the thickness of the waterproof layer, ease of swelling, and the like. When one application is insufficient, two or more applications are repeated. The coating method is not particularly limited, and a known method can be appropriately used.

  When a release agent is applied to the waterproof layer, dichloromethane penetrates into the waterproof layer, and the waterproof layer gradually swells. At the same time, since dichloromethane starts to volatilize, it is necessary to exhaust the dichloromethane immediately after coating from the viewpoint of safety and workability. The exhaust method is not particularly limited, and a known method can be appropriately used. The time required for drying varies depending on the amount of release agent applied, the temperature, the capacity of the exhaust equipment, and the like. It may dry within 1 hour and may take several hours. In this invention, in order to perform a 2nd process efficiently, it is set as the peeling agent of the said composition which is easy to volatilize and dry based on many compounding tests.

(Second step)
A 2nd process is performed after the application surface which apply | coated the release agent dries. In the second step, the waterproof layer is removed by blasting the waterproof layer.

  Once the coated surface is dried, the ease of peeling and removing the waterproof layer by blasting is rarely reduced even if it is left for a long time.

  When the coated surface is dried and the coated surface is free of moisture, the peeled coating film does not adhere again, so that the swollen waterproof layer can be efficiently peeled and removed. Moreover, since the possibility that the peeled coating film adheres to the human body is reduced, the possibility of causing health problems is also reduced. Moreover, since the generation of organic solvent gas is reduced during blast removal, there is little odor. Furthermore, by performing exhaust operation sufficiently, the atmospheric concentration of dichloromethane can be controlled below the environmental standard value, so that the working environment is improved.

  Blasting is a method in which a surface treatment of a substrate is physically performed by causing a powdery abrasive to collide with the substrate. As the blasting, methods such as shot blasting, sand blasting, and dry ice blasting are known, and any method can be applied to the present invention. An air blast that blows only compressed air without using an abrasive can also be applied to the present invention.

Shot blasting is a method in which a cut wire or steel or cast iron spherical particles (steel shots, steel beads), etc., cut from a metal wire on the surface of the substrate are sprayed with compressed air to peel off the deposits on the surface of the substrate. is there.
Sand blasting is a method in which fine particles such as alumina, silica, glass beads and the like are jetted onto the surface of the base material together with compressed air to peel off the deposits on the surface of the base material.
Dry ice blasting sprays dry ice fine particles (dry ice pellets) onto the substrate surface together with compressed air to drastically lower the surface temperature of the substrate and dry it in the gaps between deposits on the substrate surface. In this method, ice pellets are introduced to cause volume expansion and peel off the deposits.

  In shot blasting and sand blasting, the used abrasive remains, so when the waterproof layer is contaminated, the abrasive after use is also contaminated, so it is necessary to detoxify the abrasive. There is a case. On the other hand, in dry ice blasting, fine particles of dry ice are vaporized and diffused into the atmosphere, so that the abrasive after use does not remain, and the amount of contaminated waterproof layer residue generated can be reduced. Therefore, dry ice blasting is suitable as a method for removing the waterproof layer of the present invention from the viewpoint of reducing the amount of residue generated.

  The swelled waterproof layer becomes an infinite number of fragments by blasting and is peeled off from the substrate. The separated fragments are sucked and collected by a dust collector or the like so as not to diffuse and contaminate the environment. When performing decontamination work in a building, it is preferable to remove the waterproof layer by controlling the interior of the room to a negative pressure to prevent the removed pollutants from scattering.

  When the waterproof layer is contaminated with a radioactive substance or the like, blasting may be performed remotely using a robot or the like.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

As a specimen, a steel plate having a length of 1000 mm × width of 1000 mm × thickness of 1.5 mm was used. A tar epoxy resin coating was applied to the surface of the steel plate to a thickness of 200 μm and cured to prepare a steel plate A having a waterproof layer. As the tar epoxy resin coating, “Epotal BO Eco” made by Nippon Paint Co., Ltd., which is mainly composed of coal tar and mixed with epoxy resin, was used.
As the release agent 1 of the example, the following composition was prepared. The release agents 2 to 5 of the comparative examples are all commercially available products, and “Rock Remover” manufactured by Rock Paint, “Skeleton S-301” manufactured by NATCO, and “Hakuri Power # 300” manufactured by Yamaichi Chemical Co., Ltd. “Biohakuri X” manufactured by Yamaichi Chemical Co., Ltd.

(Release 1)
Dichloromethane 70-80% by mass
10-20% by weight of phenol
Acids, anti-drying agents, surfactants, thickeners

(Release agent 2)
Dichloromethane 79% by mass
Methanol 5-10% by mass
Ammonia water, toluene, anti-drying agent, benzyl alcohol

(Release agent 3)
Dichloromethane 70-80% by mass
Acetic acid, formic acid, methanol 20-30% by mass

(Release agent 4)
Dichloromethane 80-90% by mass
Methanol 5-10% by mass

(Release agent 5)
Alcohol-based high boiling point solvent 30-40% by mass
Ester-based high-boiling solvent 40-60% by mass
Accelerator, thickener, dye

In the draft which installed the forced exhaust apparatus, the peeling agents 1-5 were apply | coated to the steel plate A, and the operation | work to dry was performed as follows.
Six steel plates A having a waterproof layer were prepared. Using release agents 1 to 5 having different compositions, the surface of the steel sheet A on which the waterproof layer was formed was applied to a thickness of 250 μm using a roller. Release agents 1 to 5 were applied to the two steel plates A, respectively.

  In Experimental Example 1 using the release agent 1, the waterproof layer began to swell in about 1 minute after the release agent was applied. A large number of bubbles were generated inside the waterproof layer, which started to change the surface to be bumpy. During the reaction, the concentration of dichloromethane in the draft was measured with a gas detector and found to be 5 ppm or less. The reaction was completed in about 10 minutes, but was left as it was for 12 hours.

  In Experimental Example 1 using the release agent 1, the waterproof layer was in a dry state after 12 hours. The waterproof layer was deformed into a number of foams and was lifted from the steel plate. After drying, there was almost no odor.

  In Experimental Examples 2 to 5 using the release agents 2 to 5, although some bubbles were generated inside the waterproof layer, they were hardly peeled off.

  Two steel sheets A coated with the same release agent were swelled and dried, and then one sheet was subjected to dry ice blasting and the other sheet was subjected to shot blasting. As dry ice blasting, 3 mmφ × 3 mm pellets were used. Moreover, cut wire # 70 (particle diameter 0.7 mm) was used as shot blasting.

By applying dry ice blasting in Experimental Example 1, the waterproof layer could be peeled and removed with a removal area of 95% or more. The time required for removal was about 10 seconds / m ² .
In addition, when dry ice blasting was carried out without applying a release agent, rapid peeling / removal was not possible, and the time required for removal was about 200 minutes / m ² .

By performing shot blasting in Experimental Example 1, the waterproof layer could be peeled and removed with a removal area of 95% or more. The time required for removal was about 12 minutes / m ² .
In addition, even when shot blasting was performed without applying the coating film release agent, the waterproof layer could be peeled and removed, but the time required for removal was about 24 minutes / m ² .

  In Experimental Examples 2 to 5 using the release agents 2 to 5, dry ice blasting or shot blasting was attempted after 12 hours. However, it was hardly peeled off and it was difficult to completely remove them. Moreover, although removal of a coating film was tried with wiping, keren, a wire brush, etc., it was difficult to remove completely.

Claims (3)

A method of removing a waterproof layer mainly composed of a bitumen material,
A first step of applying a release agent containing dichloromethane as a main component and phenol to the waterproof layer;
And a second step of removing the waterproof layer by blasting after the coated surface is dried.   The method for removing a waterproof layer according to claim 1, wherein the bitumen material is a tar epoxy resin. A release agent for a waterproof layer used in the method for removing a waterproof layer according to claim 1 or 2,
A release agent for a waterproof layer mainly containing a bituminous material, containing 50 to 90% by mass of dichloromethane and 5 to 30% by mass of phenol.