Resin-deposit remover liquid and method for cleaning polymerization vessel

Abstract

Provided is a remover liquid with which a resin deposit derived from a tacky polymer can be favorably separated and removed without using any organic solvent. Also provided is a method for cleaning a polymerization vessel having a polymer scale that has adhered thereto. The remover liquid is a resin-deposit remover liquid for use in the separation and removal of a resin deposit derived from a tacky polymer. The resin-deposit remover liquid comprises electrolyzed water and a surfactant having an amine structure or an amide group in the molecule. The resin-deposit remover liquid has a pH of 12.5 or higher.

Description

Resin deposit remover and polymerization vessel cleaning method

[0001] The present invention relates to a resin deposit remover used to remove resin deposits derived from adhesive polymers and a method for cleaning a polymerization vessel. This application claims priority to Japanese Patent Application No. 2023-140604, filed on August 31, 2023, the entire contents of which are incorporated herein by reference.

[0002] Generally, pressure-sensitive adhesives (also referred to as pressure-sensitive adhesives; the same applies hereinafter) are in a soft solid (viscoelastic) state at temperatures around room temperature and have the property of easily adhering to an adherend by pressure. Because of their ease of application to an adherend, pressure-sensitive adhesives are widely used in a variety of fields in the form of a supported pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer on a support, or in the form of a supportless pressure-sensitive adhesive sheet having no support.

[0003] Polymerization vessels used in producing such adhesives become coated with gelled adhesive polymer-derived resins (hereinafter collectively referred to as "resin deposits") after use. Therefore, they must be periodically cleaned and washed to remove the resin deposits from the inner walls of the polymerization vessel. However, resin deposits firmly adhering to the wall surface cannot be easily removed by washing with a conventional organic solvent alone. Manual scraping using a sharp blade or similar tool may be required, which can be cumbersome and dangerous. Furthermore, manual cleaning is often insufficient or requires a significant amount of time, resulting in inefficient cleaning. Therefore, various studies have been conducted on cleaning solutions for peeling and removing resin deposits from polymerization vessels. Patent Documents 1 and 2 are cited as examples of documents relating to this type of technology.

[0004] Japanese Patent Application Publication No. 2003-292994 Japanese Patent Application Publication No. 2022-118434

[0005] For example, Patent Document 1 describes cleaning a polymerization vessel using a mixed solution of water, alcohol, and an alkaline compound. Patent Document 2 also describes cleaning a polymerization vessel using a cleaning agent containing an aromatic alcohol, an inorganic alkaline compound, and a solubilizing agent. However, all of the cleaning solutions in these conventional technologies contain organic solvents such as alcohol, which limits the ability to reduce the risk of fire due to static electricity, the risk that volatile substances may adversely affect the health of workers, and the burden on wastewater treatment facilities when disposing of the cleaning agent after use. Therefore, it would be beneficial to develop a stripping solution that can effectively remove resin deposits without relying on organic solvents.

[0006] Furthermore, if a resin deposit remover that can reduce the risk of adverse effects on worker health and the burden on wastewater treatment facilities could be realized, it would be expected to be used in applications other than just cleaning polymerization vessels. For example, it would be advantageous if it could be used to remove adhesive residue that occurs on an adherend when peeling and removing a PSA sheet from the adherend, or to peel and remove a PSA sheet that has firmly adhered to the adherend from the adherend.

[0007] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a remover that can suitably remove and remove resin deposits derived from adhesive polymers without relying on organic solvents. Another object of the present invention is to provide a method for cleaning a polymerization vessel to which polymer insoluble matter (hereinafter also referred to as "polymer scale") has adhered.

[0008] According to this specification, a resin deposit remover used for removing resin deposits derived from adhesive polymers is provided. The resin deposit remover contains electrolyzed water and a surfactant having an amine structure or an amide group in its molecule, and has a pH of 12.5 or higher. This resin deposit remover can effectively remove resin deposits derived from adhesive polymers without relying on organic solvents, which are prone to problems such as the risk of fire due to static electricity, the risk of adverse effects on worker health, and the burden on wastewater treatment facilities.

[0009] In some embodiments, the surfactant is selected from alkylamine oxides and polyoxyethylene alkylamides. When such surfactants are used together with electrolyzed water, the peeling and removal properties of resin deposits derived from adhesive polymers tend to be improved.

[0010] In some embodiments, the content of the surfactant is 0.05% by weight or more and 5% by weight or less. When the surfactant is used in the above content together with the electrolyzed water, the effects of the present invention are easily exhibited.

[0011] The present specification also provides a method for removing resin deposits derived from adhesive polymers using any of the resin deposit removers disclosed herein. This method makes it possible to easily remove resin deposits derived from adhesive polymers while reducing the risk of fire due to static electricity, the risk of adverse effects on the health of workers, and the burden on wastewater treatment facilities when disposing of the remover after use.

[0012] Furthermore, this specification provides a method for cleaning a polymerization vessel to which polymer scale has adhered. The cleaning method includes pouring any of the resin deposit removers disclosed herein into the polymerization vessel to which polymer scale has adhered, and stirring the resin deposit remover in the polymerization vessel at 50°C or higher. This cleaning method makes it possible to easily remove polymer scale from the polymerization vessel while reducing the risk of fire due to static electricity, the risk of adverse effects on the health of workers, and the burden on wastewater treatment facilities.

[0013] Preferred embodiments of the present invention will be described below. Matters necessary for carrying out the present invention other than those specifically mentioned in this specification can be understood by those skilled in the art based on the teachings on carrying out the invention described in this specification and the common general technical knowledge at the time of filing. The present invention can be carried out based on the contents disclosed in this specification and the common general technical knowledge in the relevant field.

[0014] In this specification, "adhesive polymer" refers to a polymer having adhesive properties, and is typically a base polymer contained in a pressure-sensitive adhesive. Here, the "base polymer" of a pressure-sensitive adhesive refers to the main component of a rubbery polymer contained in the pressure-sensitive adhesive. The rubbery polymer refers to a polymer that exhibits rubber elasticity in a temperature range around room temperature. Furthermore, in this specification, "main component" refers to a component that is contained in an amount of more than 50% by weight, unless otherwise specified.

[0015] (pH) The resin deposit remover disclosed herein is an alkaline solution having a pH of 12.5 or higher. The higher the pH of the resin deposit remover, the more likely it is to improve the ability to remove and remove resin deposits derived from adhesive polymers. The pH of the resin deposit remover may be 12.8 or higher, 13.0 or higher, 13.2 or higher, or 13.4 or higher. The upper limit of the pH of the resin deposit remover is not particularly limited, but is usually 14 or lower.

[0016] The pH of various aqueous solutions in this specification can be determined by using a pH meter (for example, a glass electrode type hydrogen ion concentration indicator (model number F-23) manufactured by HORIBA, Ltd.) and performing three-point calibration using standard buffer solutions (phthalate pH buffer solution, pH: 4.01 (25°C), neutral phosphate pH buffer solution, pH: 6.86 (25°C), carbonate pH buffer solution, pH: 10.01 (25°C)), then immersing the glass electrode in the aqueous solution to be measured and measuring the value after 2 minutes or more have passed and the solution has stabilized.

[0017] (Electrolyzed Water) The resin deposit remover solution disclosed herein contains electrolyzed water. In this specification, "electrolyzed water" refers to an aqueous solution obtained by electrolyzing water that has been chemically treated as needed. When electrolyzing water, alkaline electrolyzed water is produced at the negative electrode of an electrolytic cell containing water, and acidic electrolyzed water is produced at the positive electrode. For this reason, electrolyzed water can generally be broadly divided into two types: "alkaline electrolyzed water" and "acidic electrolyzed water." Of these, the electrolyzed water in the technology disclosed herein is preferably "alkaline electrolyzed water." The electrolyzed water in the technology disclosed herein may be electrolyzed water generally known as "strong alkaline electrolyzed water."

[0018] As described above, the resin deposit remover disclosed herein is an alkaline solution with a pH of 12.5 or higher. From the viewpoint of realizing such an alkaline resin deposit remover, the pH of the electrolyzed water disclosed herein is preferably 12.5 or higher. The pH of the electrolyzed water may be 12.8 or higher, 13.0 or higher, 13.2 or higher, or 13.4 or higher. The upper limit of the pH of the electrolyzed water is not particularly limited, but is usually 14 or lower. The higher the pH of the electrolyzed water, the higher the cleaning ability and the better the ability to remove and remove resin deposits tends to be.

[0019] Electrolyzed water, even if it is an alkaline solution with a very high pH, ​​tends to be safer for the skin and have a smaller impact on the environment than solutions with a similar pH, such as sodium hydroxide aqueous solution. Therefore, by using electrolyzed water, a resin deposit remover can be realized that exhibits excellent peeling and removal properties for resin deposits while reducing the risk of adverse effects on worker health and the burden on drainage facilities. Furthermore, the use of electrolyzed water makes it possible to realize an aqueous remover, making it easier to realize a resin deposit remover that does not rely on organic solvents such as alcohols.

[0020] In some embodiments, the content of inorganic alkali compounds in the electrolyzed water is 1.0 wt% or less, preferably 0.5 wt% or less, and more preferably 0.3 wt% or less. Herein, the content of inorganic alkali compounds in the electrolyzed water refers to the amount of inorganic alkali ions (e.g., alkali metal ions) contained in the electrolyzed water when converted to hydroxides. When the electrolyzed water contains two or more inorganic alkali ions (e.g., potassium ions, sodium ions, etc.), the content of the inorganic alkali compounds refers to the total amount of the two or more inorganic alkali ions when converted to hydroxides.

[0021] The content of electrolyzed water in the resin deposit remover is not particularly limited. From the viewpoint of the peeling and removability of resin deposits, the content of electrolyzed water is usually 65 wt% or more, preferably 70 wt% or more, more preferably 75 wt% or more, even more preferably 80 wt% or more, 85 wt% or more, 90 wt% or more, 93 wt% or more, 95 wt% or more, 98 wt% or more, 98.5 wt% or more, or 99.0 wt% or more. From the viewpoint of containing an appropriate amount of surfactant A described below, the content of electrolyzed water in the resin deposit remover may be 99.9 wt% or less, 99.8 wt% or less, 99.5 wt% or less, or 99.2 wt% or less.

[0022] (Surfactant) The resin deposit remover solution disclosed herein contains a surfactant. By including a surfactant, the peeling and removal properties of resin deposits tend to be further improved. As the surfactant, a surfactant having an amine structure or an amide group in the molecule (hereinafter also referred to as "surfactant A") is preferably used. When such surfactant A is used in combination with electrolyzed water, the peeling and removal properties of resin deposits derived from adhesive polymers tend to be improved.

[0023] In this specification, the term "amine structure" refers to a structure in which at least one (i.e., 1 to 3) of the hydrogen atoms of ammonia has been substituted with an atom or atomic group, or a quaternary ammonium salt structure.

[0024] The reason why the use of surfactant A improves the peeling and removability of resin deposits is not particularly limited, but can be understood, for example, as follows. Surfactant A, which has an amine structure or an amide group in its molecule, has a high affinity with resin deposits and tends to penetrate and swell the resin deposits. The swollen resin deposits are easily peeled from the surface of the adherend, and the presence of highly cleansing electrolyzed water there is thought to further improve the peeling and removability of the resin deposits.

[0025] The surfactant A is not particularly limited except that it has an amine structure or an amide group, and any of anionic, cationic, nonionic, and amphoteric surfactants can be used. Among these, nonionic surfactants, anionic surfactants, and amphoteric surfactants are preferably used as the surfactant A, and more preferably nonionic surfactants and amphoteric surfactants are used. Examples of the surfactant A include polyoxyethylene alkylamines such as polyoxyethylene laurylamine, polyoxyethylene stearylamine, and polyoxyethylene oleylamine; polyoxyethylene alkylamides such as polyoxyethylene fatty acid amides; and alkylamine oxides. Among these, alkylamine oxides and polyoxyethylene alkylamides are preferred. The surfactant A can be used alone or in combination of two or more.

[0026] The number of carbon atoms in the long-chain alkyl group contained in the alkylamine oxide is not particularly limited. From the viewpoint of peeling and removability of resin deposits, in some embodiments, the long-chain alkyl group contained in the alkylamine oxide has 8 or more carbon atoms (e.g., 10 or more), preferably 11 or more, and more preferably 12 or more. Furthermore, the number of carbon atoms in the long-chain alkyl group contained in the alkylamine oxide may be 20 or less, 18 or less, 16 or less, or 14 or less. The long-chain alkyl group may be substituted with a functional group. For example, a suitable example of an alkylamine oxide includes a long-chain alkyl group having 10 to 14 carbon atoms (preferably 12 to 14) and further having one or two alkyl groups having 2 or less carbon atoms (e.g., 1 carbon atom). Examples of such alkylamine oxides include N,N-dimethyllaurylamine oxide and N,N-dimethylmyristylamine oxide.

[0027] The number of carbon atoms in the long-chain alkyl group contained in the polyoxyethylene alkylamide is not particularly limited. From the viewpoint of peeling and removability of resin deposits, in some embodiments, the number of carbon atoms in the long-chain alkyl group contained in the polyoxyethylene alkylamide is 10 or more (e.g., 12 or more), preferably 14 or more, more preferably 16 or more, and may be 17 or more, or 18 or more. Furthermore, the number of carbon atoms in the long-chain alkyl group contained in the polyoxyethylene alkylamide may be 22 or less, 20 or less, or 19 or less. Furthermore, the long-chain alkyl group may be substituted with a functional group. A suitable example of the polyoxyethylene alkylamide is polyoxyethylene oleic acid amide.

[0028] The average number of moles of ethylene oxide added in the polyoxyethylene alkylamide is not particularly limited. For example, the average number of moles of ethylene oxide added in the polyoxyethylene alkylamide may be 3 or more, 4 or more, or 5 or more. Furthermore, the average number of moles of ethylene oxide added in the polyoxyethylene alkylamide may be 10 or less, 8 or less, or 6 or less.

[0029] The content of surfactant A in the resin deposit remover solution (when two or more types of surfactant A are contained, the total content thereof) is not particularly limited. From the viewpoint of the ability to remove and remove resin deposits, the content of surfactant A is typically 0.05 wt % or more, preferably 0.1 wt % or more, and may be 0.15 wt % or more, 0.3 wt % or more, 0.5 wt % or more, or 0.8 wt % or more. The content of surfactant A is typically 5 wt % or less, and may be 4.5 wt % or less, 4 wt % or less, 3 wt % or less, 2 wt % or less, 1 wt % or less, or 0.5 wt % or less.

[0030] The resin deposit remover disclosed herein may contain surfactants other than surfactant A, as long as the effects of the present invention are not significantly impaired. The content of surfactants other than surfactant A is not particularly limited, and may be, for example, 1 wt % or less, 0.1 wt % or less, 0.01 wt % or less, or 0.001 wt % or less. The resin deposit remover disclosed herein may be substantially free of surfactants other than surfactant A. Here, "substantially free of surfactants other than surfactant A" means, for example, that the content of surfactants other than surfactant A in the resin deposit remover is 1×10 －４ % by weight or less (preferably 1×10 －５ % by weight or less), and may be 0% by weight.

[0031] According to the technology disclosed herein, by using electrolyzed water in combination with a specific surfactant, resin deposits can be easily removed without relying on organic solvents (e.g., alcohols). Therefore, in order to reduce the disadvantages of using organic solvents (e.g., alcohols), it is advantageous to limit the amount of organic solvent (e.g., alcohols) contained in the resin deposit remover disclosed herein. In some preferred embodiments, the content of organic solvent (e.g., alcohols) in the resin deposit remover is less than 60 wt %, or may be less than 50 wt %, or may be 35 wt % or less (e.g., 30 wt % or less), preferably less than 20 wt %, more preferably 10 wt % or less, even more preferably 5 wt % or less, or may be 1 wt % or less, 0.5 wt % or less, 0.1 wt % or less, or 0.05 wt % or less. The resin deposit remover disclosed herein may be substantially free of organic solvents (e.g., alcohols). Here, "substantially free of organic solvents (e.g., alcohols)" means that the content of organic solvents (e.g., alcohols) in the resin deposit remover is 0.01% by weight or less (preferably 0.001% by weight or less), and may be 0% by weight. A resin deposit remover with a limited content of organic solvents (e.g., alcohols) can reduce the risk of fire due to static electricity, the risk of adverse effects on worker health due to volatile substances, and the burden on wastewater treatment facilities when the cleaner is disposed of after use.

[0032] In some embodiments, the content of inorganic alkali compounds contained in the resin deposit remover disclosed herein is 1.0 wt % or less, preferably 0.5 wt % or less, and more preferably 0.3 wt % or less. Herein, the content of inorganic alkali compounds in the resin deposit remover refers to the amount of inorganic alkali ions (e.g., alkali metal ions) contained in the resin deposit remover, converted into hydroxides. When the resin deposit remover contains two or more inorganic alkali ions (e.g., potassium ions, sodium ions, etc.), the content of the inorganic alkali compounds refers to the total amount of the two or more inorganic alkali ions converted into hydroxides.

[0033] (Uses) The resin deposit remover disclosed herein can easily remove resin deposits derived from adhesive polymers from adherends. Furthermore, the resin deposit remover disclosed herein can remove resin deposits without relying on organic solvents such as alcohol. Therefore, compared to conventional removers containing organic solvents, the risk of fire due to static electricity, the risk of adverse effects on worker health, and the burden on wastewater treatment facilities can be reduced.

[0034] The type of adherend to be used for peeling and removing resin deposits is not particularly limited. For example, the adherend may have a surface made of a corrosion-resistant metal material such as stainless steel; a glass material; a polyester resin such as PET, a polyolefin resin such as polyethylene (PE) or polypropylene (PP), or various resin materials such as fluorine-based polymers, polystyrene, polyoxymethylene, and polyvinyl acetate. Among these, an adherend having a surface made of a material that is not easily swollen by the resin deposit remover is preferred. For example, when the resin deposit remover disclosed herein is used to peel and remove polymer scale adhered to a polymerization vessel, the adherend may have a surface made of a metal or glass material. Furthermore, for example, when the resin deposit remover disclosed herein is used to remove adhesive residue generated on an adherend when peeling and removing a pressure-sensitive adhesive sheet (or adhesive) from the adherend, or when it is used to peel and remove a pressure-sensitive adhesive sheet firmly attached to the adherend, the adherend may have a surface made of a metal, glass, resin, or the like.

[0035] The resin deposit remover disclosed herein is suitable for use in peeling and removing polymer scale from a polymerization vessel (reaction vessel) to which the polymer scale has adhered. The polymerization vessel is typically a metal or glass polymerization vessel used for producing pressure-sensitive adhesives. The concept of a polymerization vessel can include those referred to as polymerization kettle, reaction kettle, polymerization tank, etc.

[0036] The resin deposit remover disclosed herein can be used to remove adhesive residue (components derived from the adhesive) that occurs on an adherend when peeling and removing a pressure-sensitive adhesive sheet (or adhesive) from the adherend. The resin deposit remover disclosed herein can also be used to peel and remove a pressure-sensitive adhesive sheet (or adhesive) that has firmly adhered to the adherend from the adherend.

[0037] (Resin Deposit) In the technology disclosed herein, the resin deposit derived from the adhesive polymer is not particularly limited as long as it is a resin derived from the adhesive polymer that is adhered to an adherend. A typical example of a resin deposit derived from the adhesive polymer is an insoluble polymer (polymer scale) that remains stuck to the inner wall of a polymerization vessel used to produce the adhesive. Other examples include adhesive residues that remain on an adherend when the adhesive is peeled off and removed from the adherend, and the adhesive that has adhered to the adherend.

[0038] The type of adhesive polymer is not particularly limited. The adhesive polymer may be, for example, an acrylic polymer, a rubber polymer, a polyester polymer, a urethane polymer, a polyether polymer, a silicone polymer, a polyamide polymer, a fluorine-based polymer, or the like, which are well known in the field of adhesives. Hereinafter, the application of the technology disclosed herein will be described using an example in which the adhesive polymer is an acrylic polymer, but this is not intended to limit the use of the present invention.

[0039] The acrylic polymer is preferably a polymer of a monomer raw material that contains, for example, an alkyl(meth)acrylate as a main monomer and may further contain a secondary monomer copolymerizable with the main monomer, where the main monomer is a component that accounts for more than 50% by weight of the monomer composition in the monomer raw material.

[0040] As the alkyl(meth)acrylate, for example, a compound represented by the following formula (1) can be preferably used: CH ２ = C(R １ ) COOR ２ (1) Here, R in the above formula (1) １is a hydrogen atom or a methyl group. ２ is a chain alkyl group having 1 to 20 carbon atoms (hereinafter, this range of carbon atoms is referred to as "C １－２０ From the viewpoint of the storage modulus of the adhesive, R ２ is C １－１２ (For example, C ２－１０ , typically C ４－８ ) alkyl (meth)acrylate, which is a chain alkyl group of the above R ２ is C １－２０ The alkyl(meth)acrylates, which are chain alkyl groups, may be used alone or in combination of two or more. Preferred alkyl(meth)acrylates include n-butyl acrylate and 2-ethylhexyl acrylate.

[0041] A secondary monomer copolymerizable with the alkyl (meth)acrylate main monomer can be useful for introducing crosslinking points into the acrylic polymer or for increasing the cohesive strength of the acrylic polymer. As the secondary monomer, for example, one or more functional group-containing monomers such as carboxy group-containing monomers, hydroxy group-containing monomers, acid anhydride group-containing monomers, amide group-containing monomers, amino group-containing monomers, and monomers having a nitrogen atom-containing ring can be used. The secondary monomer can also be a vinyl ester monomer such as vinyl acetate, an aromatic vinyl compound such as styrene, a sulfonic acid group-containing monomer, or a phosphoric acid group-containing monomer. For example, from the viewpoint of improving cohesive strength, an acrylic polymer in which a carboxy group-containing monomer or a hydroxy group-containing monomer is copolymerized as the secondary monomer is preferred. Suitable examples of the carboxy group-containing monomer include acrylic acid and methacrylic acid. Suitable examples of the hydroxy group-containing monomer include 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate.

[0042] The amount of the secondary monomer is suitably 0.5% by weight or more, preferably 1% by weight or more, of the total monomer components of the acrylic polymer. Furthermore, the amount of the secondary monomer is suitably 30% by weight or less, preferably 10% by weight or less (e.g., 5% by weight or less), of the total monomer components. When a carboxyl group-containing monomer is copolymerized into the acrylic polymer, from the viewpoint of achieving both adhesive strength and cohesive strength, the content of the carboxyl group-containing monomer is preferably about 0.1% by weight or more (e.g., 0.2% by weight or more, typically 0.5% by weight or more), and preferably about 10% by weight or less (e.g., 8% by weight or less, typically 5% by weight or less), of the total monomer components used in the synthesis of the acrylic polymer. When a hydroxyl-containing monomer is copolymerized into the acrylic polymer, from the viewpoint of achieving both adhesive strength and cohesive strength, the content of the hydroxyl-containing monomer is preferably about 0.001% by weight or more (e.g., 0.01% by weight or more, typically 0.02% by weight or more) and about 10% by weight or less (e.g., 5% by weight or less, typically 2% by weight or less) of the total monomer components used in the synthesis of the acrylic polymer. Furthermore, when a vinyl ester monomer such as vinyl acetate is copolymerized as the secondary monomer, the content of the vinyl ester monomer is preferably about 30% by weight or less (typically 10% by weight or less) and may be, for example, 0.01% by weight or more (typically 0.1% by weight or more) of the total monomer components used in the synthesis of the acrylic polymer.

[0043] The synthesis method of adhesive polymers (e.g., acrylic polymers) to which the technology disclosed herein is applicable is not particularly limited. For example, adhesive polymers obtained by various polymerization methods known as acrylic polymer synthesis methods, such as solution polymerization, emulsion polymerization, bulk polymerization, and suspension polymerization, may be applicable. Adhesive polymers obtained by active energy ray polymerization using UV or other radiation may also be applicable. In particular, polymerization by solution polymerization or emulsion polymerization tends to result in strong adhesion of polymer insoluble matter (polymer scale) to the inner wall of the polymerization vessel after polymerization. Therefore, when the technology disclosed herein is applied to cleaning polymerization vessels, the resin deposit remover may be applied to resin deposits derived from adhesive polymers prepared by solution polymerization or emulsion polymerization.

[0044] (Method for cleaning polymerization vessels) The technology disclosed herein provides a method for cleaning polymerization vessels to which polymer scale has adhered. Here, polymer scale refers to insoluble polymer matter that remains stuck to the inner wall of a polymerization vessel in which a polymer has been produced. The cleaning method includes pouring any of the resin deposit removers disclosed herein into a polymerization vessel to which polymer scale has adhered and filling it, and stirring the resin deposit remover inside the polymerization vessel.

[0045] Specifically, the resin deposit remover is poured into a polymerization vessel to which polymer scale has adhered, so that the polymer scale is fully immersed in the resin deposit remover. From the viewpoint of polymer scale removal and removability, the resin deposit remover in the polymerization vessel is preferably heated to a temperature of 50°C or higher, more preferably 60°C or higher, and even more preferably 70°C to 90°C. The resin deposit remover is stirred in the polymerization vessel by rotating a propeller or the like to generate a water flow. The action of this water flow promotes the removal and removal of the resin deposits. At this time, resin beads or other substances that further promote the removal of polymer scale may be added. The immersion time in the resin deposit remover is not particularly limited, but is typically about 1 minute to 3 hours, preferably 30 minutes to 1.5 hours. By immersing the polymer scale in the resin deposit remover, the polymer scale swells and peels off from the inner wall of the polymerization vessel.

[0046] Next, the resin deposit remover and the removed polymer scale are washed away and removed using water or the like. If necessary, the polymerization vessel may be cleaned using a high-pressure washer. After the polymer scale removal, if necessary, the polymerization solution may be dried by blowing air onto it or the like.

[0047] According to this cleaning method, a polymerization vessel having polymer scale attached thereto can be easily cleaned without relying on organic solvents, and therefore, polymer scale can be easily removed from the polymerization vessel and the polymerization vessel can be cleaned while reducing the risk of fire due to static electricity, the risk of adverse effects on the health of workers, and the burden on wastewater treatment facilities.

[0048] As will be understood from the above description and the following examples, the matters disclosed by this specification include the following.

[0049] [1] A resin deposit remover used to remove resin deposits derived from adhesive polymers, comprising electrolyzed water and a surfactant having an amine structure or an amide group in the molecule, and having a pH of 12.5 or higher. [2] The resin deposit remover according to [1] above, wherein the surfactant is selected from alkylamine oxide and polyoxyethylene alkylamide. [3] The resin deposit remover according to [1] or [2] above, wherein the content of the surfactant is 0.05% by weight or more and 5% by weight or less. [4] The resin deposit remover according to any one of [1] to [3] above, wherein the content of an organic solvent (e.g., alcohols) is less than 60% by weight. [5] A method for removing resin deposits derived from adhesive polymers using the resin deposit remover according to any one of [1] to [4] above. [6] A method for cleaning a polymerization vessel having polymer scale attached thereto, comprising: pouring the resin deposit remover according to any one of [1] to [4] above into the polymerization vessel having polymer scale attached thereto; and stirring the resin deposit remover in the polymerization vessel while heating it to 50°C or higher.

[0050] Several examples of the present invention will be described below, but it is not intended that the present invention be limited to those shown in these examples. In the following description, "parts" and "%" representing amounts used and contents are by weight unless otherwise specified.

[0051] The surfactants used in the examples are as follows: Surfactant A1: Alkylamine oxide (C14) (N,N-dimethylmyristylamine oxide) Surfactant A2: Alkylamine oxide (C12) (N,N-dimethyllaurylamine oxide) Surfactant A3: Polyoxyethylene oleic acid amide (5 E.O.) Surfactant B: Sodium alkyldiphenyl ether disulfonate Surfactant C: Sodium dodecyl sulfate Surfactant D: Sodium polyoxyethylene alkyl ether sulfate

[0052] Example 1 [Preparation of Resin Deposit Remover] Electrolyzed water and surfactant A1 were mixed to prepare a solution containing 99.85% electrolyzed water and 0.15% surfactant A1, which was used as the resin deposit remover of this example. The pH of this resin deposit remover was 13.5.

[0053] [Production of Acrylic Polymer A in a Polymerization Vessel] A rectangular stainless steel plate (SUS plate) measuring 120 mm in length, 360 mm in width, and 0.3 mm in thickness was attached to the inner wall of a polymerization vessel equipped with a thermometer, a stirrer, a nitrogen inlet tube, and a reflux condenser, and an aqueous polymer emulsion was produced in the polymerization vessel. Specifically, 0.10 parts of a surfactant (trade name "Latemul E-118B", manufactured by Kao Corporation) and 61 parts of distilled water were added to the polymerization vessel, and the atmosphere was replaced with nitrogen at room temperature (25°C) for 1 hour with stirring. Thereafter, 0.10 parts of a polymerization initiator (trade name "VA-057", manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added thereto, and the temperature was raised to 60°C. To this mixture, 85 parts of 2-ethylhexyl acrylate (2EHA), 13 parts of methyl acrylate (MA), 1.25 parts of acrylic acid (AA), 0.75 parts of methacrylic acid (MAA), 0.048 parts of t-dodecanethiol (chain transfer agent), 0.02 parts of 3-methacryloxypropyltrimethoxysilane (trade name "KBM-503", manufactured by Shin-Etsu Chemical Co., Ltd.), and 1.8 parts of a surfactant (trade name "Latemul E-118B", manufactured by Kao Corporation) were emulsified in 28 parts of distilled water, and the mixture was polymerized dropwise at 60°C over 4 hours. After aging for 3 hours at 60°C, 0.087 parts of sodium hydrogen peroxide and 0.17 parts of ascorbic acid were added. The mixture was cooled to room temperature and adjusted to pH 6 using 10% aqueous ammonia as a pH adjuster, to prepare acrylic polymer A.

[0054] [Cleaning of polymerization vessel and confirmation of polymer scale adhesion state] The obtained acrylic polymer A was completely removed from the polymerization vessel, and the inner wall of the polymerization vessel was washed with water using a weak water flow so as not to scrape off the polymer scale adhered to the wall surface. Next, the SUS plate attached to the inner wall of the polymerization vessel was removed, and the initial adhesion area X [mm ２The SUS plate was again attached to the same position on the inner wall of the polymerization vessel, and the resin deposit remover of this example was poured into the polymerization vessel until the entire SUS plate was fully immersed in the remover, and the polymerization vessel was washed at 80°C for 1 hour while stirring. Thereafter, the polymerization vessel was allowed to cool to room temperature, and the resin deposit remover in the polymerization vessel was discarded, and the empty polymerization vessel was lightly rinsed with water, after which the SUS plate was removed from the polymer vessel, and the post-wash adhesion area Y [mm ２ The adhesion area of ​​polymer scale was measured by photographing the surface of the SUS plate to obtain a surface image, and analyzing the surface image using image analysis software.

[0055] Examples 2 to 4 and Comparative Examples 2 to 4 A resin deposit remover solution of this example was prepared in the same manner as in Example 1, except that either the content of electrolyzed water or the type and content of surfactant were changed as shown in Table 1. Production of acrylic polymer A in a polymerization vessel, cleaning of the polymerization vessel, and confirmation of the state of polymer scale adhesion were carried out in the same manner as in Example 1, except that this resin deposit remover solution was used.

[0056] Example 5 Preparation of a resin deposit remover, production of acrylic polymer A in the polymerization vessel, cleaning of the polymerization vessel, and confirmation of the state of polymer scale adhesion were carried out in the same manner as in Example 4, except that the polymerization vessel was cleaned at 50°C for 1 hour.

[0057] Comparative Example 1 A resin deposit remover of this example was prepared in the same manner as in Example 1, except that distilled water was used instead of electrolyzed water. The pH of the obtained resin deposit remover was 7.5. Except for using this resin deposit remover, production of acrylic polymer A in a polymerization vessel, cleaning of the polymerization vessel, and confirmation of the state of polymer scale adhesion were carried out in the same manner as in Example 1.

[0058] An outline of Examples 1 to 5 and Comparative Examples 1 to 4 is shown in Table 1. In Table 1, "-" means not used.

[0059] (Evaluation) The peeling and removability of polymer scale was evaluated using the following formula: Removal rate [%] = {(X - Y) / X} × 100 (where X is the initial adhesion area of ​​polymer scale [mm２ ], Y is the adhesion area of ​​polymer scale after cleaning [mm ２ The removal rate was calculated based on the obtained removal rate, and the peeling removability was evaluated based on the following four-level scale. The results are shown in Table 1. AA (Excellent): Removal rate is 98% or more A (Good): Removal rate is 90% or more but less than 98% B (Fair): Removal rate is 20% or more but less than 90% C (Poor): Removal rate is less than 20%

[0060]

[0061] As is clear from Table 1, it was confirmed that the resin deposit remover solutions of Examples 1 to 5, which contain electrolyzed water and a surfactant having an amine structure or an amide group in the molecule, exhibit superior peeling and removability compared to Comparative Example 1, in which distilled water was used instead of electrolyzed water, and Comparative Examples 2 to 4, in which other surfactants were used instead of the surfactant having an amine structure or an amide group. Furthermore, a comparison of the results of Example 4 and Example 5 confirmed that even better peeling and removability could be obtained by increasing the temperature of the resin deposit remover solution to 80°C when immersing the polymer scale in the resin deposit remover solution.

[0062] Polymer scale removal using a resin-adhered body remover was carried out in the same manner as in Examples 1 to 5 and Comparative Examples 1 to 4, except that acrylic polymer B was prepared in the polymerization vessel by the following method instead of acrylic polymer A. As a result, the results of the polymer scale removal and removability showed the same tendency as when acrylic polymer A was used.

[0063] [Preparation of Acrylic Polymer B] 40 parts of distilled water was added to a reaction vessel equipped with a thermometer, a stirrer, a nitrogen inlet tube, and a reflux condenser, and the mixture was purged with nitrogen at 60°C for 1 hour while stirring. Thereafter, 0.10 parts of a polymerization initiator (trade name "VA-057", manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added. An emulsion of 68 parts of butyl acrylate (BA), 29 parts of 2-ethylhexyl acrylate (2EHA), 2.8 parts of acrylic acid (AA), 0.05 parts of lauryl mercaptan (L-SH), 0.03 parts of 3-methacryloxypropyltrimethoxysilane (trade name "KBM-503", manufactured by Shin-Etsu Chemical Co., Ltd.), and 2.0 parts of a surfactant (trade name "Latemul E-118B", manufactured by Kao Corporation) in 25 parts of distilled water was added dropwise to the reaction vessel at 60°C over 4 hours, and polymerization was carried out. After further aging at 60° C. for 3 hours, 0.075 parts of sodium hydrogen peroxide and 0.15 parts of ascorbic acid were added, and the mixture was cooled to room temperature and adjusted to pH 6 using 10% aqueous ammonia as a pH adjuster, thereby preparing acrylic polymer B.

[0064] Although specific examples of the present invention have been described above in detail, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and alterations of the specific examples exemplified above.

Claims

1. A resin deposit remover used to remove resin deposits derived from adhesive polymers, comprising electrolytic water and a surfactant having an amine structure or an amide group in its molecule, and having a pH of 12.5 or higher.

2. The resin deposit remover according to claim 1, wherein the surfactant is selected from alkylamine oxides and polyoxyethylene alkylamides.

3. The resin deposit remover according to claim 1 or 2, wherein the content of the surfactant is 0.05% by weight or more and 5% by weight or less.

4. A method for removing resin deposits derived from adhesive polymers using the resin deposit remover according to claim 1 or 2.

5. A method for cleaning a polymerization vessel having polymer scale attached thereto, comprising: pouring the resin deposit remover according to claim 1 or 2 into the polymerization vessel having polymer scale attached thereto; and stirring the resin deposit remover in the polymerization vessel at 50°C or higher.

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