Paint stripping coating agent, paint stripping coating agent diluent, paint stripping kit, coating, laminate, and paint stripping method

Abstract

The present invention provides a coating agent for paint removal that exhibits good solubility in paint removers and enables the efficient removal of paint from the coated material. [Solution] The paint-removing coating agent contains polyvinyl alcohol, a surfactant, and water.

Description

Technical Field

[0001] The present invention relates to a coating agent for paint peeling, a diluted solution of the coating agent for paint peeling, a paint peeling kit, a film, a laminate, and a paint peeling method.

Background Art

[0002] In the painting processes of various objects to be painted, including the painting process of automobiles, various painting jigs are used. When paint adheres or accumulates on the painting jigs, the workability and functions deteriorate, so it is necessary to peel the paint from the painting jigs at regular intervals.

[0003] As a method for peeling and removing paint, a portion that does not require painting with the paint of the painting jigs is pre-coated with a coating agent before the painting process, and the paint adhering or deposited on the painting jigs after passing through the painting process is peeled using a peeling agent, a solvent, or the like (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] When the solubility of the coating by the coating agent for paint peeling in the peeling agent is not sufficient, there is a risk that the coating remains on the object to be painted during peeling.

[0006] The main object of the present disclosure is to provide a coating agent for paint peeling and the like that has good solubility in a peeling agent and can realize a coating for efficiently peeling paint from an object to be painted.

Means for Solving the Problems

[0007] The aspects of this disclosure that solve the above problems are as follows:

[0008] [1] A paint stripping coating agent comprising polyvinyl alcohol, a surfactant, and water. [2] The paint stripping coating agent according to [1], wherein the weight ratio of the content of polyvinyl alcohol to the surfactant (polyvinyl alcohol / surfactant) is 0.2 to 15.0. [3] The paint stripping coating agent according to [1] or [2], wherein the degree of polymerization of the polyvinyl alcohol is 350 or more. [4] The paint-removing coating agent according to any one of [1] to [3], wherein the total amount of the polyvinyl alcohol and the surfactant in the paint-removing coating agent is 0.5% to 45% by weight. [5] The paint stripping coating agent according to any one of [1] to [4], wherein the surfactant is an anionic surfactant or a nonionic surfactant. [6] The paint stripping coating agent according to [5], wherein the anionic surfactant is at least one selected from the group consisting of fatty acids, alkyl sulfate esters, alkylbenzene sulfonic acid, polyoxyethylene alkyl ether sulfate, dialkyl sulfosuccinic acid and salts thereof. [7] The paint stripping coating agent according to [5] or [6], wherein the weight ratio of the polyvinyl alcohol content to the anionic surfactant (polyvinyl alcohol / anionic surfactant) is 0.2 to 7.0. [8] A paint-stripping coating agent diluted with water, wherein the paint-stripping coating agent described in any of [1] to [7] is used in the paint-stripping coating agent dilution solution. A paint stripping kit comprising a paint stripping coating agent described in any of [1] to [7] [9] and a paint stripping agent.

[10] A film made using the coating agent described in any of [1] to [7] or the coating diluent described in [8].

[11] The coating according to

[10] , which is soluble in a stripping agent containing benzyl alcohol.

[12] A laminate in which the coating described in

[10] or

[11] is provided between the material to be coated and the paint.

[13] A method for removing paint from a workpiece by dissolving a film described in

[10] or

[11] , which is provided between the workpiece and the paint, with a paint remover.

[14] The paint removal method according to

[13] , wherein the temperature of the paint remover is less than 90°C. [Effects of the Invention]

[0009] According to this disclosure, it is possible to provide a coating agent for paint removal that has good solubility in paint removers and can realize a coating that efficiently removes paint from the coated material. [Brief explanation of the drawing]

[0010] [Figure 1] This image explains the criteria for evaluating solubility. [Modes for carrying out the invention]

[0011] Preferred embodiments of the present disclosure are described in detail below. However, the present disclosure is not limited to these embodiments. The elements listed below can be combined in any way, and the scope of the present invention is intended to include all modifications within the claims and scopes equivalent to the claims. The upper and lower limits in each numerical range of the embodiments of the present disclosure can be combined in any way to form any numerical range.

[0012] (Paint stripping coating agent) The paint-removing coating agent of this embodiment contains polyvinyl alcohol, a surfactant, and water. The aqueous paint-removing coating agent of this embodiment, containing polyvinyl alcohol and a surfactant, has good solubility in paint removers and can form a coating with good peelability. The paint-removing coating agent of this embodiment can achieve excellent peelability even at low temperatures.

[0013] The paint-removing coating agent of this embodiment contains polyvinyl alcohol. By including hydrophilic polyvinyl alcohol, the solubility of the film made using the paint-removing coating agent in paint removers, particularly in water-soluble removers, can be increased, thereby improving the peelability of paint adhering to or deposited on the film. Polyvinyl alcohol may be used alone or in combination of two or more types.

[0014] From the viewpoint of solubility and release properties with respect to the release agent, the degree of saponification of polyvinyl alcohol is preferably 70 mol% or less, more preferably 50 mol% or less, even more preferably 45 mol% or less, and still more preferably 40 mol% or less. In particular, when the main component of the release agent is an aromatic alcohol (e.g., benzyl alcohol), when the degree of saponification of polyvinyl alcohol is 50 mol% or less, the hydrophobicity of polyvinyl alcohol is enhanced, and its solubility with the release agent becomes better. The lower limit of the degree of saponification of polyvinyl alcohol is not particularly limited, but may be 10 mol% or more, or 20 mol% or more. The degree of saponification of polyvinyl alcohol may be, for example, 10 mol% to 70 mol%.

[0015] The degree of polymerization of polyvinyl alcohol is preferably 350 to 5000, more preferably 400 to 3000, and even more preferably 450 to 1000. When the degree of polymerization is 350 or higher, the flexibility of the coating is improved, and the occurrence of painting defects caused by cracked or peeled coatings adhering to the object to be painted can be suppressed. When the degree of polymerization is 5000 or lower, the viscosity of the paint-removing coating agent can be kept low, resulting in good handling and application properties.

[0016] Polyvinyl alcohol can be obtained, for example, by saponifying polyvinyl acetate. Commercially available polyvinyl alcohol can also be used. Examples of commercially available polyvinyl alcohol include JMR-10L, JMR-20L, JMR-20M, JF05, and JT05 (all manufactured by Nippon Vinegar & Polyvinyl Alcohol Co., Ltd.).

[0017] The coating agent for paint stripping in the embodiment contains a surfactant. The surfactant contributes to improving the solubility and stripping property with respect to the stripping agent. Further, the surfactant has a function as a plasticizer and can improve the bending resistance of the film by imparting flexibility to polyvinyl alcohol.

[0018] As the surfactant, from the viewpoints of solubility and stripping property with respect to the stripping agent, an anionic surfactant and a nonionic surfactant are preferable, and an anionic surfactant is more preferable. When using polyvinyl alcohol with a low saponification degree, particularly polyvinyl alcohol with a saponification degree of 50 mol% or less, it is preferable to combine an anionic surfactant. The surfactant may be used alone or in combination of two or more.

[0019] Examples of the anionic surfactant include at least one selected from the group consisting of fatty acids, alkyl sulfates, alkylbenzene sulfonic acids, polyoxyethylene alkyl ether sulfates, dialkyl sulfosuccinates, and salts thereof. Examples of the anionic surfactant include fatty acid salts, alkyl sulfate salts, alkylbenzene sulfonate salts, polyoxyethylene alkyl ether sulfate salts, and dialkyl sulfosuccinate salts, etc., and alkylbenzene sulfonate salts are preferable. Examples of the salt include ammonium salts, lithium salts, sodium salts, potassium salts, etc., and sodium salts are preferable. Specific examples of the anionic surfactant include sodium dodecylbenzenesulfonate, sodium dodecyldiphenyloxide disulfonate, etc.

[0020] Examples of nonionic surfactants include ethers, esters, amines, and amides, with ethers being preferred. Examples of ethers include alkyl ethers, polyoxyalkylene ethers, polyoxyalkylene alkyl ethers, polyoxyethylene alkylphenyl ethers, and polyoxyethylene polyoxypropylene glycol, with polyoxyalkylene alkyl ethers being preferred. Examples of esters include glycerin fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, and polyoxysorbitol fatty acid esters. Examples of amines include polyoxyalkylene alkylamines and EO adducts of organic amines. Examples of amides include fatty acid alkanolamides and oleic acid diethanolamides.

[0021] Commercially available surfactants can also be used. Examples of commercially available surfactants include Sodium Dodecylbenzenesulfonate (hard type) (mixture) Product Code: D0990 (manufactured by Tokyo Chemical Industry Co., Ltd.), Perex SS-H (manufactured by Kao Corporation), and Dispanol WI-115 (manufactured by NOF Corporation).

[0022] The paint-removing coating agent of the embodiment contains water. The paint-removing coating agent is an aqueous coating agent obtained by dissolving or dispersing each of the above components in water. The water used in the paint-removing coating agent of the embodiment may be tap water, industrial water, deionized water, distilled water, etc., and it does not matter whether the water is hard water or soft water. Water may be used alone or in combination of two or more types.

[0023] The polyvinyl alcohol content in the paint-removing coating agent is preferably 0.5% to 35% by weight, more preferably 2.5% to 25% by weight, and even more preferably 8% to 18% by weight, from the viewpoint of peelability and handling. When two or more types are used in combination, the content refers to the total amount.

[0024] The surfactant content in the paint-removing coating agent is preferably 0.1% to 20% by weight, more preferably 1% to 13% by weight, and even more preferably 3.5% to 6% by weight, from the viewpoint of solubility and peelability. When two or more surfactants are used in combination, the content refers to the total amount.

[0025] From the viewpoint of solubility, peelability, and handling, the total content of polyvinyl alcohol and surfactant in the paint stripping coating agent is preferably 0.5% to 45% by weight, more preferably 3.5% to 33% by weight, and even more preferably 15% to 23% by weight.

[0026] In a paint-removing coating agent, the weight ratio of polyvinyl alcohol content to surfactant content (polyvinyl alcohol / surfactant) is preferably 0.2 to 15.0, more preferably 0.2 to 13.0, more preferably 0.2 to 7.0, more preferably 0.5 to 6.0, and more preferably 0.7 to 4.5. In particular, when an anionic surfactant is used as the surfactant, the weight ratio of polyvinyl alcohol content to anionic surfactant content (polyvinyl alcohol / anionic surfactant) is more preferably 0.2 to 7.0, more preferably 0.5 to 6.0, and more preferably 0.7 to 4.5. When the weight ratio of polyvinyl alcohol content to surfactant or anionic surfactant is within the above range, the liquid stability of the paint-removing coating agent is good, the film formed using the paint-removing coating agent has good peelability, and also has excellent flexural resistance.

[0027] The water content can be set as appropriate depending on the type and amount of other ingredients. The water content in the paint-removing coating agent is preferably 1% to 99% by weight, more preferably 50% to 90% by weight, and even more preferably 75% to 85% by weight. When two or more types are used in combination, the water content refers to the total amount.

[0028] The paint-removing coating agent of the embodiment may contain various additives as needed, in addition to the above-mentioned components, as long as they do not hinder the effects of the present invention. Examples of additives include preservatives.

[0029] Examples of preservatives include organic nitrogen sulfur compound preservatives, organic sulfur halides, and thiazoline compounds. Preservatives may be used alone or in combination of two or more. When preservatives are included, the amount of preservative in the paint-removing coating agent can be, for example, 2.0% by weight or less, preferably 0.01% to 2.0% by weight, from the viewpoint of preservative effect. When two or more are used in combination, the amount refers to the total amount.

[0030] From the viewpoint of applicability and handling, the viscosity of the paint-removing coating agent at 25°C is preferably 10 to 1000 mPa·s, more preferably 100 to 500 mPa·s. The viscosity of the paint-removing coating agent at 25°C can be measured using an E-type viscometer.

[0031] The paint-removing coating agent of this embodiment is obtained by mixing the above-mentioned components. The mixing method is not particularly limited, but known methods such as stirring can be used. Furthermore, the order in which the components are added is not particularly limited. The paint-removing coating agent of this embodiment is water-soluble and can be used directly as a surface coating for materials to be painted.

[0032] (Dilution solution for paint stripping coating agent) The paint-removing coating agent described above may be used in the form of a diluted paint-removing coating agent solution, which is obtained by diluting the paint-removing coating agent with water, using the paint-removing coating agent as a stock solution. The diluted paint-removing coating agent solution of the embodiment is obtained by diluting the paint-removing coating agent with water. The water used can be tap water, industrial water, deionized water, distilled water, etc., and it does not matter whether the water is hard water or soft water.

[0033] When diluting the undiluted paint-removing coating agent with water, the dilution ratio can be appropriately adjusted according to the composition of the paint-removing coating agent and the performance required during stripping. The dilution ratio is not limited, but 2 to 10 times is preferred. From the viewpoint of further enhancing the effects of the present invention and obtaining an effect commensurate with its use, 3 to 8 times is more preferred, and 4 to 6 times is even more preferred.

[0034] From the viewpoint of corrosion inhibition, the pH of the paint stripping coating agent diluent is preferably 6.5 to 11.0, and more preferably 7.0 to 11.0.

[0035] The paint-removing coating agent and its diluent according to the embodiment can be suitably used on a workpiece that is painted with paint and is intended to be stripped with a paint stripper. Examples of workpieces include painting tools such as hangers, jigs, and slatted mats, painting equipment, painting robot arms, inner walls of painting booths, floor members, and wall materials. When used in combination with a paint stripper, the paint-removing coating agent and its diluent can significantly enhance the solubility of the coating film formed using the paint-removing coating agent and its diluent in relation to the paint stripper, as well as the paint-removing effect.

[0036] The paint-removing coating agent or its diluent in the embodiment is supplied to the surface of the material to be painted, i.e., to the parts that do not require painting, before the material to be painted is painted. The method of supplying the paint-removing coating agent or its diluent to the surface of the material to be painted is not particularly limited, but for example, a method of spraying or applying the paint-removing coating agent and its diluent to the surface of the material to be painted may be used. Examples of application methods include dip coating, shower coating, spray coating, and jet coating.

[0037] (Coatings and laminates) After applying a paint-removing coating agent or its diluted solution to the surface of the material to be painted, the material is allowed to air dry or heat dry (for example, at 60-120°C) to evaporate the water in the paint-removing coating agent or its diluted solution, thereby forming a film on the surface of the material to be painted. This results in a film that is soluble in paint removers, using a paint-removing coating agent that is soluble in paint removers. Hereinafter, the film formed using the paint-removing coating agent or its diluted solution will also be referred to as the coating film.

[0038] The thickness of the coating film is not particularly limited, but from the viewpoint of peelability, solubility, and drying properties, it is preferably 0.1 μm to 80 μm, and more preferably 10 μm to 50 μm.

[0039] The paint applied to the coating film may be any one or more known paints, of which such paints are commercially available. As the paint, a water-based paint is preferred from the viewpoint of effectively exhibiting the effects of the paint-removing coating agent and its diluent in the embodiment.

[0040] When a material to be painted, having a coating film on its surface, is used in a painting process according to its respective purpose, a paint film containing paint is formed on the surface of the coating film. In this way, a laminate is formed between the material to be painted and the paint, with a coating film made of a paint-removing coating agent or its diluted solution.

[0041] The painted material is subjected to a cleaning treatment using a paint stripper. The paint stripper removes the paint that adheres to the painted material via the coating film.

[0042] As for the paint remover, it can be appropriately selected from paint removers that have been used in this field, depending on the paint removal coating agent component, the type of paint applied, the thickness of the applied paint, and the material of the material to be painted.

[0043] Water-soluble stripping agents are preferred. Examples of stripping agents include water, alkaline aqueous solutions containing alkali metal salts such as sodium hydroxide, potassium hydroxide, sodium polyphosphate, and sodium carbonate, aromatic alcohols such as benzyl alcohol, alcohols such as ethanol and isopropyl alcohol, aromatic ethers such as phenylmethyl ether (anisole), alkanolamines such as ethanolamine, glycols such as ethylene glycol and propyl glycol, aryl sulfonates such as DMF, DMSO, glycol ethers, glycol acetate, sodium benzenesulfonate, and sodium toluenesulfonate, and combinations thereof. As a stripping agent, water-soluble stripping agents containing water, aromatic alcohols, aryl sulfonates, and alkali metal salts are preferred from the viewpoint of exhibiting good solubility of the paint stripping coating agent of the embodiment, and water-soluble stripping agents containing aromatic alcohols are more preferred. As a stripping agent, those mainly composed of benzyl alcohol are preferred. In a stripping agent mainly composed of benzyl alcohol, the benzyl alcohol content can be, for example, 75% or less by weight, preferably 40% or less by weight, and more preferably 38% or less by weight, based on the total amount of the stripping agent, although this is not particularly limited.

[0044] The pH of the paint remover is preferably 7 to 14, more preferably 9 to 13.8, and even more preferably 12 to 13.5. The coating film made using the paint remover coating agent of the embodiment can dissolve even when the pH of the paint remover is around 7, and can remove the paint from the material to be painted. However, in the case of an alkaline paint remover with a pH greater than 8, for example, the solubility of the paint remover coating film of the embodiment can be further increased, and the paint removeability can be further improved.

[0045] (Coating removal kit) The paint-removing coating agent of the embodiment can be provided as a kit containing the paint-removing coating agent. The paint-removing kit of the embodiment includes the above-mentioned paint-removing coating agent and a paint remover.

[0046] (Paint removal method) The paint removal method of the embodiment is a paint removal method using the paint removal coating agent of the embodiment, and includes the step of removing the paint from the material to be painted by dissolving the coating agent film provided between the material to be painted and the paint with a paint remover.

[0047] The paint removal process can be carried out by bringing a paint stripper into contact with an object to be treated, which has a coating film and paint layered sequentially on the material to be painted. The method of bringing the paint stripper into contact with the object to be treated is not limited, but for example, the object to be treated may be immersed in a tank containing the paint stripper. Alternatively, the paint stripper may be applied to the paint surface of the object to be treated.

[0048] The peeling temperature is not particularly limited, but from the viewpoint of peelability and environmental friendliness, it is preferably less than 90°C. The peeling temperature can be, for example, 5°C or more and less than 90°C, preferably 10°C to 80°C, more preferably 20°C to 70°C, and even more preferably 25°C to 55°C. The paint peeling coating agent of the embodiment can achieve excellent peelability even at low temperatures, for example, around 50°C, thus enabling a lower peeling temperature. The peeling temperature may also be the temperature of the peeling agent supplied to the coating film.

[0049] When removing paint by immersion, there are no particular limitations on the immersion time; it is sufficient to immerse the coating agent film for a time long enough for it to dissolve in the remover. From the viewpoint of peelability and environmental friendliness, the immersion time can be set to, for example, less than 12 minutes, and more preferably less than 8 minutes, at a temperature of 50°C. [Examples]

[0050] The present invention will be described in more detail below based on examples and comparative examples, but the present invention is not intended to be limited to those examples.

[0051] (Preparation of paint-removing coating agent) [Example 1] 79.4 parts by weight of water and 5.0 parts by weight of anionic surfactant (surfactant 1) were weighed into a heat-resistant container equipped with a heating and stirring device, and the contents were melted by stirring at 25°C. Then, 15.0 parts by weight of polyvinyl alcohol 1 (PVA1) was added while stirring, and the contents were dissolved by heating to 80°C and stirring. After cooling to 25°C, 0.6 parts by weight of a preservative was added and mixed uniformly to obtain 100 parts by weight of the paint-removing coating agent of Example 1.

[0052] [Examples 2-6, 12-16] The paint-removing coating agents for each example were prepared in the same manner as in Example 1, except that the formulation composition (expressed in parts by weight) of the paint-removing coating agent was as shown in Tables 1 and 2. Note that a 50% aqueous solution of surfactant 3 was used, and the parts by weight of surfactant 3 in Example 12 in Table 2 indicates the amount added in terms of solid content. Furthermore, the amount of water in Example 12 was adjusted so that the total amount of coating agent was 100 parts by weight.

[0053] [Example 7] 77.8 parts by weight of water was weighed into the heat-resistant container described above, and 20.0 parts by weight of polyvinyl alcohol 3 (PVA3) was added while stirring. The contents were then dissolved by heating to 50°C and stirring. After cooling to 25°C, 1.6 parts by weight of the nonionic surfactant 2 and 0.6 parts by weight of the preservative were added and mixed uniformly to obtain 100 parts by weight of the paint-removing coating agent of Example 7.

[0054] [Examples 8-11] The paint-removing coating agents for each example were prepared in the same manner as in Example 7, except that the formulation of the paint-removing coating agent was as shown in Table 1.

[0055] (Preparation of test specimens) Flat test pieces (0.8 mm × 30 mm × 110 mm) of cold-rolled steel sheet (SPCC-SD), which had been polished in both vertical and horizontal directions with #40 grit sandpaper, were degreased with xylene and acetone. Next, each of the paint-removing coating agents (undiluted) from the above examples was diluted five times with water to obtain test solutions. Each of the obtained test solutions was applied to the surface of the flat test piece using the dip-coating method (pulling speed 6 mm / s). After that, it was dried in a 110°C incubator for 10 minutes to form a coating film on the surface of the flat test piece. The thickness of the coating film was approximately 90 μm or less in all cases. Next, a white water-based paint ("WP-507T-1A", manufactured by Kansai Paint Co., Ltd.) was applied using the dip-coat method (pulling speed 6 mm / s), dried at 25°C for 30 minutes, then dried and cured in a constant temperature oven at 80°C for 3 minutes, and further dried and cured at 140°C for 18 minutes to prepare a test piece with a coating film formed on the surface. As Comparative Example 1, a test piece was prepared in which no coating agent film was applied, and the coating film was formed directly on the surface of a flat test piece.

[0056] [Evaluation of peelability] Each prepared test specimen was immersed in an alkaline stripping agent ("Descoat SR-300K," manufactured by Neos Co., Ltd.) heated to 50°C, and the time until the coating film completely lifted off was measured. This time was defined as the stripping time, and the stripping time was evaluated according to the following criteria. A stripping time of less than 12 minutes was considered the desired stripping performance. The measurement results and evaluation of the stripping time are shown in Tables 1 and 2. ◎: Peeling time less than 8 minutes ○: Peeling time 8 minutes or more but less than 12 minutes ×: Peeling time 12 minutes or more

[0057] [Evaluation of solubility in release agents] The coating agent prepared using the above method was immersed in an alkaline stripping agent ("Descoat SR-300K," manufactured by Neos Co., Ltd.) heated to 50°C and left to stand for 24 hours. The appearance of the coating after standing was visually inspected and evaluated according to the following criteria. The solubility evaluation is shown in Tables 1 and 2. ◎: The coating was completely dissolved, and no residue remained. ○: The coating is swollen or partially dissolved, and a change in appearance is observed.

[0058] Figure 1 is an image illustrating the evaluation criteria for solubility. In Figure 1, the dashed circles indicate the remaining coating. Figure 1 is an illustrative image for illustrating the evaluation criteria and does not limit the actual evaluation results.

[0059] [Evaluation of flexural resistance] The paint-removing coating agent prepared by the above method was applied to a PET film to a thickness of approximately 70 μm, and dried in a constant temperature oven at 110°C for 20 minutes to form a coating of the paint-removing coating agent on the surface. For each PET film, a mandrel test was performed using a cylindrical mandrel bending tester in accordance with JIS K5600-5-1. Mandrels with diameters ranging from 2 mm to 20 mm were used. The diameter of the mandrel was gradually decreased, and the diameter of the mandrel at which the coating first cracked or peeled was recorded as the test result of the bending test. The mandrel diameters are shown in Tables 1 and 2.

[0060] [Viscosity measurement] The viscosity of the paint-removing coating agent (undiluted solution) prepared by the above method was measured using an E-type viscometer (TVE-25L, manufactured by Toki Sangyo Co., Ltd.) at 25°C and 0.1 rpm.

[0061] [Table 1]

[0062] [Table 2]

[0063] Details of each component shown in Tables 1 and 2 are as follows. In the tables, the values ​​in parentheses for polyvinyl alcohol and surfactants indicate the ratio (weight %) of each component to the total amount of polyvinyl alcohol and surfactant. The weight ratio of polyvinyl alcohol to surfactant (polyvinyl alcohol / surfactant) is also indicated. In Tables 1 and 2, the amount of preservatives shown is for a 33% aqueous solution.

[0064] • Polyvinyl alcohol PVA1: JMR-10L (manufactured by Nippon Vivaceae Co., Ltd., degree of saponification 35 mol%, degree of polymerization 250) PVA2: JMR-20L (manufactured by Nippon Vivaceae Co., Ltd., degree of saponification 35 mol%, degree of polymerization 400) PVA3: JMR-20M (manufactured by Nippon Vivaceae Co., Ltd., degree of saponification 65 mol%, degree of polymerization 400) PVA4: JMR-20H (manufactured by Nippon Vivaceae Co., Ltd., degree of saponification 80 mol%, degree of polymerization 400) PVA5:JT05 (manufactured by Nippon Bi-Val Vinegar Co., Ltd., degree of saponification 93.5 mol%~95.0 mol%, degree of polymerization 500) PVA6:JF05 (manufactured by Nippon Bi-Val Vinegar Co., Ltd., degree of saponification 98.0 mol%~99.0 mol%, degree of polymerization 500) • Surfactants Surfactant 1: Sodium Dodecylbenzenesulfonate (hard type) (mixture), Product Code: D0990, manufactured by Tokyo Chemical Industry Co., Ltd., anionic surfactant. Surfactant 2: Polyoxyalkylene alkyl ether (Dispanol WI-115, manufactured by NOF Corporation, nonionic surfactant) Surfactant 3: Sodium dodecyldiphenyl oxide disulfonate (Perex SS-H, manufactured by Kao Corporation, anionic surfactant, 50% aqueous solution) • Preservatives Benzoisothiazolin-3-one (Bioside W-B350, manufactured by Taisho Technos Co., Ltd., 33% aqueous solution)

[0065] As is clear from Tables 1 and 2, in each example using a paint-removing coating agent containing polyvinyl alcohol, a surfactant, and water, excellent peelability and solubility, as well as good flexural resistance, were confirmed. In Comparative Example 1, which did not use a paint-removing coating agent, the peelability was poor.

[0066] In Examples 1-6, which used polyvinyl alcohol with a low degree of saponification, it was confirmed that the peelability and solubility tended to be better than in Examples 7-11, which used polyvinyl alcohol with a high degree of saponification.

[0067] Examples 1 and 2 confirmed that the flexural resistance tended to improve as the degree of polymerization of polyvinyl alcohol increased. Examples 2-5 showed better peelability than Example 6, which had a smaller weight ratio of polyvinyl alcohol to surfactant. Furthermore, Examples 2-4 and 6 showed better flexural resistance than Example 5, which had a larger weight ratio of polyvinyl alcohol to surfactant.

[0068] Examples 2, 13-16 showed that the peeling time was shorter and the peeling properties improved as the total content of polyvinyl alcohol and surfactant increased. Examples 2, 15, and 16 showed that the viscosity increased as the total content of polyvinyl alcohol and surfactant increased.

[0069] Based on the above, it has been confirmed that the paint stripping coating agent of this disclosure has good solubility in paint strippers and can form a coating film that efficiently removes paint from the coated material.

Claims

1. A paint stripping coating agent containing polyvinyl alcohol, a surfactant, and water.

2. The paint stripping coating agent according to claim 1, wherein the weight ratio of the content of polyvinyl alcohol to the surfactant (polyvinyl alcohol / surfactant) is 0.2 to 15.

0.

3. The paint stripping coating agent according to claim 1 or claim 2, wherein the degree of polymerization of the polyvinyl alcohol is 350 or more.

4. The paint-removing coating agent according to claim 1, wherein the total amount of the polyvinyl alcohol content and the surfactant content in the paint-removing coating agent is 0.5% by weight to 45% by weight.

5. The paint stripping coating agent according to claim 1, wherein the surfactant is an anionic surfactant or a nonionic surfactant.

6. The paint stripping coating agent according to claim 5, wherein the anionic surfactant is at least one selected from the group consisting of fatty acids, alkyl sulfate esters, alkylbenzene sulfonic acid, polyoxyethylene alkyl ether sulfate, dialkyl sulfosuccinic acid, and salts thereof.

7. The paint stripping coating agent according to claim 5 or claim 6, wherein the weight ratio of the polyvinyl alcohol content to the anionic surfactant (polyvinyl alcohol / anionic surfactant) is 0.2 to 7.

0.

8. A paint-removing coating agent diluted with water, wherein the paint-removing coating agent described in claim 1 is diluted with water.

9. A paint removal kit comprising a paint removal coating agent and a paint remover as described in claim 1.

10. A film made using the coating agent described in claim 1 or the coating diluent described in claim 8.

11. The coating according to claim 10, which is soluble in a stripping agent containing benzyl alcohol.

12. A laminate in which the coating described in claim 10 is provided between the material to be coated and the paint.

13. A method for removing paint from a workpiece, comprising dissolving the film described in claim 10, which is provided between the workpiece and the paint, with a paint remover to remove the paint from the workpiece.

14. The paint removal method according to claim 13, wherein the temperature of the paint remover is less than 90°C.

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