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

Abstract

To provide a condensation-reactive microgel dispersion that, when used with a film-forming component, can form a film with excellent water resistance and hydrophilicity, and also exhibits excellent storage stability. [Solution] The microgel (G) comprises a core portion (C) containing a polymer of ethylenically unsaturated monomers and a hydrophilic shell portion (S), and a medium (M) comprising 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), and the mass fractions of the core portion (C), hydrophilic shell portion (S), and medium (M) used in the formation of the microgel (G) satisfy 0.05 ≤ ((C) + (S)) / (M) ≤ 1, and the condensation-reactive microgel dispersion is [(NV 105℃ -NV 150℃ ) / NV 150℃ A condensation-reactive microgel dispersion in which ΔNV (%), expressed as ] × 100, is between 5% and 50%.

Description

[Technical Field]

[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. [Background technology]

[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). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 8-003251 [Overview of the project] [Problems that the invention aims to solve]

[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 intraparticle crosslinking. On the other hand, depending on the degree of intraparticle crosslinking of the dispersible fine particles, there is a problem that the formed film may become hydrophobic, and it is necessary to appropriately control intraparticle 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. [Means for solving the problem]

[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 equation (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 100,000 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) in its molecule, and the mass fraction p of the polyoxyethylene 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, the condensation-reactive microgel dispersion according to [1].

[0008] [ka]

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

[0010] [3] The core portion (C) comprises a polymer of monomer (a1) having one ethylenically unsaturated double bond, represented by the following formula (3), 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].

[0011] [ka]

[0012] In formula (3) above, R represents a hydrogen atom (H) or a methyl group (CH3).

[0013] [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 (4) is 3 or more. I=(ΔNV-p×n 1 / 3 ) × r (4) In the above formula (4), ΔNV, p, n, and r have the same meanings as described above.

[0014] [5] The monomer constituting the core part (C) contains a monomer (a1) having one ethylenically unsaturated double bond, and may contain, if necessary, a monomer (a2) having one ethylenically unsaturated double bond other than the monomer (a1), and / or a monomer (a3) having two or more ethylenically unsaturated double bonds. The mass fraction of the monomer (a2) with respect to the total mass of the core part (C) and the hydrophilic shell part (S) used for forming the microgel (G) is 0 or more and 0.2 or less, and the mass fraction of the monomer (a3) with respect to the total mass of the core part (C) and the hydrophilic shell part (S) used for forming 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].

[0015] [6] A method for producing a condensation-reactive microgel dispersion according to any one of [1] to [5], wherein in the medium (M), the monomer constituting the core part (C) together with the compound constituting the hydrophilic shell part (S) is (co)polymerized using a radical polymerization initiator under the condition of a temperature of 60°C or more and 120°C or less. A method for producing a condensation-reactive microgel dispersion.

[0016] [7] A hydrophilization treatment agent containing the condensation-reactive microgel dispersion according to any one of [1] to [5], an aqueous resin and / or a crosslinking agent, wherein the aqueous resin and / or the crosslinking agent has a reactive group that can react with the reactive group of the condensation-reactive microgel dispersion by heating.

[0017] [8] The reactive group of the condensation-reactive microgel dispersion is a methylol group. The reactive group of the aqueous resin and / or the crosslinking agent is a hydroxy group. The hydrophilization treatment agent according to [7].

[0018] [9] A hydrophilization treatment method including a step of applying the hydrophilization treatment agent according to [7] or [8] to a substrate.

[0019]

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

[0020] A hydrophilic film formed by the hydrophilization treatment method described in

[11] [9]. [Effects of the Invention]

[0021] 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. [Modes for carrying out the invention]

[0022] The embodiments of this disclosure are described below. This disclosure is not limited to the embodiments described below.

[0023] <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.

[0024] The condensation-reactive microgel dispersion (hereinafter may be referred to as "dispersion") is such that when the above microgel (G) is dispersed in a medium (M) composed of water and / or a hydroxy group-containing organic solvent, the reactive groups (e.g., methylol groups) possessed by the core part (C) are protected by the hydrophilic shell part (S). Thereby, the reactive groups possessed by the core part (C) in the dispersion are preserved for a long period. Therefore, until a hydrophilic film is formed by reacting the microgel (G) with the above aqueous resin and / or crosslinking agent, the reactive groups possessed by the core part (C) can be sufficiently retained in the dispersion. Therefore, a film having a dense crosslinked structure excellent in water resistance, chemical resistance, solvent resistance, appearance, etc. can be formed.

[0025] In the above dispersion, the core part (C) may be partially crosslinked, but does not necessarily have to retain a particle structure. Therefore, by appropriately controlling the degree of crosslinking, unreacted functional groups can be retained and physical properties such as the toughness and flexibility of the coating film can be improved. Furthermore, the new microgel having high reactivity and flexible shape change not only enables the reaction with the third component to proceed efficiently and form a film having a dense crosslinked structure, but also has the property of enhancing the transparency of the film. Also, the shell part (S) which is expected to have a function of coating the core component in the treatment agent is uniformly dispersed in the film itself when it becomes a film, and can exhibit the function as a chemical substance contained in the shell part (S).

[0026] 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)

[0027] 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℃This refers to the mass percentage (%) of the residue after heating the dispersion at 150°C for 1 hour, relative to the total mass of the dispersion before heating. That is, NV 105℃ This approximates the mass ratio (solid content concentration) of the core portion (C) and the hydrophilic shell portion (S) to the total mass of the dispersion. NV 150℃ This approximates the mass ratio of the core portion (C) to the hydrophilic shell portion (S) after the reactive group-derived components have been eliminated from the core portion (C) (for example, H2O may be eliminated by a condensation reaction) relative to the total mass of the dispersion. Therefore, ΔNV (%) is a value that correlates with the amount of condensation-reactive groups remaining in the core portion (C).

[0028] The ΔNV(%) of the dispersion is 5% or more and 50% or less. When ΔNV(%) is 5% or more, it is presumed that a sufficient amount of reactive groups remain in the core (C), so a film with excellent water resistance and solvent resistance can be formed. When ΔNV(%) is 50% or less, the film components remain sufficiently without vaporizing even when exposed to high temperatures, so the functions expected of a microgel can be preferably obtained. From the viewpoint of condensation reactivity and crosslinking effect, ΔNV(%) is preferably 5% or more and 30%, and more preferably 8% or more and 20% or less. ΔNV(%) can be controlled by adjusting the type and amount of reactive groups in the core (C) and the degree of protection of the core (C) by the hydrophilic shell (S).

[0029] The core (C) is composed of polymers of one or more ethylenically unsaturated monomers (hereinafter sometimes referred to as "monomers"). Preferably, such monomers include monomer (a1) having one ethylenically unsaturated double bond. Examples of monomer (a1) include those represented by the following formula (3). Monomer (a1) may be used individually or in combination of two types.

[0030] [ka]

[0031] In formula (3) above, R represents a hydrogen atom (H) or a methyl group (CH3).

[0032] Monomer (a1), as shown in formula (3) above, has polymerizable ethylenically unsaturated bonds, methylol groups that have high reactivity with hydroxyl groups, etc., and hydrophilic amide groups. In the core portion (C) of the dispersion, the methylol groups in the polymerized monomer (a1) are protected by the hydrophilic shell portion (S), and their 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 portion (C) of the dispersion. During film formation, strong chemical bonds are formed by a dehydration condensation reaction between the methylol groups and the hydroxyl groups of the aqueous resin and / or crosslinking agent, and desirable hydrophilicity is imparted to the film by the amide groups.

[0033] The mass fraction r of the core portion (C) and the hydrophilic shell portion (S) used in forming the microgel (G) of 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 core portion (C) and hydrophilic shell portion (S) added. 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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) within its molecule and is preferably immobilized on the surface of the core portion (C) by chemical bonding and / or physical adsorption.

[0040] [ka]

[0041] In equation (2) above, n is between 8 and 2000.

[0042] The amphiphilic compound has a polyoxyethylene structure represented by formula (2) above, and it is preferable that the mass fraction p of the polyoxyethylene structure, relative 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. A mass fraction p of 0.1 or higher improves the dispersion stability in the medium (M) as a microgel and the storage stability of the crosslinking reactive groups of the core portion (C). A mass fraction p of 0.5 or lower ensures that the amount of reactive groups in the condensation-reactive microgel dispersion is sufficient, and that 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 higher and 0.45 or lower.

[0043] The amphiphilic compound preferably 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 through 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 an ethylenically unsaturated double bond (acryloyl group, methacryloyl group, allyl group, etc.).

[0044] The amphiphilic compound may have functional groups (reactive groups) other than the polymerizable groups at the terminal ends of the polyoxyethylene structure. Examples of functional groups include alkoxy groups such as methoxy groups, glycidyl groups, and hydroxyl groups.

[0045] The amphiphilic compound constituting the hydrophilic shell portion (S) may include compounds other than the polyoxyethylene structure represented by formula (2) above. For example, it may include amphiphilic compounds such as polyvinylpyrrolidone, polypropylene oxide, polyvinyl alcohol, and carboxymethylcellulose. These compounds may be copolymers with compounds having a polyoxyethylene structure, or they may be compounds consisting only of compounds other than the polyoxyethylene structure.

[0046] 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 the above formula (2), it is preferable that the dispersion has an index I represented by the following formula (4) of 3 or more. I=(ΔNV-p×n 1 / 3 ) × r (4)

[0047] In equation (4) above, ΔNV, p, n, and r are the same as those described above. Equation (4) is a correction equation for equation (1) and is an empirically derived equation. In equation (1), NV 150℃ The value shown does not necessarily represent the amount of reactive group-derived components that have been removed 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 that are removed from the core (C). Equation (4) above identifies the components that make up 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 remain in the core (C), thus enabling the formation of a coating with excellent water resistance, solvent resistance, etc.

[0048] 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.

[0049]

number

[0050] 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.

[0051] 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.

[0052] In the above dispersion, the mass fraction of the core portion (C) and hydrophilic shell portion (S) used for forming the microgel (G) in relation to the mass of the medium (M) ((C) + (S)) / (M) is between 0.05 and 1.0. If the above ratio is less than 0.05, the concentration of the dispersed phase in the dispersion becomes too low, making it economically ineffective. 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 between 0.10 and 0.70.

[0053] 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, by diluting the dispersion with water to a predetermined measurement concentration and using a concentrated particle size analyzer FPAR-1000 (manufactured by Otsuka Electronics Co., Ltd.).

[0054] The above dispersion may contain any other components not mentioned above, as long as they do not impair the effects of the present disclosure.

[0055] <Method for producing condensation-reactive microgel dispersions> The condensation-reactive microgel dispersion according to the above embodiment is preferably produced by (co)polymerizing the monomer constituting the core portion (C) together with the compound 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 depending on the type of radical polymerization initiator.

[0056] 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.

[0057] The radical polymerization initiators mentioned above are 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.

[0058] 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.

[0059] 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 (C) can be (co)polymerized together with the compounds constituting the hydrophilic shell (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 (S) in the dispersion.

[0060] 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.

[0061] <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.

[0062] 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.

[0063] The aqueous resins mentioned above are not particularly limited as long as they are hydrophilic resins, 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 resins, aqueous polyester resins, aqueous polyamide resins, aqueous epoxy resins, aqueous polyurethane resins, aqueous phenolic resins, aqueous amino resins, and the like.

[0064] 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.

[0065] 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.

[0066] 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, silane coupling agents and other rust inhibitors; 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.

[0067] <Hydrophilicization Treatment Method> The hydrophilization treatment method using the above-mentioned hydrophilization agent includes a coating step of applying the hydrophilization agent to a substrate made of a metal material or the like (hereinafter referred to as a metal substrate). In addition to the above, the hydrophilization treatment method may also include a degreasing step, a pretreatment step, a heating step, etc.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] <Hydrophilic film> The hydrophilic coating is a coating formed on a substrate such as a metal substrate by the hydrophilic treatment method described above. The coating exhibits 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, which undergoes intermolecular interactions or chemical reactions. As a result, the resulting coating structure becomes 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. [Examples]

[0072] The contents of this disclosure will be described in more detail below based on the examples. The contents of this disclosure are not limited to the examples described below.

[0073] [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 above "Polymerizable group". a1, a2, and a3 mean monomer (a1), monomer (a2), and monomer (a3) ​​in the above embodiment, respectively. R means substituent R in formula (3) above. Mass fraction means the mass fraction of the core portion (C) and hydrophilic shell portion (S) relative to the amount charged.

[0074] 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.

[0075] [Table 1]

[0076] Details of the abbreviations in Table 1 are shown below. The initiators (radical polymerization initiators) were appropriately selected and used 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

[0077] The dispersions for each example and comparative example were synthesized according to the following procedure. The medium (M) was placed in a reaction vessel and, under a nitrogen atmosphere, stirred to the predetermined temperatures shown in Table 2. Monomers (a1) to (a3) ​​having ethylenically unsaturated bonds, which constitute 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.

[0078] [NV measurement] The dispersions according to each example and comparative example were cooled after synthesis, 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.

[0079] [Calculation of Indicator I] Based on the mass fractions p and r, index I was calculated using formula (4) or the formula described above. The results are shown in Table 2.

[0080] [Table 2]

[0081] [Preparation of hydrophilic treatment agent] The dispersions from each of the above examples and comparative examples were added to an aqueous solution of polyvinyl alcohol (Kurarepoval 25-100) in a 1:1 ratio of solid content 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 at 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.

[0082] [Preparing the test board] 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 1-3 caused film swelling, making it impossible to perform the following tests.

[0083] [Measurement of film 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, removed from the running water, dried at 40°C, and the weight of the coating was measured again to determine the coating weight. The coating retention rate ((weight before test) - (weight after test)) / (weight before test) × 100 (%) was calculated from the weight difference of the coating before and after the test. The results are shown in Table 3. A higher coating retention rate indicates that the coating has superior water resistance.

[0084] [Water Wetness Assessment] Similar to the coating retention rate measurement described above, each test panel was stored under running water for two days. After being removed from the water, the wettability (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. A score of ○ was considered a pass. The results are shown in Table 3. (Evaluation Criteria) ○: 85% to 100% (completely wet) ×: 0% or more and less than 85%

[0085] [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). Similarly, processing oil (Idemitsu, Daphne Punch Oil AF-8) was applied to each test plate, and the water contact angle of the dried plates at 150°C for 5 minutes was measured. Furthermore, similar to the measurement of film retention, 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.

[0086] [Table 3]

[0087] 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 microgel (G) consisting of a core portion (C) containing a polymer of ethylenically unsaturated monomers and a hydrophilic shell portion (S), A condensation-reactive microgel dispersion having a medium (M) consisting of water and / or a hydroxyl group-containing organic solvent, The hydrophilic shell portion (S) provides 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 in forming the microgel (G) satisfy 0.05 ≤ ((C) + (S)) / (M) ≤ 1, and the condensation-reactive microgel dispersion is a condensation-reactive microgel dispersion in which ΔNV (%) represented by the following formula (1) is 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 hydrophilic shell portion (S) is composed of an amphiphilic compound. The aforementioned amphiphilic compound has a number-average molecular weight of 400 or more and 100,000 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) within its molecule, and the mass fraction p of the polyoxyethylene 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, as described in claim 1. 【Chemistry 1】 In equation (2) above, n is between 8 and 2000.

3. The core portion (C) is composed of a polymer of monomer (a1) having one ethylenically unsaturated double bond, as shown in the following formula (3): The condensation-reactive microgel dispersion according to claim 2, wherein 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 in forming the microgel (G) satisfies 0.5 ≤ r ≤ 0.

9. 【Chemistry 2】 In formula (3) 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 represented by the following formula (4) is 3 or more. I=(ΔNV-p×n １／３ )×r (4) In equation (4) above, ΔNV, p, n, and r are equivalent to those defined above.

5. The monomers constituting the core portion (C) include 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 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 0 or more and 0.2 or less. The condensation-reactive microgel dispersion according to claim 1, wherein 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 0 or more and 0.05 or less.

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

7. The condensation-reactive microgel dispersion described in claim 1 comprises an aqueous resin and / or a crosslinking agent, The aqueous resin and / or crosslinking agent is a hydrophilic treatment agent having reactive groups that can react with the reactive groups of the condensation-reactive microgel dispersion upon heating.

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

9. A method for hydrophilization treatment, comprising the step of applying the hydrophilization treatment agent described in 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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