Stripping solution and method for stripping resin

Abstract

To provide a peeling solution that can effectively remove resin. [Solution] This stripping solution contains water, an organic solvent having a δP value of 5.0 to 11.9, a δH value of 4.3 to 15.8, and a δD value of 15.9 to 18.6, and an alkaline compound having a pH of 12 or higher in the aqueous phase.

Description

Technical Field

[0001] This invention relates to a stripping liquid and a method for stripping a resin.

Background Art

[0002] Conventionally, stripping liquids are known (see, for example, Patent Document 1).

[0003] Patent Document 1 discloses a cleaning agent (stripping liquid) for an adhesive containing water, a hydrophilic organic solvent, an alkaline agent, and a surfactant.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The cleaning agent (stripping liquid) for an adhesive of Patent Document 1 contains water, a hydrophilic organic solvent, an alkaline agent, and a surfactant. Here, depending on the type of the hydrophilic organic solvent, the hydrophilic organic solvent, the alkaline agent, and the surfactant may mutually inhibit the stripping action, and it may be difficult to strip the adhesive (resin) well. Therefore, a stripping liquid capable of stripping the resin well is desired.

[0006] This invention has been made to solve the above problems, and one object of this invention is to provide a stripping liquid and a method for stripping a resin that can strip the resin well.

Means for Solving the Problems

[0007] To achieve the above objective, the inventors of this application focused on the Hansen solubility parameters of organic solvents, namely the δP, δH, and δD values, and, through repeated trial and error and diligent research, focused on the pH of the alkaline compound in the aqueous phase. As a result, they discovered that resin can be effectively peeled off by using a peeling solution containing water, an organic solvent having a δP value of 5.0 to 11.9, a δH value of 4.3 to 15.8, and a δD value of 15.9 to 18.6, and an alkaline compound having a pH of 12 or higher in the aqueous phase.

[0008] In other words, the stripping solution according to the first aspect of this invention contains water, an organic solvent having a δP value of 5.0 to 11.9, a δH value of 4.3 to 15.8, and a δD value of 15.9 to 18.6, and an alkaline compound having a pH of 12 or higher in the aqueous phase.

[0009] In the stripping solution according to the first aspect of this invention, it is considered that the organic solvent having the above-mentioned δP, δH, and δD values ​​and the alkaline compound having a pH of 12 or higher in the aqueous phase do not mutually inhibit each other's activity (stripping effect on resin), thus enabling effective stripping of resin. This point has been confirmed by experiments (examples) described later.

[0010] In the stripping solution according to the first aspect described above, it is preferably used for stripping thermosetting resins. With this configuration, a stripping agent capable of effectively stripping thermosetting resins can be provided. This point has also been confirmed by experiments (examples) described later.

[0011] In the stripping solution according to the first aspect described above, it is preferable that it does not contain a surfactant. With this configuration, it is possible to suppress the formation of a film on the resin by the surfactant, which prevents the organic solvent and alkali compound from acting on the resin (hindering the stripping action), thereby enabling better stripping of the resin.

[0012] In the stripping solution according to the first aspect described above, preferably, the alkali compound is tripotassium phosphate, contained in an amount of 1 to 50 parts by mass, and the organic solvent is benzyl alcohol, contained in an amount of 5 to 70 parts by mass. With this configuration, the resin can be effectively stripped by the action of the alkali tripotassium phosphate and the organic solvent benzyl alcohol.

[0013] In the stripping solution according to the first aspect described above, preferably, the alkali compound is at least one of sodium hydroxide and potassium hydroxide, contained in an amount of 1 to 9 parts by mass, and the organic solvent is benzyl alcohol, contained in an amount of 5 to 70 parts by mass. With this configuration, by including at least one of sodium hydroxide and potassium hydroxide, which are alkali compounds with strong alkalinity, in an amount of 1 part by mass or more, the resin can be stripped more effectively by the action of the strong alkali. Furthermore, by limiting the content of at least one of the strong alkali compounds, sodium hydroxide and potassium hydroxide, to 9 parts by mass or less, it is possible to suppress the alkalinity from becoming excessively strong, thereby reducing the complexity of managing the stripping solution. In addition, the resin can be stripped effectively by the action of the organic solvent, benzyl alcohol.

[0014] In the stripping solution according to the first aspect described above, preferably, the amount of water is greater than 45 parts by mass and 86 parts by mass or less. With this configuration, by making the water content greater than 45 parts by mass, it is possible to suppress an increase in the content of the organic solvent, thereby suppressing the ease with which the stripping solution volatilizes due to the components of the organic solvent. Furthermore, by making the water content 86 parts by mass or less, it is possible to suppress a decrease in the content of the organic solvent and alkaline compounds that act on the resin.

[0015] In the stripping solution according to the first aspect described above, preferably, the organic solvent has a flash point of 100°C or higher. This configuration makes the stripping solution less likely to ignite, thus reducing the complexity of managing the stripping solution.

[0016] In this case, preferably, the organic solvent includes one selected from the group consisting of benzyl alcohol and 1,3-dimethyl-2-imidazolidinone. With this configuration, the resin can be effectively removed by the action of the organic solvent, either benzyl alcohol or 1,3-dimethyl-2-imidazolidinone.

[0017] In the stripping solution according to the first phase described above, preferably, the alkaline compound is contained in an amount of 1 to 50 parts by mass such that the pH in the aqueous phase is 12 or higher. With this configuration, the resin can be stripped more effectively by the action of a strong alkali with a pH of 12 or higher.

[0018] In the stripping solution according to the first phase described above, preferably, the organic solvent comprises one selected from the group consisting of benzyl alcohol, 1,3-dimethyl-2-imidazolidinone, isophorone, CPN (cyclopentane), 2MTHF (2-methyltetrahydrofuran), THF (tetrahydrofuran), 1-pentanol, methyl ethyl ketone, and 1-butanol, or two selected from the group consisting of CPN (cyclopentane), γ-butyrolactone, NMP (N-methylpyrrolidone), propylene glycol, 1-butanol, and cyclohexanol. With this configuration, the resin can be effectively removed by the action of an organic solvent such as benzyl alcohol, 1,3-dimethyl-2-imidazolidinone, isophorone, CPN (cyclopentane), 2MTHF (2-methyltetrahydrofuran), THF (tetrahydrofuran), 1-pentanol, methyl ethyl ketone, 1-butanol, γ-ptylolactone, NMP (N-methylpyrrolidone), propylene glycol, or cyclohexanol.

[0019] In the stripping solution according to the first phase described above, preferably, the alkali compound includes one selected from the group consisting of tripotassium phosphate, DBU (diazabicycloundecene), tetrabutylammonium hydroxide, sodium hydroxide, and potassium hydroxide. With this configuration, the resin can be stripped more effectively by the action of the alkali of tripotassium phosphate, DBU (diazabicycloundecene), tetrabutylammonium hydroxide, sodium hydroxide, or potassium hydroxide.

[0020] Furthermore, in order to achieve the above objective, the inventors of this application focused on the Hansen solubility parameters of organic solvents, namely the δP, δH, and δD values, and, through repeated trial and error and diligent research focusing on the pH of the alkaline compound, discovered a method for peeling resin that can effectively peel off resin by containing water, an organic solvent having a δP value of 5.0 to 11.9, a δH value of 4.3 to 15.8, and a δD value of 15.9 to 18.6, and an alkaline compound having a pH of 12 or higher in the aqueous phase.

[0021] In other words, the resin peeling method according to the second aspect of this invention comprises the step of immersing an object to which resin is attached in a peeling solution containing water, an organic solvent having a δP value of 5.0 to 11.9, a δH value of 4.3 to 15.8, and a δD value of 15.9 to 18.6, and an alkaline compound having a pH of 12 or higher in the aqueous phase.

[0022] In the resin peeling method according to the second aspect of this invention, it is considered that the organic solvent having the above-mentioned δP, δH, and δD values ​​and the alkaline compound having a pH of 12 or higher in the aqueous phase do not mutually inhibit each other's activity (peeling effect on the resin), thus enabling effective resin peeling. This point has been confirmed by experiments (examples) described later.

[0023] In the method for peeling the resin according to the second aspect, preferably, the resin to be peeled from the object contains a thermosetting resin. With this configuration, it is possible to provide a method for peeling a resin that can peel the thermosetting resin well. This point has also been confirmed by the experiments (Examples) described later.

[0024] In the method for peeling the resin according to the second aspect, preferably, the step of immersing in the peeling liquid includes a step of heating the object to which the resin is attached while immersing it in the peeling liquid. With this configuration, since the peeling action of the resin is improved by heating, the resin can be peeled better.

[0025] In the method for peeling the resin according to the second aspect, preferably, the step of heating while immersing in the peeling liquid includes a step of heating at a temperature of 40°C or higher. With this configuration, the peeling action of the resin can be effectively improved by heating to a temperature of 40°C or higher.

[0026] In the method for peeling the resin according to the second aspect, preferably, after the step of immersing in the peeling liquid, the method further includes a step of stirring the peeling liquid in which the object to which the resin is attached is immersed. With this configuration, the resin can be effectively peeled from the object by stirring.

[0027] In the method for peeling the resin according to the second aspect, preferably, the organic solvent is one selected from the group consisting of benzyl alcohol, 1,3-dimethyl-2-imidazolidinone, isophorone, CPN (cyclopentane), 2MTHF (2-methyltetrahydrofuran), THF (tetrahydrofuran), 1-pentanol, methyl ethyl ketone, and 1-butanol, or two selected from the group consisting of CPN (cyclopentane), γ-butyrolactone, NMP (N-methylpyrrolidone), propylene glycol, 1-butanol, and cyclohexanol. With such a configuration, the resin can be peeled well by the action of the organic solvent of benzyl alcohol, 1,3-dimethyl-2-imidazolidinone, isophorone, CPN (cyclopentane), 2MTHF (2-methyltetrahydrofuran), THF (tetrahydrofuran), 1-pentanol, methyl ethyl ketone, γ-butyrolactone, NMP (N-methylpyrrolidone), propylene glycol, 1-butanol, or cyclohexanol.

[0028] In the method for peeling the resin according to the second aspect, preferably, the alkali compound contains one selected from the group consisting of tripotassium phosphate, DBU (1,8-diazabicyclo[5.4.0]undec-7-ene), tetrabutylammonium hydroxide, sodium hydroxide, and potassium hydroxide. With such a configuration, the resin can be peeled better by the action of the alkali of tripotassium phosphate, DBU (1,8-diazabicyclo[5.4.0]undec-7-ene), tetrabutylammonium hydroxide, sodium hydroxide, or potassium hydroxide.

Advantages of the Invention

[0029] According to the present invention, as described above, the resin can be peeled well.

Brief Description of the Drawings

[0030] [Figure 1] It is a diagram showing the δP value and δH value of the organic solvents of Examples 1 to 12 and Comparative Examples 1 to 9.

Modes for Carrying Out the Invention

[0031] Embodiments of the present invention will be described below.

[0032] (Stripting solution) The stripping solution of this embodiment is a stripping solution for stripping resin from an object. The resin to be stripped from the object is, for example, a thermosetting resin. However, the resin to be stripped from the object may also be a resin other than a thermosetting resin. The stripping solution may be a two-phase liquid having an aqueous phase and an organic phase, or a one-phase liquid having an aqueous phase.

[0033] The release agent is used, for example, to remove adhesives. The release agent is used when removing adhesives containing thermosetting resins. The adhesive to be removed is, for example, an epoxy adhesive containing an epoxy resin, which is a thermosetting resin. The thermosetting resin may also be, for example, a phenolic resin, a melamine resin, a urea resin, an unsaturated polyester resin, an alkyd resin, a silicone resin, a polyurethane resin, or a thermosetting polyimide resin. Resins other than thermosetting resins may also be, for example, polyurea-based resins.

[0034] The stripping solution contains water, an organic solvent, and an alkaline compound.

[0035] The water contained in the stripping solution is H2O. The water contained in the stripping solution may be pure water free of impurities, or it may be water containing trace amounts of impurities. Pure water may be distilled water, RO water, or ion-exchanged water. Alternatively, the water contained in the stripping solution may be tap water.

[0036] In the stripping solution, the amount of water may be greater than 45 parts by mass but less than or equal to 86 parts by mass. For example, in the stripping solution, the amount of water may be greater than 71 parts by mass but less than or equal to 86 parts by mass. This allows for a larger amount of water, thereby raising the flash point of the stripping solution. As a result, it is possible to reduce the complexity of managing the stripping solution.

[0037] In this embodiment, the organic solvent contained in the stripping solution has a δP value of 5.0 to 11.9, a δH value of 4.3 to 15.8, and a δD value of 15.9 to 18.6. The δP, δH, and δD values ​​are Hansen solubility parameters (HSP) of the organic solvent.

[0038] Here, the Hansen solubility parameter is generally an indicator of how well one substance dissolves in another, and is quantitatively expressed by dividing it into three components: polarity, hydrogen bonding force, and dispersion force. Therefore, it does not directly affect the peelability of the stripping solution, but as a result of diligent research by the inventors of this application, it was found that including an organic solvent having Hansen solubility parameters (δP value, δH value, and δD value) within a specific range improves the peelability of the stripping solution.

[0039] In the Hansen solubility parameter, the δP value represents the polar component. The δH value represents the hydrogen bonding component. The δD value represents the dispersion component. Furthermore, the δP, δH, and δD values ​​of the Hansen solubility parameter for an organic solvent represent the values ​​of the single organic solvent if it contains only one type of organic solvent. If it contains multiple types of organic solvents, the δP, δH, and δD values ​​represent the values ​​of the liquid mixture containing those multiple organic solvents.

[0040] The organic solvent contained in the stripping solution may include one selected from the group consisting of cyclic alcohols, cyclic ketones, cyclic ethers, alcohols, and ketones. For example, the organic solvent contained in the stripping solution may include one selected from the group consisting of benzyl alcohol and 1,3-dimethyl-2-imidazolidinone. Alternatively, the organic solvent may include one selected from the group consisting of benzyl alcohol, 1,3-dimethyl-2-imidazolidinone, isophorone, CPN (cyclopentane), 2MTHF (2-methyltetrahydrofuran), THF (tetrahydrofuran), 1-pentanol, methyl ethyl ketone, and 1-butanol, or two selected from the group consisting of CPN (cyclopentane), γ-butyrolactone, NMP (N-methylpyrrolidone), propylene glycol, 1-butanol, and cyclohexanol.

[0041] The stripping solution may contain 5 to 70 parts by mass of an organic solvent.

[0042] Furthermore, it is preferable that the organic solvent contained in the stripping solution has a flash point of 100°C or lower.

[0043] Furthermore, it is preferable that the stripping solution does not contain phenols as an organic solvent. The stripping solution may also contain an alcohol with an acidity constant pKa of 15.5 or higher as an organic solvent.

[0044] In this embodiment, the alkaline compound contained in the stripping solution is an alkaline compound whose pH in the aqueous phase is 12 or higher. For example, the alkaline compound contained in the stripping solution may be an alkaline compound whose pH in the aqueous phase is 12 or higher but less than 13. This ensures that the pH in the aqueous phase of the stripping solution is less than 13 and does not become excessively high (the alkalinity does not become excessively strong), thus reducing the complexity of managing the stripping solution.

[0045] The alkaline compound contained in the stripping solution may include one selected from the group consisting of tripotassium phosphate, DBU (diazabicycloundecene), tetrabutylammonium hydroxide, sodium hydroxide, and potassium hydroxide.

[0046] In the stripping solution, the alkaline compound may be contained in an amount of 1 to 50 parts by mass such that the pH in the aqueous phase is 12 or higher. Preferably, the alkaline compound is contained in an amount of 1 to less than 20 parts by mass in the stripping solution.

[0047] Furthermore, it is preferable that the stripping solution does not contain surfactants. This is because if the stripping solution contains surfactants, a film of surfactants is thought to form on the resin, inhibiting the stripping action of organic solvents and alkaline compounds. Surfactants are substances that contain both hydrophilic and lipophilic groups in a single molecule. Surfactants are also substances that have the effect of lowering surface tension. Furthermore, surfactants include ionic surfactants and nonionic surfactants. An example of a surfactant is diethanolamine.

[0048] Furthermore, in the stripping solution, the alkaline compound may be tripotassium phosphate, contained in an amount of 1 to 50 parts by mass, and the organic solvent may be benzyl alcohol, contained in an amount of 5 to 70 parts by mass.

[0049] Furthermore, the stripping solution may contain 20 parts by mass or less of an alkaline compound and 45 parts by mass or more of water.

[0050] Furthermore, in the stripping solution, the alkaline compound is at least one of sodium hydroxide and potassium hydroxide, and is contained in an amount of 1 to 9 parts by mass, and the organic solvent is benzyl alcohol, and may be contained in an amount of 5 to 70 parts by mass.

[0051] (Method for removing resin using a release agent) Next, we will explain a method for removing resin using a stripping solution.

[0052] The resin removal method comprises the step of immersing an object to which resin is attached in a stripping solution containing water, an organic solvent having a δP value of 5.0 to 11.9, a δH value of 4.3 to 15.8, and a δD value of 15.9 to 18.6, and an alkaline compound having a pH of 12 or higher in the aqueous phase.

[0053] Furthermore, in the resin removal method, the step of immersing the object in the removal solution may include a step of heating the object with the resin attached while it is immersed in the removal solution. The step of heating while immersed in the removal solution may also include a step of heating at a temperature of 40°C or higher. For example, the object with the resin attached is heated to a temperature in the range of 40°C to 80°C while it is immersed in the removal solution. Preferably, the object with the resin attached is heated to a temperature in the range of 50°C to 70°C while it is immersed in the removal solution.

[0054] Furthermore, the resin removal method may include a step of immersing the object with the resin attached in a removal solution, followed by a step of stirring the removal solution in which the object is immersed. The stirring of the removal solution can be performed by stirring by rotating a stirring blade, stirring by rotating a stirring bar (stirrer tip), stirring with a stirring rod, or stirring with a discharge flow.

[0055] (Examples) Next, embodiments of the present invention will be described.

[0056] In each example, a test specimen (object coated with a thermosetting resin adhesive and cured) was immersed in a release solution and heated, and the release properties of the adhesive were evaluated after a predetermined time had elapsed. In each example, the release solution in which the test specimen was immersed was heated to approximately 60°C and left to stand for 1 hour. A 15 mm x 10 mm glass substrate was used as the test specimen.

[0057] Furthermore, the adhesive's release properties using a release agent were evaluated according to the following criteria. 5 points: After letting it stand for 1 hour, complete separation is achieved by gently stirring. 4 points: After standing for 1 hour, some peeling occurs with slight stirring, and complete peeling is performed with a scraper. 3. After letting it stand for 1 hour, completely remove it with a scraper. Point 2: After letting it stand for 1 hour, partially remove it with a scraper. 1. After letting it stand for 1 hour, it could not be removed even with a scraper (the resin remained hard). Furthermore, a score of 3 or higher indicated that the peeling performance was sufficient (at a level that poses no practical problems).

[0058] In Examples 1-36 and Comparative Examples 1-20, adhesives (epoxy adhesives) with the components shown in Table 1 were applied to test specimens and cured.

[0059] [Table 1]

[0060] In Examples 1 to 9, the results shown in Table 2 were obtained. In Examples 1 to 9, a stripping solution containing 10 parts by mass of one type of organic solvent was used.

[0061] [Table 2]

[0062] (Example 1) The stripping solution of Example 1 was prepared to contain 81 parts by mass of water, 10 parts by mass of benzyl alcohol as an organic solvent, and 9 parts by mass of tripotassium phosphate as an alkali compound. The stripping solution of Example 1, as shown by point "Fact 1" in Figure 1, had a δP value of 6.3, a δH value of 13.7, and a δD value of 18.4 for benzyl alcohol as an organic solvent. The solubility of benzyl alcohol as an organic solvent in water was 4 g / 100 mL, and the stripping solution was a two-phase system consisting of an aqueous phase and an oil phase. The flash point of benzyl alcohol as an organic solvent was 100°C. The pH of the aqueous phase was 12.6. The stripping solution of Example 1 scored 4 points, indicating good stripping properties.

[0063] (Example 2) The stripping solution in Example 2 was prepared in the same manner as in Example 1, except that it contained 10 parts by mass of isophorone as the organic solvent. In addition, the stripping solution in Example 2 had a δP value of 8.0, a δH value of 5.0, and a δD value of 17 for isophorone as the organic solvent, as shown by point "Act 2" in Figure 1. The solubility of isophorone as the organic solvent in water was 1.6 g / 100 mL, and the stripping solution was a two-phase system consisting of an aqueous phase and an oil phase. The flash point of isophorone as the organic solvent was 90°C. The pH of the aqueous phase was 12.6. The stripping solution in Example 2 had a stripping performance of 3 points, indicating that the stripping performance was reasonably good (sufficient for practical use).

[0064] (Example 3) The stripping solution in Example 3 was prepared in the same manner as in Example 1, except that it contained 10 parts by mass of cyclopentane as the organic solvent. The stripping solution in Example 3, as shown by point "3" in Figure 1, had a δP value of 11.9, a δH value of 5.2, and a δD value of 17.9. The solubility of cyclopentane as the organic solvent in water was 10 g / 100 mL, and the stripping solution was a two-phase system consisting of an aqueous phase and an oil phase. The flash point of cyclopentane as the organic solvent was 34°C. The pH of the aqueous phase was 12.6. The stripping solution in Example 3 scored 4 points, indicating good stripping properties.

[0065] (Example 4) The stripping solution of Example 4 was prepared in the same manner as in Example 1, except that it contained 10 parts by mass of 2-methyltetrahydrofuran as the organic solvent. Furthermore, as shown by point "4" in Figure 1, the δP value of 2-methyltetrahydrofuran as the organic solvent in the stripping solution of Example 4 was 5.0, the δH value was 4.3, and the δD value was 16.9. The solubility of 2-methyltetrahydrofuran as the organic solvent in water was 4.4 g / 100 mL, and the stripping solution was a two-phase system consisting of an aqueous phase and an oil phase. The flash point of 2-methyltetrahydrofuran as the organic solvent was -11°C. The pH of the aqueous phase was 12.6. The stripping performance of the stripping solution of Example 4 was rated at 3 points, indicating that the stripping performance was reasonably good.

[0066] (Example 5) The stripping solution in Example 5 was prepared in the same manner as in Example 1, except that it contained 10 parts by mass of tetrahydrofuran as the organic solvent. Furthermore, as shown by point "5" in Figure 1, the δP value of tetrahydrofuran as the organic solvent in Example 5 was 5.7, the δH value was 8.0, and the δD value was 18.6. The stripping solution was a one-phase system consisting of a mixed aqueous phase and an oil phase. The flash point of tetrahydrofuran as the organic solvent was -17°C. The pH of the aqueous phase was 12.6. The stripping solution in Example 5 scored 5 points, indicating very good stripping properties.

[0067] (Example 6) The stripping solution of Example 6 was prepared in the same manner as in Example 1, except that it contained 10 parts by mass of 1-pentanol as the organic solvent. Furthermore, as shown by point "6" in Figure 1, the δP value of 1-pentanol as the organic solvent in the stripping solution of Example 6 was 5.9, the δH value was 13.9, and the δD value was 15.9. The solubility of 1-pentanol as the organic solvent in water was 2.4 g / 100 mL, and the stripping solution was a two-phase system consisting of an aqueous phase and an oil phase. The flash point of 1-pentanol as the organic solvent was 49°C. The pH of the aqueous phase was 12.6. The stripping performance of the stripping solution of Example 6 was rated at 3 points, indicating that the stripping performance was reasonably good.

[0068] (Example 7) The stripping solution of Example 7 was prepared in the same manner as in Example 1, except that it contained 10 parts by mass of methyl ethyl ketone as the organic solvent. Furthermore, as shown by point "7" in Figure 1, the δP value of methyl ethyl ketone as the organic solvent in the stripping solution of Example 7 was 9.0, the δH value was 5.1, and the δD value was 16. The solubility of methyl ethyl ketone as the organic solvent in water was 27.5 g / 100 mL, and the stripping solution was a single-phase system with an aqueous phase. The flash point of methyl ethyl ketone as the organic solvent was -9°C. The pH of the aqueous phase was 12.6. The stripping solution of Example 7 had a stripping performance of 5 points, indicating very good stripping performance.

[0069] (Example 8) The stripping solution of Example 8 was prepared in the same manner as in Example 1, except that it contained 10 parts by mass of 1,3-dimethyl-2-imidazolidinone as the organic solvent. Furthermore, as shown by point "8" in Figure 1, the δP value of 1,3-dimethyl-2-imidazolidinone as the organic solvent in Example 8 was 9.6, the δH value was 8.6, and the δD value was 18. The stripping solution was a single-phase system with an aqueous phase. The flash point of 1,3-dimethyl-2-imidazolidinone as the organic solvent was 120°C. The pH of the aqueous phase was 12.6. The stripping solution of Example 8 achieved a stripping score of 4, indicating good stripping properties.

[0070] (Example 9) The stripping solution of Example 9 was prepared in the same manner as in Example 1, except that it contained 10 parts by mass of 1-butanol as the organic solvent. Furthermore, as shown by the point labeled "Act 9" in Figure 1, the δP value of 1-butanol as the organic solvent in Example 9 was 5.7, the δH value was 15.8, and the δD value was 16. The stripping solution was a two-phase system consisting of an aqueous phase and an oil phase. The flash point of 1-butanol as the organic solvent was 29°C. The pH of the aqueous phase was 12.6. The stripping solution of Example 9 scored 4 points, indicating good stripping properties.

[0071] In Examples 10-12, the results shown in Table 3 were obtained. In Examples 10-12, a stripping solution containing 5 parts by mass each of two types of organic solvents was used.

[0072] [Table 3]

[0073] (Example 10) The stripping solution of Example 10 was prepared to contain 81 parts by mass of water, 5 parts by mass of N-methylpyrrolidone as an organic solvent, 5 parts by mass of 1-butanol as an organic solvent, and 9 parts by mass of tripotassium phosphate as an alkali compound. The stripping solution of Example 10, as shown by the point labeled "Example 10" in Figure 1, had a total δP value of 9.0, a δH value of 11.5, and a δD value of 17 for the N-methylpyrrolidone and 1-butanol organic solvents. The stripping solution was a two-phase system consisting of an aqueous phase and an oil phase. The pH of the aqueous phase was 12.6. The stripping solution of Example 10 achieved a stripping score of 4, indicating good stripping performance.

[0074] (Example 11) The stripping solution in Example 11 was the same as in Example 10, except that it was prepared to contain 5 parts by mass of cyclohexanol as the organic solvent. Furthermore, as shown by the point labeled "Example 11" in Figure 1, the total δP value of N-methylpyrrolidone and cyclohexanol in the stripping solution of Example 11 was 8.2, the δH value was 10.4, and the δD value was 17.7. The stripping solution was a two-phase system consisting of an aqueous phase and an oil phase. The pH of the aqueous phase was 12.6. The stripping solution of Example 11 scored 4 points, indicating good stripping performance.

[0075] (Example 12) The stripping solution in Example 12 was prepared in the same manner as in Example 10, except that it contained 5 parts by mass of propylene glycol as the organic solvent. Furthermore, as shown by the point labeled "Example 12" in Figure 1, the total δP value of N-methylpyrrolidone and propylene glycol in the stripping solution of Example 12 was 11.4, the δH value was 14.3, and the δD value was 17.4. The stripping solution was a single-phase system with an aqueous phase. The pH of the aqueous phase was 12.6. The stripping solution of Example 12 achieved a stripping performance of 3 points, indicating that the stripping performance was reasonably good.

[0076] The results shown in Table 4 were obtained in Comparative Examples 1 to 9. In Comparative Examples 1 to 8, a stripping solution containing 10 parts by mass of one type of organic solvent was used. In Comparative Example 9, a stripping solution containing 5 parts by mass each of two types of organic solvents was used.

[0077] [Table 4]

[0078] (Comparative Example 1) The stripping solution of Comparative Example 1 was prepared to contain 81 parts by mass of water, 10 parts by mass of limonene as an organic solvent, and 9 parts by mass of tripotassium phosphate as an alkali compound. Furthermore, the stripping solution of Comparative Example 1 had a δP value of 1.8, a δH value of 4.3, and a δD value of 17.2 for limonene as the organic solvent, as indicated by the "Ratio 1" point in Figure 1. The stripping solution was a two-phase system consisting of an aqueous phase and an oil phase. The pH of the aqueous phase was 12.6. The stripping solution of Comparative Example 1 was found to have extremely poor stripping properties, with a stripping performance of 1 point. In other words, the stripping solution of Comparative Example 1, with a δP value of 1.8 for the limonene organic solvent (outside the range enclosed by the square frame in Figure 1), was found to have extremely poor stripping properties.

[0079] (Comparative Example 2) The stripping solution of Comparative Example 2 was the same as that of Comparative Example 1, except that it was prepared to contain 10 parts by mass of γ-butyrolactone as the organic solvent. In addition, the stripping solution of Comparative Example 2 had a δP value of 16.6, a δH value of 7.4, and a δD value of 18 for γ-butyrolactone as the organic solvent, as shown by the point labeled "Ratio 2" in Figure 1. The stripping solution was a one-phase system in which the aqueous phase and the oil phase were mixed. The pH of the aqueous phase was 12.6. The stripping solution of Comparative Example 2 was found to have extremely poor stripping properties, with a stripping performance of 1 point. In other words, the stripping solution of Comparative Example 2, with a δP value of 16.6 for the γ-butyrolactone contained as the organic solvent, which is outside the range enclosed by the square frame in Figure 1, was found to have extremely poor stripping properties.

[0080] (Comparative Example 3) The stripping solution of Comparative Example 3 was the same as that of Comparative Example 1, except that it was prepared to contain 10 parts by mass of N-methylpyrrolidone as the organic solvent. In addition, the stripping solution of Comparative Example 3 had a δP value of 12.3, a δH value of 7.2, and a δD value of 18 for N-methylpyrrolidone as the organic solvent, as indicated by the "Ratio 3" point in Figure 1. The stripping solution was a one-phase system in which the aqueous phase and the oil phase were mixed. The pH of the aqueous phase was 12.6. The stripping solution of Comparative Example 3 was found to have poor stripping properties, with a stripping performance of 2 points. In other words, the stripping solution of Comparative Example 3, which has a δP value of 12.3 for the N-methylpyrrolidone organic solvent, which is outside the range enclosed by the square frame in Figure 1, was found to have poor stripping properties.

[0081] (Comparative Example 4) The stripping solution of Comparative Example 4 was the same as that of Comparative Example 1, except that it was prepared to contain 10 parts by mass of dimethylformamide as the organic solvent. In addition, the stripping solution of Comparative Example 4 had a δP value of 13.7, a δH value of 11.3, and a δD value of 17.4 for dimethylformamide as the organic solvent, as indicated by the "Ratio 4" point in Figure 1. The stripping solution was a one-phase system in which the aqueous phase and the oil phase were mixed. The pH of the aqueous phase was 12.6. The stripping solution of Comparative Example 4 was found to have poor stripping properties, with a stripping performance of 2 points. In other words, the stripping solution of Comparative Example 4, which has a δP value of dimethylformamide as the organic solvent (13.7), which is outside the range enclosed by the square frame in Figure 1, was found to have poor stripping properties.

[0082] (Comparative Example 5) The stripping solution of Comparative Example 5 was the same as that of Comparative Example 1, except that it was prepared to contain 10 parts by mass of ε-caprolactone as the organic solvent. In addition, the stripping solution of Comparative Example 5 had a δP value of 15.0, a δH value of 7.4, and a δD value of 18 for ε-caprolactone as the organic solvent, as indicated by the "Ratio 5" point in Figure 1. The stripping solution was a one-phase system in which the aqueous phase and the oil phase were mixed. The pH of the aqueous phase was 12.6. The stripping solution of Comparative Example 5 was found to have extremely poor stripping properties, with a stripping performance of 1 point. In other words, the stripping solution of Comparative Example 5, which has a δP value of 15.0 for the ε-caprolactone contained as the organic solvent, which is outside the range enclosed by the square frame in Figure 1, was found to have extremely poor stripping properties.

[0083] (Comparative Example 6) The stripping solution of Comparative Example 6 was the same as that of Comparative Example 1, except that it was prepared to contain 10 parts by mass of propylene glycol as the organic solvent. In addition, the stripping solution of Comparative Example 6 had a δP value of 10.4, a δH value of 21.3, and a δD value of 16.8 for the propylene glycol as the organic solvent, as shown by the "Ratio 6" point in Figure 1. The stripping solution was a one-phase system in which the aqueous phase and the oil phase were mixed. The pH of the aqueous phase was 12.6. The stripping solution of Comparative Example 6 was found to have poor stripping properties, with a stripping performance of 2 points. In other words, the stripping solution of Comparative Example 6, which has a δH value of 21.3 for the propylene glycol contained as the organic solvent, which is outside the range enclosed by the square frame in Figure 1, was found to have poor stripping properties.

[0084] (Comparative Example 7) The stripping solution of Comparative Example 7 was prepared in the same way as that of Comparative Example 1, except that it contained 10 parts by mass of dipropylene glycol (isomer mixture) as the organic solvent. In addition, the stripping solution of Comparative Example 7 had a δP value of 9.4, a δH value of 16.6, and a δD value of 16.6 for the dipropylene glycol (isomer mixture) as the organic solvent, as shown by the "Ratio 7" point in Figure 1. The stripping solution was a one-phase system in which the aqueous phase and the oil phase were mixed. The pH of the aqueous phase was 12.6. The stripping solution of Comparative Example 7 was found to have poor stripping properties, with a stripping performance of 2 points. In other words, the stripping solution of Comparative Example 7, in which the δH value of the contained organic solvent dipropylene glycol (isomer mixture) was 16.6, which is outside the range enclosed by the square frame in Figure 1, was found to have extremely poor stripping properties.

[0085] (Comparative Example 8) The stripping solution of Comparative Example 8 was the same as that of Comparative Example 1, except that it was prepared to contain 10 parts by mass of cyclohexanol as the organic solvent. In addition, the stripping solution of Comparative Example 8 had a δP value of 4.1, a δH value of 13.5, and a δD value of 17.4 for cyclohexanol as the organic solvent, as shown by the "Ratio 8" point in Figure 1. The stripping solution was a two-phase system consisting of an aqueous phase and an oil phase. The pH of the aqueous phase was 12.6. The stripping solution of Comparative Example 8 was found to have poor stripping properties, with a stripping performance of 2 points. In other words, the stripping solution of Comparative Example 8, in which the δH value of the contained organic solvent cyclohexanol was 4.1, which is outside the range enclosed by the square frame in Figure 1, was found to have poor stripping properties.

[0086] (Comparative Example 9) The stripping solution of Comparative Example 9 was prepared in the same manner as that of Comparative Example 1, except that it contained 5 parts by mass of γ-butyrolactone and 5 parts by mass of cyclopentane as organic solvents. In addition, the stripping solution of Comparative Example 9 had a total δP value of 14.3, a δH value of 6.3, and a δD value of 18.0 for γ-butyrolactone and cyclopentane as organic solvents, as indicated by the "Ratio 9" point in Figure 1. The stripping solution was a single-phase system with an aqueous phase. The pH of the aqueous phase was 12.6. The stripping solution of Comparative Example 9 was found to have poor stripping properties, with a stripping performance of 2 points. In other words, the stripping solution of Comparative Example 9, with a total δP value of 14.3 for γ-butyrolactone and cyclopentane as organic solvents, which is outside the range enclosed by the square frame in Figure 1, was found to have poor stripping properties.

[0087] From the evaluation results of the peelability of Examples 1 to 12 and Comparative Examples 1 to 9 described above, it was found that a peeling solution containing water, an organic solvent having a δP value of 5.0 to 11.9, a δH value of 4.3 to 15.8, and a δD value of 15.9 to 18.6, and an alkaline compound having a pH of 12 or higher in the aqueous phase, exhibits good peelability.

[0088] Here, we will examine the δP and δH values ​​among the Hansen dissolution parameters (δP, δH, and δD values). Note that the δD value changes less significantly than the δP and δH values, and in all of Examples 1-12 and Comparative Examples 1-9, it falls within the range of 15.9 to 18.6. Therefore, we will examine the δP and δH values ​​here.

[0089] As shown in Figure 1, the stripping solutions containing a single organic solvent in Examples 1-9 and the stripping solutions containing a mixed organic solvent in Examples 10-12 all have a δP value of 5.0 to 11.9 and a δH value of 4.3 to 15.8, which are within the range enclosed by the square frame in Figure 1. Furthermore, it was found that the stripping solutions of Examples 1-12, which contain an organic solvent with a δP value of 5.0 to 11.9 and a δH value of 4.3 to 15.8, exhibited good stripping properties. On the other hand, the stripping solutions containing a single organic solvent in Comparative Examples 1-8 and the stripping solution containing a mixed organic solvent in Comparative Example 9 all have a δP value of less than 5.0 or greater than 11.9, or a δH value greater than 15.8, which are outside the range enclosed by the square frame in Figure 1. Furthermore, it was found that the stripping solutions of Comparative Examples 1 to 9, which contained organic solvents with δP values ​​less than 5.0 or greater than 11.9, or δH values ​​greater than 15.8, outside the range enclosed by the square frame in Figure 1, exhibited poor stripping performance.

[0090] Furthermore, when only one type of organic solvent, N-methylpyrrolidone, was used as the organic solvent, as in Comparative Example 3, the δP value was 12.3, which is outside the range enclosed by the square frame in Figure 1, indicating poor peelability. However, as in Examples 10 to 12, by adding 1-butanol, cyclohexanol, or propylene glycol to N-methylpyrrolidone as the organic solvent, it was found that the peelability improved by bringing the δP value to between 5.0 and 11.9, which is within the range enclosed by the square frame in Figure 1.

[0091] Furthermore, when only one type of organic solvent, cyclohexanol, was used, as in Comparative Example 8, the δP value was 4.1, which is outside the range enclosed by the square frame in Figure 1, indicating poor peelability. However, as in Example 11, by adding N-methylpyrrolidone to cyclohexanol as the organic solvent, the δP value was brought within the range of 5.0 to 11.9, which is within the range enclosed by the square frame in Figure 1, and it was found that the peelability improved.

[0092] Furthermore, when only one type of organic solvent, propylene glycol, was used, as in Comparative Example 6, the δH value was 21.3, which is outside the range enclosed by the square frame in Figure 1, resulting in poor peelability. However, as in Example 12, by adding N-methylpyrrolidone to propylene glycol as the organic solvent, and bringing the δH value to between 4.3 and 15.8, which is within the range enclosed by the square frame in Figure 1, it was found that the peelability improved.

[0093] Furthermore, when only one type of organic solvent, cyclopentane, was used as the organic solvent, as in Example 3, the δP value was 11.9, which falls within the range enclosed by the square frame in Figure 1, indicating good peelability. However, as in Comparative Example 9, when γ-butyrolactone was added to cyclopentane as the organic solvent, the δP value rose to 14.3, which falls outside the range enclosed by the square frame in Figure 1, indicating poor peelability.

[0094] Examples 13-20 yielded the results shown in Table 5. Examples 13-20 show different proportions of benzyl alcohol as the organic solvent.

[0095] [Table 5]

[0096] (Example 13) The stripping solution in Example 13 was prepared to contain 86 parts by mass of water, 5 parts by mass of benzyl alcohol as an organic solvent, and 9 parts by mass of tripotassium phosphate as an alkali compound. The stripping solution in Example 13 had a stripping score of 4, indicating good stripping properties.

[0097] (Example 14) The stripping solution of Example 14 was prepared to contain 81 parts by mass of water, 10 parts by mass of benzyl alcohol as an organic solvent, and 9 parts by mass of tripotassium phosphate as an alkali compound. In other words, Example 14 is the same stripping solution as Example 1. The stripping solution of Example 14 had a stripping score of 4, indicating good stripping properties.

[0098] (Example 15) The stripping solution in Example 15 was prepared to contain 71 parts by mass of water, 20 parts by mass of benzyl alcohol as an organic solvent, and 9 parts by mass of tripotassium phosphate as an alkali compound. The stripping solution in Example 15 had a stripping score of 4, indicating good stripping properties.

[0099] (Example 16) The stripping solution in Example 16 was prepared to contain 61 parts by mass of water, 30 parts by mass of benzyl alcohol as an organic solvent, and 9 parts by mass of tripotassium phosphate as an alkali compound. The stripping solution in Example 16 had a stripping score of 4, indicating good stripping properties.

[0100] (Example 17) The stripping solution in Example 17 was prepared to contain 51 parts by mass of water, 40 parts by mass of benzyl alcohol as an organic solvent, and 9 parts by mass of tripotassium phosphate as an alkali compound. The stripping solution in Example 17 had a stripping score of 4, indicating good stripping properties.

[0101] (Example 18) The stripping solution in Example 18 was prepared to contain 41 parts by mass of water, 50 parts by mass of benzyl alcohol as an organic solvent, and 9 parts by mass of tripotassium phosphate as an alkali compound. The stripping solution in Example 18 had a stripping score of 4, indicating good stripping properties.

[0102] (Example 19) The stripping solution in Example 19 was prepared to contain 31 parts by mass of water, 60 parts by mass of benzyl alcohol as an organic solvent, and 9 parts by mass of tripotassium phosphate as an alkali compound. The stripping solution in Example 19 had a stripping score of 4, indicating good stripping properties.

[0103] (Example 20) The stripping solution in Example 20 was prepared to contain 21 parts by mass of water, 70 parts by mass of benzyl alcohol as an organic solvent, and 9 parts by mass of tripotassium phosphate as an alkali compound. The stripping solution in Example 20 had a stripping performance of 3 points, indicating that it had reasonably good stripping properties.

[0104] The results for Comparative Examples 10-13 are shown in Table 6. Comparative Examples 10-13 show examples with different proportions of benzyl alcohol as the organic solvent.

[0105] [Table 6]

[0106] (Comparative Example 10) The stripping solution of Comparative Example 10 was prepared to contain 91 parts by mass of water, 0 parts by mass of benzyl alcohol as an organic solvent, and 9 parts by mass of tripotassium phosphate as an alkali compound. In other words, the stripping solution of Comparative Example 10 did not contain benzyl alcohol as an organic solvent. The stripping solution of Comparative Example 10 was found to have extremely poor stripping properties, with a stripping performance of 1 point.

[0107] (Comparative Example 11) The stripping solution for Comparative Example 11 was prepared to contain 90 parts by mass of water, 1 part by mass of benzyl alcohol as an organic solvent, and 9 parts by mass of tripotassium phosphate as an alkali compound. The stripping solution for Comparative Example 11 was found to have poor stripping properties, with a stripping performance score of 2.

[0108] (Comparative Example 12) The stripping solution of Comparative Example 12 was prepared to contain 88 parts by mass of water, 3 parts by mass of benzyl alcohol as an organic solvent, and 9 parts by mass of tripotassium phosphate as an alkali compound. The stripping solution of Comparative Example 12 was found to have poor stripping properties, with a stripping score of 2.

[0109] (Comparative Example 13) The stripping solution of Comparative Example 13 was prepared to contain 10 parts by mass of water, 81 parts by mass of benzyl alcohol as an organic solvent, and 9 parts by mass of tripotassium phosphate as an alkali compound. The stripping solution of Comparative Example 13 was found to have poor stripping properties, with a stripping performance score of 2.

[0110] From the evaluation results of the peelability of Examples 13-20 and Comparative Examples 10-13 described above, it was found that a peeling solution containing 21 to 86 parts by mass of water and 5 to 70 parts by mass of an organic solvent exhibited good peelability. Furthermore, it was found that a peeling solution containing 5 to 70 parts by mass of benzyl alcohol also exhibited good peelability.

[0111] Examples 21-27 yielded the results shown in Table 7. Examples 21-27 show different proportions of water, benzyl alcohol as an organic solvent, and tripotassium phosphate as an alkali compound.

[0112] [Table 7]

[0113] (Example 21) The stripping solution in Example 21 was prepared to contain 88 parts by mass of water, 11 parts by mass of benzyl alcohol as an organic solvent, and 1 part by mass of tripotassium phosphate as an alkali compound. The stripping solution in Example 21 had a stripping performance of 3 points, indicating that it had reasonably good stripping properties.

[0114] (Example 22) The stripping solution in Example 22 was prepared to contain 86 parts by mass of water, 11 parts by mass of benzyl alcohol as an organic solvent, and 3 parts by mass of tripotassium phosphate as an alkali compound. The stripping solution in Example 22 had a stripping performance of 3 points, indicating that it had reasonably good stripping properties.

[0115] (Example 23) The stripping solution in Example 23 was prepared to contain 85 parts by mass of water, 10 parts by mass of benzyl alcohol as an organic solvent, and 5 parts by mass of tripotassium phosphate as an alkali compound. The stripping solution in Example 23 had a stripping score of 4, indicating good stripping properties.

[0116] (Example 24) The stripping solution of Example 24 was prepared to contain 81 parts by mass of water, 10 parts by mass of benzyl alcohol as an organic solvent, and 9 parts by mass of tripotassium phosphate as an alkali compound. The stripping solution of Example 24 had a stripping score of 4, indicating good stripping properties.

[0117] (Example 25) The stripping solution in Example 25 was prepared to contain 71 parts by mass of water, 9 parts by mass of benzyl alcohol as an organic solvent, and 20 parts by mass of tripotassium phosphate as an alkali compound. The stripping solution in Example 25 had a stripping score of 4, indicating good stripping properties.

[0118] (Example 26) The stripping solution in Example 26 was prepared to contain 53 parts by mass of water, 7 parts by mass of benzyl alcohol as an organic solvent, and 40 parts by mass of tripotassium phosphate as an alkali compound. The stripping solution in Example 26 had a stripping performance of 5 points, indicating that it had very good stripping properties.

[0119] (Example 27) The stripping solution in Example 27 was prepared to contain 44 parts by mass of water, 6 parts by mass of benzyl alcohol as an organic solvent, and 50 parts by mass of tripotassium phosphate as an alkali compound. The stripping solution in Example 27 had a stripping score of 4, indicating good stripping properties.

[0120] The results for Comparative Examples 14-18 are shown in Table 8. Comparative Examples 14-18 show examples with different proportions of water, benzyl alcohol as an organic solvent, and tripotassium phosphate as an alkali compound.

[0121] [Table 8]

[0122] (Comparative Example 14) The stripping solution of Comparative Example 14 was prepared to contain 89 parts by mass of water, 11 parts by mass of benzyl alcohol as an organic solvent, and 0 parts by mass of tripotassium phosphate as an alkali compound. In other words, the stripping solution of Comparative Example 14 did not contain an alkali compound. The stripping solution of Comparative Example 14 was found to have poor stripping properties, with a stripping performance score of 2.

[0123] (Comparative Example 15) The stripping solution of Comparative Example 15 was the same as that of Comparative Example 14, except that it contained 0.1 parts by mass of tripotassium phosphate as an alkaline compound. The stripping solution of Comparative Example 15 was found to have poor stripping properties, with a stripping performance score of 2.

[0124] (Comparative Example 16) The stripping solution of Comparative Example 16 was prepared in the same manner as that of Comparative Example 14, except that it contained 0.5 parts by mass of tripotassium phosphate as an alkaline compound. The stripping solution of Comparative Example 16 was found to have poor stripping properties, with a stripping performance score of 2.

[0125] (Comparative Example 17) The stripping solution of Comparative Example 17 was prepared to contain 50 parts by mass of water, 50 parts by mass of benzyl alcohol as an organic solvent, and 0 parts by mass of tripotassium phosphate as an alkali compound. In other words, the stripping solution of Comparative Example 17 did not contain an alkali compound. The stripping solution of Comparative Example 17 was found to have poor stripping properties, with a stripping performance score of 2.

[0126] (Comparative Example 18) The stripping solution of Comparative Example 18 was prepared to contain 10 parts by mass of water, 90 parts by mass of benzyl alcohol as an organic solvent, and 0 parts by mass of tripotassium phosphate as an alkali compound. In other words, the stripping solution of Comparative Example 18 did not contain an alkali compound. The stripping solution of Comparative Example 18 was found to have poor stripping properties, with a stripping performance score of 2.

[0127] From the evaluation results of the peelability of Examples 21-27 and Comparative Examples 14-18 described above, it was found that peeling solutions containing 1 to 50 parts by mass of tripotassium phosphate exhibited good peelability.

[0128] In Examples 28-31 and Comparative Examples 19-20, the results shown in Table 9 were obtained. Examples 28-31 show different types of alkali compounds when benzyl alcohol is used as the organic solvent.

[0129] [Table 9]

[0130] (Example 28) The stripping solution in Example 28 was prepared to contain 81 parts by mass of water, 10 parts by mass of benzyl alcohol as an organic solvent, and 9 parts by mass of tripotassium phosphate as an alkali compound. In other words, Example 28 is the same stripping solution as in Example 1. The pH of the aqueous phase was 12.6. The stripping solution in Example 28 had a stripping performance of 4 points, indicating good stripping performance.

[0131] (Example 29) The stripping solution in Example 29 was prepared in the same manner as in Example 28, except that it contained 9 parts by mass of diazabicycloundecene as the alkaline compound. The pH of the aqueous phase was 12.9. The stripping solution in Example 29 had a stripping score of 4, indicating good stripping properties.

[0132] (Example 30) The stripping solution in Example 30 was prepared in the same manner as in Example 28, except that it contained 9 parts by mass of tetrabutylammonium hydroxide as the alkaline compound. The pH of the aqueous phase was 12.9. The stripping solution in Example 30 had a stripping score of 4, indicating good stripping properties.

[0133] (Example 31) The stripping solution in Example 31 was prepared in the same manner as in Example 28, except that it contained 9 parts by mass of sodium hydroxide as the alkaline compound. The pH of the aqueous phase was 13.7. The stripping solution in Example 31 had a stripping performance of 5 points, indicating that it had very good stripping properties.

[0134] (Comparative Example 19) The stripping solution of Comparative Example 19 was prepared to contain 89.55 parts by mass of water, 10 parts by mass of benzyl alcohol as an organic solvent, and 0.45 parts by mass of sodium hydroxide as an alkali compound. The pH of the aqueous phase was 12.6. The stripping solution of Comparative Example 19 was found to have poor stripping properties, with a stripping performance score of 2.

[0135] (Comparative Example 20) The stripping solution for Comparative Example 20 was prepared to contain 89.95 parts by mass of water, 10 parts by mass of benzyl alcohol as an organic solvent, and 0.05 parts by mass of sodium hydroxide as an alkali compound. The pH of the aqueous phase was 11.4. The stripping solution for Comparative Example 20 was found to have poor stripping properties, with a stripping performance score of 2.

[0136] From the evaluation of the peelability of Examples 28-31 and Comparative Examples 19-20 described above, it was found that peeling solutions containing an alkaline compound with a pH of 12 or higher in the aqueous phase exhibited good peelability. However, it was found that peelability deteriorated when the alkaline compound content was trace.

[0137] Examples 32-36 yielded the results shown in Table 10. Examples 32-36 demonstrate different types of alkali compounds when 1,3-dimethyl-2-imidazolidinone is used as the organic solvent.

[0138] [Table 10]

[0139] (Example 32) The stripping solution of Example 32 was prepared to contain 81 parts by mass of water, 10 parts by mass of 1,3-dimethyl-2-imidazolidinone as an organic solvent, and 9 parts by mass of tripotassium phosphate as an alkali compound. The stripping solution of Example 32 had a stripping score of 4, indicating good stripping properties.

[0140] (Example 33) The stripping solution of Example 33 was prepared in the same manner as in Example 32, except that it contained 9 parts by mass of diazabicycloundecene as the alkaline compound. The stripping solution of Example 33 had a stripping performance of 3 points, indicating that it had reasonably good stripping properties.

[0141] (Example 34) The stripping solution in Example 34 was prepared in the same manner as in Example 32, except that it contained 9 parts by mass of sodium hydroxide as an alkaline compound. The stripping solution in Example 34 had a stripping performance of 5 points, indicating that it had very good stripping properties.

[0142] (Example 35) The stripping solution of Example 35 was prepared to contain 85 parts by mass of water, 10 parts by mass of 1,3-dimethyl-2-imidazolidinone as an organic solvent, and 5 parts by mass of sodium hydroxide as an alkali compound. The stripping solution of Example 35 had a stripping performance of 5 points, indicating that it had very good stripping properties.

[0143] (Example 36) The stripping solution of Example 36 was prepared to contain 88 parts by mass of water, 10 parts by mass of 1,3-dimethyl-2-imidazolidinone as an organic solvent, and 1 part by mass of sodium hydroxide as an alkali compound. The stripping solution of Example 36 had a stripping score of 4, indicating good stripping properties.

[0144] From the evaluation results of the peelability in Examples 32 to 36 described above, it was found that when 1,3-dimethyl-2-imidazolidinone is used as the organic solvent, the peelability is good regardless of the type of alkali compound used.

[0145] In Examples 37-39, adhesive removal was performed differently from that in Examples 1-36. The adhesive removal solution used was the same as that used in Example 1.

[0146] (Example 37) In Example 37, a polyurea-based adhesive was applied to a test specimen that had been cured, and the adhesive was removed using the stripping solution from Example 1. Specifically, in Example 37, the adhesive was removed from a test specimen that had been cured with an adhesive containing 100 parts by weight of an aspartic acid ester derivative and 140 parts by weight of a hexamethylene diisocyanate derivative. The adhesive used was cured at 25°C for 24 hours. In Example 37, the stripping performance of the stripping solution from Example 1 was rated at 5 points, indicating that it had very good stripping properties.

[0147] (Example 38) In Example 38, the epoxy / DICY adhesive was applied to a test specimen that had been cured, and the adhesive was removed using the stripping solution from Example 1. Specifically, in Example 38, the adhesive was removed from a test specimen that had been cured with an adhesive containing 100 parts by weight of bisphenol A type epoxy, 10 parts by weight of dicyandiamide, and 2 parts by weight of modified aliphatic polyamine. The adhesive used was cured at 150°C for 30 minutes. In Example 38, the stripping performance of the stripping solution from Example 1 was rated at 5 points, indicating that it had very good stripping properties.

[0148] (Example 39) In Example 39, the epoxy / amine-based adhesive was applied to a test specimen that had been cured, and the adhesive was removed using the stripping solution from Example 1. Specifically, in Example 39, the adhesive was removed from a test specimen that had been cured with an adhesive containing 100 parts by weight of polyfunctional aliphatic epoxy and 35 parts by weight of aliphatic polyamine. The adhesive used was cured at 25°C for 24 hours. In Example 39, the stripping performance of the stripping solution from Example 1 was rated at 5 points, indicating that it had very good stripping properties.

[0149] From the evaluation results of the peelability of Examples 37 to 39 described above, it was found that the peeling solution according to the present invention can peel off various types of adhesives.

Claims

1. Water and, An organic solvent having a δP value of 5.0 to 11.9, a δH value of 4.3 to 15.8, and a δD value of 15.9 to 18.6, A stripping solution containing an alkaline compound whose pH in the aqueous phase is 12 or higher.

2. The stripping solution according to claim 1, used for stripping thermosetting resins.

3. The stripping solution according to claim 1, which does not contain a surfactant.

4. The aforementioned alkali compound is tripotassium phosphate, and is contained in an amount of 1 to 50 parts by mass. The stripping solution according to claim 1, wherein the organic solvent is benzyl alcohol and is contained in an amount of 5 parts by mass or more and 70 parts by mass or less.

5. The alkali compound is at least one of sodium hydroxide and potassium hydroxide, and is contained in an amount of 1 part by mass or more and 9 parts by mass or less. The stripping solution according to claim 1, wherein the organic solvent is benzyl alcohol and is contained in an amount of 5 parts by mass or more and 70 parts by mass or less.

6. The stripping solution according to claim 1, wherein the amount of water is greater than 45 parts by mass and 86 parts by mass or less.

7. The stripping solution according to claim 1, wherein the organic solvent has a flash point of 100°C or higher.

8. The stripping solution according to claim 7, wherein the organic solvent comprises one selected from the group consisting of benzyl alcohol and 1,3-dimethyl-2-imidazolidinone.

9. The stripping solution according to claim 1, wherein the alkali compound is contained in an amount of 1 to 50 parts by mass such that the pH in the aqueous phase is 12 or higher.

10. The stripping solution according to claim 1, wherein the organic solvent comprises one selected from the group consisting of benzyl alcohol, 1,3-dimethyl-2-imidazolidinone, isophorone, CPN (cyclopentane), 2MTHF (2-methyltetrahydrofuran), THF (tetrahydrofuran), 1-pentanol, methyl ethyl ketone, and 1-butanol, or two selected from the group consisting of CPN (cyclopentane), γ-butyrolactone, NMP (N-methylpyrrolidone), propylene glycol, 1-butanol, and cyclohexanol.

11. The stripping solution according to claim 1, wherein the alkali compound comprises one selected from the group consisting of tripotassium phosphate, DBU (diazabicycloundecene), tetrabutylammonium hydroxide, sodium hydroxide, and potassium hydroxide.

12. A method for removing resin, A method for removing resin, comprising the step of immersing an object to which resin is attached in a stripping solution containing water, an organic solvent having a δP value of 5.0 to 11.9, a δH value of 4.3 to 15.8, and a δD value of 15.9 to 18.6, and an alkaline compound having a pH of 12 or higher in the aqueous phase.

13. The method for peeling a resin according to claim 12, wherein the resin peeled off from the object includes a thermosetting resin.

14. The resin removal method according to claim 12, wherein the step of immersing the object to which the resin is attached is heated while immersed in the peeling solution.

15. The method for peeling a resin according to claim 14, wherein the step of heating while immersed in the peeling solution includes a step of heating at a temperature of 40°C or higher.

16. The method for removing resin according to claim 12, further comprising the step of immersing the object in the stripping solution, followed by the step of stirring the stripping solution in which the object to which the resin has adhered is immersed.

17. The method for peeling a resin according to claim 12, wherein the organic solvent comprises one selected from the group consisting of benzyl alcohol, 1,3-dimethyl-2-imidazolidinone, isophorone, CPN (cyclopentane), 2MTHF (2-methyltetrahydrofuran), THF (tetrahydrofuran), 1-pentanol, methyl ethyl ketone, and 1-butanol, or two selected from the group consisting of CPN (cyclopentane), γ-butyrolactone, NMP (N-methylpyrrolidone), propylene glycol, 1-butanol, and cyclohexanol.

18. The resin peeling method according to claim 12, wherein the alkali compound comprises one selected from the group consisting of tripotassium phosphate, DBU (diazabicycloundecene), tetrabutylammonium hydroxide, sodium hydroxide, and potassium hydroxide.

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