Methods for removing contaminants

Abstract

To provide a pollutant removal method which can easily perform pollutant removal and recovery work of a coated film absorbing pollutant for a short time by using a self-exfoliate film formation composition in which a coated film is spontaneously exfoliated through dehydration after coating an object surface.SOLUTION: A pollutant removal method removing pollutant adhered to an object surface comprises the steps of: coating a self-exfoliate film formation composition where following components (A)-(C) are contained and mass ratio (B) / [(A)+(B)] of the component (B) to total amount of the component (A) and the component (B) is between 0.6 and 0.95 on the object surface on which the pollutant is adhered to form a coated film; dehydrating the coated film; and removing pollutant with the coated film by spontaneous exfoliation of the coated film in accompany with dehydration. (A) Polymer including viny alcohol as a constitutional unit, (B) Polystyrene sulfonate or salt thereof where sulfonation ratio is 89% or more, and (C) Volatile solvent.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for removing contaminants using a self-peeling film that spontaneously peels off after being applied to a target surface and drying. [Background technology]

[0002] Generally, methods for removing dirt, fine particles, and other dust adhering to or remaining on equipment surfaces include washing with water or solvents, wiping, scraping with mechanical force, and suction. However, these operations carry the risk of workers inhaling cleaning solutions or scattered dust. In particular, if the cleaning solution used is a substance harmful to the human body, or if the substance to be removed is a contaminant containing asbestos, hazardous chemicals, or radioactive materials, measures are needed to prevent workers from inhaling the cleaning solution or contaminants. For example, since contaminants at nuclear power plants contain radioactive materials, there is a risk of exposure to radiation through inhalation or contact with these materials for workers during cleaning and decommissioning work. Therefore, there is a need for technologies that can remove such contaminants efficiently and safely.

[0003] Contaminants tend to remain on equipment surfaces, especially in fine details such as uneven surfaces. One effective technique for removing such contaminants without scattering them is to use a releaseable coating, which involves applying a coating to the target surface, drying it, and then peeling off the coating to remove the adsorbed contaminants. While this technique is effective for removing contaminants remaining in fine details, it is difficult to create a starting point for peeling at the edges of the coating after drying. If this process takes a long time, the risk of workers inhaling or being exposed to harmful substances increases. Furthermore, in environments where people cannot enter, it is difficult to recover the peeled coating.

[0004] To address these problems, if a self-peeling film that spontaneously peels off after drying can be developed, the recovery process could be carried out easily and quickly, and remote work by robots or other means would also be possible.

[0005] Regarding technologies related to self-peeling films, Patent Document 1 discloses a self-peeling penetrant developer removal material obtained by dissolving a cellulose-based synthetic resin having the ability to form a peelable resin film in a volatile organic solvent. Patent Document 2 discloses a method for peeling off a film mainly composed of an aqueous paint and containing a water-soluble thickener by swelling it with water. On the other hand, Patent Document 3 discloses a technology different from self-peeling films, in which a coating composition is applied to a substrate in advance to form a barrier coating, and after contaminants have accumulated on the barrier coating, the barrier coating and contaminants are removed from the substrate. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 59-171841 [Patent Document 2] Japanese Patent Publication No. 2000-327958 [Patent Document 3] Special Publication No. 2010-530806 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] The technology described in Patent Document 1 had problems such as generating an unpleasant odor due to the presence of a considerable amount of organic solvent and insufficient self-peelability. The method described in Patent Document 2 required the addition of water to the film to cause swelling. The method described in Patent Document 3 involved removing the barrier coating and contaminants by washing or wiping, making the method of removing the coating film inconvenient.

[0008] Therefore, the present invention relates to a method for removing contaminants, which enables the removal of contaminants and the removal and recovery of a coating film that has adsorbed contaminants to be easily and quickly by using a self-peeling film-forming composition that spontaneously peels off the coating film simply by drying after application to the target surface. [Means for solving the problem]

[0009] The inventors have found that by including a polymer containing vinyl alcohol as a constituent unit and polystyrene sulfonic acid or a salt thereof in a volatile solvent in a specific ratio, it is possible to remove the aforementioned contaminants, thus completing the present invention.

[0010] The present invention is a method for removing contaminants adhering to a target surface, A step of forming a coating film by applying a self-peelable film-forming composition containing the following components (A) to (C), wherein the mass ratio of component (B) to the total amount of component (A) and component (B) (B) / [(A)+(B)] is 0.6 or more and 0.95 or less, to a target surface to which a contaminant is attached, A step of drying the coating film, A step of removing contaminants along with the paint film by the self-peeling of the paint film during drying. This invention provides a method for removing contaminants, which includes the following features: (A) Polymers containing vinyl alcohol as a constituent unit (B) Polystyrene sulfonic acid or its salt with a sulfonation rate of 89% or more (C) Volatile solvents

[0011] Furthermore, the present invention provides a self-peeling film-forming composition containing the following components (A) to (C), wherein the mass ratio of component (B) to the total amount of component (A) and component (B) (B) / [(A)+(B)] is 0.6 or more and 0.95 or less, for use in removing contaminants on a target surface by self-peeling as the coating film dries. (A) Polymers containing vinyl alcohol as a constituent unit (B) Polystyrene sulfonic acid or its salt with a sulfonation rate of 89% or more (C) Volatile solvents

[0012] Furthermore, the present invention provides a self-peelable film-forming composition containing the following components (A) to (C), wherein the mass ratio of component (B) to the total amount of component (A) and component (B) (B) / [(A)+(B)] is 0.6 or more and 0.95 or less. (A) Polymers containing vinyl alcohol as a constituent unit (B) Polystyrene sulfonic acid with a sulfonation rate of 89% or more or its salt (C) Volatile solvent

Advantages of the Invention

[0013] The method for removing contaminants of the present invention can easily perform the operations of removing contaminants and peeling and recovering the coating film adsorbed with contaminants in a short time by using a composition for forming a self-peeling film that peels from around the coating film during the drying process after being applied to the target surface.

Embodiments for Carrying Out the Invention

[0014] In the present invention, "self-peeling" means that after applying the composition for forming a self-peeling film to the target surface, as the volatile solvent evaporates, without applying a peeling force, it gradually peels from the peripheral edge of the coating film due to the internal stress of the coating film components. More specifically, it is preferable that the peeling degree of the dried coating film measured by the following evaluation method is 20% or more and 100% or less. This peeling degree is preferably 30% or more and 100% or less, more preferably 40% or more and 100% or less, still more preferably 50% or more and 100% or less, still more preferably 60% or more and 100% or less, and still more preferably 70% or more and 100% or less. <Evaluation Method> Apply the composition to an epoxy resin-coated substrate at 0.3 g / cm 2 and dry for 24 hours. Measure the adhesion area S1 between the composition spread wet on the substrate before drying and the substrate, and the area S2 where the dried coating film contacts the substrate, and take the value of (S1 - S2) / S1 calculated as the peeling degree.

[0015] Examples of the polymer containing vinyl alcohol as a constituent unit of component (A) include polyvinyl alcohol, modified polyvinyl alcohol such as anionic modification and cationic modification, vinyl acetate-ethylene copolymer, and its hydrolyzate. Among these, polyvinyl alcohol and the hydrolyzate of vinyl acetate-ethylene copolymer are preferable in terms of forming an appropriate coating film by the intermolecular hydrogen bond interaction with component (B) and further expressing the self-peeling property of the dried coating film.

[0016] Furthermore, the glass transition temperature of the polymer of component (A) is preferably 0°C or higher, more preferably 10°C or higher, even more preferably 20°C or higher, and still more preferably 30°C or higher, from the viewpoint of exhibiting self-peelability due to internal stress during drying. Also, from the viewpoint of improving film strength, it is preferably 120°C or lower, more preferably 110°C or lower, even more preferably 100°C or lower, and still more preferably 90°C or lower. If the glass transition temperature is below 0°C, self-peelability will not be exhibited.

[0017] Furthermore, the weight-average molecular weight of component (A) is preferably 5,000 or more, more preferably 10,000 or more, even more preferably 20,000 or more, and even more preferably 40,000 or more, from the viewpoint of improving coating film formation and the self-peelability of the dried coating film. Also, from the viewpoint of improving coatability, it is preferably 10,000,000 or less, more preferably 1,000,000 or less, even more preferably 500,000 or less, and even more preferably 200,000 or less.

[0018] Commercially available polyvinyl alcohol products that can be used include Kuraray Poval 3-98, 5-98, 28-98, 60-98, 27-95, 27-96, 17-94, 7-92, 3-88, 5-88, 22-88, 44-88, 95-88, and 48-80 (manufactured by Kuraray Co., Ltd.). Furthermore, commercially available hydrolyzed vinyl acetate copolymers such as Exceval RS-2117 and RS-1717 (manufactured by Kuraray Co., Ltd.) can be used.

[0019] The content of component (A) in the self-peelable film-forming composition of the present invention is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, even more preferably 1% by mass or more, and even more preferably 1.5% by mass or more, from the viewpoint of sufficiently exhibiting the self-peelability of the dried coating film. Furthermore, from the viewpoint of improving coatability, it is preferably 20% by mass or less, more preferably 15% by mass or less, even more preferably 10% by mass or less, even more preferably 7% by mass or less, and even more preferably 5% by mass or less. In addition, the content of component (A) in the self-peelable film-forming composition can also be preferably 1.5 to 20% by mass, more preferably 1.5 to 15% by mass, even more preferably 1.5 to 10% by mass, even more preferably 1.5 to 7% by mass, and even more preferably 1.5 to 5% by mass.

[0020] The sulfonation rate of polystyrene sulfonic acid or its salt in component (B) is 89% or higher, but from the viewpoint of sufficiently exhibiting self-peeling properties when used in combination with component A, it is preferably 95% or higher, more preferably 98% or higher, and even more preferably 99% or higher.

[0021] Literature has shown that polystyrene sulfonic acid or its salts have a higher glass transition temperature as the sulfonation rate increases (BALDING, Paul, et al. Physical Properties of Sodium Poly (styrene sulfonate): Comparison to Incompletely Sulfonated Polystyrene. Macromolecules, 2022, 55.5: 1747-1762). For example, the Tg of polystyrene with a sulfonation rate of 89% is approximately 210°C, and the Tg is said to exceed the decomposition temperature (440°C) when the sulfonation rate is close to 100%. The glass transition temperature of component (B) is preferably 210°C or higher, more preferably 300°C or higher, even more preferably 400°C or higher, and even more preferably 440°C or higher, in order to sufficiently exhibit self-delamination properties due to internal stress during drying.

[0022] Furthermore, the weight-average molecular weight of component (B) is preferably 5,000 or more, more preferably 10,000 or more, even more preferably 50,000 or more, and even more preferably 100,000 or more, from the viewpoint of improving coating film formation and self-peelability of the dried coating film, and is preferably 10,000,000 or less, more preferably 5,000,000 or less, and even more preferably 2,000,000 or less, from the viewpoint of improving coatability.

[0023] Commercially available polystyrene sulfonic acid or its salts include PS-100 (manufactured by Tosoh Finechem Co., Ltd.), PS-50 (same company), PS-5 (same company), etc.

[0024] The content of component (B) in the self-peelable film-forming composition of the present invention is preferably 5% by mass or more, more preferably 7% by mass or more, even more preferably 8% by mass or more, and even more preferably 10% by mass or more, from the viewpoint of sufficiently exhibiting the self-peelability of the dried coating film, and from the viewpoint of improving coatability, it is preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less, and even more preferably 25% by mass or less. That is, the content of component (B) in the self-peelable film-forming composition is preferably 5 to 50% by mass, more preferably 7 to 40% by mass, even more preferably 8 to 30% by mass, and even more preferably 10 to 25% by mass.

[0025] Furthermore, the mass ratio (B) / [(A)+(B)] of component (B) to the total amount of component (A) and component (B) is 0.6 or more, preferably 0.65 or more, more preferably 0.70 or more, even more preferably 0.75 or more, and even more preferably 0.80 or more, and also 0.95 or less, preferably 0.94 or less, and even more preferably 0.93 or less, from the viewpoint of sufficiently exhibiting the self-peelability of the dried coating film and from the viewpoint of the strength of the dried coating film. In addition, such mass ratio (B) / [(A)+(B)] can also be preferably 0.70~0.94, more preferably 0.75~0.94, even more preferably 0.75~0.93, and even more preferably 0.80~0.93.

[0026] The volatile solvent of component (C) is a substance that is volatile in a liquid state and is selected from water and volatile organic solvents. It is preferable that it contains water, and even more preferable that it is mainly water. Furthermore, from the viewpoint of drying after application to form a suitable dry coating film, a volatile organic solvent can be used in combination with water. Examples of volatile organic solvents include alcohols such as ethanol, methanol, and propanol, ketones such as acetone, and tetrahydrofuran, and it is preferable that one or more are selected from alcohols and ketones. Furthermore, the vapor pressure of the volatile organic solvent is preferably 0.01 kPa or more and 106.66 kPa or less at 20°C, more preferably 0.13 kPa or more and 66.66 kPa or less, even more preferably 0.67 kPa or more and 40.00 kPa or less, and even more preferably 1.33 kPa or more and 40.00 kPa or less. When component (C) contains a volatile organic solvent, its proportion is preferably 50% by mass or less of the total component (C), more preferably 20% by mass or less, and even more preferably 10% by mass or less.

[0027] The content of component (C) in the self-peelable film-forming composition of the present invention is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more, from the viewpoint of improving the applicability to the target surface, and preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 85% by mass or less, from the viewpoint of improving self-peelability.

[0028] The self-peelable film-forming composition of the present invention may further contain potassium iodide as component (D). If the contaminant is a substance that reacts with iodine, such as radioactive substances like cesium-134, cesium-137, strontium-90, and cobalt-60, the coating will become discolored, which serves as a sign of cleaning. The removal effect can be confirmed by repeating the application and peeling process until the discoloration disappears.

[0029] The content of component (D) in the self-peelable film-forming composition of the present invention is preferably 1% by mass or more, more preferably 2% by mass or more, and even more preferably 3% by mass or more, from the viewpoint of exhibiting iodide-derived coloration, and preferably 15% by mass or less, more preferably 12% by mass or less, and even more preferably 10% by mass or less, from the viewpoint of compatibility with the self-peelable film-forming composition.

[0030] [Optional ingredients] The self-peeling film-forming composition of the present invention may further contain components such as surfactants, thickeners, plasticizers, and preservatives, to the extent that they do not impair the self-peeling properties of the dried coating film.

[0031] Any of the following surfactants can be used: anionic surfactants, cationic surfactants, nonionic surfactants, or amphoteric surfactants.

[0032] As a thickening agent, any component other than component (A) of the present invention may be used, for example, an organic thickening agent such as xanthan gum, gellan gum, locust bean gum, or guar gum, or an inorganic thickening agent such as bentonite, aluminum magnesium silicate, laponite, hectorite, or anhydrous silicic acid, at a low concentration such that it does not form a film on its own. Examples of plasticizers include propylene glycol, 1,3-butylene glycol, glycerin, isopentylene glycol, hexylene glycol, dipropylene glycol, polyethylene glycol, and polypropylene glycol. Examples of preservatives include phenoxyethanol, benzoic acid, benzisothiazoline, sorbic acid, and propionic acid.

[0033] [Methods for removing contaminants] The present invention provides a method for removing contaminants, comprising the steps of: applying a self-peeling film-forming composition containing components (A) to (C), wherein the mass ratio of component (B) to component (A) (B) / [(A)+(B)] is 0.6 or more and 0.95 or less, to a target surface to which contaminants are attached to form a coating film; drying the coating film; and removing the contaminants together with the coating film by the self-peeling of the coating film during drying.

[0034] In this invention, by applying the self-peeling film-forming composition of the present invention to a target surface to which contaminants are attached, the contaminants on the target surface are adsorbed onto the composition, and as the composition dries, the contaminants are adsorbed onto the dried coating film. As a result, as it dries, the dried coating film with the adsorbed contaminants spontaneously peels off from the target surface. At this time, the coating film of the self-peeling film-forming composition of the present invention peels off gradually from the periphery of the coating film as it dries. Subsequently, the contaminants on the target surface can be removed by collecting the peeled dried coating film.

[0035] The target surfaces for contaminant removal include surfaces of synthetic resins (epoxy resin, polyvinyl chloride, acrylic resin, polyethylene, etc.), painted surfaces of synthetic resins, metal surfaces, glass surfaces, ceramic surfaces, concrete surfaces, mortar surfaces, cement solidified surfaces, and asphalt surfaces, and the surfaces may be smooth or have fine irregularities. Fine irregularities are applicable to surfaces that do not hinder the self-peeling of cement surfaces, etc. The target surfaces may be installed on floors, walls, ceilings, or other inclined areas such as slopes in various facilities such as power plants, factories, warehouses, office buildings, condominiums, parking lots, roads, bridges, and tunnels. Furthermore, the technology can handle a wide range of contaminants, including powdery or granular deposits (e.g., asbestos, dust, sand, sludge, soot, etc.), oily deposits (e.g., crude oil, tar, and other oily stains, as well as painted surfaces such as oil-based pens and lacquer sprays), plant and animal deposits (moss, algae, bird droppings, insect carcasses, etc.), and salt. In addition to contaminants in nuclear power plants, the technology of this invention can also be used for the removal of asbestos and other hazardous substances, as well as for work in harsh environments.

[0036] For application to the target surface, tools such as spatulas, rakes, brushes, rollers, sprayers, and sprayers can be used. Application methods include direct spreading using the aforementioned tools, as well as application by spraying. From the viewpoint of enhancing the self-peeling properties of the dried coating film, the amount of the self-peeling film-forming composition of the present invention applied to the target surface is preferably 0.1 kg / m². 2More than 0.5 kg / m 2 More preferably 1 kg / m 2 In addition, from the viewpoint of ease of curing and film formation, a density of 10 kg / m² is preferred. 2 More preferably 8 kg / m 2 More preferably 5 kg / m 2 More preferably, 3 kg / m 2 The following applies:

[0037] The drying process of the coating film after applying the composition to the target surface may be carried out by natural drying, air drying, or by using a heat source such as a halogen heater. The ambient temperature during the drying process is preferably -10°C or higher, more preferably 0°C or higher, even more preferably 5°C or higher, and also preferably 60°C or lower, more preferably 55°C or lower, and even more preferably 50°C or lower.

[0038] In the method for removing contaminants of the present invention, from the viewpoint of avoiding inhibition of self-peeling, it is preferable that the process up to the start of self-peeling does not include a step of applying or coating water, or an aqueous composition containing 50% by mass or more of water other than the self-peeling film-forming composition of the present invention. Furthermore, it is even more preferable to perform a drying step of the coating film immediately after the application step of the self-peeling film-forming composition of the present invention, without any other steps in between.

[0039] The self-peelable film-forming composition of the present invention, after being applied to a target surface, begins to shrink as the volatile solvent (water) of component (C) evaporates. However, while in a high-moisture state, the molecular chains of the film-forming component (A) can move freely, and no internal stress is generated. As drying progresses and the moisture content decreases, the coating shrinks further, and the thermal motion of the molecular chains of component (A) is frozen. This generates strong internal stress, causing the coating to exhibit a peeling force greater than its adhesive force to the target surface, making it more likely to spontaneously peel off from the edges.

[0040] With respect to the embodiments described above, preferred embodiments of the present invention are further disclosed below.

[0041] <1> A method for removing contaminants adhering to a target surface, comprising: applying a self-peeling film-forming composition containing the following components (A) to (C) onto the target surface where contaminants are adhering, with the mass ratio of component (B) to the total amount of components (A) and (B), (B) / [(A)+(B)], being 0.6 or more and 0.95 or less, to form a coating film; drying the coating film; and removing the contaminants together with the coating film by self-peeling of the coating film during the drying. A contaminant removal method comprising the above steps. (A) A polymer containing vinyl alcohol as a structural unit (B) Polystyrene sulfonic acid with a sulfonation rate of 89% or more or a salt thereof (C) A volatile solvent

[0042] <2> Use of a self-peeling film-forming composition containing the following components (A) to (C), with the mass ratio of component (B) to the total amount of components (A) and (B), (B) / [(A)+(B)], being 0.6 or more and 0.95 or less, for removing contaminants on a target surface by self-peeling during drying of the coating film. (A) A polymer containing vinyl alcohol as a structural unit (B) Polystyrene sulfonic acid with a sulfonation rate of 89% or more or a salt thereof (C) A volatile solvent

[0043] <3> The method for removing contaminants or the use according to <1> or <2>, wherein the application of the self-peeling film-forming composition onto the target surface is preferably carried out using a dragonfly, a rake, a brush, a roller or a spray.

[0044] <4> The application amount of the self-peeling film-forming composition onto the target surface is preferably 0.1 kg / m 2 or more, more preferably 0.5 kg / m 2 or more, still more preferably 1 kg / m 2 or more, and is preferably 10 kg / m 2 or less, more preferably 8 kg / m2 More preferably 5 kg / m 2 More preferably, 3 kg / m 2 The following is: <1> ~ <3> The method or use of removing contaminants described in any one of the following.

[0045] <5> Preferably, after the step of applying the self-peeling film-forming composition to the target surface to form a coating film, the step of drying the coating film is performed without any other steps. <1> ~ <4> The method or use of removing contaminants described in any one of the following.

[0046] <6> The drying process is preferably carried out in an environment at -10°C or higher, more preferably at 0°C or higher, even more preferably at 5°C or higher, and preferably at 60°C or lower, more preferably at 55°C or lower, and even more preferably at 50°C or lower. <1> ~ <5> The method or use of removing contaminants described in any one of the following.

[0047] <7> The coating film of the self-peeling composition preferably peels off from the periphery as it dries. <1> ~ <6> The method or use of removing contaminants described in any one of the following.

[0048] <8> Component (A) is polyvinyl alcohol, anionically modified polyvinyl alcohol, cationically modified polyvinyl alcohol, vinyl acetate-ethylene copolymer, or a hydrolysate of vinyl acetate-ethylene copolymer. <1> ~ <7> The method or use of removing contaminants described in any one of the following.

[0049] <9> The glass transition temperature of component (A) is preferably 0°C or higher, more preferably 10°C or higher, even more preferably 20°C or higher, even more preferably 30°C or higher, and also preferably 120°C or lower, more preferably 110°C or lower, even more preferably 100°C or lower, and even more preferably 90°C or lower, which is between 0°C and 120°C. <1> ~ <8> The method or use of removing contaminants described in any one of the following.

[0050] <10> The weight-average molecular weight of component (A) is preferably 5,000 or more, more preferably 10,000 or more, even more preferably 20,000 or more, even more preferably 40,000 or more, and also preferably 10,000,000 or less, more preferably 1,000,000 or less, even more preferably 500,000 or less, and even more preferably 200,000 or less. <1> ~ <9> The method or use of removing contaminants described in any one of the following.

[0051] <11> The content of component (A) in the self-peelable film-forming composition is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, even more preferably 1% by mass or more, and even more preferably 1.5% by mass or more, and also preferably 20% by mass or less, more preferably 15% by mass or less, even more preferably 10% by mass or less, even more preferably 7% by mass or less, and even more preferably 5% by mass or less. <1> ~ <10> The method or use of removing contaminants described in any one of the following.

[0052] <12> The content of component (A) in the self-peelable film-forming composition is preferably 1.5 to 20% by mass, more preferably 1.5 to 15% by mass, even more preferably 1.5 to 10% by mass, even more preferably 1.5 to 7% by mass, and even more preferably 1.5 to 7% by mass. <1> ~ <10> The method or use of removing contaminants described in any one of the following.

[0053] <13> The sulfonation rate of component (B) is preferably 95% or more, more preferably 98% or more, and even more preferably 99% or more. <1> ~ <12> The method or use of removing contaminants described in any one of the following.

[0054] <14> The glass transition temperature of component (B) is preferably 210°C or higher, more preferably 300°C or higher, even more preferably 400°C or higher, and even more preferably 440°C or higher. <1> ~ <13> The method or use of removing contaminants described in any one of the following.

[0055] <15> The weight-average molecular weight of component (B) is preferably 5,000 or more, more preferably 10,000 or more, even more preferably 50,000 or more, even more preferably 100,000 or more, and also preferably 10,000,000 or less, more preferably 5,000,000 or less, and even more preferably 2,000,000 or less. <1> ~ <14> The method or use of removing contaminants described in any one of the following.

[0056] <16> The content of component (B) in the self-peelable film-forming composition is preferably 5% by mass or more, more preferably 7% by mass or more, even more preferably 8% by mass or more, and even more preferably 10% by mass or more, and also preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less, and even more preferably 25% by mass or less. <1> ~ <15> The method or use of removing contaminants described in any one of the following.

[0057] <17> The content of component (B) in the self-peelable film-forming composition is preferably 5 to 50% by mass, more preferably 7 to 40% by mass, even more preferably 8 to 30% by mass, even more preferably 8 to 20% by mass, and even more preferably 10 to 25% by mass. <1> ~ <15> The method or use of removing contaminants described in any one of the following.

[0058] <18> The mass ratio of component (B) to the total amount of component (A) and component (B) (B) / [(A)+(B)] is preferably 0.65 or more, more preferably 0.70 or more, even more preferably 0.75 or more, even more preferably 0.80 or more, and also preferably 0.94 or less, more preferably 0.93 or less. <1> ~ <17> The method or use of removing contaminants described in any one of the following.

[0059] <19> The mass ratio of component (B) to the total amount of component (A) and component (B) (B) / [(A)+(B)] is preferably 0.70~0.94, more preferably 0.75~0.94, even more preferably 0.75~0.93, and even more preferably 0.80~0.93. <1> ~ <17> The method or use of removing contaminants described in any one of the following.

[0060] <20> Component (C) is preferably selected from water and volatile organic solvents, more preferably contains water, and even more preferably has water as the main component. <1> ~ <19> The method or use of removing contaminants described in any one of the following.

[0061] <21> The vapor pressure of component (C) at 20°C is preferably 0.01 kPa or more and 106.66 kPa or less, more preferably 0.13 kPa or more and 66.66 kPa or less, even more preferably 0.67 kPa or more and 40.00 kPa or less, and even more preferably 1.33 kPa or more and 40.00 kPa or less. <1> ~ <20> The method or use of removing contaminants described in any one of the following.

[0062] <22> The content of component (C) in the self-peelable film-forming composition is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, and also preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 85% by mass or less. <1> ~ <21> The method or use of removing contaminants described in any one of the following.

[0063] <23> Furthermore, it contains potassium iodide as component (D). <1> ~ <22> The method or use of removing contaminants described in any one of the following.

[0064] <24> The content of component (D) in the self-peelable film-forming composition is preferably 1% by mass or more, more preferably 2% by mass or more, even more preferably 3% by mass or more, and also preferably 15% by mass or less, more preferably 12% by mass or less, and even more preferably 10% by mass or less. <23> The method or use of removing contaminants as described above.

[0065] <25> A self-peeling film-forming composition containing the following components (A) to (C), wherein the mass ratio of component (B) to the total amount of component (A) and component (B) (B) / [(A)+(B)] is 0.6 or more and 0.95 or less. (A) Polymers containing vinyl alcohol as a constituent unit (B) Polystyrene sulfonic acid or its salt with a sulfonation rate of 89% or more (C) Volatile solvents

[0066] <26> A self-peeling film-forming composition containing the following components (A) to (C), wherein the degree of peeling measured by the evaluation method described below is between 20% and 100%. (A) Polymers containing vinyl alcohol as a constituent unit (B) Polystyrene sulfonic acid or its salt with a sulfonation rate of 89% or more (C) Volatile solvents <Evaluation Method> Apply the composition to an epoxy resin coated substrate at a concentration of 0.3 g / cm³. 2 The coating is applied and allowed to dry for 24 hours. The adhesion area S1 of the composition that has spread wet on the substrate before drying and the area S2 of the coating film that is in contact with the substrate after drying are measured, and the value of (S1-S2) / S1 calculated is defined as the degree of peeling.

[0067] <27> Component (A) is polyvinyl alcohol, anionically modified polyvinyl alcohol, cationically modified polyvinyl alcohol, vinyl acetate-ethylene copolymer, or a hydrolysate of vinyl acetate-ethylene copolymer. <25> or <26> The self-peeling film-forming composition described above.

[0068] <28> The glass transition temperature of component (A) is preferably 0°C or higher, more preferably 10°C or higher, even more preferably 20°C or higher, even more preferably 30°C or higher, and also preferably 120°C or lower, more preferably 110°C or lower, even more preferably 100°C or lower, and even more preferably 90°C or lower, which is between 0°C and 120°C. <25> ~ <27> A self-peeling film-forming composition according to any one of the following.

[0069] <29> The weight-average molecular weight of component (A) is preferably 5,000 or more, more preferably 10,000 or more, even more preferably 20,000 or more, even more preferably 40,000 or more, and also preferably 10,000,000 or less, more preferably 1,000,000 or less, even more preferably 500,000 or less, and even more preferably 200,000 or less. <25> ~ <28> A self-peeling film-forming composition according to any one of the following.

[0070] <30> The content of component (A) in the self-peelable film-forming composition is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, even more preferably 1% by mass or more, and even more preferably 1.5% by mass or more, and also preferably 20% by mass or less, more preferably 15% by mass or less, even more preferably 10% by mass or less, even more preferably 7% by mass or less, and even more preferably 5% by mass or less. <25> ~ <29> A self-peeling film-forming composition according to any one of the following.

[0071] <31> The content of component (A) in the self-peelable film-forming composition is preferably 1.5 to 20% by mass, more preferably 1.5 to 15% by mass, even more preferably 1.5 to 10% by mass, even more preferably 1.5 to 7% by mass, and even more preferably 1.5 to 7% by mass. <25> ~ <29> A self-peeling film-forming composition according to any one of the following.

[0072] <32> The sulfonation rate of component (B) is preferably 95% or more, more preferably 98% or more, and even more preferably 99% or more. <25> ~ <31> A self-peeling film-forming composition as described in any one of the following.

[0073] <33> The glass transition temperature of component (B) is preferably 210°C or higher, more preferably 300°C or higher, even more preferably 400°C or higher, and even more preferably 440°C or higher. <25> ~ <32> A self-peeling film-forming composition according to any one of the following.

[0074] <34> The weight-average molecular weight of component (B) is preferably 5,000 or more, more preferably 10,000 or more, even more preferably 50,000 or more, even more preferably 100,000 or more, and also preferably 10,000,000 or less, more preferably 5,000,000 or less, and even more preferably 2,000,000 or less. <25> ~ <33> A self-peeling film-forming composition according to any one of the following.

[0075] <35> The content of component (B) in the self-peelable film-forming composition is preferably 5% by mass or more, more preferably 7% by mass or more, even more preferably 8% by mass or more, and even more preferably 10% by mass or more, and also preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less, and even more preferably 25% by mass or less. <25> ~ <34> A self-peeling film-forming composition according to any one of the following.

[0076] <36> The content of component (B) in the self-peelable film-forming composition is preferably 5 to 50% by mass, more preferably 7 to 40% by mass, even more preferably 8 to 30% by mass, even more preferably 8 to 20% by mass, and even more preferably 10 to 25% by mass. <25> ~ <35> A self-peeling film-forming composition according to any one of the following.

[0077] <37> The mass ratio of component (B) to the total amount of component (A) and component (B) (B) / [(A)+(B)] is preferably 0.65 or more, more preferably 0.70 or more, even more preferably 0.75 or more, even more preferably 0.80 or more, and also preferably 0.94 or less, more preferably 0.93 or less. <25> ~ <36> A self-peeling film-forming composition according to any one of the following.

[0078] <38> The mass ratio of component (B) to the total amount of component (A) and component (B) (B) / [(A)+(B)] is preferably 0.70~0.94, more preferably 0.75~0.94, even more preferably 0.75~0.93, and even more preferably 0.80~0.93. <25> ~ <36> A self-peeling film-forming composition according to any one of the following.

[0079] <39> Component (C) is preferably selected from water and volatile organic solvents, more preferably contains water, and even more preferably has water as the main component. <25> ~ <38> A self-peeling film-forming composition according to any one of the following.

[0080] <40> The vapor pressure of component (C) at 20°C is preferably 0.01 kPa or more and 106.66 kPa or less, more preferably 0.13 kPa or more and 66.66 kPa or less, even more preferably 0.67 kPa or more and 40.00 kPa or less, and even more preferably 1.33 kPa or more and 40.00 kPa or less. <25> ~ <39> A self-peeling film-forming composition according to any one of the following.

[0081] <41> The content of component (C) in the self-peelable film-forming composition is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, and also preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 85% by mass or less. <25> ~ <40> A self-peeling film-forming composition according to any one of the following.

[0082] <42> Furthermore, it contains potassium iodide as component (D). <25> ~ <41> A self-peeling film-forming composition according to any one of the following.

[0083] <43> The content of component (D) in the self-peelable film-forming composition is preferably 1% by mass or more, more preferably 2% by mass or more, even more preferably 3% by mass or more, and also preferably 15% by mass or less, more preferably 12% by mass or less, and even more preferably 10% by mass or less. <42> The self-peeling film-forming composition described above.

[0084] <44> Furthermore, it contains surfactants, thickeners, plasticizers, or preservatives. <25> ~ <43> A self-peeling film-forming composition according to any one of the following. [Examples]

[0085] Examples 1-6, Comparative Examples 1-3 The compositions shown in Table 1 were prepared, and the degree of peeling (%) and film strength were evaluated according to the method described below.

[0086] (Method for evaluating the degree of peeling) Each composition is placed on a cement solidified substrate at a depth of 10 cm 2 0.3 g / cm³ within the range 2 The sample was prepared by coating the material and drying it at 25°C and 40% RH for 24 hours. The adhesion area S1 of the composition that has spread wet on the substrate before drying and the area S2 of the coating film that is in contact with the substrate after drying are measured, and the value of (S1-S2) / S1 calculated is defined as the degree of peeling.

[0087] (Method for evaluating membrane strength) The composition was dried on a glass plate or Teflon® sheet in an environment of 25°C and 50% RH to obtain a dry film with a dry thickness of 500 μm. The obtained film was folded 180° and then unfolded. Films that did not break were designated as a, those that broke were designated as c, and those that showed creases or cracks but did not break were designated as b.

[0088] <Glass transition temperature> The glass transition points of components (A) and (B) described in the examples were determined by DSC measurement under the following conditions on the dried solids obtained by drying each sample at room temperature for 24 hours and then further drying under reduced pressure at 80°C. Measurement device: DSC7000X (Hitachi High-Tech Science Co., Ltd.) Temperature profile: 1. Increase the temperature from 20°C to the target temperature at a rate of 10°C / min, and maintain the temperature for 5 minutes. 2. Cool from the target temperature to 20°C at a rate of 10°C / min and hold for 5 minutes. 3. Increase the temperature from 20°C to the target temperature at a rate of 10°C / min, and hold for 5 minutes. 4. Cool from the target temperature to 20°C at a rate of 10°C / min and hold for 5 minutes. The target temperatures measured were 250°C for Kuraray Poval 22-98, 5-98, and Exceval RS-2117; 440°C for PS-100 and PS-50; and 100°C for HA-LATEX.

[0089] [Table 1]

[0090] Test Examples 1-3 The color change of the composition of Example 2, and the composition of Example 2 to which 2% by mass or 5% by mass of potassium iodide was added and the same amount of water was reduced, was evaluated according to the following method. (Method for evaluating hue changes) As an alternative to radiation irradiation testing, UV-C irradiation testing was performed using the following method. Each composition is placed on a polyester substrate at 10 cm 2 Within the range of 0.1 g / cm³ 2 The sample was applied and dried for 24 hours under fluorescent and UV-C irradiation at 25°C and 40% RH, and the change in hue was observed visually. Fluorescent irradiation was performed in a normal laboratory environment. For UV-C irradiation, a compact germicidal lamp GPL27 manufactured by Sankyo Electric Co., Ltd. was used, and the lamp was positioned 15 cm away from the light source.

[0091] As a result, no change in hue was observed in the composition of Example 2 under either fluorescent lamp irradiation or UV-C irradiation. On the other hand, the compositions of Example 2 to which 2% by mass or 5% by mass of potassium iodide was added showed no change in hue under fluorescent lamp irradiation, but browned under UV-C irradiation. Furthermore, the degree of peelability and film strength did not change even with the addition of potassium iodide.

Claims

1. A method for removing contaminants adhering to a target surface, A step of forming a coating film by applying a self-peelable film-forming composition containing the following components (A) to (C), wherein the mass ratio of component (B) to the total amount of component (A) and component (B) (B) / [(A) + (B)] is 0.6 or more and 0.95 or less, to a target surface to which a contaminant is attached, A step of drying the coating film, A step of removing contaminants along with the paint film by the self-peeling of the paint film during drying. A method for removing contaminants, comprising the following features. (A) Polymers containing vinyl alcohol as a constituent unit (B) Polystyrene sulfonic acid or its salt with a sulfonation rate of 89% or more (C) Volatile solvents

2. The method for removing contaminants according to claim 1, wherein the step of removing contaminants together with the coating film includes a step of recovering the peeled-off dried coating film.

3. The method for removing contaminants according to claim 1 or 2, wherein the coating film of the self-peeling composition peels off from the periphery as it dries.

4. The amount of self-peeling composition applied to the target surface is 0.1 kg / m². 2 The above describes the method for removing pollutants according to claim 1 or 2.

5. The method for removing contaminants according to claim 1 or 2, wherein the drying step is carried out in an environment of -10°C to 60°C.

6. The method for removing contaminants according to claim 1 or 2, wherein the glass transition temperature of component (A) is 0°C or higher and 120°C or lower.

7. The method for removing contaminants according to claim 1 or 2, wherein the polymer containing vinyl alcohol of component (A) as a constituent unit is polyvinyl alcohol, anionically modified polyvinyl alcohol, cationically modified polyvinyl alcohol, vinyl acetate-ethylene copolymer, or a hydrolysate thereof.

8. The method for removing contaminants according to claim 1 or 2, wherein component (B) is polystyrene sulfonic acid or a salt thereof having a weight-average molecular weight of 5,000 or more and 10,000,000 or less.

9. The method for removing contaminants according to claim 1 or 2, wherein component (C) contains water.

10. Use of a self-peeling film-forming composition containing the following components (A) to (C), wherein the mass ratio of component (B) to the total amount of component (A) and component (B) (B) / [(A) + (B)] is 0.6 or more and 0.95 or less, for the purpose of removing contaminants on a target surface by self-peeling as the coating film dries. (A) Polymers containing vinyl alcohol as a constituent unit (B) Polystyrene sulfonic acid or its salt with a sulfonation rate of 89% or more (C) Volatile solvents

11. A self-peeling film-forming composition containing the following components (A) to (C), wherein the mass ratio of component (B) to the total amount of component (A) and component (B) (B) / [(A) + (B)] is 0.6 or more and 0.95 or less. (A) Polymers containing vinyl alcohol as a constituent unit (B) Polystyrene sulfonic acid or its salt with a sulfonation rate of 89% or more (C) Volatile solvents

12. The self-peelable film-forming composition according to claim 11, wherein the glass transition temperature of component (A) is 0°C or higher and 120°C or lower.

13. The self-peelable film-forming composition according to claim 11 or 12, wherein component (B) is polystyrene sulfonic acid or a salt thereof having a weight-average molecular weight of 5,000 or more and 10,000,000 or less.

14. The self-peelable film-forming composition according to claim 11 or 12, wherein the glass transition temperature of component (B) is 210°C or higher.

15. Furthermore, the self-peeling film-forming composition according to claim 11 or 12, further comprising component (D) potassium iodide.

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