Method for peeling cement-based coating film and peeling aid for cement-based coating film

Abstract

To provide a method for peeling a cement-based coating film by which the peeling work of the cement-based coating film can be efficiently performed, and to provide a cement-based coating film peeling auxiliary.SOLUTION: A method for peeling a cement-based coating film 12 is a method for peeling and removing a cement-based coating film 12 formed on a surface of a building 11 from the surface of the building 11, and includes a coating step of coating the surface of the cement-based coating film 12 with a peeling aid 10 containing an organic acid as a main component as an acid component and having a pH of 1.0 or more and 3.0 or less, and a peeling step of peeling the cement-based coating film 12 from the surface of the building 11 with a peeling tool before the coated peeling aid 10 is dried.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for removing a cement-based coating film and a cement-based coating film removal aid. [Background technology]

[0002] Conventionally, in order to improve the durability and aesthetics of buildings, it has been known to prepare the surface of the building's framework with a base conditioner such as cement filler, and then apply paint or the like to form a coating film on the surface of the structure, or to form a finishing material by spraying cement lysine onto the surface of the building's framework.

[0003] When such buildings are demolished or renovated, it is necessary to remove the cementitious coating film formed as a surface preparation material or finishing material. When removing the cementitious coating film, physical removal methods such as blasting, grinding, and washing with high-pressure or ultra-high-pressure water are generally used.

[0004] Since physical peeling methods tend to generate dust, which is the pulverized product of the cement-based coating film, in order to improve the working environment and surrounding environment, suction devices are installed to collect the dust or water is used to suppress the generation of dust. This requires large-scale equipment such as a power supply, dust collection and recovery device, and water treatment device, making the peeling of cement-based coating films not easy.

[0005] For example, Patent Document 1 below describes applying a stripping aid to a cement-based coating film to make it easier to strip. The pH of the stripping aid is in the range of 1 to 5, and the stripping aid corrodes the cement-based coating film. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2022-142124 Summary of the Invention [Problem to be solved by the invention]

[0007] However, even with the use of the above-mentioned stripping aids, it is difficult to make the cement-based coating film brittle, and in many cases physical stripping methods have to be used. For this reason, large-scale equipment is required as a safety and health measure, and the stripping of cement-based coating films is not easy.

[0008] The present invention was completed based on the above circumstances, and an object of the present invention is to provide a method for removing a cement-based coating film and a cement-based coating film removal aid that can easily perform the work of removing the cement-based coating film. [Means for solving the problem]

[0009] The method for removing a cement-based coating film of the present invention 1 is a method for removing a cement-based coating film formed on the surface of a building from the surface of the building, and includes: an application step of applying a stripping aid having an acid component mainly composed of an organic acid and a pH of 1.0 or more and 3.0 or less to the surface of the cement-based coating film; and a stripping step of stripping the cement-based coating film from the surface of the building with a stripping tool before the applied stripping aid dries.

[0010] The method for peeling a cement-based coating film of the present invention 2 is a method for peeling and removing, from the surface of a building, a cement-based coating film formed on the surface of the building and an exterior coating film containing calcium carbonate and formed on the surface of the cement-based coating film, the method comprising: an application step of applying a stripping aid having an acid component mainly composed of an organic acid and a pH of 1.0 or more and 3.0 or less to the surface of the exterior coating film; and a peeling step of peeling the exterior coating film and the cement-based coating film from the surface of the building with a stripping tool before the applied stripping aid dries.

[0011] The cement-based coating film stripping aid of the present invention 3 is a stripping aid used in the method for stripping a cement-based coating film, and contains citric acid as an organic acid. [Effects of the Invention]

[0012] According to the method for removing a cementitious coating film of the present invention 1, the stripping aid applied to the surface of the cementitious coating film penetrates into the cementitious coating film, and the acid component of the stripping aid quickly dissolves the cement component of the cementitious coating film. This reduces the bonding strength of the cementitious coating film and weakens it. The cementitious coating film weakened by the stripping aid is removed in a wet state using a stripping tool, so dust generation is reduced. The stripping aid, whose main acid component is an organic acid, is highly safe, so safety measures can be reduced. Therefore, no large-scale equipment is required for safety and hygiene measures, making the removal of the cementitious coating film easy.

[0013] According to the method for removing a cement-based coating film of the present invention 2, the stripping aid decomposes the calcium carbonate in the exterior coating film, penetrates into the exterior coating film, and reaches the cement-based coating film. Once the stripping aid reaches the cement-based coating film, it penetrates into the interior of the cement-based coating film, where the acid component of the stripping aid quickly dissolves the cement component of the cement-based coating film. This weakens the bonding strength of the cement-based coating film and weakens it. The weakened cement-based coating film makes the exterior coating film more likely to peel off from the cement-based coating film. Because the exterior coating film and the weakened cement-based coating film are removed together using a stripping tool, work efficiency is improved compared to when the exterior coating film and the cement-based coating film are removed separately. Furthermore, because the exterior coating film and the cement-based coating film are removed in a wet state, dust generation is reduced. The safety of the stripping aid, whose acid component is primarily an organic acid, reduces the need for safety measures. Therefore, large-scale equipment is not required for safety and hygiene measures, and the cement-based coating film can be easily removed.

[0014] According to the cement-based coating film stripping aid of the present invention 3, the stripping aid containing citric acid as an organic acid is highly safe, and therefore the safety measures required for the cement-based coating film stripping operation can be reduced, and the cement-based coating film stripping operation can be carried out more efficiently. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a schematic view showing how a cement-based coating film is peeled off in the method for peeling off a cement-based coating film in Example 1. As shown in FIG. [Figure 2] FIG. 2 is a schematic diagram showing a cement-based coating film formed on the surface of a building. [Figure 3] FIG. 3 is a schematic diagram showing how the release aid penetrates into the cement-based coating film. [Figure 4] FIG. 4 is a schematic diagram showing the state in which the cement component of the cement-based coating film has been dissolved by the stripping aid. [Figure 5] FIG. 5 is a schematic diagram showing how the stripping aid penetrates into the cementitious coating film in the method for stripping the cementitious coating film in Example 2. [Figure 6] FIG. 6 is a schematic diagram showing how the exterior coating film and the cement-based coating film are peeled off. DETAILED DESCRIPTION OF THE INVENTION

[0016] A preferred embodiment of the present invention is shown below. [1] The method for removing a cement-based coating film according to the present invention 1 is a method for removing a cement-based coating film formed on the surface of a building from the surface of the building, comprising: a coating step of applying a stripping aid having an acid component primarily composed of an organic acid and a pH of 1.0 to 3.0 to the surface of the cement-based coating film; and a stripping step of stripping the cement-based coating film from the surface of the building using a stripping tool before the applied stripping aid dries. According to this method, the stripping aid applied to the surface of the cement-based coating film penetrates into the cement-based coating film, and the acid component of the stripping aid quickly dissolves the cement component of the cement-based coating film. This reduces the bonding strength of the cement-based coating film and weakens it. The cement-based coating film weakened by the stripping aid is removed in a wet state using a stripping tool, reducing the generation of dust. The high safety of a stripping aid containing an organic acid as its primary acid component reduces the need for safety measures. Therefore, large-scale equipment is not required for safety and hygiene measures, making the removal of the cement-based coating film easy.

[0017] [2] The method for removing a cement-based coating film according to the second aspect of the present invention is a method for removing a cement-based coating film formed on the surface of a building and an exterior coating film containing calcium carbonate formed on the surface of the cement-based coating film from the surface of the building. The method includes the steps of: applying a stripping aid to the surface of the exterior coating film, the stripping aid having an acid component primarily composed of an organic acid and a pH of 1.0 to 3.0; and stripping the exterior coating film and the cement-based coating film from the surface of the building using a stripping tool before the applied stripping aid dries. According to this method, the stripping aid decomposes the calcium carbonate in the exterior coating film and penetrates into the exterior coating film, eventually reaching the cement-based coating film. Once the stripping aid reaches the cement-based coating film, it penetrates into the interior of the cement-based coating film, where the acid component of the stripping aid quickly dissolves the cement component of the cement-based coating film. This weakens the bonding strength of the cement-based coating film, weakening it. This weakening of the cement-based coating film makes the exterior coating film more susceptible to peeling from the cement-based coating film. Since the exterior coating film and the weakened cementitious coating film are peeled off together using a peeling tool, work efficiency can be improved compared to peeling off the exterior coating film and the cementitious coating film separately. Furthermore, since the exterior coating film and the cementitious coating film are peeled off in a wet state, dust generation is reduced. Since the peeling aid, whose main acid component is an organic acid, is highly safe, safety measures can be reduced. Therefore, large-scale equipment is not required for safety and hygiene measures, and the cementitious coating film peeling work can be easily performed.

[0018] [3] In the method for removing a cement-based coating film described in [1] or [2] above, the cement-based coating film may be removed while the removal aid is being applied. This method allows a sufficient amount of the removal aid to penetrate into the cement-based coating film, reliably dissolving the cement components. The high safety of the removal aid makes it easy to carry out the application and removal processes simultaneously.

[0019] [4] The method for removing a cement-based coating film according to any one of [1] to [3] above may further include a penetration step of causing the removal aid to penetrate into the cement-based coating film after the application step. According to this method, a large amount of the removal aid can penetrate into the cement-based coating film, sufficiently dissolving the cement components solidified in the cement-based coating film, and reliably promoting the weakening of the cement-based coating film.

[0020] [5] In the method for removing a cement-based coating film described in any one of [1] to [4] above, the removal tool may be an electric scraper with a tip that vibrates left and right or back and forth. According to this method, the vibration of the tip of the electric scraper allows the removal aid to penetrate sufficiently into the cement-based coating film. This sufficiently dissolves the hardened cement components of the cement-based coating film, ensuring the weakening of the cement-based coating film.

[0021] [6] The cement-based coating film stripping aid of Invention 3 is a stripping aid used in the cement-based coating film stripping method described in any one of [1] to [5] above, which contains citric acid as the organic acid. According to this configuration, the stripping aid containing citric acid as the organic acid is highly safe, so that the safety measures required for the cement-based coating film stripping operation can be reduced, and the cement-based coating film stripping operation can be performed more easily.

[0022] [7] In the cement-based coating film stripping aid described in [6] above, the stripping aid may be free of inorganic acids. Inorganic acids have a nasal irritating odor and are more dangerous than organic acids. By not including inorganic acids in the stripping aid, worker safety can be reliably improved, thereby further reducing the safety measures required for cement-based coating film stripping work.

[0023] [8] The cementitious coating film stripping aid described in [6] or [7] above may contain the organic acid in a range of 20% by weight to 50% by weight. Here, if the organic acid content is less than 20% by weight, sufficient stripping effect may not be achieved, or the stripping aid may have difficulty penetrating into the cementitious coating film. On the other hand, if the organic acid content is more than 50% by weight, only the solvent (water) in the stripping aid may be absorbed into the cementitious coating film, and excess organic acid components may remain on the surface of the cementitious coating film, potentially preventing sufficient dissolution of cement components. By containing the organic acid in a range of 20% by weight to 50% by weight in the stripping aid, the penetration of the stripping aid is appropriately adjusted, allowing the stripping aid to fully penetrate into the cementitious coating film and fully demonstrate its effect of dissolving cement components.

[0024] [9] In the cement-based coating film stripping aid described in any one of [6] to [8] above, the organic acid may contain lactic acid. This configuration further enhances the safety of the stripping aid, further reducing the need for safety measures.

[0025]

[10] In the cementitious coating film stripping aid described in any of [6] to [9] above, the viscosity of the stripping aid at 23°C may be in the range of 1 dPa·s or more and 50 dPa·s or less. This configuration makes it easy to adjust the drying time of the stripping aid and to fix the stripping aid to the cementitious coating film or exterior coating film formed on the wall or ceiling surface of a building. Furthermore, by having a viscosity at 23°C in the range of 1 dPa·s or more and 50 dPa·s or less, the penetration of the stripping aid can be appropriately adjusted, allowing the stripping aid to fully penetrate into the cementitious coating film and fully demonstrate its effect of dissolving the cement components.

[0026] Example 1 Example 1 embodying the present invention will be described in detail below with reference to Figures 1 to 4. In this example, the method for removing a cementitious coating film 12 is to embrittle the cementitious coating film 12 formed on the surface of a building 11 using a removal aid 10, and then remove it from the surface of the building 11 using an electric scraper (removal tool) 13, as shown in Figure 1.

[0027] The building 11 includes buildings and structures. Buildings include ordinary houses (such as apartment buildings and detached houses) and various commercial facilities. Structures include bridges, tunnels, and retaining walls. As shown in FIG. 2, a coating layer 14 is applied to the surface of the skeleton of the building 11. The coating layer 14 is provided to protect the skeleton of the building 11 from rain, wind, fire, rust, dirt, and the like, and to decorate the building 11.

[0028] The cementitious coating film 12 is formed on the surface of the skeleton of the building 11 as a surface preparation material or finishing material for the coating film layer 14. The cementitious coating film 12 is formed by applying a cementitious material to the surface of the skeleton by a roller, spraying, or the like. The surface preparation material may contain asbestos.

[0029] Cementitious materials are made by adding water to a powdered material that is a mixture of cement and filler components. The cement includes ordinary Portland cement, high-early-strength Portland cement, and white cement. The filler components include silica sand and calcium carbonate. Cementitious materials may also contain resin components such as synthetic resin emulsions, water retention agents, surfactants, etc.

[0030] When the cementitious coating film 12 is formed on the surface of the building 11 as a surface preparation material, a finishing material 15 is laminated on the outside of the cementitious coating film 12. In Fig. 2, the finishing material 15 is indicated by a dashed line. The finishing material 15 is formed by applying a commonly used paint such as an acrylic, urethane, or silicone resin paint for finishing purposes.

[0031] When the cement-based coating film 12 is formed on the surface of the building 11 as a finishing material, the cement-based coating film 12 is formed by spraying cement lysine onto the surface of the framework of the building 11, for example.

[0032] The stripping aid 10 is used in the stripping operation of the cementitious coating film 12. As shown in FIG. 3, the stripping aid 10 is applied to the surface of the cementitious coating film 12. The stripping aid 10 is liquid. The stripping aid 10 mainly contains an organic acid as an acid component. The pH of the stripping aid 10 is 1.0 or more and 3.0 or less. The pH of the stripping aid 10 is adjusted using the organic acid.

[0033] Organic acids are a general term for organic compounds that exhibit acidity, and many organic acids are carboxylic acids with a carboxyl group. Examples of organic acids include citric acid, lactic acid, paratoluenesulfonic acid, acetic acid, formic acid, oxalic acid, and ascorbic acid.

[0034] The stripping aid 10, which is primarily composed of an organic acid, can reduce the amount of highly hazardous inorganic acids used, such as sulfuric acid, hydrochloric acid, hydrofluoric acid, and nitric acid. Inorganic acids have an odor that irritates the nose, and prolonged use can cause headaches for workers. Reducing the amount of highly hazardous inorganic acids used can improve the safety of the stripping aid 10. It is preferable that the stripping aid 10 does not contain inorganic acids. This can further improve the safety of the stripping aid 10.

[0035] The stripping aid 10 uses citric acid as the organic acid. Citric acid is an organic compound found in citrus fruits such as vinegar and lemons, and is a hydroxy acid. Citric acid is a white solid at room temperature, non-volatile, odorless, and friendly to both people and the environment. Because citric acid is highly safe, it can reduce the safety measures required for stripping the cement-based coating film 12, allowing the stripping work of the cement-based coating film 12 to be carried out efficiently. Because citric acid is highly soluble in water, it is easy to adjust the pH and acidity. Citric acid is easily available.

[0036] The stripping aid 10 contains lactic acid as an organic acid. This can further enhance the safety of the stripping aid 10. Because lactic acid is highly safe, the safety measures required for stripping the cement-based coating film 12 can be further reduced, and the stripping work of the cement-based coating film 12 can be performed efficiently. Lactic acid is highly soluble in water, so the pH and acidity can be easily adjusted. Lactic acid is easily available. Lactic acid can complement the effects of citric acid.

[0037] The stripping aid 10 applied to the surface of the cementitious coating film 12 penetrates into the cementitious coating film 12 as shown by arrow 16 in Figure 3. The acid component of the stripping aid 10 that penetrates into the cementitious coating film 12 quickly dissolves the hardened cement components. This reduces the bonding strength of the cementitious coating film 12, causing it to crumble and become weak (see Figure 4).

[0038] Here, when removing only an organic coating film, a conventional method has been to use a stripping aid whose main component is an organic solvent, which swells and dissolves the resin component of the organic coating film, making the coating film easier to remove. However, when removing an inorganic coating film such as the cement-based coating film 12, there has been no stripping aid that can effectively weaken the cement-based coating film 12. In contrast, the stripping aid 10 can effectively dissolve and weaken the cement component of the cement-based coating film 12.

[0039] Furthermore, if calcium carbonate is contained in the cementitious coating film 12 due to deterioration of the cementitious coating film 12, the acid component of the stripping aid 10 quickly dissolves the calcium carbonate. The stripping aid 10 quickly dissolves the calcium carbonate as well as the cement components contained in the cementitious coating film 12, causing the cementitious coating film 12 to crumble further, reducing the bonding strength of the cementitious coating film 12, and weakening the cementitious coating film 12.

[0040] The pH of the stripping aid 10 is preferably 2.0 or less. If the pH of the stripping aid 10 is higher than 2.0, the speed at which the cementitious coating film is weakened tends to be slow. By making the pH of the stripping aid 10 2.0 or less, the speed at which the cementitious coating film is weakened increases, allowing the stripping work to be carried out efficiently.

[0041] The permeability of the stripping aid 10 to penetrate into the cementitious coating film 12 is appropriately adjusted so as not to be too high or too low. If the stripping aid 10 does not easily penetrate into the cementitious coating film 12, the stripping aid 10 applied to the surface of the cementitious coating film 12 may crystallize and not sufficiently penetrate into the cementitious coating film 12. In this case, the stripping aid 10 may only be able to erode the surface of the cementitious coating film 12.

[0042] On the other hand, if the stripping aid 10 penetrates too far into the cementitious coating film 12, the stripping aid 10 may be too dispersed inside the cementitious coating film 12, and may not be able to fully dissolve the cement components, or may become dry. Also, if the stripping aid 10 penetrates too far into the cementitious coating film 12, a large amount of the stripping aid 10 may reach the surface of the skeleton of the building 11 and dissolve the cement components on the surface of the skeleton.

[0043] By appropriately adjusting the permeability of the stripping aid 10 so that it is neither too high nor too low, the stripping aid 10 can quickly and evenly penetrate into the interior of the cement-based coating film 12 and sufficiently dissolve the cement component of the cement-based coating film 12.

[0044] It is preferable that the permeability of the stripping aid 10 is appropriately adjusted according to the type of cementitious coating film 12. Depending on the type of cementitious coating film 12, even the same stripping aid 10 may not penetrate well or may penetrate too much.

[0045] The permeability of the stripping aid 10 can be adjusted by the organic acid content. If the organic acid content is less than 20% by weight, the permeability of the stripping aid 10 tends to be too low. If the organic acid content is more than 50% by weight, the permeability of the stripping aid 10 tends to be too high. If the permeability of the stripping aid 10 is too low, the stripping aid 10 may not achieve sufficient stripping effectiveness or may have difficulty penetrating into the cement-based coating film 12. On the other hand, if the organic acid content is more than 50% by weight, only the solvent (water) of the stripping aid 10 is absorbed into the cement-based coating film 12, and excess organic acid components remain on the surface of the cement-based coating film 12, which may prevent the stripping aid 10 from sufficiently dissolving the cement components. For this reason, the organic acid content in the stripping aid 10 is preferably in the range of 20% by weight to 50% by weight. By including an organic acid in the range of 20% by weight or more and 50% by weight or less in the stripping aid 10, it is possible to appropriately adjust the permeability of the stripping aid 10. Stripping aid 10 with appropriately adjusted permeability quickly and evenly penetrates into the cementitious coating film 12, and a sufficient amount of stripping aid 10 for dissolving the cement components is retained within the cementitious coating film 12, allowing the cement components of the cementitious coating film 12 to be sufficiently dissolved.

[0046] A surfactant may be added to the peeling aid 10 to appropriately adjust the penetration. Some surfactants have antifoaming effects, and an appropriate surfactant may be selected and used as needed. Depending on the properties of the surfactant, multiple types may be used, which is preferable.

[0047] A viscosity adjuster (thickener) may be added to the stripping aid 10 to appropriately adjust the penetration. By adding a viscosity adjuster, the viscosity of the stripping aid 10 can be adjusted. By adding a viscosity adjuster, the amount of the stripping aid 10 that can be applied can be increased, and the wet state of the cement-based coating film 12 can be prolonged. In addition, the effect of the stripping aid 10 can be maintained for a long time.

[0048] Furthermore, increasing the viscosity of the stripping aid 10 makes it easier to apply to cement-based coatings on walls and ceilings, allowing for thicker application to the cement-based coating film 12 and a larger amount of stripping aid 10 to be applied. On the other hand, increasing the viscosity of the stripping aid 10 too much may reduce its permeability. For this reason, the viscosity of the stripping aid 10 at 23°C is preferably in the range of 1 dPa·s or more and 50 dPa·s or less. A stripping aid 10 with an appropriately adjusted viscosity can quickly penetrate into the cement-based coating film 12 and maintain its effect of dissolving cement components for a long period of time.

[0049] Examples of viscosity modifiers include amide, silica, hectorite, bentonite, and cellulose-based thickeners. A single viscosity modifier may be used, or multiple viscosity modifiers may be used in combination. Viscosity modifiers may be appropriately selected and used as needed.

[0050] The pH, acidity, and permeability of the stripping aid 10 can be easily adjusted by using two or more organic acids as the main components. In this case, it is preferable to use two or more organic acids with significantly different molecular weights. Organic acids with low molecular weights (such as formic acid and acetic acid) are easily soluble in water, while organic acids with high molecular weights (such as benzoic acid) are less soluble in water. Organic acids with low molecular weights penetrate deep into the cement-based coating film 12 relatively quickly, while organic acids with high molecular weights tend to remain near the surface of the cement-based coating film 12, making it easy to adjust the permeability into the cement-based coating film 12.

[0051] Furthermore, the pH of the peeling aid 10 can be easily adjusted by using sulfonic acid as the organic acid. Sulfonic acid is an organic compound substituted with a sulfo group that exhibits strong acidity, so the pH of the peeling aid 10 can be adjusted with a small amount.

[0052] A small amount of organic solvent may be added to the stripping aid 10. For example, the organic solvent may be added in a range of 20% to 25%. By adding an organic solvent, the stripping aid 10 can swell and dissolve the synthetic resin components contained in the cementitious coating film 12. The stripping aid 10 uses organic acid to dissolve the cement components of the cementitious coating film 12, causing them to crumble, and the organic solvent to swell and dissolve the synthetic resin components, reducing their strength, making the cementitious coating film 12 easier to strip.

[0053] The organic solvent should be one that is easily miscible with water and does not affect the pH. For example, the organic solvent may be a plasticizer used in synthetic resin products. Examples of organic solvents include alcohols, heterocyclic compounds, dibasic acid esters, carbonate compounds, etc. Examples of alcohols include lower alcohols and aromatic alcohols. Examples of lower alcohols include methanol, ethanol, propanol, isopropanol, and butanol. Examples of aromatic alcohols include benzyl alcohol, 4-methylbenzyl alcohol, 2-ethylbenzyl alcohol, and phenethyl alcohol.

[0054] Examples of the heterocyclic compound include five-membered heterocyclic compounds, such as γ-butyrolactone, γ-valerolactone, N-methylpyrrolidone, and 1-ethyl-2-pyrrolidone.

[0055] Examples of dibasic acid esters include esters obtained by condensation reaction of dibasic acids having 4 to 6 carbon atoms with alkyl alcohols. Examples of dibasic acids having 4 to 6 carbon atoms include dimethyl adipate, dimethyl succinate, dimethyl glutarate, diethyl adipate, diethyl succinate, and diethyl glutarate.

[0056] Examples of the carbonate compound include propylene carbonate, ethylene carbonate, and butylene carbonate.

[0057] The above-described release aid 10 is produced by mixing the constituent materials using a stirrer or the like. The stirrer may be a dissolver, a butterfly mixer, a propeller mixer, a planetary mixer, or the like. It is preferable to use a dissolver because it can easily improve uniformity.

[0058] Next, an example of the work of peeling and removing the cementitious coating film 12 from the surface of a building 11 using the peeling aid 10 will be described. The work of peeling the cementitious coating film 12 includes an application step of applying the peeling aid 10 to the surface of the cementitious coating film 12, and a peeling step of peeling the cementitious coating film 12 from the surface of the building 11 with an electric scraper 13.

[0059] When a finishing material 15 is laminated on the outside of the cementitious coating film 12 (see FIG. 2), a finishing material removal step is performed to remove the finishing material 15 before the application step. The finishing material removal step may be performed by a known method. For example, the finishing material 15 may be removed using tools such as a diamond cutter, chisel, chisel, or hammer, or by using ultra-high pressure water. By performing the finishing material removal step, the cementitious coating film 12 is exposed.

[0060] In the application process, as shown in Figure 3, a stripping aid 10 is applied to the surface of a cement-based coating film 12. The application of the stripping aid 10 may be carried out by a known method, such as using an applicator such as a spray, a paint roller, or a brush. The stripping aid 10, which is mainly composed of an organic acid, is highly safe, so safety measures in the application process can be reduced.

[0061] The amount of the peeling aid 10 applied is 0.1 kg / m 2 More than 1.0kg / m 2 After the peeling aid 10 is applied to the cement-based coating film 12, it may be left for a predetermined time. The leaving time is preferably a time that allows the cement-based coating film 12 to be kept wet by the peeling aid 10.

[0062] As shown by arrow 16 in Figure 3, the stripping aid 10 applied to the surface of the cementitious coating film 12 penetrates thoroughly from the surface to the interior of the cementitious coating film 12, and the acid component of the stripping aid 10 dissolves the hardened cement components. If the cementitious coating film 12 contains calcium carbonate, the stripping aid 10 also dissolves the calcium carbonate in the cementitious coating film 12. The time required for the stripping aid 10 to dissolve the cement components and calcium carbonate is significantly shorter than the time required for conventional stripping aids to dissolve synthetic resin components.

[0063] As the cement components and calcium carbonate are dissolved, the cement-based coating film 12 crumbles as shown in Figure 4, the bonding strength of the cement-based coating film 12 decreases, and the cement-based coating film 12 becomes more susceptible to crumbling. Even when the cement-based coating film 12 contains asbestos, the stripping aid 10 penetrates from the surface to the interior of the cement-based coating film 12, dissolving the cement components and weakening the cement-based coating film 12, just as when the cement-based coating film 12 does not contain asbestos.

[0064] The stripping step is performed before the applied stripping aid 10 dries. "Before the stripping aid 10 dries" means before the stripping aid 10 that has permeated into the cementitious coating film 12 has completely dried. If the stripping aid 10 has dried, it may be applied again. Alternatively, the stripping step may be performed while additional stripping aid 10 is applied before the stripping aid 10 dries. Because the stripping aid 10 is highly safe, the stripping step can be easily performed while applying the stripping aid 10. By performing the application step and the stripping step simultaneously, the time required for stripping the cementitious coating film 12 can be shortened and the cementitious coating film 12 can be stripped while being reliably moistened.

[0065] The stripping process is performed using an electric scraper 13, as shown in FIG. 1. The electric scraper 13 has a tip 13A that can move back and forth or left and right. The tip 13A is a wide, plate-shaped blade. In the stripping process, the tip 13A of the electric scraper 13 is inserted between the weakened cementitious coating film 12 and the surface of the building 11. The stripping aid 10 adheres to the tip 13A of the electric scraper 13 and penetrates into the cementitious coating film 12 together with the tip 13A. By moving the tip 13A of the electric scraper 13 back and forth or left and right, the stripping aid 10 is further dispersed inside the cementitious coating film 12. The vibration of the tip 13A further promotes the penetration of the stripping aid 10 into the cementitious coating film 12.

[0066] The cementitious coating film 12 penetrated by the stripping aid 10 quickly becomes brittle and crumbles, allowing it to be easily peeled off from the surface of the building 11 with an electric scraper 13. During this process, the cementitious coating film 12 contains the liquid stripping aid 10 and is in a wet state, so dust generation is suppressed. This eliminates the need to install a suction device to collect dust or to suppress dust generation with water. This eliminates the need for large-scale equipment such as a power supply, dust collection and recovery device, and water treatment device, making it easy to strip the cementitious coating film 12 in a short period of time and at low cost. In this way, the cementitious coating film 12 is peeled off and removed from the surface of the building 11, completing the stripping process.

[0067] After the application step, a penetration step may be performed in which the stripping aid 10 penetrates into the cementitious coating film 12. The penetration step may be performed or not depending on the type of cementitious coating film 12, climatic conditions, etc. By performing the penetration step, a large amount of the stripping aid 10 penetrates into the cementitious coating film 12, sufficiently dissolving the hardened cement components and reliably promoting the weakening of the cementitious coating film 12. After the penetration step, the application step may be performed again.

[0068] The cementitious coating film 12 scrapped from the surface of the building 11 by the above-described method is in a wet state and contains the liquid stripping aid 10. The liquid stripping aid 10 contained in the cementitious coating film 12 scrap continues to dissolve the cement components remaining in the scrap, thereby reducing the volume of the scrap. The collected cementitious coating film 12 scrap may be sprayed with additional stripping aid 10 or immersed in stripping aid 10 stored in a container to further promote volume reduction.

[0069] Next, the operation and effect of the embodiment configured as described above will be described. The method for removing a cement-based coating film 12 according to Example 1 is a method for removing a cement-based coating film 12 formed on the surface of a building 11 from the surface of the building 11. The method for removing a cement-based coating film 12 includes an application step of applying a removal aid 10 to the surface of the cement-based coating film 12, and a removal step of removing the cement-based coating film 12 from the surface of the building 11 using an electric scraper 13. The removal aid 10 contains an organic acid as a main acid component, and has a pH of 1.0 or more and 3.0 or less. The removal step is performed before the applied removal aid 10 dries.

[0070] According to the method for removing a cementitious coating film 12 of this embodiment, the removal aid 10 applied to the surface of the cementitious coating film 12 penetrates into the cementitious coating film 12, and the acid component of the removal aid 10 quickly dissolves the cement component of the cementitious coating film 12. This reduces the bonding strength of the cementitious coating film 12, effectively weakening the cementitious coating film 12 and making it easier to remove. The cementitious coating film 12 weakened by the removal aid 10 is removed in a wet state by the electric scraper 13, so dust generation is reduced. The removal aid 10, whose acid component is primarily an organic acid, is highly safe, reducing the need for safety measures. Therefore, no large-scale equipment is required for safety and hygiene measures, making the removal of the cementitious coating film easy.

[0071] The method for removing the cement-based coating film 12 involves applying the stripping aid 10 while removing the cement-based coating film 12. This method allows the stripping aid 10 to penetrate sufficiently into the cement-based coating film 12, ensuring that the cement components are dissolved. The high safety of the stripping aid 10, which is primarily composed of an organic acid, makes it easy to carry out the application and removal processes in parallel.

[0072] The stripping aid 10 is used in a method for stripping a cement-based coating film 12. The stripping aid 10 contains citric acid as an organic acid. Because the stripping aid 10 containing citric acid as an organic acid is highly safe, it is possible to reduce the safety measures required for stripping the cement-based coating film 12, and the stripping work of the cement-based coating film 12 can be carried out more easily.

[0073] The stripping aid 10 does not contain an inorganic acid. This configuration reliably enhances the safety of the stripping aid 10, thereby further reducing the safety measures required for the stripping operation of the cement-based coating film 12.

[0074] <Example 2> Next, a cement-based coating film stripping method and cement-based coating film stripping aid according to Example 2 embodying the present invention will be described with reference to Figures 5 and 6. The cement-based coating film stripping method of this Example is a method for stripping and removing the deteriorated exterior coating film 17 together with the cement-based coating film 12 when the exterior coating film 17 has deteriorated. Note that the same components as those in Example 1 are designated by the same reference numerals, and redundant explanations will be omitted.

[0075] The cementitious coating film 12 is formed on the surface of the building 11 as a surface conditioner. The exterior coating film 17 is laminated on the outside of the cementitious coating film 12. The exterior coating film 17 is formed by applying a finishing paint to the outside of the cementitious coating film 12. The exterior coating film 17 is often formed by applying multiple layers of finishing paint, such as an undercoat, an intermediate coat, and a top coat. Finishing paint generally uses a synthetic resin, such as an acrylic synthetic resin, as a binder, with pigment components, such as titanium oxide and calcium carbonate, dispersed in the binder. Deteriorated exterior coating film 17 contains calcium carbonate.

[0076] The method for removing the cement-based coating film 12 includes an application step and a removal step, similar to the first embodiment.

[0077] In the application step, the peeling aid 10 is applied to the surface of the exterior coating film 17. As in Example 1, the application of the peeling aid 10 may be carried out by a known method, such as using an applicator such as a spray, a paint roller, or a brush. The application amount of the peeling aid 10 is 0.1 kg / m 2 More than 1.0kg / m 2 After the peeling aid 10 is applied to the exterior coating film 17, it may be left for a predetermined period of time.

[0078] The stripping aid 10 applied to the surface of the exterior coating film 17 dissolves calcium carbonate and penetrates into the exterior coating film 17, making the exterior coating film 17 brittle. The stripping aid 10 passes through gaps where the calcium carbonate has been dissolved and reaches the cementitious coating film 12. As in Example 1, the stripping aid 10 penetrates into the cementitious coating film 12 and dissolves the cement components and calcium carbonate of the cementitious coating film 12. This reduces the bonding strength of the cementitious coating film 12 and makes it brittle.

[0079] The peeling step is carried out before the applied peeling aid 10 dries, as in Example 1. If the peeling aid 10 has dried, the peeling step may be carried out while the peeling aid 10 is being applied, as in Example 1.

[0080] In the peeling step, as shown in Fig. 6, the tip 13A of the electric scraper 13 is inserted from the brittle exterior coating film 17 to the surface of the building 11. The inserted tip 13A of the electric scraper 13 simultaneously peels off the exterior coating film 17 and the cementitious coating film 12 from the surface of the building 11. This shortens the working time compared to removing the exterior coating film 17 first and then the cementitious coating film 12, thereby improving working efficiency.

[0081] When the exterior coating film 17 and the cementitious coating film 12 are simultaneously peeled and removed, the exterior coating film 17 and the cementitious coating film 12 are kept wet by the peeling aid 10, so the generation of dust is suppressed as in Example 1. Therefore, as in Example 1, it is not necessary to install a suction device to collect dust or to suppress the generation of dust by using water.

[0082] As described above, according to the method for removing a cement-based coating film 12 of Example 2, the stripping aid 10 decomposes the calcium carbonate in the exterior coating film 17, penetrates into the exterior coating film 17, and reaches the cement-based coating film 12. The stripping aid 10 penetrates into the cement-based coating film 12, and the acid component of the stripping aid 10 quickly dissolves the cement component of the cement-based coating film 12. This reduces the bonding strength of the cement-based coating film 12 and weakens it. The weakening of the cement-based coating film 12 makes the exterior coating film 17 more easily peeled from the cement-based coating film 12. The exterior coating film 17 and the weakened cement-based coating film 12 are simultaneously removed by the electric scraper 13, thereby reducing work time. The exterior coating film 17 and the weakened cement-based coating film 12 are removed in a wet state, reducing dust generation. The stripping aid 10, whose acid component is primarily an organic acid, is highly safe, reducing the need for safety measures. Therefore, since no large-scale equipment is required for safety and hygiene measures, the cement-based coating film 12 can be easily removed in a short time and at low cost.

[0083] <Other Examples> The present invention is not limited to the embodiments described above and illustrated in the drawings, and the following embodiments are also included within the technical scope of the present invention.

[0084] (1) In the above embodiment, the stripping aid 10 does not contain inorganic acid. However, inorganic acids may be added as long as the total amount of inorganic acids is 10% or less of the stripping aid. Since inorganic acids are more corrosive to concrete and the like than organic acids, sufficient care must be taken when manufacturing the stripping aid 10 and when using the stripping aid 10 for stripping work.

[0085] (2) In the above embodiment, the peeling tool is the electric scraper 13. However, the peeling tool is not limited to this, and may be any other known tool other than an electric tool. [Explanation of symbols]

[0086] 10... Peeling aid 11…Buildings 12...Cement-based coating 13...Electric scraper (peeling tool) 13A...Tip 14...Coating layer 15...Finishing materials 16...Arrow 17...Exterior paint film

Claims

1. A method for peeling and removing a cement-based coating film formed on a surface of a building from the surface of the building, comprising: a coating step of coating a surface of the cement-based coating film with a stripping aid having an organic acid as a main component and a pH of 1.0 or more and 3.0 or less; a stripping step of stripping the cement-based coating film from the surface of the building using a stripping tool before the applied stripping aid dries; A method for removing a cement-based coating film, comprising:

2. A method for peeling and removing a cement-based coating film formed on a surface of a building and an exterior coating film containing calcium carbonate formed on the surface of the cement-based coating film from the surface of the building, comprising: a coating step of coating a peeling aid having an acid component mainly composed of an organic acid and a pH of 1.0 or more and 3.0 or less on the surface of the exterior coating film; a stripping step of stripping the exterior coating film and the cement-based coating film from the surface of the building using a stripping tool before the applied stripping aid dries; A method for removing a cement-based coating film, comprising:

3. 3. The method for removing a cement-based coating film according to claim 1, wherein the cement-based coating film is removed while the removal aid is being applied.

4. 3. A cement-based coating film stripping aid used in the cement-based coating film stripping method according to claim 1 or 2, comprising citric acid as the organic acid.

5. The cementitious coating stripping aid according to claim 4, wherein the stripping aid does not contain an inorganic acid.

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