Acrylic resin, method for producing same, and acrylic resin composition

Abstract

Provided is, for metal materials, an acrylic resin capable of forming a film having both excellent hydrophilicity and excellent adhesion durability in environments where the film is immersed in water. The acrylic resin has an N-hydroxyalkyl group, a mercapto group and / or sulfide group, and a polyoxyalkylene group, and the ratio (N2 / N1) of the total number N2 of mercapto groups and sulfide groups to the number1 of oxyalkylene groups constituting polyoxyalkylene groups is in the 0.02-1.00 range.

Description

Acrylic resin, its manufacturing method, and acrylic resin composition

[0001] The present invention relates to an acrylic resin, a method for producing the same, and an acrylic resin composition.

[0002] In recent years, various acrylic resins have been used in a variety of fields. For example, Patent Document 1 discloses the use of an acrylic resin described as a crosslinkable fine particle as a hydrophilic treatment agent for metal materials. The crosslinkable fine particle is a resin particle obtained by copolymerizing a monomer such as N-methylolacrylamide, a monomer having a polyoxyalkylene chain and a polymerizable double bond, and other polymerizable monomers in a water-miscible organic solvent at a specific ratio.

[0003] The crosslinkable microparticles have a relatively large number of unreacted functional groups, and therefore can react with other hydrophilic resins to form hydrophilic coatings that are excellent in hydrophilicity, particularly in the persistence of hydrophilicity after contamination, and also in adhesion. Furthermore, because they have a relatively small swelling rate in water, the hydrophilic coatings formed are prevented from dissolving in water.

[0004] The hydrophilic coating formed from the crosslinkable fine particles is used on the aluminum fin material of the heat exchanger for air conditioners. During cooling operation of the air conditioner, condensed water on the fin surface causes clogging, increasing ventilation resistance and reducing efficiency. To prevent this problem, hydrophilic coatings have traditionally been applied to the fin surface.

[0005] Japanese Patent Application Laid-Open No. 2005-2151

[0006] However, the hydrophilic film formed from the crosslinkable fine particles described in Patent Document 1 does not exhibit sufficient adhesion to metal materials, and therefore does not have excellent adhesion durability in a water-immersed environment. Although the adhesion of the hydrophilic film itself is maintained by the reaction of the crosslinkable fine particles with other hydrophilic resins, the metal material and the crosslinkable fine particles are not directly adhered to each other, and therefore this is not a fundamental solution.

[0007] In view of the above circumstances, in one embodiment, the present invention aims to provide an acrylic resin capable of forming a coating on a metal material that has both excellent hydrophilicity and excellent adhesion durability in a water-immersed environment, a method for producing the same, and an acrylic resin composition.

[0008] The present invention is exemplified as follows: [1] An acrylic resin having an N-hydroxyalkyl group, a mercapto group and / or a sulfide group, and a polyoxyalkylene group, wherein the ratio (N2 / N1) of the total number N2 of mercapto groups and sulfide groups to the number N1 of oxyalkylene groups constituting the polyoxyalkylene group is within a range of 0.02 to 1.00. [2] The acrylic resin according to [1], wherein the N2 / N1 is within a range of 0.03 to 1.00. [3] The acrylic resin according to [1] or [2], wherein the N-hydroxyalkyl group contains an N-methylol group and / or an N-ethylol group, and the polyoxyalkylene group contains a polyoxyethylene group and / or a polyoxypropylene group. [4] The acrylic resin according to any one of [1] to [3], wherein the cumulant diameter of the acrylic resin is 30 nm or less. [5] The acrylic resin according to any one of [1] to [4], wherein the acrylic resin has a weight-average molecular weight of 1,000 to 300,000. [6] A method for producing an acrylic resin, comprising copolymerizing, in an aqueous solvent, monomer components containing 10 to 90 parts by mass of N-alkylol(meth)acrylamide and 5 to 40 parts by mass of a monomer having a polyoxyalkylene group and a polymerizable double bond and a degree of polymerization of 2 to 90, relative to 100 parts by mass of all monomers having a polymerizable double bond, in the presence of 3 to 10 parts by mass of a water-soluble organic compound having a mercapto group and a carboxy group and / or a hydroxy group. [7] The method for producing an acrylic resin according to [6], wherein the N-alkylol(meth)acrylamide comprises N-methylol(meth)acrylamide and / or N-ethylol(meth)acrylamide. [8] An acrylic resin composition containing an aqueous solvent and the acrylic resin according to any one of [1] to [5] dispersed or dissolved in the aqueous solvent.

[0009] According to one embodiment of the present invention, it is possible to provide an acrylic resin capable of forming a coating on a metal material that has both excellent hydrophilicity and excellent adhesion durability in a water-immersed environment, a method for producing the same, and an acrylic resin composition.

[0010] 1. Acrylic Resin An acrylic resin according to one embodiment of the present invention has an N-hydroxyalkyl group, a mercapto group (—SH) and / or a sulfide group (—S—), and a polyoxyalkylene group.

[0011] The N-hydroxyalkyl group is not limited to, but for example, an N-hydroxyalkyl group having 1 to 4 carbon atoms can be suitably used. Specific examples of suitable N-hydroxyalkyl groups include an N-methylol group, an N-ethylol group, an N-hydroxypropyl group, and an N-hydroxybutyl group. The acrylic resin may have one type of N-hydroxyalkyl group, or two or more types of N-hydroxyalkyl groups. The N-hydroxyalkyl group preferably contains an N-methylol group and / or an N-ethylol group.

[0012] The polyoxyalkylene group includes, but is not limited to, a polyoxyethylene group (-(CHO) n -), polyoxypropylene group (-(CHO) n -), polyoxybutylene (-(C4H8O) nExamples of suitable polyoxyalkylene groups include oxyalkylene groups and polyoxyalkylene groups having 1 to 4 carbon atoms in the repeating unit, such as hydroxypropyl acrylate (hydroxypropyl acrylate), ...

[0013] It is preferable to use an acrylic resin in which the ratio (N2 / N1) of the total number N2 of mercapto groups and sulfide groups to the number N1 of oxyalkylene groups constituting the polyoxyalkylene group is within a range of 0.02 to 1.00. N2 / N1 is preferably within a range of 0.03 to 1.00, more preferably within a range of 0.05 to 0.80, and even more preferably within a range of 0.10 to 0.50. N2 / N1 can be controlled by adjusting the compounding ratio of the reactive surfactant (a2) and the chain transfer agent (a3), which will be described later.

[0014] In this specification, N2 / N1 is difficult to measure directly, and is therefore calculated by the formula {Σ(charge amount (mass) of chain transfer agent ÷ molecular weight)} / {Σ(charge amount (mass) of reactive surfactant × degree of polymerization ÷ molecular weight)} when producing the acrylic resin. Σ means that the sum is calculated when multiple types of chain transfer agents and / or reactive surfactants are used.

[0015] The aqueous solvent for the acrylic resin is not particularly limited as long as it is water or a mixture of water and a water-miscible organic solvent. The mass % of water in the mixture of water and a water-miscible organic solvent is 50 mass % or more, and more preferably 80 mass % or more, 90 mass % or more, 95 mass % or more, and 99 mass % or more in that order.

[0016] The water-miscible organic solvent is not particularly limited as long as it is miscible with water, and examples thereof include ketone solvents such as acetone and methyl ethyl ketone; amide solvents such as N,N'-dimethylformamide and dimethylacetamide; alcohol solvents such as methanol, ethanol, and isopropanol; ether solvents such as ethylene glycol monobutyl ether and ethylene glycol monohexyl ether; and pyrrolidone solvents such as 1-methyl-2-pyrrolidone and 1-ethyl-2-pyrrolidone. One of these water-miscible organic solvents may be mixed with water, or two or more of them may be mixed with water.

[0017] The cumulant diameter of the acrylic resin is not particularly limited, but is, for example, 30 nm or less in an aqueous solvent, preferably in the range of 0.3 to 25 nm. The cumulant diameter is the average particle diameter XDLS measured using a particle size measuring device in accordance with JIS Z8828:2019 based on the principle of photon correlation spectroscopy.

[0018] The weight-average molecular weight of the acrylic resin is not particularly limited and is, for example, in the range of 1,000 to 300,000, preferably in the range of 2,000 to 200,000, and more preferably in the range of 5,000 to 100,000. The weight-average molecular weight is measured by gel permeation chromatography (GPC) and is converted into polystyrene.

[0019] 2. Method for Producing Acrylic Resin The acrylic resin according to one embodiment of the present invention can be produced, for example, by sequentially blending an aqueous solvent, a crosslinkable monomer (a1), a reactive surfactant (a2), and a chain transfer agent (a3) ​​in a predetermined ratio, and reacting them in an atmosphere of an inert gas such as nitrogen or argon at a predetermined temperature (preferably 60 to 90° C.). It is preferable to add an appropriate amount of a radical polymerization initiator (a4) to promote the reaction.

[0020] (Crosslinking Monomer (a1)) As the crosslinking monomer (a1), N-alkylol(meth)acrylamide is used. Specific examples of N-alkylol(meth)acrylamide include N-methylol acrylamide, N-methylol methacrylamide, N-ethylol acrylamide, and N-ethylol methacrylamide. The N-alkylol(meth)acrylamide preferably contains N-methylol(meth)acrylamide and / or N-ethylol(meth)acrylamide. However, the N-alkylol(meth)acrylamide is not limited to these. These crosslinking monomers (a1) may be used alone or in combination of two or more.

[0021] (Reactive Surfactant (a2)) As the reactive surfactant (a2), a monomer having a polyoxyalkylene group and a polymerizable double bond is used. The degree of polymerization of the polyoxyalkylene group is preferably 1 to 100, more preferably 20 to 90, and even more preferably within the range of 30 to 70. Examples of types of monomers having a polymerizable double bond include compounds having a vinyl group terminal (acrylic group, methacrylic group, etc.). The degree of polymerization of the polyoxyalkylene group of the reactive surfactant (a2) can be calculated by the following procedure. First, the weight average molecular weight of the reactive surfactant (a2) is measured by gel permeation chromatography (GPC), and the formula weight of the portion other than the polyoxyalkylene group constituting the reactive surfactant (a2) (e.g., the vinyl group terminal) is subtracted from the weight average molecular weight to determine the formula weight of the polyoxyalkylene group, and this is further divided by the formula weight of the repeating unit of the polyoxyalkylene group (e.g., the oxyethylene group (44), the oxypropylene group (58)). Measurement of the weight-average molecular weight by gel permeation chromatography (GPC) can be performed under the following conditions, calculated using polystyrene as a standard sample. (GPC conditions) Column: Semi-micro column manufactured by Tosoh Corporation; two columns connected together; Standard sample: PStQuick B manufactured by Tosoh Corporation; Mobile phase: N,N'-dimethylformamide; Detection equipment: RI, UV

[0022] The alkylene portion of the polyoxyalkylene group may be, for example, a linear alkylene group having 1 to 20 carbon atoms, preferably an ethylene group or a propylene group. The reactive surfactant may further have a hydroxy group and / or an alkoxy group, for example, a methoxy group and / or an ethoxy group. Specific examples include, but are not limited to, polyethylene glycol monoacrylate, polyethylene glycol monomethacrylate, polypropylene glycol monoacrylate, polypropylene glycol monomethacrylate, methoxypolyethylene glycol monoacrylate, methoxypolypropylene glycol monomethacrylate, methoxypolypropylene glycol monoacrylate, methoxypolypropylene glycol monomethacrylate, polyethylene glycol diacrylate, and polypropylene glycol diacrylate. These reactive surfactants (a2) may be used alone or in combination of two or more.

[0023] (Chain Transfer Agent (a3)) As the chain transfer agent (a3), a water-soluble organic compound having a mercapto group and a carboxy group and / or a hydroxy group is used. In this specification, the term "water-soluble organic compound" refers to an organic compound having a solubility of 0.1% by mass or more in water at room temperature (20°C), with the solubility preferably being 0.5% by mass or more, and more preferably being 1% by mass or more. The chain transfer agent (a3) ​​may have two or more carboxy groups and / or hydroxy groups in one molecule. Specific examples include, but are not limited to, 2-mercaptoethanol, 3-mercaptopropionic acid, 3-mercapto-1,2-propanediol, mercaptoacetic acid, and mercaptosuccinic acid. It is to be noted that these chain transfer agents (a3) ​​may be used alone or in combination of two or more.

[0024] (Radical Polymerization Initiator (a4)) The radical polymerization initiator (a4) refers to a compound that generates radicals by heat or light. Specific examples include peroxides such as benzoyl peroxide, lauroyl peroxide, di-t-butyl peroxide, cumene hydroperoxide, t-butyl peroctoate, and t-butylperoxy 2-ethylhexanoate; 2,2'-azobisisobutyronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), and dimethyl 2,2'-azobisisobutylene; azo compounds such as 2,2'-azobis(2-amidinopropane) dihydrochloride, 2,2'-azobis(N-N'-dimethyleneisobutylamidine), 2,2'-azobis(N-N'-dimethyleneisobutylamidine) dihydrochloride; and persulfides such as potassium persulfate and ammonium persulfate, but are not limited thereto. These radical polymerization initiators (a4) may be used alone or in combination of two or more.

[0025] In the production of the acrylic resin, in addition to the crosslinkable monomer (a1) and the reactive surfactant (a2), another polymerizable monomer (a5) may be further blended. As the other polymerizable monomer (a5), a monomer having a polymerizable double bond (e.g., a vinyl group terminal) is used. There are no particular restrictions on the blending amount of the other polymerizable monomer (a5), but it can be, for example, 5 to 40 parts by mass, preferably 10 to 30 parts by mass, per 100 parts by mass of the crosslinkable monomer (a1). Specific examples of the other polymerizable monomer (a5) include, but are not limited to, acrylic acid, methacrylic acid, itaconic acid, maleic acid, vinyl acetate, 2-hydroxyethyl acrylate, hydroxypropyl acrylate, N-vinylacetamide, N-vinylformamide, N-vinylpyrrolidone, N-vinylimidazole, acrylonitrile, methyl acrylate, methyl methacrylate, styrene, acrylamide, methacrylamide, N-methylacrylamide, N-vinylsulfonic acid, N-allylsulfonic acid, sodium styrenesulfonate, and 2-acrylamido-2-methylpropanesulfonic acid. These other polymerizable monomers (a5) may be used alone or in combination of two or more. Note that the other polymerizable monomer (a5) does not include the crosslinkable monomer (a1) or the reactive surfactant (a2).

[0026] An acrylic resin is obtained by radical polymerization via the polymerizable double bonds contained in the crosslinkable monomer (a1), reactive surfactant (a2), other polymerizable monomer (a5), etc. In this case, the chain transfer agent (a3) ​​transfers a radical from one molecule undergoing the propagating reaction to another molecule, and simultaneously, a sulfide group is obtained.

[0027] In the production of the acrylic resin, the amount of the crosslinkable monomer (a1) to be blended is not particularly limited, but is, for example, in the range of 10 to 95 parts by mass, and preferably in the range of 20 to 70 parts by mass, where the total amount of the monomers having a polymerizable double bond is 100 parts by mass.

[0028] In the production of the acrylic resin, the amount of the reactive surfactant (a2) to be blended is not particularly limited, but is, for example, in the range of 5 to 90 parts by mass, and preferably in the range of 10 to 50 parts by mass, relative to 100 parts by mass of all monomers having a polymerizable double bond.

[0029] In the production of the acrylic resin, the amount of the chain transfer agent (a3) ​​to be added is not particularly limited, but is, for example, in the range of 1 to 15 parts by mass, and preferably in the range of 3 to 10 parts by mass, relative to 100 parts by mass of all monomers having a polymerizable double bond.

[0030] In the production of the acrylic resin, in order to control the ratio (N2 / N1) of the total number N2 of mercapto groups and sulfide groups to the number N1 of oxyalkylene groups constituting the polyoxyalkylene group within an appropriate range, the mass ratio (a3 / a2) of the amount of the chain transfer agent (a3) ​​to the amount of the reactive surfactant (a2) is within a range of 0.05 to 3, and preferably within a range of 0.1 to 1.

[0031] In the production of the acrylic resin, the amount of the radical polymerization initiator (a4) to be added is not particularly limited, but is, for example, in the range of 0.1 to 5 parts by mass, and preferably in the range of 1 to 3 parts by mass, relative to 100 parts by mass of all monomers having a polymerizable double bond.

[0032] 3. Acrylic Resin Composition An acrylic resin composition according to one embodiment of the present invention contains an aqueous solvent and an acrylic resin dispersed or dissolved in the aqueous solvent. The acrylic resin composition may contain only an acrylic resin and an aqueous solvent, or may contain other components. Examples of other components include, but are not limited to, additives used in existing hydrophilic treatment agents, such as pigments, dispersants, surfactants, and mildew inhibitors, and can be added to the extent that the effects of the present invention are not impaired. In the acrylic resin composition according to one embodiment of the present invention, the total content of the acrylic resin in the total mass excluding the aqueous solvent is 80% by mass or more, typically 85% by mass or more, more typically 90% by mass or more, and even more typically 95% by mass or more.

[0033] 4. Method for Producing Acrylic Resin Composition The acrylic resin composition according to this embodiment can be produced by mixing an acrylic resin with an aqueous solvent. The aqueous solvent used in producing the acrylic resin may be used as is, or may be partially or completely removed to adjust the concentration of the acrylic resin in the acrylic resin composition, or a separately prepared aqueous solvent may be added. The amount of aqueous solvent in the acrylic resin composition is not limited, but is preferably 1 to 99 parts by mass, and more preferably 2 to 20 parts by mass, of the aqueous solvent per 1 part by mass of the acrylic resin.

[0034] 5. Uses of the Acrylic Resin Composition The acrylic resin composition according to one embodiment of the present invention can form a film that is hydrophilic and has excellent adhesion durability even in a water-immersed environment by applying or immersing the composition on the surface of a metal material or the like, followed by drying. During drying, the acrylic resin composition is preferably heated to 100°C or higher, and more preferably to 100 to 200°C, for example. Therefore, the acrylic resin composition according to one embodiment of the present invention is useful as a film-forming agent or a component thereof. For example, it is useful as a film-forming agent or a component thereof for metal materials used in electronic components and micro-device components that constitute industrial products such as automobiles, home appliances, office automation equipment, medical devices, and medical instruments, as well as in cookware, ships, and building materials. It is particularly useful as a film-forming agent or a component thereof for aluminum fin materials in heat exchangers for air conditioners. It is also useful as a film-forming agent or a component thereof for not only metal materials, but also plastics, rubber, ceramics, glass, fibers, magnetic materials, and the like.

[0035] The present invention will be described in more detail below with reference to examples and reference examples, but the present invention is not limited to these.

[0036] <<Production of Acrylic Resin>> (Production Example 1) 400 parts by mass of water, 40 parts by mass of N-methylolacrylamide, 40 parts by mass of methoxypolyethylene glycol monomethacrylate (BLEMMER PME-4000, NOF Corporation) with a degree of polymerization (manufacturer's nominal value) of 90, and 3 parts by mass of mercaptopropionic acid were mixed. 1 part by mass of ammonium persulfate was added to the mixture, and the mixture was heated and stirred at 70°C for 5 hours under a nitrogen atmosphere to polymerize. During polymerization, the amount of water was maintained by replenishing water lost through evaporation. The ratio (N2 / N1) of the total number N2 of mercapto groups and sulfide groups to the number N1 of oxyalkylene groups constituting the polyoxyalkylene groups of the resulting acrylic resin was 0.03, the cumulant diameter was 1 nm, and the weight-average molecular weight was 20,000.

[0037] (Production Example 2) 400 parts by mass of water, 40 parts by mass of N-methylolacrylamide, 5 parts by mass of methoxypolyethylene glycol monomethacrylate (BLEMMER PME-100, NOF Corporation) with a degree of polymerization (manufacturer's nominal value) of 2, and 3 parts by mass of mercaptopropionic acid were mixed. 1 part by mass of ammonium persulfate was added to the mixture, and the mixture was heated and stirred at 70°C for 5 hours under a nitrogen atmosphere to polymerize. During the polymerization, the amount of water was maintained by replenishing water lost through evaporation. The ratio (N2 / N1) of the total number N2 of mercapto groups and sulfide groups to the number N1 of oxyalkylene groups constituting the polyoxyalkylene groups of the resulting acrylic resin was 0.28, the cumulant diameter was 20 nm, and the weight-average molecular weight was 10,000.

[0038] (Production Example 3) 400 parts by mass of water, 40 parts by mass of N-methylolacrylamide, 40 parts by mass of methoxypolyethylene glycol monomethacrylate (BLEMMER PME-100, NOF Corporation) with a degree of polymerization (manufacturer's nominal value) of 2, and 10 parts by mass of mercaptopropionic acid were mixed. 1 part by mass of ammonium persulfate was added to the mixture, and the mixture was heated and stirred at 70°C for 5 hours under a nitrogen atmosphere to polymerize. During polymerization, the amount of water was maintained by replenishing water lost through evaporation. The ratio (N2 / N1) of the total number N2 of mercapto groups and sulfide groups to the number N1 of oxyalkylene groups constituting the polyoxyalkylene groups of the resulting acrylic resin was 0.12, the cumulant diameter was 20 nm, and the weight-average molecular weight was 10,000.

[0039] (Production Example 4) 400 parts by mass of water, 40 parts by mass of N-methylolacrylamide, 5 parts by mass of methoxypolyethylene glycol monomethacrylate (BLEMMER PME-4000, NOF Corporation) with a degree of polymerization (manufacturer's nominal value) of 90, and 10 parts by mass of mercaptopropionic acid were mixed. 1 part by mass of ammonium persulfate was added to the mixture, and the mixture was heated and stirred at 70°C for 5 hours under a nitrogen atmosphere to polymerize. During polymerization, the amount of water was maintained by replenishing water lost through evaporation. The ratio (N2 / N1) of the total number N2 of mercapto groups and sulfide groups to the number N1 of oxyalkylene groups constituting the polyoxyalkylene groups of the resulting acrylic resin was 0.84, the cumulant diameter was 1 nm, and the weight-average molecular weight was 20,000.

[0040] (Production Example 5) 400 parts by mass of water, 40 parts by mass of N-ethylolacrylamide, 20 parts by mass of methoxypolyethylene glycol monoacrylate (BLEMMER AME-400, NOF Corporation) with a degree of polymerization (manufacturer's nominal value) of 9, and 5 parts by mass of mercaptopropionic acid were mixed. 1 part by mass of ammonium persulfate was added to the mixture, and the mixture was heated and stirred at 70°C for 5 hours under a nitrogen atmosphere to polymerize. During polymerization, the amount of water was maintained by replenishing water lost through evaporation. The ratio (N2 / N1) of the total number N2 of mercapto groups and sulfide groups to the number N1 of oxyalkylene groups constituting the polyoxyalkylene groups of the resulting acrylic resin was 0.10, the cumulant diameter was 10 nm, and the weight-average molecular weight was 15,000.

[0041] (Production Example 6) 400 parts by mass of water, 40 parts by mass of N-ethylolacrylamide, 20 parts by mass of polypropylene glycol monomethacrylate (BLEMMER PP-800, NOF Corporation) with a degree of polymerization (manufacturer's nominal value) of 13, and 5 parts by mass of mercaptopropionic acid were mixed. 1 part by mass of ammonium persulfate was added to the mixture, and the mixture was heated and stirred at 70°C for 5 hours under a nitrogen atmosphere to polymerize. During polymerization, the amount of water was maintained by replenishing water lost through evaporation. The ratio (N2 / N1) of the total number N2 of mercapto groups and sulfide groups to the number N1 of oxyalkylene groups constituting the polyoxyalkylene groups of the resulting acrylic resin was 0.14, the cumulant diameter was 5 nm, and the weight-average molecular weight was 15,000.

[0042] (Production Example 7) 400 parts by mass of water, 40 parts by mass of N-methylol methacrylamide, 20 parts by mass of methoxypolyethylene glycol monomethacrylate (BLEMMER PME-100, NOF Corporation) with a degree of polymerization (manufacturer's nominal value) of 2, and 5 parts by mass of 1-thioglycerol were mixed. 1 part by mass of ammonium persulfate was added to the mixture, and the mixture was heated and stirred at 70°C for 5 hours under a nitrogen atmosphere to polymerize. During the polymerization, the amount of water was maintained by replenishing water lost through evaporation. The ratio (N2 / N1) of the total number N2 of mercapto groups and sulfide groups to the number N1 of oxyalkylene groups constituting the polyoxyalkylene groups of the resulting acrylic resin was 0.12, the cumulant diameter was 20 nm, and the weight-average molecular weight was 10,000.

[0043] (Production Example 8) 400 parts by mass of water, 40 parts by mass of N-methylol methacrylamide, 20 parts by mass of methoxypolyethylene glycol monomethacrylate (BLEMMER PME-100, NOF Corporation) with a degree of polymerization (manufacturer's nominal value) of 2, and 5 parts by mass of mercaptosuccinic acid were mixed. 1 part by mass of ammonium persulfate was added to the mixture, and the mixture was heated and stirred at 70°C for 5 hours under a nitrogen atmosphere to polymerize. During polymerization, the amount of water was maintained by replenishing water lost through evaporation. The ratio (N2 / N1) of the total number N2 of mercapto groups and sulfide groups to the number N1 of oxyalkylene groups constituting the polyoxyalkylene groups of the resulting acrylic resin was 0.08, the cumulant diameter was 20 nm, and the weight-average molecular weight was 10,000.

[0044] (Production Example 9) 400 parts by mass of water, 90 parts by mass of N-methylolacrylamide, 5 parts by mass of methoxypolyethylene glycol monomethacrylate (BLEMMER PME-4000, NOF Corporation) with a degree of polymerization (manufacturer's nominal value) of 90, and 5 parts by mass of mercaptopropionic acid were mixed. 1 part by mass of ammonium persulfate was added to the mixture, and the mixture was heated and stirred at 70°C for 5 hours under a nitrogen atmosphere to polymerize. During polymerization, the amount of water was maintained by replenishing water lost through evaporation. The ratio (N2 / N1) of the total number N2 of mercapto groups and sulfide groups to the number N1 of oxyalkylene groups constituting the polyoxyalkylene groups of the resulting acrylic resin was 0.42, the cumulant diameter was 25 nm, and the weight-average molecular weight was 5,000.

[0045] (Production Example 10) 400 parts by mass of water, 10 parts by mass of N-methylolacrylamide, 40 parts by mass of methoxypolyethylene glycol monomethacrylate (BLEMMER PME-4000, NOF Corporation) with a degree of polymerization (manufacturer's nominal value) of 90, 5 parts by mass of mercaptopropionic acid, 20 parts by mass of acrylic acid, and 20 parts by mass of acrylamide were mixed. 1 part by mass of ammonium persulfate was added to the mixture, and the mixture was heated and stirred at 70°C for 5 hours under a nitrogen atmosphere to polymerize. During polymerization, the amount of water was maintained by replenishing water lost through evaporation. The ratio (N2 / N1) of the total number N2 of mercapto groups and sulfide groups to the number N1 of oxyalkylene groups constituting the polyoxyalkylene groups of the resulting acrylic resin was 0.05, the cumulant diameter was 1 nm, and the weight-average molecular weight was 250,000.

[0046] Comparative Production Example 1 400 parts by mass of water, 40 parts by mass of methoxypolyethylene glycol monomethacrylate (BLEMMER PME-100, NOF Corporation) with a degree of polymerization (manufacturer's nominal value) of 2, and 5 parts by mass of mercaptopropionic acid were mixed. 1 part by mass of ammonium persulfate was added to the mixture, and the mixture was heated and stirred at 70°C for 5 hours under a nitrogen atmosphere to polymerize. During the polymerization, the amount of water was maintained by replenishing water lost through evaporation. The ratio (N2 / N1) of the total number N2 of mercapto groups and sulfide groups to the number N1 of oxyalkylene groups constituting the polyoxyalkylene groups of the obtained acrylic resin was 0.06, the cumulant diameter was 1 nm, and the weight-average molecular weight was 500,000.

[0047] Comparative Production Example 2: 400 parts by mass of water, 40 parts by mass of N-ethylolacrylamide, 40 parts by mass of methoxypolyethylene glycol monomethacrylate (BLEMMER PME-100, NOF Corporation) with a degree of polymerization (manufacturer's nominal value) of 2, and 1 part by mass of 1-thioglycerol were mixed. 1 part by mass of ammonium persulfate was added to the mixture, and the mixture was heated and stirred at 70°C for 5 hours under a nitrogen atmosphere to polymerize. During polymerization, the amount of water was maintained by replenishing water lost through evaporation. The ratio (N2 / N1) of the total number N2 of mercapto groups and sulfide groups to the number N1 of oxyalkylene groups constituting the polyoxyalkylene groups of the resulting acrylic resin was 0.01, the cumulant diameter was 150 nm, and the weight-average molecular weight was 100,000.

[0048] Comparative Production Example 3: 400 parts by weight of water, 5 parts by weight of mercaptosuccinic acid, 40 parts by weight of acrylic acid, and 40 parts by weight of acrylamide were mixed. 1 part by weight of ammonium persulfate was added to the mixture, and the mixture was heated and stirred at 70°C for 5 hours under a nitrogen atmosphere to polymerize. During polymerization, the amount of water was maintained by replenishing water lost through evaporation. The ratio (N2 / N1) of the total number N2 of mercapto groups and sulfide groups to the number N1 of oxyalkylene groups constituting the polyoxyalkylene groups of the resulting acrylic resin was incalculable, but the cumulant diameter was 1 nm and the weight-average molecular weight was 10,000.

[0049] Comparative Production Example 4 400 parts by mass of water, 40 parts by mass of N-methylolacrylamide, and 40 parts by mass of methoxypolyethylene glycol monomethacrylate (BLEMMER PME-4000, NOF Corporation) with a degree of polymerization (manufacturer's nominal value) of 90 were mixed. 1 part by mass of ammonium persulfate was added to the mixture, and the mixture was heated and stirred at 70°C for 5 hours under a nitrogen atmosphere to allow polymerization. During polymerization, the amount of water was maintained by replenishing water lost through evaporation. The ratio (N2 / N1) of the total number N2 of mercapto groups and sulfide groups to the number N1 of oxyalkylene groups constituting the polyoxyalkylene groups of the obtained acrylic resin was 0, and the cumulant diameter and weight average molecular weight were unmeasurable.

[0050] Comparative Production Example 5: 400 parts by mass of water, 40 parts by mass of N-methylolacrylamide, 40 parts by mass of methoxypolyethylene glycol monomethacrylate (BLEMMER PME-4000, NOF Corporation) with a degree of polymerization (manufacturer's nominal value) of 90, and 115 parts by mass of mercaptopropionic acid were mixed. 1 part by mass of ammonium persulfate was added to the mixture, and the mixture was heated and stirred at 70°C for 5 hours under a nitrogen atmosphere to polymerize. During polymerization, the amount of water was maintained by replenishing water lost through evaporation. The ratio (N2 / N1) of the total number N2 of mercapto groups and sulfide groups to the number N1 of oxyalkylene groups constituting the polyoxyalkylene groups of the resulting acrylic resin was 1.2, the cumulant diameter was 1 nm, and the weight-average molecular weight was 5,000.

[0051] For the acrylic resins of Production Examples 1 to 10 and Comparative Production Examples 1 to 5, the ratio (N2 / N1) of the total number N2 of mercapto groups and sulfide groups to the number N1 of oxyalkylene groups constituting the polyoxyalkylene group was calculated from the charged amount, degree of polymerization, and molecular weight of the reactive surfactant (a2) and the charged amount and molecular weight of the chain transfer agent, as described above.

[0052] The cumulant diameters of the acrylic resins of Production Examples 1 to 10 and Comparative Production Examples 1 to 5 were measured using a nanoparticle analyzer (Model SZ-100Z) manufactured by Horiba, Ltd. under the following conditions: Measurement temperature: 25°C, Sample refractive index: 1.490-1.00i, Dispersion medium refractive index: 1.333

[0053] The weight-average molecular weights of the acrylic resins of Production Examples 1 to 10 and Comparative Production Examples 1 to 5 were measured by gel permeation chromatography (GPC) under the following conditions, and were converted using polystyrene as a standard sample. (GPC conditions) Column: Semi-micro column manufactured by Tosoh Corporation; two columns connected together; Standard sample: PStQuick B manufactured by Tosoh Corporation; Mobile phase: N,N'-dimethylformamide; Detection equipment: RI, UV

[0054] The above information regarding Preparation Examples 1 to 10 and Comparative Preparation Examples 1 to 5 is summarized in Table 1 below.

[0055] <<Production of Aluminum Material Having a Coating>> An aluminum material [A1050, plate thickness: 0.6 mm] was degreased by immersion in an alkaline degreasing agent [FC-315E, manufactured by Nihon Parkerizing Co., Ltd.; an aqueous solution diluted with water to a concentration of 20 g / L] at 60°C for 2 minutes, and then rinsed with water by spraying for 10 seconds.

[0056] The acrylic resins of Production Examples 1 to 10 and Comparative Production Examples 1 to 5 were in a dispersed or dissolved state in the water used during production. This is referred to as the "pre-moisture-adjustment acrylic resin composition." The pre-moisture-adjustment acrylic resin composition and water were blended in the mass ratios shown in Table 2 to obtain the post-moisture-adjustment acrylic resin compositions of Examples 1 to 10 and Comparative Examples 1 to 5. Next, aluminum materials washed with water were immersed in each of the post-moisture-adjustment acrylic resin compositions and then dried at 150°C for 6 minutes to produce aluminum materials (Nos. 1 to 15) having various coatings.

[0057]

[0058] <Performance Evaluation> The following performance evaluation was carried out to evaluate the hydrophilicity of the film and its adhesion durability in a water-immersed environment.

[0059] <Initial Hydrophilicity> One drop of water was dropped onto the aluminum material having each of the coatings No. 1 to 15, and the contact angle immediately after the drop was measured using a contact angle measuring device (Model DM-501, manufactured by Kyowa Interface Science Co., Ltd.), and the initial hydrophilicity was evaluated according to the following evaluation criteria. (Evaluation criteria) ◎: Contact angle is less than 10° ○: Contact angle is 10° or more and less than 20° △: Contact angle is 20° or more and less than 30° ×: Contact angle is 30° or more

[0060] <Durable Hydrophilicity> Aluminum materials having various coatings Nos. 1 to 15 were immersed in water for 24 hours. Next, the aluminum materials were removed from the water, leaned against a wall at an angle of 60° from the horizontal, and left to dry in room temperature air for 24 hours. Thereafter, one drop of water was dropped on the material, and the contact angle immediately after the drop was measured using the contact angle measuring device described above. Durable hydrophilicity was evaluated according to the following evaluation criteria. (Evaluation Criteria) ◎: Contact angle is less than 10° ○: Contact angle is 10° or more and less than 20° △: Contact angle is 20° or more and less than 30° ×: Contact angle is 30° or more

[0061] <Adhesion durability in a water-soaked environment> The aluminum materials having the various coatings Nos. 1 to 15 were immersed in water for 24 hours. The aluminum materials were then removed from the water, leaned against a wall at an angle of 60° from the horizontal, and left to dry in the atmosphere at room temperature for 24 hours. After that, the mass of the evaluation sample (E M ) was measured, and the mass (S M ) to the rate of change [(1-E M / S M ) × 100] (%) was calculated, and the adhesion durability in a water immersion environment was evaluated according to the following evaluation criteria: (Evaluation criteria) ◎: The rate of change is 5% or less; ○: The rate of change is more than 5% and 10% or less; △: The rate of change is more than 10% and 25% or less; ×: The rate of change is more than 25%.

[0062] The evaluation results of the initial hydrophilicity, durable hydrophilicity, and immersion durability of the aluminum materials having various coatings are shown in Table 3. Each evaluation result was evaluated as pass if it was ◯ or ⊚.

Claims

1. An acrylic resin having an N-hydroxyalkyl group, a mercapto group and / or a sulfide group, and a polyoxyalkylene group, in which the ratio (N2 / N1) of the total number N2 of mercapto groups and sulfide groups to the number N1 of oxyalkylene groups constituting the polyoxyalkylene group is within the range of 0.02 to 1.

00.

2. The acrylic resin according to claim 1, wherein the N2 / N1 ratio is within the range of 0.03 to 1.

00.

3. The acrylic resin according to claim 1, wherein the N-hydroxyalkyl group contains an N-methylol group and / or an N-ethylol group, and the polyoxyalkylene group contains a polyoxyethylene group and / or a polyoxypropylene group.

4. The acrylic resin according to claim 1, wherein the cumulant diameter of said acrylic resin is 30 nm or less.

5. The acrylic resin according to claim 1, wherein the weight average molecular weight of the acrylic resin is 1,000 to 300,000.

6. A method for producing an acrylic resin, comprising copolymerizing, in an aqueous solvent, monomer components containing 10 to 90 parts by mass of N-alkylol(meth)acrylamide and 5 to 40 parts by mass of a monomer having a polyoxyalkylene group and a polymerizable double bond and a degree of polymerization of 2 to 90, where the total amount of monomers having a polymerizable double bond is 100 parts by mass, in the presence of 3 to 10 parts by mass of a water-soluble organic compound having a mercapto group and a carboxy group and / or a hydroxy group.

7. The method for producing an acrylic resin according to claim 6, wherein the N-alkylol(meth)acrylamide comprises N-methylol(meth)acrylamide and / or N-ethylol(meth)acrylamide.

8. An acrylic resin composition comprising an aqueous solvent and the acrylic resin according to any one of claims 1 to 5 dispersed or dissolved in the aqueous solvent.

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