Condensation-reactive microgel dispersion, method for producing same, hydrophilization treatment agent, hydrophilization treatment method, and hydrophilic film

Abstract

The present invention addresses the problem of providing a condensation-reactive microgel dispersion which is capable of forming a film having excellent water resistance and hydrophilicity by being used together with a film-forming component, and which has excellent storage stability. One aspect for solving the above problem is a condensation-reactive microgel dispersion having: a microgel (G) comprising a hydrophilic shell part (S) and a core part (C) containing a polymer of an ethylenically unsaturated monomer; and a medium (M) comprising water and / or a hydroxy group-containing organic solvent, wherein the hydrophilic shell part (S) imparts dispersion stability to the core part (C) in the medium (M), the mass fractions of the core part (C) and the hydrophilic shell part (S) used in forming the microgel (G) and that of the medium (M) satisfy 0.05 ≤ ((C) + (S)) / (M) ≤ 1, and the condensation-reactive microgel dispersion has a ΔNV (%) of 5-50%, the ΔNV (%) being represented by [(NV105ºC − NV150ºC) / NV150ºC] × 100.

Description

Condensation-reactive microgel dispersion, method for producing the same, hydrophilic treatment agent, hydrophilic treatment method, and hydrophilic coating

[0001] This disclosure relates to a condensation-reactive microgel dispersion, a method for producing the same, a hydrophilic treatment agent, a hydrophilic treatment method, and a hydrophilic coating.

[0002] Conventionally, techniques for imparting functions such as hydrophilicity to the surface of a substrate such as a metal material by forming a film are known. The above film is formed, for example, by a composition containing dispersible fine particles and a film-forming resin. As dispersible fine particles, hydrophilic crosslinked polymer fine particles that are crosslinked within the particles by monomer components and dispersed in a medium have been disclosed (see, for example, Patent Document 1).

[0003] Japanese Patent Application Publication No. 8-003251

[0004] The hydrophilic crosslinked polymer fine particles disclosed in Patent Document 1 can maintain their shape even in media containing a large amount of water or when heated due to interparticle crosslinking. On the other hand, depending on the degree of interparticle crosslinking of the dispersible fine particles, there is a problem that the formed film may become hydrophobic, and it is necessary to appropriately control the interparticle crosslinking. Furthermore, in order to form a film with excellent water resistance and solvent resistance by reacting dispersible fine particles with a film-forming resin, it is more important that reactive groups remain sufficiently within the dispersible fine particles by the time of reaction with the film-forming resin, rather than maintaining the shape of the fine particles.

[0005] This disclosure has been made in view of the above, and aims to provide a condensation-reactive microgel dispersion that can form a film with excellent water resistance and hydrophilicity when used together with a film-forming component, and that also has excellent storage stability.

[0006] [1] The present disclosure relates to a condensation-reactive microgel dispersion comprising a microgel (G) consisting of a core portion (C) containing a polymer of an ethylenically unsaturated monomer and a hydrophilic shell portion (S), and a medium (M) consisting of water and / or a hydroxyl group-containing organic solvent, wherein the hydrophilic shell portion (S) imparts dispersion stability to the core portion (C) in the medium (M), the mass fractions of the core portion (C), the hydrophilic shell portion (S), and the medium (M) used to form the microgel (G) satisfy 0.05 ≤ ((C) + (S)) / (M) ≤ 1, and the condensation-reactive microgel dispersion has a ΔNV (%) represented by the following formula (1) of 5% or more and 50% or less. ΔNV (%) = [(NV １０５℃ -NV １５０℃ ) / NV １５０℃ ] × 100 (1) In the above formula (1), NV １０５℃ This refers to the mass percentage (%) of the residue after heating the condensation-reactive microgel dispersion at 105°C for 1 hour, relative to the total mass before heating. １５０℃ This refers to the mass percentage (%) of the residue remaining after heating the condensation-reactive microgel dispersion at 150°C for 1 hour, relative to the total mass before heating.

[0007] [2] The hydrophilic shell portion (S) is composed of an amphiphilic compound, the amphiphilic compound having a number average molecular weight of 400 or more and 940,000 or less, the amphiphilic compound is immobilized on the surface of the core portion (C) by chemical bonding and / or physical adsorption, the amphiphilic compound has a polyoxyethylene structure represented by the following formula (2) or a polyvinylpyrrolidone structure represented by the following formula (3) in its molecule, and the mass fraction p of the polyoxyethylene structure or the polyvinylpyrrolidone structure with respect to the total mass of the core portion (C) and the hydrophilic shell portion (S) used in forming the microgel (G) satisfies 0.1 ≤ p ≤ 0.5, the condensation-reactive microgel dispersion according to [1].

[0008]

[0009] In equation (2) above, n is between 8 and 2000.

[0010]

[0011] In the above equation (3), n is between 40 and 8600.

[0012] [3] The core portion (C) comprises a polymer of monomer (a1) having one ethylenically unsaturated double bond, represented by the following formula (4), and the mass fraction r of the monomer (a1) with respect to the total mass of the core portion (C) and the hydrophilic shell portion (S) used to form the microgel (G) is 0.5 ≤ r ≤ 0.9, the condensation-reactive microgel dispersion according to [1] or [2].

[0013]

[0014] In formula (4) above, R is a hydrogen atom (H) or a methyl group (CH ３ ) means.

[0015] [4] The condensation-reactive microgel dispersion is further the condensation-reactive microgel dispersion according to any one of [1] to [3], wherein the index I shown by the following formula (5) is 3 or more. I = (ΔNV - p × n １／３ ) × r (5) In equation (5) above, ΔNV, p, n, and r are the same as those described above.

[0016] [5] The monomer constituting the core portion (C) includes a monomer (a1) having one ethylenically unsaturated double bond, and may optionally include monomers (a2) having one ethylenically unsaturated double bond other than monomer (a1), and / or monomers (a3) ​​having two or more ethylenically unsaturated double bonds, wherein the mass fraction of monomer (a2) with respect to the total mass of the core portion (C) and the hydrophilic shell portion (S) used to form the microgel (G) is 0 or more and 0.2 or less, and the mass fraction of monomer (a3) ​​with respect to the total mass of the core portion (C) and the hydrophilic shell portion (S) used to form the microgel (G) is 0 or more and 0.05 or less, the condensation-reactive microgel dispersion according to any one of [1] to [4].

[0017] [6] A method for producing a condensation-reactive microgel dispersion according to any one of [1] to [5], wherein monomers constituting the core portion (C) together with compounds constituting the hydrophilic shell portion (S) are (co)polymerized in the medium (M) using a radical polymerization initiator at a temperature of 60°C to 120°C.

[0018] [7] A hydrophilic treatment agent comprising a condensation-reactive microgel dispersion according to any one of [1] to [5], and an aqueous resin and / or a crosslinking agent, wherein the aqueous resin and / or crosslinking agent has reactive groups that can react with the reactive groups of the condensation-reactive microgel dispersion by heating.

[0019] [8] The hydrophilic treatment agent according to [7], wherein the reactive group of the condensation-reactive microgel dispersion is a methylol group, and the reactive group of the aqueous resin and / or crosslinking agent is a hydroxyl group.

[0020] A method for hydrophilic treatment, comprising the step of applying the hydrophilic treatment agent described in [9] [7] or [8] to a substrate.

[0021]

[10] The hydrophilization treatment method according to [9], wherein the substrate is a metal substrate.

[0022]

[11] A hydrophilic film formed by the hydrophilization treatment method described in [9].

[0023] According to this disclosure, a condensation-reactive microgel dispersion can be provided that, when used with a film-forming component, can form a film with excellent water resistance and hydrophilicity, and also has excellent storage stability.

[0024] The embodiments of this disclosure are described below. This disclosure is not limited to the embodiments described below.

[0025] <Condensation-Reactive Microgel Dispersion> The condensation-reactive microgel dispersion according to this embodiment comprises a microgel (G) consisting of a core portion (C) containing a polymer of ethylenically unsaturated monomers and a hydrophilic shell portion (S), and a medium (M) which is a dispersion medium consisting of water and / or a hydroxyl group-containing organic solvent. Such a condensation-reactive microgel dispersion can be used, for example, together with an aqueous resin and / or a crosslinking agent which are film-forming components, to form a hydrophilic film on the surface of a substrate such as a metal material. Since the microgel has high dispersibility in the treatment agent, it can form a hydrophilic film with uniform and consistent performance.

[0026] In a condensation-reactive microgel dispersion (hereinafter sometimes referred to as "dispersion"), when the microgel (G) is dispersed in a medium (M) consisting of water and / or a hydroxyl group-containing organic solvent, the reactive groups (e.g., methylol groups) of the core portion (C) are protected by the hydrophilic shell portion (S). As a result, the reactive groups of the core portion (C) are preserved in the dispersion for a long period of time. Therefore, the reactive groups of the core portion (C) can be sufficiently retained in the dispersion until the microgel (G) is reacted with the aqueous resin and / or crosslinking agent to form a hydrophilic film. Consequently, a film with a dense crosslinked structure and excellent water resistance, chemical resistance, solvent resistance, and appearance can be formed.

[0027] In the above dispersion, the core portion (C) may be partially crosslinked, but it is not necessarily required to maintain a particle structure. Therefore, by appropriately controlling the degree of crosslinking, unreacted functional groups can be retained, improving the physical properties of the coating film, such as toughness and flexibility. Furthermore, the new microgel, which is highly reactive and has flexible shape changes, reacts efficiently with the third component, forming a film with a dense crosslinked structure, and also has the property of enhancing the transparency of the film. In addition, the shell portion (S), which is expected to function as a coating for the core component in the treatment agent, becomes uniformly dispersed within the film when it forms a film, and can exert its function as a chemical substance contained in the shell portion (S).

[0028] The activity of the core part (C), that is, the amount of reactive groups remaining in the core part (C) can be approximately estimated by the following formula (1). ΔNV (%) = [(NV １０５℃ - NV １５０℃ ) / NV １５０℃ ] × 100 (1)

[0029] In the above formula (1), NV １０５℃ means the mass ratio (%) of the residue after heating the dispersion at 105°C for 1 hour to the total mass of the dispersion before heating, and NV １５０℃ means the mass ratio (%) of the residue after heating the dispersion at 150°C for 1 hour to the total mass of the dispersion before heating. That is, NV １０５℃ approximates the mass ratio (solid content concentration) of the core part (C) and the hydrophilic shell part (S) to the total mass of the dispersion. NV １５０℃ approximates the mass ratio of the core part (C) and the hydrophilic shell part (S) after the component derived from the reactive group has desorbed from the core part (C) (for example, H ２ O can desorb by a condensation reaction). Therefore, ΔNV (%) is a numerical value correlated with the amount of condensation reactive groups remaining in the core part (C).

[0030] The above ΔNV (%) of the dispersion is 5% or more and 50% or less. When ΔNV (%) is at least 5%, it is presumed that a sufficient amount of reactive groups remain in the core part (C), so that a film excellent in water resistance, solvent resistance, etc. can be formed. When ΔNV (%) is 50% or less, even when exposed to high temperatures, the film components do not vaporize and remain sufficiently, so that the functions expected as a microgel can be preferably obtained. From the viewpoints of condensation reactivity and crosslinking effect, ΔNV (%) is preferably 5% or more and 30% or less, and more preferably 8% or more and 20% or less. ΔNV (%) can be controlled by adjusting the type and amount of reactive groups possessed by the core part (C) and the degree of protection of the core part (C) by the hydrophilic shell part (S).

[0031] The core part (C) is composed of a polymer of one or more ethylenically unsaturated monomers (hereinafter sometimes referred to as "monomers"). As such a monomer, it is preferably essentially included a monomer (a1) having one ethylenically unsaturated double bond. Examples of the monomer (a1) include monomers represented by the following formula (4). As the monomer (a1), one kind may be used, or two kinds may be used in combination.

[0032]

[0033] In the above formula (4), R represents a hydrogen atom (H) or a methyl group (CH ３ ).

[0034] As shown in the above formula (4), the monomer (a1) has an ethylenically unsaturated bond having polymerizability, a methylol group having high reactivity with a hydroxy group or the like, and an amide group having hydrophilicity. In the core part (C) of the dispersion, the methylol group in the polymerized monomer (a1) is protected by the hydrophilic shell part (S), and the reaction with the medium (M) is suppressed. Therefore, a sufficient amount of methylol groups for the crosslinking reaction during film formation is retained in the core part (C) of the dispersion. During film formation, a strong chemical bond is formed by the dehydration condensation reaction between the methylol group and the hydroxy group of the aqueous resin and / or the crosslinking agent, and favorable hydrophilicity is imparted to the film by the amide group.

[0035] The mass fraction r of the core portion (C) and the hydrophilic shell portion (S) used in forming the microgel (G) of the monomer (a1) preferably satisfies 0.5 ≤ r ≤ 0.9. In this specification, each mass fraction can be determined based on the mass of each component used in forming the microgel (G), i.e., the amount of the core portion (C) and the hydrophilic shell portion (S) charged. A mass fraction r of 0.5 or higher allows the core portion (C) to contain a sufficient amount of reactive groups (methylol groups) and maintain sufficient condensation reactivity. If the mass fraction r exceeds 0.9, the mass of the hydrophilic shell portion (S) will be insufficient, which may lead to problems such as increased particle size of the microgel and aggregation, impaired dispersion stability, or inability to obtain long-term stability of the reactive groups due to a thin coating layer. From the above viewpoint, a mass fraction r of 0.55 or higher and 0.85 or lower is more preferable.

[0036] The ethylenically unsaturated monomer constituting the core (C) may optionally include at least one of monomer (a2) and monomer (a3). Monomer (a2) is a monomer other than monomer (a1) that has one ethylenically unsaturated double bond. Monomer (a3) ​​is a monomer that has two or more ethylenically unsaturated double bonds. Only one compound corresponding to monomer (a2) and monomer (a3) ​​may be used, or two or more may be used in combination.

[0037] The monomer (a2) preferably has characteristic functional groups such as an amide group or a (meth)acrylic group. It is thought that the monomer (a2), as a component of the microgel (G), can be uniformly dispersed in the treated film, and that the characteristic functional groups can be positioned within the film. Specific examples of monomer (a2) are not particularly limited, but include acrylic acid, methacrylic acid, acrylamide, methacrylamide, N-(2-hydroxyethyl)acrylamide, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl acrylate, N-vinylacetamide, N-vinylformamide, N-methoxymethylacrylamide, N-methoxymethylmethacrylamide, N,N-dimethylacrylamide, N-vinylpyrrolidone, acrylonitrile, methacrylonitrile, methyl acrylate, methyl methacrylate, glycidyl methacrylate, styrene, sodium vinylsulfonate, sodium allylsulfonate, sodium styrenesulfonate, sodium 2-acrylamido-2-methylpropanesulfonate, etc. It is particularly preferable to use at least one selected from the group consisting of acrylic acid, methacrylic acid, acrylamide, and N-(2-hydroxyethyl)acrylamide.

[0038] The mass fraction of the monomer (a2) with respect to the total mass of the core portion (C) and the hydrophilic shell portion (S) used in forming the microgel (G) is preferably 0 or more and 0.2 or less.

[0039] Monomer (a3), by having two or more ethylenically unsaturated double bonds, is thought to increase the internal crosslinking density of the microgel (G), thereby enhancing the toughness of the treated film while maintaining the flexible shape change characteristic of the microgel. Specific examples of monomer (a3) ​​are not particularly limited, but include allyl methacrylate, N,N'-methylenebisacrylamide, ethylene glycol dimethacrylate, and glycerol dimethacrylate.

[0040] The mass fraction of the monomer (a3) ​​with respect to the total mass of the core portion (C) and the hydrophilic shell portion (S) used in forming the microgel (G) is preferably 0 or more and 0.05 or less.

[0041] The hydrophilic shell portion (S) provides dispersion stability to the core portion (C) in the medium (M). The hydrophilic shell portion (S) is preferably composed of an amphiphilic compound. The amphiphilic compound has a polyoxyethylene structure represented by the following formula (2) or a polyvinylpyrrolidone structure represented by the following formula (3) within its molecule, and is preferably immobilized on the surface of the core portion (C) by chemical bonding and / or physical adsorption.

[0042]

[0043] In equation (2) above, n is between 8 and 2000.

[0044]

[0045] In formula (3) above, n is between 40 and 8600. The numerical range of n may be determined by converting the K value (Fikentscher K value). The K value of the compound having a polyvinylpyrrolidone structure represented by formula (3) above, corresponding to the numerical range of n above, may be between 15 and 90.

[0046] The amphiphilic compound has a polyoxyethylene structure represented by formula (2) above, or a polyvinylpyrrolidone structure represented by formula (3) below, and it is preferable that the mass fraction p of the polyoxyethylene structure or polyvinylpyrrolidone structure, relative to the total mass of the core portion (C) and the hydrophilic shell portion (S) used in forming the microgel (G), satisfies 0.1 ≤ p ≤ 0.5. By having a mass fraction p of 0.1 or more, the dispersion stability in the medium (M) as a microgel and the storage stability of the crosslinking reactive groups of the core portion (C) can be improved. By having a mass fraction p of 0.5 or less, the amount of reactive groups in the condensation-reactive microgel dispersion is secured, and the amount of components that function as shell components is also sufficient. Furthermore, the condensation reactivity is sufficiently maintained. From the viewpoint of dispersion stability and condensation reactivity, it is more preferable that the mass fraction p is 0.15 or more and 0.45 or less.

[0047] The amphiphilic compound preferably has a number average molecular weight of 400 or more and 940,000 or less. More preferably, it has a number average molecular weight of 400 or more and 100,000 or less. The amphiphilic compound may or may not have polymerizable groups. That is, the amphiphilic compound may be immobilized on the surface of the core (C) by chemical bonding with polymerizable groups, or it may not have polymerizable groups and be immobilized on the surface of the core (C) mainly by physical adsorption. Examples of polymerizable groups include groups having ethylenically unsaturated double bonds (acryloyl groups, methacryloyl groups, allyl groups, etc.).

[0048] The amphiphilic compound may have functional groups (reactive groups) other than the polymerizable groups at the ends of the polyoxyethylene structure or polyvinylpyrrolidone structure. Examples of functional groups include alkoxy groups such as methoxy groups, glycidyl groups, and hydroxyl groups.

[0049] The amphiphilic compound constituting the hydrophilic shell portion (S) may include compounds other than the polyoxyethylene structure or polyvinylpyrrolidone structure represented by formula (2) or (3) above. For example, it may include amphiphilic compounds such as polypropylene oxide, polyvinyl alcohol, and carboxymethylcellulose. These compounds may be copolymers with compounds having a polyoxyethylene structure or a polyvinylpyrrolidone structure, or they may be compounds consisting only of compounds other than the polyoxyethylene structure or polyvinylpyrrolidone structure.

[0050] When the core portion (C) is composed of a polymer of monomer (a1) and the hydrophilic shell portion (S) is composed of an amphiphilic compound having a polyoxyethylene structure represented by formula (2) above, it is preferable that the dispersion has an index I represented by the following formula (5) of 3 or more. I = (ΔNV - p × n) １／３ ) × r (5)

[0051] In equation (5) above, ΔNV, p, n, and r are the same as those described above. Equation (5) is a correction of equation (1) and is an empirically derived equation. In equation (1), NV １５０℃ The value shown does not necessarily represent the detachment of only reactive group-derived components from the core (C). To more accurately estimate the amount of reactive groups remaining in the core (C), it is necessary to consider the influence of other decomposition products and other substances detaching from the core (C). Formula (5) above identifies the components constituting the core (C) and the hydrophilic shell (S), and by considering the influence of these components, it is possible to calculate index I, which has a higher correlation with the amount of reactive groups remaining in the core (C). An index I of 3 or higher suggests that a sufficient amount of reactive groups remains in the core (C), thus enabling the formation of a coating with excellent water resistance, solvent resistance, etc.

[0052] When the hydrophilic shell portion (S) contains k types of amphiphilic compounds having a polyoxyethylene structure represented by formula (2) above, index I can be calculated by the following formula.

[0053]

[0054] In the above formula, n ｉ This represents the number of repeating polyoxyethylene structures in each compound. ｉ This represents the mass fraction of the polyoxyethylene structure of each compound. ΔNV and r are equivalent to those described above.

[0055] The medium (M) consists of water and / or a hydroxyl group-containing organic solvent. The hydroxyl group-containing organic solvent is not particularly limited, but examples include alcohols such as propanol and butanol, and alkylene glycol monoalkyl ethers such as ethylene glycol monobutyl ether, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, and propylene glycol monopropyl ether.

[0056] In the above dispersion, the mass fraction of the core portion (C) and hydrophilic shell portion (S) used to form the microgel (G) in relation to the mass of the medium (M): ((C) + (S)) / (M) is 0.05 or more and 1.0 or less. If the above ratio is less than 0.05, the concentration of the dispersed phase in the dispersion becomes too low and is not economically effective. If the above ratio exceeds 1.0, abnormalities such as gelation occur during polymerization and a stable microgel dispersion cannot be obtained. From the above viewpoint, it is preferable that the mass fraction: ((C) + (S)) / (M) is 0.10 or more and 0.70 or less.

[0057] The particle size of the microgel in the above dispersion is not particularly limited, but for example, the average particle size measured by the cumulant method is between 10 nm and 600 nm. The above particle size can be measured, for example, at a measurement temperature of 25°C using a concentrated particle size analyzer FPAR-1000 (manufactured by Otsuka Electronics Co., Ltd.). The measurement can be performed by adding the dispersion to pure water, stirring thoroughly, adjusting the concentration of the dispersion and the light source filter so that the scattered light intensity is between 15,000 cps and 30,000 cps, and then using the value obtained after 1 to 10 minutes following the adjustment of the concentration and light source filter.

[0058] The above dispersion may contain any other components not mentioned above, as long as they do not impair the effects of the present disclosure.

[0059] <Method for producing condensation-reactive microgel dispersions> The condensation-reactive microgel dispersion according to the above embodiment is preferably produced by (co)polymerizing the monomers constituting the core portion (C) together with the compounds constituting the hydrophilic shell portion (S) in a medium (M) using a radical polymerization initiator at a temperature of 60°C to 120°C. The above reaction temperature can be adjusted according to the type of radical polymerization initiator.

[0060] If the copolymerization temperature is below 60°C, the polymerization reaction will be insufficient, and if it exceeds 120°C, it will be difficult to control the reaction. The reaction time is usually 0.2 to 8 hours. If it is less than 0.2 hours, the polymerization reaction will be insufficient, and if it exceeds 8 hours, the reaction will not change, which is economically disadvantageous.

[0061] The radical polymerization initiator is not particularly limited, and known radical polymerization initiators can be used. Examples of radical polymerization initiators include peroxides such as benzoyl peroxide, lauroyl peroxide, t-butyl hydroperoxide, di-t-butyl peroxide, and t-butylperoxy-2-ethylhexanoate, or azo compounds such as 2,2'-azobisisobutyronitrile, 2,2'-azobis-2-methylbutyronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl 2,2'-azobisisobutyrate, and 4,4'-azobis(4-cyanovaleric acid). These may be used alone or in combination of two or more. The amount used can usually be in the range of 0.2 to 5% by mass relative to the total amount of monomers.

[0062] A dispersant may be used in combination with the above copolymerization. Examples of such dispersants include dispersion resins such as polyvinylpyrrolidone, polyvinyl alcohol, and polycarboxylic acid, as well as various anionic, cationic, and nonionic surfactants.

[0063] In the above manufacturing method, when water and a hydroxyl group-containing organic solvent are used together as the medium (M), water may be added after the copolymerization reaction. That is, the monomers constituting the core portion (C) may be (co)polymerized together with the compounds constituting the hydrophilic shell portion (S) in the hydroxyl group-containing organic solvent as the medium (M) to produce a dispersion, after which water can be added. In this case, water is not essential during the (co)polymerization reaction, but it contributes to improving the dispersion stability of the hydrophilic shell portion (S) in the dispersion.

[0064] The above manufacturing method may include steps other than those described above, as long as they do not impair the effects of the disclosure. For example, monomers and radical polymerization initiators included in the disclosure may undergo neutralization or emulsification steps using acids, bases, surfactants, etc., when added in order to adjust their reactivity.

[0065] <Hydrophilic Treatment Agent> The hydrophilic treatment agent comprises a condensation-reactive microgel dispersion according to the above embodiment and an aqueous resin and / or a crosslinking agent. The hydrophilic treatment agent can form a film with excellent water resistance and hydrophilicity on the surface of a substrate made of a metal material or the like to be treated. Examples of metal materials are not particularly limited, but include aluminum or aluminum alloys.

[0066] The aqueous resin and / or crosslinking agent is a film-forming component. The aqueous resin and / or crosslinking agent preferably has a reactive group that can react with the reactive group (e.g., methylol group) of the dispersion. Examples of such reactive groups include hydroxyl groups and carboxyl groups. When the reactive group of the microgel is a methylol group, the reactive group of the aqueous resin and / or crosslinking agent is preferably a hydroxyl group.

[0067] The above-mentioned aqueous resin is not particularly limited as long as it is a hydrophilic resin, and examples include polymers of unsaturated polymerizable monomers containing carboxyl groups and / or hydroxyl groups, natural polymer compounds or derivatives thereof containing carboxyl groups and / or hydroxyl groups, polyvinylpyrrolidone resin, aqueous polyester resin, aqueous polyamide resin, aqueous epoxy resin, aqueous polyurethane resin, aqueous phenolic resin, aqueous amino resin, and the like.

[0068] Examples of the crosslinking agents mentioned above include amino resins, epoxy resins, blocked isocyanates, phenolic resins, silane compounds such as silane coupling agents, silica compounds, aluminum compounds, zirconium compounds, and the like. The crosslinking agent can be in any form, such as a sol or gel. The crosslinking agent may be used alone or in combination with other agents.

[0069] In the above hydrophilic treatment agent, the mixing ratio of the dispersion to the aqueous resin and / or crosslinking agent is preferably 1 / 99 to 80 / 20 in terms of solid content by mass. If it is less than 1 / 99, the water resistance of the film may decrease. If it exceeds 80 / 20, the processability may decrease. The above mixing ratio is more preferably 5 / 95 to 70 / 30.

[0070] The above-mentioned hydrophilic treatment agent may contain components other than those listed above, as long as they do not impair the effects of the present disclosure. Examples of components other than those listed above include acid and base neutralizing agents, surfactants, colloidal silica, titanium dioxide, sugars, and other hydrophilic additives; rust inhibitors such as tannic acid, imidazoles, triazines, triazoles, guanines, hydrazines, phenolic resins, zirconium compounds, and silane coupling agents; pigments such as inorganic pigments and organic pigments; sol compounds such as aluminum and silane; colorants, antibacterial agents, antifungal agents, dispersants, lubricants, deodorants, photocatalytic compounds, fillers, solvents, and the like.

[0071] <Hydrophilic Treatment Method> The hydrophilic treatment method using the above-mentioned hydrophilic treatment agent includes a coating step of applying the above-mentioned hydrophilic treatment agent to a substrate made of a metal material or the like (hereinafter described as a metal substrate) that is to be treated. In addition to the above, the hydrophilic treatment method may also include a degreasing step, a pretreatment step, a heating step, etc.

[0072] The degreasing process involves degreasing the surface of a metal substrate using a degreasing agent such as a known solvent or alkaline solution. The pretreatment process involves applying a chemical conversion treatment or resin primer to the surface of the metal substrate after degreasing.

[0073] The application step is a step of applying the hydrophilizing agent to the surface of a metal substrate that has optionally undergone the degreasing and pretreatment steps described above. The application method is not particularly limited and includes methods such as roll coating, bar coating, immersion, spraying, and brushing.

[0074] The heating step is a process of curing the coating film formed on the surface of the metal substrate by the coating step described above by heating it. The heating temperature can be set to, for example, 120 to 350°C in the oven so that the temperature of the object to be coated reaches 100 to 200°C, and the heating time can be, for example, 3 seconds to 60 minutes.

[0075] <Hydrophilic Coating> The hydrophilic coating is a coating formed on a substrate such as a metal substrate by the hydrophilic treatment method described above. The coating has excellent water resistance and hydrophilicity. In this embodiment, the hydrophilic coating is formed by the mixing of each component contained in the hydrophilic treatment agent, causing intermolecular interactions or chemical reactions. As a result, the resulting coating structure is complex, making it impossible or impractical to directly identify the hydrophilic coating by its structure. In other words, there are circumstances (impossible / impractical circumstances) that make it impossible or impractical to directly identify the hydrophilic coating of this embodiment by its structure or properties.

[0076] The contents of this disclosure will be described in more detail below based on the following examples. The contents of this disclosure are not limited to the following examples.

[0077] [Preparation of Condensation-Reactive Microgel Dispersions] Condensation-reactive microgel dispersions for each example and comparative example were prepared using the formulations shown in Table 1. Unless otherwise specified, the numerical values ​​indicating the content of each component in Table 1 are based on mass. In Table 1, "POE chain content (%)" refers to the mass fraction of the polyoxyethylene structure in the amphiphilic compound. p, n, and n １／３The definition of , is the same as the definition in the above embodiment. "Polymerizable group" means a group having an ethylenically unsaturated double bond. "Functional group" means a functional group at the end of the polyoxyethylene structure other than the "polymerizable group" mentioned above. a1, a2, and a3 mean monomer (a1), monomer (a2), and monomer (a3) ​​in the above embodiment, respectively. R means substituent R in formula (4) above. Mass fraction means the mass fraction of the core portion (C) and hydrophilic shell portion (S) relative to the amount charged.

[0078] In Examples 11 and 12, two types of substances having a polyoxyethylene structure (POE chain) were used in combination as compounds constituting the hydrophilic shell portion (S). In Example 13, a substance having a polyoxyethylene structure (POE chain) and polyvinylpyrrolidone were used in combination as compounds constituting the hydrophilic shell portion (S). The mass fraction of the polyvinylpyrrolidone core portion (C) and hydrophilic shell portion (S) relative to the amount charged was set to 0.1.

[0079]

[0080] The details of the abbreviations in Table 1 are shown below. Note that the initiator (radical polymerization initiator) was appropriately selected from those disclosed in the above embodiments. BC: Ethylene glycol monobutyl ether MP: 1-methoxy-2-propanol GYL group: Glycidyl group AA: Acrylic acid HEAA: N-(2-hydroxyethyl)acrylamide AAm: Acrylamide MAA: Methacrylic acid AMA: Allyl methacrylate MBAA: N,N'-Methylenebisacrylamide

[0081] The dispersions for each example and comparative example were synthesized according to the following procedure. A medium (M) was placed in a reaction vessel and stirred under a nitrogen atmosphere to the predetermined temperatures shown in Table 2. Monomers (a1) to (a3) ​​having ethylenically unsaturated bonds, which are components of the core (C), were added to the compound constituting the shell (S). A radical polymerization initiator was added in the amount shown in Table 1 relative to the monomers, and the reaction was carried out for the predetermined time shown in Table 2 to obtain the dispersion. In the case of Comparative Example 5, the reaction time was set to 4 hours, but the reaction was stopped because thickening occurred.

[0082] [Measurement of NV] After synthesis, the dispersions for each example and comparative example were cooled, diluted with water as necessary, and then the dispersions were removed. After filtering to remove coarse particles and aggregates, approximately 2 g of the filtrate was accurately weighed into an aluminum cup, and the non-volatile content (NV%) of the filtrate was measured under two heating conditions: 105°C for 1 hour and 150°C for 1 hour. The obtained non-volatile content was expressed as NV. １０５℃ , and NV １５０℃ The ΔNV (%) was calculated using the above formula (1). The results are shown in Table 2. The ΔNV (%) over time was calculated using the same method as above, except that the sample was stored for 180 days under conditions of 25 degrees Celsius.

[0083] [Calculation of Index I] Based on the mass fraction p and mass fraction r, Index I was calculated using the above formula (5) or the above mathematical formula. The results are shown in Table 2.

[0084]

[0085] [Preparation of Hydrophilic Treatment Agent] The dispersions according to each of the above examples and comparative examples were added to an aqueous solution of polyvinyl alcohol (Kurarepoval 25-100) in a solid content ratio of 1:1 to obtain a hydrophilic treatment agent with a solid content of 10% by mass. For Example 17 in Table 3, the dispersion from Example 10 was used after being stored for 180 days under conditions of 25 degrees Celsius. Similarly, for Example 18, the dispersion from Example 15 was used, and for Example 19, the dispersion from Example 1 was used, both after being stored under the above conditions. For Comparative Example 6 in Table 3, only polyvinylpyrrolidone was used instead of the dispersion.

[0086] [Preparation of test plate] The above hydrophilic treatment agent was applied to a degreased aluminum plate (Al3000 series), baked and dried at 150°C for 30 minutes, and the dry coating amount was approximately 0.5 g / m². ２ A test plate with the specified coating was obtained. However, the hydrophilic treatment agents in Comparative Examples 1 to 3 caused film swelling, making it impossible to perform the following tests.

[0087] [Measurement of Coating Retention Rate] The weight of the coating was determined by measuring the weight of the test plates for each example and comparative example. Then, each test plate was stored under running water for two days, after which it was removed from the running water, dried at 40°C, and the weight of the test plate was measured to determine the weight of the coating. The coating retention rate was calculated from the difference in weight of the coating before and after the test: ((Weight before test) - (Weight after test)) / (Weight before test) × 100 (%). The results are shown in Table 3. A higher coating retention rate indicates that the coating has superior water resistance.

[0088] [Water Wetness Evaluation] Similar to the film retention rate measurement described above, each test panel was stored under running water for two days. After being removed from the water, the water wetness (the percentage of the surface area wet when the painted surface is immersed in water) was visually evaluated 5 seconds after removal according to the following evaluation criteria. Evaluation A was considered a pass, and evaluation B was considered a fail. The results are shown in Table 3. (Evaluation Criteria) A: 85% or more and 100% or less (completely wet) B: 0% or more and less than 85%

[0089] [Water Contact Angle Measurement] The water contact angle of the test plates for each example and comparative example was measured using a contact angle meter (DSA20E, KRUSS). In addition, processing oil (Idemitsu, Daphne Punch Oil AF-8) was applied to each test plate, and the water contact angle of the test plates dried at 150°C for 5 minutes was measured in the same manner. Furthermore, similar to the measurement of the film retention rate described above, each test plate was stored under running water for 2 days, then removed from the running water, dried at 40°C, and the water contact angle (after water resistance) was measured in the same manner. The results are shown in Table 3.

[0090]

[0091] From the results of the above examples and comparative examples, it is clear that the dispersions according to each example, when used together with a film-forming component, can form a film with excellent water resistance and hydrophilicity, and also exhibit excellent storage stability.

Claims

1. A condensation-reactive microgel dispersion comprising a microgel (G) consisting of a core portion (C) containing a polymer of an ethylenically unsaturated monomer and a hydrophilic shell portion (S), and a medium (M) consisting of water and / or a hydroxyl group-containing organic solvent, wherein the hydrophilic shell portion (S) imparts dispersion stability to the core portion (C) in the medium (M), the mass fractions of the core portion (C), the hydrophilic shell portion (S), and the medium (M) used to form the microgel (G) satisfy 0.05 ≤ ((C) + (S)) / (M) ≤ 1, and the condensation-reactive microgel dispersion has a ΔNV (%) represented by the following formula (1) of 5% or more and 50% or less. ΔNV (%) = [(NV １０５℃ -NV １５０℃ ) / NV １５０℃ ] × 100 (1) In the above formula (1), NV １０５℃ This refers to the mass percentage (%) of the residue after heating the condensation-reactive microgel dispersion at 105°C for 1 hour, relative to the total mass before heating. １５０℃ This refers to the mass percentage (%) of the residue remaining after heating the condensation-reactive microgel dispersion at 150°C for 1 hour, relative to the total mass before heating.

2. The condensation-reactive microgel dispersion according to claim 1, wherein the hydrophilic shell portion (S) is composed of an amphiphilic compound, the amphiphilic compound has a number average molecular weight of 400 or more and 940,000 or less, the amphiphilic compound is immobilized on the surface of the core portion (C) by chemical bonding and / or physical adsorption, the amphiphilic compound has a polyoxyethylene structure represented by the following formula (2) or a polyvinylpyrrolidone structure represented by the following formula (3) in its molecule, and the mass fraction p of the polyoxyethylene structure or the polyvinylpyrrolidone structure with respect to the total mass of the core portion (C) and the hydrophilic shell portion (S) used in the formation of the microgel (G) satisfies 0.1 ≤ p ≤ 0.

5. In equation (2) above, n is between 8 and 2000. In the above equation (3), n is between 40 and 8600.

3. The condensation-reactive microgel dispersion according to claim 2, wherein the core portion (C) comprises a polymer of monomer (a1) having one ethylenically unsaturated double bond, represented by the following formula (4), and the mass fraction r of the monomer (a1) with respect to the total mass of the core portion (C) and the hydrophilic shell portion (S) used to form the microgel (G) satisfies 0.5 ≤ r ≤ 0.

9. In formula (4) above, R is a hydrogen atom (H) or a methyl group (CH ３ ) means.

4. The condensation-reactive microgel dispersion according to claim 3, wherein the index I shown by the following formula (5) is 3 or more: I = (ΔNV - p × n １／３ ) × r (5) In equation (5) above, ΔNV, p, n, and r are the same as those described above.

5. The condensation-reactive microgel dispersion according to claim 1, wherein the monomer constituting the core portion (C) includes a monomer (a1) having one ethylenically unsaturated double bond, and may optionally include monomers (a2) having one ethylenically unsaturated double bond other than monomer (a1), and / or monomers (a3) ​​having two or more ethylenically unsaturated double bonds, the mass fraction of monomer (a2) with respect to the total mass of the core portion (C) and the hydrophilic shell portion (S) used to form the microgel (G) is 0 or more and 0.2 or less, and the mass fraction of monomer (a3) ​​with respect to the total mass of the core portion (C) and the hydrophilic shell portion (S) used to form the microgel (G) is 0 or more and 0.05 or less.

6. A method for producing a condensation-reactive microgel dispersion according to claim 1, comprising (co)polymerizing in a medium (M) a monomer constituting the core portion (C) together with a compound constituting the hydrophilic shell portion (S) using a radical polymerization initiator at a temperature of 60°C to 120°C.

7. A hydrophilic treatment agent comprising a condensation-reactive microgel dispersion according to claim 1 and an aqueous resin and / or a crosslinking agent, wherein the aqueous resin and / or crosslinking agent has reactive groups that can react with the reactive groups of the condensation-reactive microgel dispersion by heating.

8. The hydrophilic treatment agent according to claim 7, wherein the reactive group of the condensation-reactive microgel dispersion is a methylol group, and the reactive group of the aqueous resin and / or crosslinking agent is a hydroxyl group.

9. A hydrophilization treatment method comprising the step of applying the hydrophilization treatment agent according to claim 7 or 8 to a substrate.

10. The hydrophilization treatment method according to claim 9, wherein the substrate is a metal substrate.

11. A hydrophilic film formed by the hydrophilization treatment method described in claim 9.

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