Coating agent for paint peeling, coating agent diluent for paint peeling, paint peeling kit, film, laminate, and paint peeling method

Abstract

The present invention provides a coating agent for paint peeling, which is excellent in solubility in a peeling agent and enables coating for efficiently peeling paint from a painted material. The coating agent for paint peeling comprises polyvinyl alcohol, a surfactant, and water.

Description

Technical Field

[0001] This invention relates to coating agents for paint stripping, diluents for coating agents for paint stripping, paint stripping kits, coatings, laminates, and methods for paint stripping. Background Technology

[0002] In painting processes for various objects, primarily automobiles, various types of painting fixtures are used. If paint adheres to or accumulates on the painting fixtures, workability and functionality are reduced; therefore, it is necessary to remove the paint from the painting fixtures at regular intervals.

[0003] As a method for removing coatings, the following technique is disclosed: before the coating process, a coating agent is applied to the parts of the coating fixture that do not need to be coated, and a stripping agent, solvent, etc. are used to remove the coatings that have adhered to or accumulated on the coating fixture after the coating process (for example, Patent Document 1).

[0004] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2002-275394 Summary of the Invention

[0005] The technical problem that the invention aims to solve If the coating agent used for paint stripping is not sufficiently soluble in the stripping agent, coating residue may remain on the coated material during stripping.

[0006] The main objective of this invention is to provide a coating agent for removing coatings, which has good solubility in a release agent and can achieve coating for efficiently removing coatings from the coated material.

[0007] Technical solutions for solving technical problems The present invention addresses the above-mentioned technical problems as follows.

[0008] [1] A coating stripping agent comprising polyvinyl alcohol, a surfactant and water.

[0009] [2] According to the coating stripping agent of [1], the weight ratio of the content of polyvinyl alcohol to the content of the surfactant (polyvinyl alcohol / surfactant) is 0.2 to 15.0.

[0010] [3] The coating agent for peeling off the coating according to [1] or [2], wherein the degree of polymerization of the polyvinyl alcohol is 350 or more.

[0011] [4] The coating stripping agent according to any one of [1] to [3], wherein the total content of the polyvinyl alcohol and the content of the surfactant in the coating stripping agent is 0.5% to 45% by weight.

[0012] [5] The coating stripping agent according to any one of [1] to [4], wherein the surfactant is an anionic surfactant or a nonionic surfactant.

[0013] [6] According to the coating stripping agent of [5], wherein the anionic surfactant is selected from at least one of fatty acids, alkyl sulfates, alkylbenzene sulfonic acids, fatty alcohol polyoxyethylene ether sulfuric acid (polyoxyethylene alkyl ether sulfuric acid), dialkyl sulfosuccinic acid and their salts.

[0014] [7] The coating stripping agent according to [5] or [6], wherein the weight ratio of the polyvinyl alcohol to the content of the anionic surfactant (polyvinyl alcohol / anionic surfactant) is 0.2 to 7.0.

[0015] [8] A coating stripping agent diluent, wherein it is obtained by diluting the coating stripping agent described in any one of [1] to [7] with water.

[0016] [9] A paint stripping kit comprising a paint stripping agent and a stripping agent as described in any one of [1] to [7].

[0017]

[10] A coating obtained by using any one of the coating agents described in [1] to [7] or a diluent of the coating agent described in [8].

[0018]

[11] The coating according to

[10] , wherein the coating is soluble in a stripping agent containing benzyl alcohol.

[0019]

[12] A laminate having a coating as described in

[10] or

[11] between the material to be coated and the coating.

[0020]

[13] A method for peeling off a coating, which uses a peeling agent to dissolve the coating

[10] or

[11] disposed between the coating material and the coating, thereby peeling the coating off the coating material.

[0021]

[14] According to the coating stripping method described in

[13] , the temperature of the stripping agent is less than 90°C.

[0022] Invention Effects According to the present invention, a coating agent for removing coatings can be provided, which has good solubility in a release agent and can achieve coating for efficiently removing coatings from the coated material. Attached Figure Description

[0023] Figure 1 It is an image illustrating the evaluation criteria for solubility. Detailed Implementation

[0024] The preferred embodiments of the present invention will now be described in detail. However, the present invention is not limited to the following embodiments. The elements listed below can be combined arbitrarily, and the scope of the present invention is intended to include all modifications within the claims and the scope equivalent to the claims. The upper and lower limits of the numerical ranges in the embodiments of the present invention can be combined arbitrarily to form any numerical range.

[0025] (Coating stripping agent) The coating agent for paint release in this embodiment contains polyvinyl alcohol, a surfactant, and water. The water-based coating agent for paint release in this embodiment, containing polyvinyl alcohol and a surfactant, exhibits good solubility in the release agent, enabling the formation of a coating with excellent release properties. The coating agent for paint release in this embodiment achieves excellent release properties even at low temperatures.

[0026] The coating agent for paint stripping in this embodiment contains polyvinyl alcohol. By containing hydrophilic polyvinyl alcohol, the solubility of the coating made using the coating agent for paint stripping in the stripping agent, especially in water-soluble stripping agents, can be improved, thus improving the peelability of the coating adhering to or deposited on the coating. Polyvinyl alcohol can be used alone or in combination with two or more other agents.

[0027] From the viewpoint of solubility and release properties in 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 even more preferably 40 mol% or less. Particularly 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 in the release agent becomes better. The lower limit of the degree of saponification of polyvinyl alcohol is not particularly limited and can be 10 mol% or more, or 20 mol% or more. For example, the degree of saponification of polyvinyl alcohol can be from 10 mol% to 70 mol%.

[0028] 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 flexural strength of the coating can be improved, and coating defects caused by broken or peeling coating adhering to the object being coated can be suppressed. When the degree of polymerization is 5000 or lower, the viscosity of the coating agent for paint release can be kept low, resulting in good workability and coatability.

[0029] Polyvinyl alcohol (PVA) is obtained, for example, by saponifying polyvinyl acetate. Commercially available PVA products are also available. Examples of commercially available PVA products include JMR-10L, JMR-20L, JMR-20M, JF05, and JT05 (all manufactured by VAM&POVAL Corporation of Japan).

[0030] The coating agent for paint release in this embodiment contains a surfactant. The surfactant helps improve solubility and release properties in the release agent. Additionally, the surfactant functions as a plasticizer, improving the flexural strength of the coating by imparting softness to polyvinyl alcohol.

[0031] From the viewpoint of solubility and stripping properties in stripping agents, anionic and nonionic surfactants are preferred as surfactants, with anionic surfactants being more preferred. When using polyvinyl alcohol with a low degree of saponification, particularly 50 mol% or less, as the polyvinyl alcohol, a combination of anionic surfactants is preferred. Surfactants can be used alone or in combination of two or more.

[0032] Examples of anionic surfactants include at least one selected from fatty acids, alkyl sulfates, alkylbenzene sulfonic acids, fatty alcohol polyoxyethylene ether sulfates, dialkyl sulfosuccinic acids, and their salts. Examples of anionic surfactants include fatty acid salts, alkyl sulfate salts, alkylbenzene sulfonates, fatty alcohol polyoxyethylene ether sulfates, and dialkyl sulfosuccinic acids, with alkylbenzene sulfonates being preferred. Examples of salts include ammonium salts, lithium salts, sodium salts, and potassium salts, with sodium salts being preferred. Specific examples of anionic surfactants include sodium dodecylbenzene sulfonate and sodium dodecyl diphenyl ether disulfonate.

[0033] Examples of nonionic surfactants include ethers, esters, amines, and amides, with ethers being preferred. Examples of ethers include alkyl ethers, polyoxyalkylene ethers, polyoxyalkylene ethers, polyoxyethylene alkylphenyl ethers, and polyoxyethylene polyoxypropylene glycol, with polyoxyalkylene ethers being preferred. Examples of esters include glycerol fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, and polyoxysorbitol fatty acid esters. Examples of amines include polyoxyalkylene amines and EO adducts of organic amines. Examples of amides include fatty acid alkanolamides and oleic acid diethanolamides.

[0034] 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.), PELEX SS-H (manufactured by Kao Corporation), and DISPANOL WI-115 (manufactured by Nippon Oil Co., Ltd.).

[0035] The coating agent for paint stripping in this embodiment contains water. The coating agent for paint stripping is an aqueous coating agent prepared by dissolving or dispersing the above-mentioned components in water. The water used in the coating agent for paint stripping in this embodiment can be any of tap water, industrial water, ion-exchanged water, distilled water, etc., and can be hard water or soft water. Water can be used alone or in combination with two or more types.

[0036] In coating agents for paint release, from the viewpoint of release properties and workability, the content of polyvinyl alcohol 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. When two or more are used, the content refers to the total amount.

[0037] In coating agents for paint stripping, from the viewpoint of solubility and stripping properties, the content of surfactant 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. When two or more surfactants are used, the content refers to the total amount.

[0038] In coating agents for paint stripping, from the viewpoints of solubility, stripping properties and workability, the total content of polyvinyl alcohol and surfactant 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.

[0039] In the coating agent for paint release, the weight ratio of polyvinyl alcohol (PVA) to surfactant (PVA / surfactant) is preferably 0.2 to 15.0, more preferably 0.2 to 13.0, even more preferably 0.2 to 7.0, even more preferably 0.5 to 6.0, and even more preferably 0.7 to 4.5. Particularly when an anionic surfactant is used, the weight ratio of PVA to anionic surfactant (PVA / anionic surfactant) is more preferably 0.2 to 7.0, more preferably 0.5 to 6.0, and even more preferably 0.7 to 4.5. When the weight ratio of PVA to surfactant or anionic surfactant is within the above range, the coating agent for paint release exhibits good liquid stability, the coating made using the coating agent for paint release exhibits good peelability, and excellent flexural strength.

[0040] The water content can be appropriately set based on the type and content of other co-components. In coating agents for paint stripping, the water content 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 components are used, the content refers to the total amount.

[0041] In addition to the components described above, the coating agent for removing coatings according to the embodiments may contain various additives as needed, without impairing the effects of the present invention. Examples of additives include preservatives.

[0042] Examples of preservatives include organonitrogen-sulfur compounds, organosulfur halides, and thiazoline compounds. Preservatives can be used alone or in combination of two or more. When preservatives are included, from a corrosion prevention point of view, the content of preservatives in the coating agent for paint stripping can be, for example, 2.0% by weight or less, preferably 0.01% by weight to 2.0% by weight. When two or more are used together, the content refers to the total amount.

[0043] From the viewpoint of coatability and operability, the viscosity of the coating agent for paint release at 25°C is preferably 10–1000 mPa·s, more preferably 100–500 mPa·s. The viscosity of the coating agent for paint release at 25°C can be measured using an E-type viscometer.

[0044] The paint stripping agent of this embodiment is obtained by mixing the above-mentioned components. There are no particular limitations on the mixing method; for example, known methods such as stirring can be used. Furthermore, there are no particular limitations on the order in which the components are added. The paint stripping agent of this embodiment is water-soluble and can be directly applied to the surface of the material to be coated.

[0045] (Coating stripping agent thinner) The aforementioned paint stripping agent can be used as a concentrate, diluted with water to form a paint stripping agent diluent. The paint stripping agent diluent of the embodiment is obtained by diluting the paint stripping agent with water. The water used can be any of tap water, industrial water, ion-exchanged water, distilled water, etc., and can be hard water or soft water.

[0046] The dilution ratio when diluting the undiluted paint release agent with water can be appropriately adjusted according to the composition of the paint release agent and the performance required during release. The dilution ratio is not limited, but is preferably 2 to 10 times. From the viewpoint of further improving the effect of the invention and obtaining an effect commensurate with its use, a dilution ratio of 3 to 8 times is more preferred, and 4 to 6 times is even more preferred.

[0047] From the viewpoint of corrosion inhibition, the pH of the coating agent diluent for coating stripping is preferably 6.5 to 11.0, more preferably 7.0 to 11.0.

[0048] The paint stripping agent and its diluent of the embodiment are coating materials that have been coated with paint, and are suitable for use on coating materials for which a stripping agent is intended to be applied. Examples of coating materials include, for example, painting tools such as hangers, clamps, and drip trays, painting apparatus, painting robotic arms, the inner walls of painting booths, floor components, and wall materials. By using the paint stripping agent and its diluent in combination with a stripping agent, the paint stripping agent and its diluent can significantly enhance the solubility of the film made using the paint stripping agent and its diluent in the stripping agent and the paint stripping effect.

[0049] The paint release agent or its diluent of the embodiment is supplied in advance to the surface of the material to be coated, i.e., the part that does not require coating, before coating the material. There is no particular limitation on the method of supplying the paint release agent or its diluent to the surface of the material to be coated; for example, methods such as spraying or applying the paint release agent or its diluent to the surface of the material to be coated can be used. Examples of coating methods include dip coating, spray coating, mist coating, and jet coating.

[0050] (Covered and laminated products) After applying a paint release agent or its diluent to the surface of the material to be coated, it is allowed to air dry or heat dry (e.g., at 60–120°C) to evaporate the moisture in the paint release agent or its diluent, thereby forming a film on the surface of the material to be coated by drying the paint release agent or its diluent. This results in a paint release agent-soluble film made using a paint release agent. Hereinafter, films made using paint release agents or their diluents will also be referred to as coating films.

[0051] The thickness of the coating film is not particularly limited, but from the viewpoints of peelability, solubility and drying properties, it is preferably 0.1 μm to 80 μm, and more preferably 10 μm to 50 μm.

[0052] The coating applied to the coating agent film can be any one or more known coatings that are commercially available. From the viewpoint of effectively utilizing the coating stripping agent and its diluent as described in the embodiments, water-based coatings are preferred.

[0053] When a material to be coated, having a coating agent film on its surface, is used in a coating process for its respective purpose, a coating film containing paint is formed on the surface of the coating agent film. Thus, a laminate is formed in which a coating agent film made using a paint release agent or its diluent is disposed between the material to be coated and the paint.

[0054] The coated material is cleaned using a stripping agent. The stripping agent causes the paint to peel off the coating material that has adhered to it through the coating film.

[0055] As a release agent, an appropriate selection can be made from release agents previously used in this field, depending on the composition of the coating agent used for coating release, the type of coating to be applied, the thickness of the coating, and the material of the material being coated.

[0056] The stripping agent is preferably a water-soluble stripping agent. 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 isopropanol; aromatic ethers such as phenyl methyl ether (anisole); alkanolamines such as ethanolamine; glycols such as ethylene glycol and propylene glycol; DMF, DMSO, glycol ethers, glycol acetate, aryl sulfonates such as sodium benzenesulfonate and sodium toluenesulfonate; and combinations thereof. From the viewpoint of effectively utilizing the solubility of the coating agent for removing coatings according to the embodiments, water-soluble stripping agents containing water, aromatic alcohols, aryl sulfonates, and alkali metal salts are preferred, and water-soluble stripping agents containing aromatic alcohols are more preferred. As a stripping agent, a stripping agent with benzyl alcohol as the main component is preferred. In stripping agents with benzyl alcohol as the main component, the content of benzyl alcohol is not particularly limited, and based on the total amount of the stripping agent, it can be, for example, 75% by weight or less, preferably 40% by weight or less, and more preferably 38% by weight or less.

[0057] The pH of the release agent 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 coating release agent of the embodiment dissolves even when the pH of the release agent is around 7, enabling the coating to be released from the coated material. For example, in the case of an alkaline release agent with a pH exceeding 8, the solubility of the coating film of the embodiment can be further improved, and the coating film release properties can be further enhanced.

[0058] (Reagent kit for film peeling) The paint stripping agent of the embodiments can be provided as a kit containing the paint stripping agent. The paint stripping kit of the embodiments comprises the above-described paint stripping agent and stripping agent.

[0059] (Coating stripping method) The paint stripping method of the embodiment is a paint stripping method using the paint stripping coating agent of the embodiment, including the step of dissolving the coating agent film disposed between the coating material and the paint using a stripping agent, thereby stripping the paint from the coating material.

[0060] The process of removing coatings can be performed by contacting a release agent with a workpiece to which a coating agent film and a paint layer are sequentially stacked on top of the coated material. There is no limitation on the method of contacting the release agent with the workpiece; for example, the workpiece can be immersed in a tank containing the release agent. Alternatively, the release agent can be applied to the paint surface of the workpiece.

[0061] 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 higher 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 coating agent for peeling the paint according to the embodiment can achieve excellent peelability even at low temperatures, such as around 50°C, thus enabling a lower peeling temperature. The peeling temperature can be the temperature of the peeling agent supplied to the coating film.

[0062] When peeling off coatings by immersion, there is no particular limitation on the immersion time, as long as it is sufficient for the coating film to dissolve in the release agent. From the viewpoint of peelability and environmental friendliness, the immersion time can be preferably set to less than 12 minutes, more preferably less than 8 minutes, for example at a temperature of 50°C.

[0063] Example The present invention will be further described in detail below based on embodiments and comparative examples, but the present invention is not intended to be limited to these embodiments.

[0064] (Preparation of coating agent for paint stripping) [Example 1] In a heat-resistant container equipped with a heating and stirring device, 79.4 parts by weight of water and 5.0 parts by weight of anionic surfactant 1 were measured and stirred at 25°C to dissolve the contents. Then, while stirring, 15.0 parts by weight of polyvinyl alcohol 1 (PVA1) were added, and the mixture was heated to 80°C and stirred to dissolve the contents. After cooling to 25°C, 0.6 parts by weight of preservative were added and the mixture was thoroughly mixed to obtain 100 parts by weight of the coating release agent of Example 1.

[0065] [Examples 2-6, 12-16] The formulation composition (in parts by weight) of the coating agent for paint release is shown in Tables 1 and 2. Except as otherwise provided in Example 1, the coating agents for paint release in each example were prepared in the same manner. It should be noted that surfactant 3 was a 50% aqueous solution, and the parts by weight of surfactant 3 in Example 12 in Table 2 represent the amount calculated as solid components. Furthermore, the amount of water in Example 12 was adjusted so that the total amount of the coating agent was 100 parts by weight.

[0066] [Example 7] 77.8 parts by weight of water were measured in the aforementioned heat-resistant container. While stirring, 20.0 parts by weight of polyvinyl alcohol 3 (PVA3) were added, and the mixture was heated to 50°C and stirred to dissolve the contents. After cooling to 25°C, 1.6 parts by weight of nonionic surfactant 2 and 0.6 parts by weight of preservative were added and mixed evenly to obtain 100 parts by weight of the coating release agent of Example 7.

[0067] [Examples 8-11] The formulation of the coating agent for paint stripping is shown in Table 1. Except as otherwise provided, the coating agents for paint stripping of each embodiment are prepared in the same manner as in Example 7.

[0068] (Production of the experimental film) A flat test piece (0.8mm × 30mm × 110mm) of cold-rolled steel sheet (SPCC-SD) polished with #40 sandpaper in both longitudinal and transverse directions was degreased using xylene and acetone. Next, the coating stripping agent (concentrate) from each of the above examples was diluted 5 times with water to obtain a test solution. The obtained test solutions were applied to the surface of the flat test piece using a dip-coating method (lifting speed 6mm / s). Then, the surface was dried in a thermostat at 110°C for 10 minutes to form a coating film. The thickness of each coating film was approximately 90μm or less. Next, a white water-based paint (“WP-507T-1A”, manufactured by Kansai Paint Co., Ltd.) was applied using a dip-coating method (lifting speed 6mm / s), dried at 25°C for 30 minutes, then cured at 80°C for 3 minutes using a thermostat, and further cured at 140°C for 18 minutes, thereby producing a test piece with a coating film formed on its surface. In addition, as a comparative example 1, a test piece without a coating agent film was prepared, and a coating film was directly formed on the surface of the flat test piece.

[0069] [Evaluation of peelability] Each test piece was immersed in an alkaline stripping agent ("SR-300K" (Japanese trade name: デスコートSR-300K), manufactured by NEOS Corporation) heated to 50°C, and the time until the coating completely floated was measured. This time was taken as the peel time, and the peel time was evaluated according to the following criteria. A peel time of less than 12 minutes was considered the desired peelability. The measurement results and evaluation of the peel time are shown in Tables 1 and 2.

[0070] ◎: Peeling time less than 8 minutes ○: The peeling time is more than 8 minutes but less than 12 minutes. ×: Peeling time is 12 minutes or more. [Evaluation of solubility in stripping agents] The coating prepared by the above method was immersed in an alkaline release agent (DESCOAT SR-300K”, manufactured by Neos) heated to 50°C and left to stand for 24 hours. The appearance of the coating after standing was visually confirmed and evaluated according to the following criteria. The evaluation of solubility is shown in Tables 1 and 2.

[0071] ◎: The coating completely dissolves, leaving no residue. ○: The coating swells or partially dissolves, and changes in appearance are visible. Figure 1 It is an image illustrating the evaluation criteria for solubility. Figure 1 In the middle, the dashed circle represents the remaining coating. Figure 1 These are illustrative images used to illustrate evaluation criteria and do not limit the actual evaluation results.

[0072] [Evaluation of flexural strength] The paint release agent prepared by the above method was applied to a PET film with a film thickness of approximately 70 μm. The film was then dried at 110°C for 20 minutes using a thermostat, thereby forming a coating of the paint release agent on the surface. For each PET film, a mandrel test was performed using a cylindrical mandrel bending tester according to JIS K5600-5-1. Mandrels with diameters ranging from 2 mm to 20 mm were used. The mandrel diameter was gradually decreased, and the diameter of the mandrel at which the coating initially cracked or peeled was taken as the test result of the bending test. The mandrel diameters are shown in Tables 1 and 2.

[0073] [Viscosity Measurement] For the coating stripping agent (stock solution) prepared by the above method, the viscosity was measured at 25°C and 0.1 rpm using an E-type viscometer (TVE-25L, manufactured by Toki Sangyo Co., Ltd.).

[0074] [Table 1]

[0075] [Table 2]

[0076] The details of each component shown in Tables 1 and 2 are as follows. In the tables, the values ​​in parentheses for polyvinyl alcohol (PVA) and surfactant indicate the percentage (by weight) of each component relative to the total amount of PVA and surfactant. The weight ratio of PVA to surfactant (PVA / surfactant) is also listed. In Tables 1 and 2, preservatives are indicated in amounts in a 33% aqueous solution.

[0077] Polyvinyl alcohol PVA1: JMR-10L (manufactured by VAM&POVAL Corporation, Japan, saponification degree 35 mol%, polymerization degree 250) PVA2: JMR-20L (manufactured by VAM&POVAL Corporation of Japan, saponification degree 35 mol%, polymerization degree 400) PVA3: JMR-20M (manufactured by VAM&POVAL Corporation of Japan, saponification degree 65 mol%, polymerization degree 400) PVA4: JMR-20H (manufactured by VAM&POVAL Corporation of Japan, saponification degree 80 mol%, polymerization degree 400) PVA5: JT05 (manufactured by VAM&POVAL Co., Ltd. of Japan, saponification degree 93.5 mol%~95.0 mol%, degree of polymerization 500) PVA6: JF05 (manufactured by VAM&POVAL Co., Ltd. of Japan, saponification degree 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 ether (DISPANOL WI-115, manufactured by Nippon Oil Company, nonionic surfactant) Surfactant 3: Sodium dodecyl diphenyl ether disulfonate (PELEX SS-H, manufactured by Kao Corporation, anionic surfactant, 50% aqueous solution) ·preservative Benzoisothiazolin-3-one (BIOSAIDO WB 350, manufactured by Taisho Technos, 33% aqueous solution) As shown in Tables 1 and 2, in the examples using a paint release agent comprising polyvinyl alcohol, a surfactant, and water, excellent peelability and solubility, as well as good flexural strength, were confirmed. In Comparative Example 1, which did not use a paint release agent, peelability was poor.

[0078] Compared with examples 7-11, which used polyvinyl alcohol with a high degree of saponification, examples 1-6, which used polyvinyl alcohol with a low degree of saponification, showed a tendency to improve peelability and solubility.

[0079] Examples 1 and 2 confirm that the higher the degree of polymerization of polyvinyl alcohol, the better the flexural strength tends to be. Examples 2-5 show better peelability compared to Example 6, where the weight ratio of polyvinyl alcohol to surfactant is smaller. Furthermore, Examples 2-4 and 6 show better flexural strength compared to Example 5, where the weight ratio of polyvinyl alcohol to surfactant is larger.

[0080] As shown in Examples 2, 13-16, the higher the total content of polyvinyl alcohol and surfactant, the shorter the peeling time, and the better the peelability. According to Examples 2, 15, and 16, the higher the total content of polyvinyl alcohol and surfactant, the higher the viscosity.

[0081] As confirmed above, the coating agent for paint stripping of the present invention has good solubility in the stripping agent and can form a coating agent film for efficiently stripping the paint from the coated material.

Claims

1. A coating agent for paint stripping, characterized in that, It contains polyvinyl alcohol, surfactants, and water.

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

0.

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

4. The coating agent for paint stripping according to claim 1, wherein, In the coating agent for peeling off the coating, the total content of the polyvinyl alcohol and the content of the surfactant is 0.5% to 45% by weight.

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

6. The coating agent for paint stripping according to claim 5, wherein, The anionic surfactant is selected from at least one of fatty acids, alkyl sulfates, alkylbenzene sulfonic acids, fatty alcohol polyoxyethylene ether sulfuric acid, dialkyl sulfosuccinic acid and their salts.

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

0.

8. A coating stripping agent diluent, characterized in that, It is obtained by diluting the coating stripping agent of claim 1 with water.

9. A paint stripping kit, characterized in that, It includes the coating agent and release agent for coating removal as described in claim 1.

10. A coating, characterized in that, It is obtained using the coating agent according to claim 1 or the coating agent diluent according to claim 8.

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

12. A laminated body, characterized in that, It has a coating as described in claim 10 between the material to be coated and the coating.

13. A method for peeling off coatings, characterized in that, The coating of claim 10, disposed between the coating material and the paint, is dissolved by a stripping agent, thereby peeling the paint off the coating material.

14. The coating stripping method according to claim 13, wherein, The temperature of the stripping agent is less than 90°C.

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