JP7770879B2 - Surface Modification Method - Google Patents

Description

The present invention relates to a surface modification method and a surface modification treatment agent set.

Conventionally, methods for modifying solid surfaces, such as hydrophilization and water-repellent treatments, are known to control the wetting of solid surfaces. Hydrophilization treatments, in particular, reduce the contact angle of solid surfaces with water, making them more easily wetted by water. This is expected to make it easier to wash off dirt that adheres to the treated solid surface, and to prevent the dirt from re-adhering. Hydrophilization treatments are also expected to have other effects, such as anti-fogging and anti-static properties for glass and mirrors, preventing frost formation on aluminum fins in heat exchangers, and imparting anti-fouling properties to bathtub and toilet surfaces. Therefore, hydrophilization treatments are used in a variety of industrial fields, and research into methods for modifying solid surfaces has been ongoing.

For example, Patent Document 1 describes a method for depositing a coating material to reduce or prevent biofilm formation on a surface, in which a solution mixture of a dopamine coating material is brought into contact with the surface to form a dopamine coating on the surface, thereby reducing biofilm formation.
Patent Document 2 aims to provide a method for producing a composite material that is suitable for controlling interfacial properties, imparting functions such as preventing adhesion of contaminants, and is applicable in a wide range of fields. The method describes a method for producing a composite material in which a substrate is bonded to a compound A having an aliphatic hydrocarbon group, an aromatic hydrocarbon group, or a heterocyclic group, which includes a functional group capable of bonding to a compound B, and the compound A is bonded to the compound B.
Patent Document 3 discloses a method for forming a hydrophilic coating covalently bonded to the surface of a substrate, the method comprising the steps of: (a) contacting the surface with a mixture comprising components A and B, optional component C, optional component D, and a radical initiator, wherein component A comprises one or more C2-C16 hydrophilic monomers each comprising one or more alkene and/or alkyne groups; component B comprises one or more hydrophilic polymers each comprising two or more alkene and/or alkyne groups; component C, when present, comprises one or more beneficial chemicals each comprising one or more alkene or alkyne groups; and component D, when present, comprises one or more beneficial chemicals independently selected from thiols, alkenes, and alkyne groups. and (b) initiating radical polymerization involving the alkene and/or alkyne groups of components A, B, and C (if present) and the functional groups of component D (if present) to form a crosslinked copolymer of components A, B, and optionally C and D, wherein said copolymer covalently bonds to the surface; and (c) optionally incorporating into the hydrophilic coating a component E comprising one or more beneficial chemicals, wherein component E does not form a copolymer with components A, B, C (if present), and D (if present).

International Publication No. 2011/005258 Japanese Patent Application Publication No. 10-287862 Special Publication No. 2016-508776

However, it has been found that the techniques of Patent Documents 1 to 3 do not sufficiently modify the target surface.
An object of the present invention is to provide a surface modification method and a surface modification treatment agent set that can impart a high modification effect to a target surface.

The present inventors have found that the above-mentioned problems can be solved by treating the target surface with a compound containing a benzene ring and a cationic compound.
That is, the present invention provides the following [1] and [2].
[1] A surface modification method for modifying a target surface, comprising:
Step 1: applying a treatment agent containing a cationic compound (B) to a polymer of a compound (A) containing a benzene ring on a target surface,
The surface modification method, wherein the compound (A) containing a benzene ring is at least one selected from a compound containing a structure in which two or more hydroxyl groups are bonded to a benzene ring, and a derivative of the compound in which at least one hydroxyl group is substituted with an acetoxy group.
[2] A pretreatment agent containing a compound (A) having a benzene ring and a treatment agent containing a cationic compound (B),
The surface modification treatment agent set is one or more compounds selected from the group consisting of compounds having a structure in which two or more hydroxyl groups are bonded to a benzene ring and derivatives of such compounds in which at least one hydroxyl group is substituted with an acetoxy group.

The present invention provides a surface modification method and a surface modification treatment agent set that can impart a high modification effect to the target surface.

[Surface modification method]
The surface modification method of the present invention is a surface modification method for modifying a target surface, comprising:
Step 1: applying a treatment agent containing a cationic compound (B) to a polymer of a compound (A) containing a benzene ring on a target surface,
The compound (A) containing a benzene ring is at least one selected from compounds containing a structure in which two or more hydroxyl groups are bonded to a benzene ring, and derivatives of such compounds in which at least one hydroxyl group is substituted with an acetoxy group.
In the present invention, the "cationic compound" refers to a compound that has a cationic group and exhibits cationic properties as a whole.
In the present invention, the term "cationic group" refers to a cationic group or a group that can be ionized to become a cationic group. Examples of the cationic group include a primary amino group, a secondary amino group, a tertiary amino group, and a quaternary ammonium group.

According to the present invention, it is possible to impart a high modification effect to the target surface. The reason for this effect is not clear, but is thought to be as follows.
In the present invention, a target surface has a polymer of a compound containing a specific benzene ring. By applying a treatment agent containing a cationic compound to such a surface, the cationic compound can be efficiently adsorbed to the target surface via the polymer of the compound containing a benzene ring due to a cation-π interaction between the cationic group of the cationic compound and the π electrons derived from the compound containing a benzene ring contained in the polymer of the compound containing a benzene ring, and it is believed that the modification effect due to the properties of the cationic compound can be enhanced.

(Step 1)
Step 1 is a step of applying a treatment agent containing a cationic compound (B) to a polymer of a compound (A) containing a benzene ring on the target surface, from the viewpoint of enhancing the modifying effect imparted to the target surface.
The polymer of the compound (A) containing a benzene ring preferably has a crosslinked structure from the viewpoint of enhancing the modifying effect imparted to the target surface. The crosslinked structure is preferably a three-dimensional network crosslinked structure.
When the polymer of the compound (A) containing a benzene ring has a crosslinked structure, the polymer of the compound (A) containing a benzene ring is not soluble in a solvent that dissolves the compound (A) containing a benzene ring.

<Target surface>
The target surface to be modified according to the present invention is preferably a solid surface.
In the present invention, the term "solid surface" means the interface between a solid and the atmosphere.
The solid is not particularly limited, and examples thereof include synthetic resins such as polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytetrafluoroethylene (PTFE), polycarbonate (PC), polyurethane (PU), acrylonitrile/butadiene/styrene copolymer (ABS), polyamide (PA), melamine resin, and FRP; natural fibers such as cotton, silk, and wool; synthetic fibers such as polyester, nylon, and rayon; metals such as aluminum, stainless steel (SUS), and brass; glass, pottery, porcelain, enamel, tile, ceramics, wood, hair, nails, and teeth. The shape of the solid surface is not particularly limited.

The surface to be modified by the present invention may be either a hydrophobic surface or a hydrophilic surface, depending on the properties of the cationic compound (B).
In the present invention, a "hydrophobic surface" means a surface having a contact angle of 70° or more, and a "hydrophilic surface" means a surface having a contact angle of less than 70°. The contact angle can be measured by the method described in the examples.
For example, when the cationic compound (B) has a function of imparting a hydrophilic effect, the target surface is preferably a hydrophobic surface, and when the cationic compound (B) has a function of imparting a hydrophobic effect, the target surface is preferably a hydrophilic surface.
The hydrophobic surface is preferably made of one or more materials selected from synthetic resins, metals, and ceramics.
The hydrophilic surface is preferably glass.

[Step 1-1]
The polymer of the compound (A) containing a benzene ring on the target surface in step 1 is preferably formed by including the following step 1-1 before step 1, from the viewpoint of enhancing the modifying effect imparted to the target surface.
Step 1-1: A step of applying a pretreatment agent containing a compound (A) having a benzene ring to a target surface, and then forming a polymer of the compound (A) The pretreatment agent containing the compound (A) having a benzene ring according to the present invention and the treatment agent containing the cationic compound (B) are preferably used as a surface modification treatment agent set.

<Pretreatment agent>
(Benzene ring-containing compound (A))
The pretreatment agent according to the present invention contains a compound (A) containing a benzene ring (hereinafter also simply referred to as "compound (A)").
The benzene ring-containing compound (A) is at least one selected from compounds having a structure in which two or more hydroxyl groups are bonded to a benzene ring, and derivatives of such compounds in which at least one hydroxyl group is substituted with an acetoxy group.
The compound (A) is not particularly limited as long as it can form a polymer after being applied to a target surface and can exhibit cation-π interaction with the cationic compound (B). The compound (A) can be used alone or in combination of two or more.
Among these, from the viewpoint of enhancing the modifying effect imparted to the target surface, compound (A) is preferably one or more compounds selected from compounds having a catechol (1,2-diphenol) structure or a gallol (1,2,3-triphenol) structure, and derivatives of the compounds in which at least one hydroxyl group is substituted with an acetoxy group, more preferably one or more compounds selected from compounds having a catechol structure and derivatives of the compounds in which at least one hydroxyl group is substituted with an acetoxy group, and even more preferably one or more compounds selected from compounds having a catechol structure in which at least one hydrogen atom at the 4th and 5th positions is substituted with a group containing at least one selected from an amino group, a carboxy group, and a nitro group, and derivatives of the compounds in which at least one hydroxyl group is substituted with an acetoxy group.

Examples of compounds having a catechol structure include catecholamine compounds; dihydroxycinnamic acid compounds such as 3,4-dihydroxycinnamic acid and 3,4-dihydroxyhydrocinnamic acid; and 4-nitrocatechol.
Among these, from the viewpoint of enhancing the modifying effect imparted to the target surface, compound (A) is even more preferably one or more selected from catecholamine compounds and derivatives of the compounds in which at least one hydroxyl group is substituted with an acetoxy group. The catecholamine compound is a compound having a catechol structure and an amino group in one molecule. The amino group contained in the catecholamine compound is at least one selected from a primary amino group, a secondary amino group, and a tertiary amino group.

From the viewpoint of enhancing the modifying effect imparted to the target surface, compound (A) is even more preferably at least one selected from the group consisting of indole compounds represented by the following formula (1-1) and salts thereof, indoline compounds represented by the following formula (1-2) and salts thereof, and dopamine compounds represented by the following formula (1-3).

[In formula (1-1), R ^A1 each independently represents a hydroxyl group or an acetoxy group, R ^A2 represents a hydrogen atom or —COOR (R is a hydrogen atom, a methyl group, or an ethyl group), and R ^A3 represents a hydrogen atom, an acetyl group, a methyl group, or an ethyl group.]

[In formula (1-2), R ^A1 to R ^A3 are the same as those in formula (1-1).]

[In formula (1-3), R ^A4 to R ^A12 each independently represent a hydrogen atom, an alkyl group having from 1 to 8 carbon atoms, an alkenyl group having from 2 to 8 carbon atoms, an alkynyl group having from 2 to 8 carbon atoms, a hydroxyl group, —COOH, or an acyl group having from 2 to 9 carbon atoms.]

In the formulas (1-1) and (1-2), specific examples or preferred embodiments of R ^A1 to R ^A3 are as follows, from the viewpoint of enhancing the modifying effect imparted to the target surface.
R ^A1 is preferably a hydroxyl group.
R ^A2 is preferably a hydrogen atom or —COOH, more preferably a hydrogen atom.
R ^A3 is preferably a hydrogen atom.

Examples of the indole compound represented by formula (1-1) include 5,6-dihydroxyindole, 5,6-dihydroxyindole-2-carboxylic acid, methyl 5,6-dihydroxyindole-2-carboxylate, ethyl 5,6-dihydroxyindole-2-carboxylate, N-methyl-5,6-dihydroxyindole, N-methyl-5,6-dihydroxyindole-2-carboxylic acid, N-ethyl-5,6-dihydroxyindole, N-ethyl-5,6-dihydroxyindole-2-carboxylic acid, N-acetyl-5,6-dihydroxyindole, N-acetyl-5,6-dihydroxyindole-2-carboxylic acid, 5-acetoxy-6-hydroxyindole, and 5-acetoxy-6-hydroxyindole-2-carboxylic acid.

Examples of the indoline compound represented by formula (1-2) include 5,6-dihydroxyindoline, 5,6-dihydroxyindoline-2-carboxylic acid, methyl 5,6-dihydroxyindoline-2-carboxylate, ethyl 5,6-dihydroxyindoline-2-carboxylate, N-methyl-5,6-dihydroxyindoline, N-methyl-5,6-dihydroxyindoline-2-carboxylic acid, N-ethyl-5,6-dihydroxyindoline, N-ethyl-5,6-dihydroxyindoline-2-carboxylic acid, N-acetyl-5,6-dihydroxyindoline, N-acetyl-5,6-dihydroxyindoline-2-carboxylic acid, 5-acetoxy-6-hydroxyindoline, and 5-acetoxy-6-hydroxyindoline-2-carboxylic acid.

Examples of salts of the compounds represented by the formulas (1-1) and (1-2) include hydrochlorides, hydrobromides, sulfates, phosphates, acetates, propionates, lactates, citrates, etc. Among these, hydrobromides are preferred from the viewpoint of availability.
When R ^A2 is —COOH in the formulas (1-1) and (1-2), examples of the salts of the compounds represented by the formulas (1-1) and (1-2) include carboxylates thereof (R ^A2 is —COO ⁻ (X ⁿ⁺ ) _1/n (n is an integer of 1 or more, and X ⁿ⁺ is an alkali metal ion such as K ⁺ , Na ⁺ , or Li ⁺ , an alkaline earth metal ion such as Ca ²⁺ or Mg ²⁺ , or a cation such as an ammonium ion)). From the viewpoint of the solubility of the salts of the compounds represented by the formulas (1-1) and (1-2) in water, the alkali metal ion is preferably K ⁺ , Na ⁺ , or Li ⁺ , more preferably K ⁺ or Na ⁺ , and even more preferably K ⁺ . From the same viewpoint, the alkaline earth metal ion is preferably Ca ²⁺ or Mg ²⁺ , more preferably Ca ²⁺ .

In the formula (1-3), specific examples or preferred embodiments of R ^A4 to R ^A12 are as follows, from the viewpoint of enhancing the modifying effect imparted to the target surface.
R ^A4 to R ^A6 are preferably hydrogen atoms.
R ^A7 and R ^A8 are preferably a hydrogen atom or a hydroxyl group, more preferably a hydrogen atom.
R ^A9 and R ^A10 are preferably a hydrogen atom or —COOH, more preferably a hydrogen atom.
R ^A11 and R ^A12 are preferably a hydrogen atom or a methyl group, more preferably a hydrogen atom.

Examples of compounds represented by formula (1-3) include dopamine, noradrenaline, adrenaline, 3-(3,4-dihydroxyphenyl)-L-alanine, etc. Among these, dopamine is preferred.

Among these, from the viewpoint of enhancing the modifying effect imparted to the target surface, compound (A) is even more preferably one or more compounds selected from the indole compounds represented by formula (1-1) and salts thereof, even more preferably one or more compounds selected from 5,6-dihydroxyindole, 5,6-dihydroxyindole-2-carboxylic acid, and salts thereof, even more preferably one or more compounds selected from 5,6-dihydroxyindole and 5,6-dihydroxyindole-2-carboxylic acid, and even more preferably 5,6-dihydroxyindole.

The content or blending amount of compound (A) in the pretreatment agent according to the present invention is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, and even more preferably 0.2% by mass or more, from the viewpoint of enhancing the modifying effect imparted to the target surface. From the viewpoints of safety and economy, it is preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 2% by mass or less, and even more preferably 1% by mass or less.

(Other ingredients)
In addition to compound (A), the pretreatment agent of the present invention may contain various additives as appropriate, provided that the object of the present invention is not impaired. Examples of such additives include pH adjusters, anionic surfactants, nonionic surfactants, amphoteric surfactants, polymers, oils, preservatives, disinfectants, dyes, antidandruff agents, anti-inflammatory agents, chelating agents, moisturizers, pearlizing agents, ceramides, fragrances, and ultraviolet absorbers.

[Alkaline agent]
The pretreatment agent according to the present invention preferably further contains an alkaline agent, which promotes the formation of a polymer of compound (A) on the target surface and enhances the modifying effect imparted to the target surface.
The alkaline agent includes organic alkaline agents and inorganic alkaline agents.
Examples of organic alkaline agents include ammonia; alkanolamines such as monomethanolamine, dimethanolamine, trimethanolamine, monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, 2-amino-2-methylpropanol, and 2-amino-2-hydroxymethyl-1,3-propanediol; alkylamines such as methylamine, dimethylamine, ethylamine, diethylamine, N-methylethylamine, propylamine, and butylamine; aralkylamines such as benzylamine; and basic amino acids such as arginine, lysine, and histidine.
Examples of inorganic alkaline agents include sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate.
The alkaline agents can be used alone or in combination of two or more.
The number of carbon atoms in the alkanolamine, alkylamine, or aralkylamine is preferably 10 or less, more preferably 8 or less, and even more preferably 6 or less from the viewpoint of water solubility, and is preferably 2 or more from the viewpoints of availability and economy.
From the viewpoint of promoting the formation of a polymer of compound (A) on the target surface and enhancing the modifying effect imparted to the target surface, as well as from the viewpoint of the resistance of the target surface and skin irritation, the alkaline agent is preferably an organic alkaline agent, more preferably one or more selected from ammonia and alkanolamines having from 2 to 10 carbon atoms, even more preferably an alkanolamine having from 2 to 10 carbon atoms, and still more preferably 2-amino-2-hydroxymethyl-1,3-propanediol.

From the viewpoints of promoting the formation of a polymer of compound (A) on the target surface and enhancing the modifying effect imparted to the target surface, the content or blending amount of the alkaline agent in the pretreatment agent according to the present invention is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.3% by mass or more, even more preferably 0.5% by mass or more, even more preferably 0.7% by mass or more, and even more preferably 1% by mass or more; and from the viewpoints of the resistance of the target surface and skin irritation, it is preferably 10% by mass or less, more preferably 5% by mass or less, even more preferably 3% by mass or less, and even more preferably 2% by mass or less.

[Oxidizing Agent]
The pretreatment agent according to the present invention may preferably further contain an oxidizing agent.
The formation of a polymer of compound (A) in step 1-1 can be performed under oxidative conditions using oxygen without using any additives. However, when the pretreatment agent further contains an oxidizing agent, polymerization of compound (A) by the oxidizing agent can be promoted, and the formation of a polymer of compound (A) can be promoted.
Examples of the oxidizing agent include hydrogen peroxide; alkali metal persulfates such as sodium persulfate and potassium persulfate; and ammonium persulfate, and these may be used alone or in combination of two or more.

(aqueous medium)
The pretreatment agent according to the present invention preferably further contains an aqueous medium.
Examples of aqueous media include water; lower alcohols such as ethanol and isopropyl alcohol; and low-molecular-weight diols and triols having 6 or less carbon atoms, such as 1,3-butylene glycol, glycerin, ethylene glycol, and propylene glycol.
As described above, when a polymer of compound (A) containing a benzene ring has a crosslinked structure and is insoluble in a solvent that dissolves compound (A), the aqueous medium of the pretreatment agent is preferably one that dissolves compound (A) but does not dissolve the polymer of compound (A). This allows a polymer of compound (A) to be efficiently formed on the target surface, and in step 1, cationic compound (B) can be efficiently adsorbed to the target surface via the polymer of compound (A), thereby enhancing the modifying effect due to the properties of cationic compound (B). From this perspective, the aqueous medium is preferably one or more selected from water and lower alcohols, more preferably contains at least water, and even more preferably is water.
When water is used as the aqueous medium, the content or blending amount of the aqueous medium in the pretreatment agent according to the present invention is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, still more preferably 80% by mass or more, still more preferably 85% by mass or more, still more preferably 90% by mass or more, still more preferably 95% by mass or more, and preferably 99% by mass or less, from the viewpoint of enhancing the modifying effect imparted to the target surface and of the adsorption properties of compound (A).

The pretreatment agent according to the present invention can be prepared, for example, by blending compound (A), an aqueous medium, and, if necessary, other components such as an alkaline agent and an oxidizing agent, and mixing them using a known stirring device or the like.

The method for applying the pretreatment agent to the target surface in step 1-1 is not particularly limited, and examples thereof include the following methods (i-1) to (iii-1).
(i-1) A method of immersing a target surface in a pretreatment agent. (ii-1) A method of spraying or applying a pretreatment agent to a target surface. (iii-1) A method of cleaning a target surface using a pretreatment agent in a conventional manner. From the viewpoint of enhancing the modifying effect imparted to the target surface and of ease of operation, the ambient temperature when applying the pretreatment agent to the target surface is preferably 5°C or higher, more preferably 10°C or higher, even more preferably 15°C or higher, and is preferably 50°C or lower, more preferably 40°C or lower, even more preferably 30°C or lower.
The immersion time in the method (i-1) is, from the viewpoint of enhancing the modifying effect imparted to the target surface and from the viewpoint of economy, preferably 0.1 minute or more, more preferably 0.3 minute or more, even more preferably 0.5 minute or more, and still more preferably 1 minute or more, and is preferably 48 hours or less, more preferably 24 hours or less.
The spraying or application method in the above method (ii-1) can be appropriately selected depending on the size (area) of the target surface, etc. After spraying, the solution may be thinly spread using a sponge or the like.
The amount of the pretreatment agent applied to the target surface in step 1-1 depends on the content or blend amount of compound (A) in the pretreatment agent. For example, when the target surface is a hydrophobic surface, the amount is preferably 20 mL or more and 300,000 mL or less, more preferably 100 mL or more and 200,000 mL or less, and even more preferably 1,000 mL or more and 100,000 mL or less, per ^{1 m2} of the target surface.

In step 1-1, the formation of a polymer of compound (A) is not particularly limited as long as it is under oxidative conditions using oxygen. Preferred examples include method (I) in which compound (A) is polymerized under oxidative conditions using dissolved oxygen in the pretreatment agent when the pretreatment agent is applied to the target surface, and method (II) in which compound (A) is polymerized under oxidative conditions using oxygen-containing air after the pretreatment agent is applied to the target surface.
In the case of method (I), the method of applying the pretreatment agent to the target surface in step 1-1 is preferably method (i-1) described above. In this case, from the viewpoint of the efficiency of the modification treatment, the preferred range of the polymerization time of compound (A) in step 1-1 is the same as the preferred range of the immersion time described above, and the polymerization temperature is the same as the preferred range of the ambient temperature described above.
In the case of method (II), the method for applying the pretreatment agent to the target surface in step 1-1 may be any of the methods (i-1) to (iii-1) described above. In this case, the polymerization time of compound (A) by exposure to air after application of the pretreatment agent to the target surface is not particularly limited, but is preferably 30 minutes or more and preferably 24 hours or less. In addition, the polymerization temperature of compound (A) by exposure to air after application of the pretreatment agent to the target surface is not particularly limited, but can be room temperature (25°C).

In step 1-1, after the pretreatment agent is applied to the target surface, preferably after the polymer of compound (A) is formed, a treatment may be carried out to remove excess pretreatment agent from the surface to which the pretreatment agent has been applied, using an aqueous medium.
The method for removing excess pretreatment agent is not particularly limited, and examples include a method of immersing the surface to which the pretreatment agent has been applied in an aqueous medium, a method of spraying or applying the aqueous medium to the surface to which the pretreatment agent has been applied, and a method of rinsing the surface to which the pretreatment agent has been applied with an aqueous medium in accordance with a conventional method.
Examples of aqueous media used in the method for removing excess pretreatment agent include water; lower alcohols such as ethanol and isopropyl alcohol; and low-molecular-weight diols and triols having 6 or less carbon atoms such as 1,3-butylene glycol, glycerin, ethylene glycol, and propylene glycol. Of these, those containing water are preferred.
The water used as the aqueous medium in the method for removing excess pretreatment agent is not particularly limited, and tap water, distilled water, ion-exchanged water, hard water, soft water, ultrapure water, etc. can be used.
The water content in the aqueous medium used in the method for removing excess pretreatment agent is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and still more preferably 95% by mass or more, with the upper limit being 100% by mass.

<Treatment Agent>
(Cationic Compound (B))
The treating agent according to the present invention contains a cationic compound (B) (hereinafter also simply referred to as "compound (B)") from the viewpoint of enhancing the modifying effect imparted to the target surface.
The cationic compound (B) is preferably at least one selected from cationic surfactants and cationic polymers. The compound (B) may be used alone or in combination of two or more.

Examples of the cationic surfactant include alkyltrimethylammonium salts, alkoxyalkyltrimethylammonium salts, dialkyldimethylammonium salts, alkylamidoalkyltrimethylammonium salts, alkyldimethylamines and salts thereof, alkoxyalkyldimethylamines and salts thereof, and alkylamidoalkyldimethylamines and salts thereof, and one or more of these can be used.
The cationic surfactant preferably has a long-chain alkyl group having from 8 to 22 carbon atoms, more preferably from 8 to 18 carbon atoms, and even more preferably from 12 to 18 carbon atoms.
The salt of the amine of the cationic surfactant may be a salt with an organic acid or an inorganic acid.The organic acid may be, for example, an aliphatic monocarboxylic acid such as acetic acid or propionic acid; an aliphatic dicarboxylic acid such as malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, or fumaric acid; an aromatic dicarboxylic acid such as phthalic acid or isophthalic acid; a polycarboxylic acid such as polyglutamic acid; a hydroxycarboxylic acid such as glycolic acid, lactic acid, hydroxyacrylic acid, glyceric acid, malic acid, tartaric acid, or citric acid; or an acidic amino acid such as glutamic acid or aspartic acid.The inorganic acid may be, for example, hydrochloric acid, sulfuric acid, or phosphoric acid.

The cationic polymer is at least one selected from synthetic polymers having a cationic group, naturally occurring polymers, and salts thereof.
Specific examples of synthetic polymers having a cationic group include quaternized dialkylaminoalkyl (meth)acrylate polymers such as poly[methacrylic acid 2-(dimethylamino)ethyl diethyl sulfate], methacrylic acid 2-(dimethylamino)ethyl diethyl sulfate/vinylpyrrolidone copolymer, and methacrylic acid 2-(dimethylamino)ethyl diethyl sulfate/N,N-dimethylacrylamide/dimethacrylic acid polyethylene glycol copolymer; diallyl quaternized ammonium salt polymers such as polydiallyldimethylammonium chloride, diallyldimethylammonium chloride/acrylic acid copolymer, diallyldimethylammonium chloride/acrylamide copolymer, and diallyldimethylammonium chloride/acrylic acid/acrylamide copolymer; vinylimidazolium chloride Examples of the cationic polymer include alkylacrylamide/vinylpyrrolidone copolymer; vinylpyrrolidone/alkylamino(meth)acrylate copolymer; vinylpyrrolidone/alkylamino(meth)acrylate/vinylcaprolactam copolymer; vinylpyrrolidone/(meth)acrylamidopropyl trimethylammonium chloride copolymer; alkylacrylamide/(meth)acrylate/alkylaminoalkylacrylamide/polyethylene glycol (meth)acrylate copolymer; dimethylaminohydroxypropylethylenetriamine/adipic acid copolymer; cationic silicone; cationized polyvinyl alcohol; and the cationic polymers described in JP-A-53-139734 and JP-A-60-36407, and one or more of these may be used.
In this specification, "(meth)acrylic acid" means acrylic acid or methacrylic acid, and "(meth)acrylate" means acrylate or methacrylate.

Naturally occurring polymers with cationic groups include polymers obtained by extraction, purification, etc. from natural products, as well as chemically modified versions of such polymers, and include those with glucose residues in the polymer backbone. Specific examples include cationized guar gum; cationized tara gum; cationized locust bean gum; cationized cellulose; cationized hydroxyethyl cellulose, cationized hydroxypropyl cellulose, and other cationized hydroxyalkyl celluloses; and cationic starch.

Of these, the cationic compound (B) is more preferably a cationic polymer, and even more preferably at least one selected from cationic vinyl polymers (BI) and cationic silicones (BII), from the viewpoint of exhibiting cation-π interactions and enhancing the modifying effect imparted to the target surface.

[Cationic vinyl polymer (BI)]
The cationic vinyl polymer (BI) preferably contains a structural unit (b1) having a cationic group represented by the following formula (2), from the viewpoint of expressing a cation-π interaction and enhancing the modifying effect imparted to the target surface:

[In formula (2),
R ²¹ to R ²³ are the same or different and each represent a hydrogen atom or an alkyl group having 1 or 2 carbon atoms;
X ¹ represents an oxygen atom or NR ³⁰ , where R ³⁰ represents a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms;
^R24 represents an alkylene group having 1 to 4 carbon atoms;
^X2 represents N ^{+ R25R26R27X3} or ^NR28R29 , ^R25 to ^{R29 may} be the same or ^different and represent a hydrogen atom or ^a hydrocarbon group having 1 to 4 carbon atoms, ^{and X3} represents an anion.

The structural unit (b1) is, for example, a structural unit derived from the monomer (b1') represented by the following formula (2'):

[In formula (2'), R ²¹ to R ²⁴ , X ¹ and X ² are the same as those in formula (2).]

In the formulas (2) and (2′), specific examples or preferred aspects of R ²¹ to R ²⁴ , X ¹ , and X ² are as follows, from the viewpoint of developing cation-π interactions and enhancing the modifying effect imparted to the target surface:
R ²¹ and R ²² are preferably hydrogen atoms.
R ²³ is preferably a hydrogen atom or a methyl group, more preferably a methyl group.
X ¹ is preferably an oxygen atom.
R ²⁴ is preferably an alkylene group having 2 or 3 carbon atoms, and more preferably an alkylene group having 2 carbon atoms.
When ^X2 is N ^{+ R25R26R27X3} , ^R25 , ^{R26 and R27} are preferably each a methyl group or an ethyl group, ^and more preferably any one of ^R25 , ^R26 and ^R27 is ^an ethyl group.
^X3 is preferably ^a _{halogen ion or C2H5SO4-} , more _{preferably C2H5SO4-} ^.
When X ² is NR ²⁸ R ²⁹ , R ²⁸ and R ²⁹ are preferably a methyl group or an ethyl group, more preferably a methyl group, from the viewpoint of ease of the quaternization reaction.
^{Among these} , ^{X2 is} preferably N ^{+ R25R26R27X3} .

From the viewpoint of efficiently realizing cation-π interactions and enhancing the surface modification effect of the target, the structural unit (b1) is preferably a structural unit derived from an N,N-(dialkylamino)alkyl(meth)acrylic acid or a quaternized product thereof, more preferably a structural unit derived from a quaternized N,N-(dialkylamino)alkyl(meth)acrylic acid, even more preferably a structural unit derived from at least one selected from a quaternized product of 2-(dimethylamino)ethyl (meth)acrylate, a quaternized product of 2-(diethylamino)ethyl (meth)acrylate, and a quaternized product of 3-(dimethylamino)propyl (meth)acrylate, and even more preferably a structural unit derived from diethyl sulfate of 2-(dimethylamino)ethyl (meth)acrylate.

The cationic vinyl polymer (BI) can be appropriately selected from homopolymers consisting of the structural unit (b1) alone or copolymers containing the structural unit (b1) and a structural unit other than the structural unit (b1) depending on the intended modifying effect. When the cationic vinyl polymer (BI) is a copolymer, it may be any of a block copolymer, a random copolymer, and an alternating copolymer.
Examples of other structural units include nonionic monomers such as (meth)acrylic acid esters, alkyl(meth)acrylamides, vinylpyrrolidones, and styrene-based monomers; anionic monomers such as anionic group-containing polymerizable unsaturated monomers; and structural units derived from other monomers such as betaine monomers having a betaine group.
As used herein, "(meth)acrylamide" means acrylamide or methacrylamide.

(Meth)acrylic acid esters include (meth)acrylic acid esters having a linear or branched alkyl group such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, iso-butyl (meth)acrylate, sec-butyl (meth)acrylate, t-butyl (meth)acrylate, n-hexyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-decyl (meth)acrylate, lauryl (meth)acrylate, myristyl (meth)acrylate, palmityl (meth)acrylate, stearyl (meth)acrylate, and behenyl (meth)acrylate; (meth)acrylic acid esters having an alicyclic alkyl group such as cyclohexyl (meth)acrylate; and (meth)acrylic acid esters having a hydrocarbon group having 1 to 30 carbon atoms, such as aromatic group-containing (meth)acrylic acid esters such as benzyl (meth)acrylate. esters; polyalkylene glycol (meth)acrylates such as polyethylene glycol (meth)acrylate (the average number of moles of alkylene oxide added is preferably 2 or more and 30 or less); alkoxypolyalkylene glycol (meth)acrylates such as methoxypolyethylene glycol (meth)acrylate, methoxypolypropylene glycol (meth)acrylate, and octoxy (polyethylene glycol/polypropylene glycol copolymer) (meth)acrylate (the average number of moles of alkylene oxide added is preferably 2 or more and 30 or less); and phenoxypolyalkylene glycol (meth)acrylates such as phenoxypolyethylene glycol (meth)acrylate and phenoxy (polyethylene glycol/polypropylene glycol copolymer) (meth)acrylate (the average number of moles of alkylene oxide added is preferably 2 or more and 30 or less).

Examples of alkyl(meth)acrylamides include N-alkyl(meth)acrylamides having an alkyl group having from 1 to 22 carbon atoms, such as N-ethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-t-butyl(meth)acrylamide, N,N-dimethylacrylamide, and N,N-diethyl(meth)acrylamide.
Examples of the styrene-based monomer include styrene, α-methylstyrene, and 2-methylstyrene.

Examples of the anionic group-containing polymerizable unsaturated monomer include a carboxy group-containing polymerizable unsaturated monomer, a sulfonic acid group-containing polymerizable unsaturated monomer, and a phosphoric acid group-containing polymerizable unsaturated monomer.
Examples of the carboxyl group-containing polymerizable unsaturated monomer include (meth)acrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, citraconic acid, and 2-methacryloyloxymethylsuccinic acid.
Examples of the sulfonic acid group-containing polymerizable unsaturated monomer include styrenesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, and 3-sulfopropyl(meth)acrylate.
Examples of the phosphoric acid group-containing polymerizable unsaturated monomer include vinylphosphonic acid, vinyl phosphate, bis(methacryloyloxyethyl)phosphate, diphenyl-2-acryloyloxyethyl phosphate, and diphenyl-2-methacryloyloxyethyl phosphate.

In this specification, the "betaine group" in a betaine monomer having a betaine group means a functional group having a cationic moiety and an anionic moiety, and the functional group as a whole does not have an electric charge.
The cationic moiety of the betaine group is a positively charged atomic group, preferably a cationic group.
The anionic portion of the betaine group is a negatively charged atomic group, preferably an anionic group.
As used herein, the term "anionic group" refers to an anionic group or a group that can be ionized to become an anionic group.
Examples of the anionic group include a carboxy group (-COOM ¹ ), a sulfonic acid group (-SO ₃ M ¹ ), a phosphate group (-OPO ₃ M ¹ ₂ ), etc. In the above chemical formula, M ¹ represents a hydrogen atom, an alkali metal, ammonium, or an organic ammonium.

From the viewpoint of enhancing the modifying effect imparted to the target surface, the betaine group of the betaine monomer is preferably a sulfobetaine group, a phosphobetaine group, or a carbobetaine group, more preferably a sulfobetaine group or a phosphobetaine group, and even more preferably a sulfobetaine group, and the cationic moiety of these betaine groups is preferably a quaternary ammonium group.
The betaine group may be of one type or of two or more types.

Among these, the cationic vinyl polymer (BI) is preferably a cationic betaine polymer containing a structural unit (b1) having a cationic group represented by the above formula (2) and a structural unit (b2) having a betaine group represented by the following formula (3). This allows the betaine group introduced into the side chain of the polymer to impart hydrophilicity to the target surface as a modification effect. In other words, the surface modification method of the present invention is preferably used as a surface hydrophilization method.

[In formula (3),
R ³¹ to R ³³ are the same or different and each represents a hydrogen atom or an alkyl group having 1 or 2 carbon atoms;
^X4 represents an oxygen atom or ^NR37 , where ^R37 represents a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms;
R ³⁴ represents an alkylene group having 1 to 4 carbon atoms or -Y ¹ -OPO ₃ ^- -Y ² -, Y ¹ and Y ² are the same or different and represent an alkylene group having 1 to 4 carbon atoms;
R ³⁵ and R ³⁶ are the same or different and each represent a hydrocarbon group having 1 to 4 carbon atoms;
^X5 represents ^{R38SO3- or} _R38COO- when ^R34 is an alkylene group having from 1 to 4 carbon ^atoms , ^R38 represents an alkylene group having from 1 to 4 carbon atoms which may have a hydroxyl group, ^{and X5} represents a hydrogen atom or a hydrocarbon group having from 1 to 4 carbon atoms when ^R34 is ^-Y1 - _OPO3 ^{-- Y2-} .

The structural unit (b2) is preferably a structural unit having a sulfobetaine group, a phosphobetaine group, or a carbobetaine group.
The structural unit (b2) may be one type, or may be two or more different types of structural units.
The structural unit (b2) is, for example, a structural unit derived from a monomer represented by the following formula (3′).

[In formula (3'), R ³¹ to R ³⁶ , X ⁴ and X ⁵ are the same as in formula (3).]

In the formulas (3) and (3′), specific examples or preferred embodiments of R ³¹ to R ³⁶ , X ⁴ , and X ⁵ are as follows, from the viewpoint of enhancing the modifying effect of the betaine group and enhancing the hydrophilic effect imparted to the target surface.
R ³¹ and R ³² are preferably hydrogen atoms.
R ³³ is preferably a hydrogen atom or a methyl group, more preferably a methyl group.
^X4 is preferably an oxygen atom.
R ³⁴ is preferably an alkylene group having 1 to 4 carbon atoms, more preferably an alkylene group having 2 or 3 carbon atoms, and even more preferably an alkylene group having 2 carbon atoms.
R ³⁵ and R ³⁶ are preferably a methyl group or an ethyl group, more preferably a methyl group.
When ^R34 is an alkylene group ^having from 1 to 4 carbon atoms, ^X5 represents ^R38SO3- or _R38COO- ^, preferably ^R38SO3- . ^R38 represents _an alkylene group having from 1 to 4 carbon atoms which may have a hydroxyl group, preferably ^an alkylene group having from 1 ^to 3 carbon atoms or a hydroxyalkylene group having from 2 to 4 carbon atoms, more preferably an alkylene group having from 1 to 3 carbon atoms, even more preferably an alkylene group having 2 or 3 carbon atoms, and still more preferably an alkylene group having 3 carbon atoms.
When R ³⁴ is —Y ¹ —OPO ₃ ^— —Y ² —, X ⁵ is a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms, preferably a hydrocarbon group having 1 to 4 carbon atoms, and more preferably a methyl group.

From the viewpoint of enhancing the modifying effect of the betaine group and enhancing the hydrophilic effect imparted to the target surface, the structural unit (b2) is preferably a monomer having a sulfobetaine group, such as N-(3-sulfopropyl)-N-(meth)acryloyloxyethyl-N,N-dimethylammonium betaine or N-(3-sulfopropyl)-N-(meth)acryloylamidopropyl-N,N-dimethylammonium betaine; a monomer having a phosphobetaine group, such as 2-methacryloyloxyethyl phosphorylcholine; or a monomer having a carbobetaine group, such as N-carboxymethyl-N-(meth)acryloyloxyethyl-N,N-dimethylammonium betaine or N-carboxymethyl-N-(meth)acryloylamidopropyl-N,N-dimethylammonium betaine. It is a structural unit derived from at least one monomer, more preferably a structural unit derived from at least one monomer selected from a monomer having a sulfobetaine group and a monomer having a phosphobetaine group, even more preferably a structural unit derived from a monomer having a sulfobetaine group, even more preferably a structural unit derived from at least one monomer selected from N-(3-sulfopropyl)-N-(meth)acryloyloxyethyl-N,N-dimethylammonium betaine and N-(3-sulfopropyl)-N-(meth)acryloylamidopropyl-N,N-dimethylammonium betaine, and even more preferably a structural unit derived from N-(3-sulfopropyl)-N-(meth)acryloyloxyethyl-N,N-dimethylammonium betaine.

The content of the structural unit (b1) in all structural units of the cationic vinyl polymer (BI) is, from the viewpoint of expressing a cation-π interaction to enhance the modifying effect imparted to the target surface and from the viewpoint of enhancing the hydrophilizing effect imparted to the target surface, preferably 1 mol% or more, more preferably 2 mol% or more, even more preferably 3 mol% or more, and is preferably 45 mol% or less, more preferably 40 mol% or less, even more preferably 35 mol% or less, still more preferably 30 mol% or less, still more preferably 25 mol% or less, still more preferably 20 mol% or less, still more preferably 15 mol% or less, still more preferably 10 mol% or less, and still more preferably 7 mol% or less.
From the viewpoint of enhancing the modifying effect of the betaine group and enhancing the hydrophilizing effect imparted to the target surface, the content of the structural unit (b2) in all structural units of the cationic vinyl polymer (BI) is preferably 55 mol% or more, more preferably 60 mol% or more, even more preferably 65 mol% or more, still more preferably 70 mol% or more, still more preferably 75 mol% or more, still more preferably 80 mol% or more, still more preferably 85 mol% or more, still more preferably 90 mol% or more, still more preferably 93 mol% or more, and preferably 99 mol% or less, more preferably 98 mol% or less, even more preferably 97 mol% or less.
The content of each structural unit in all structural units of the cationic vinyl polymer (BI) can be measured by analysis such as NMR, or can be calculated from the charge ratio of each monomer in the production of the cationic vinyl polymer (BI).

When the cationic compound (B) is the above-mentioned cationic betaine polymer, the method for producing the cationic betaine polymer is not particularly limited, and examples thereof include the following methods (x) and (y).
(x) A method of copolymerizing raw material monomers including a monomer represented by the formula (2') and a monomer represented by the formula (3'). (y) A method of copolymerizing raw material monomers including a monomer represented by the formula (2') and a monomer represented by the following formula (3'-1), followed by betaining with a betaining agent. Among these, method (y) is preferred from the viewpoints of monomer availability and ease of production.

[In formula (3'-1), R ³¹ to R ³⁶ and X ⁴ are the same as those in formula (3), and preferred embodiments are also the same as those in formula (3)]

When using method (y), for example, when the structural unit (b2) is a structural unit derived from a monomer having a sulfobetaine group, a preferred method involves polymerizing raw material monomers containing the monomer represented by formula (3'-1) above, and then reacting them with a betaining agent, such as a compound represented by formula (3'-2) or a compound represented by formula (3'-3) below. Among these, the betaining agent is preferably a compound represented by formula (3'-2) below.

[In formula (3'-2), m is 1 or 2, preferably 1.]

Z-R ³⁸ -SO ₃ M ³ (3'-3)
[In formula (3'-3), Z is Cl or Br, preferably Cl; R ³⁸ is an alkylene group having 2 to 4 carbon atoms which may have a hydroxyl group, preferably a 2-hydroxypropylene group; and M ³ is Na or K.]

The weight-average molecular weight of the cationic vinyl polymer (BI) is preferably 1,000 or more, more preferably 3,000 or more, even more preferably 5,000 or more, even more preferably 10,000 or more, and even more preferably 30,000 or more, from the viewpoint of enhancing the modifying effect imparted to the target surface and enhancing the hydrophilic effect imparted to the target surface. From the viewpoint of compounding stability of the treatment agent, it is preferably 3,000,000 or less. The weight-average molecular weight of the cationic vinyl polymer (BI) can be measured by the method described in the Examples.

[Cationic Silicone (BII)]
The cationic silicone (BII) is a modified silicone into which a cationic group has been introduced, and is preferably a modified silicone having a cationic group on a side chain, one end, or both ends of the polysiloxane skeleton.
By using the cationic silicone (BII) as the cationic compound (B), a cation-π interaction can be exerted, and a hydrophobic effect can be imparted to the target surface as a modification effect. From this viewpoint, in this case, the modification method of the present invention is preferably used as a surface hydrophobization method.

Examples of the cationic silicone (BII) include quaternary ammonium cation-modified silicones in which quaternary ammonium salt groups are introduced into a polysiloxane skeleton, and amino-modified silicones in which amino groups are introduced into a polysiloxane skeleton and which exhibit cationicity by cationizing the amino groups. Among these, quaternary ammonium cation-modified silicones are preferred.
Specifically, the quaternary ammonium cation-modified silicone is preferably a side-chain type quaternary ammonium cation-modified silicone having a structure represented by the following formula (4-1) or a terminal type quaternary ammonium cation-modified silicone having a structure represented by the following formula (4-2):

[In formula (4-1), R ⁴¹ represents a monovalent hydrocarbon group having 1 to 6 carbon atoms. R ⁴² represents a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, or a hydrocarbon group containing an amide bond having 1 to 20 carbon atoms. L represents a divalent organic group. ^{Q −} is a counter ion of a quaternary ammonium ion. r represents a number of 2 or more, and s represents a number of 1 or more. The structural units in parentheses may be bonded in any order, and may be bonded in either a block or random form. Furthermore, multiple R ⁴¹ and R ⁴² may be the same or different.]

[In formula (4-2), R ⁴¹ , R ⁴² , L, Q ⁻ and r are the same as defined above.]

In the formulas (4-1) and (4-2), R ⁴¹ is preferably each independently an alkyl group having 1 to 6 carbon atoms or a phenyl group, more preferably a methyl group or an ethyl group, and even more preferably a methyl group.
In the formulas (4-1) and (4-2), R ⁴² is preferably a hydrocarbon group having from 1 to 20 carbon atoms or a hydrocarbon group having from 1 to 20 carbon atoms and containing an amide bond, and it is more preferable that at least one of the multiple R ^42s is a hydrocarbon group having from 1 to 20 carbon atoms and containing an amide bond.
In the formulas (4-1) and (4-2), L is preferably * ¹ - ^R43 - _CH2 -CHOH- _CH2- * ² , where ^R43 is a divalent organic group, preferably an alkylene group having 1 to 20 carbon atoms, or an oxyalkylene group having 1 to 20 carbon atoms. * ¹ indicates the bonding site to the silicon atom, and * ² indicates the bonding site to the nitrogen atom.
In the formula (4-1), r is preferably a number of 2 or more and 200 or less, more preferably a number of 2 or more and 50 or less. s is preferably a number of 1 or more and 50 or less, more preferably a number of 2 or more and 20 or less, and even more preferably a number of 2 or more and 10 or less.
In the formula (4-2), r is preferably a number of 2 or more and 200 or less, and more preferably a number of 2 or more and 100 or less.
In the formulas (4-1) and (4-2), Q ^represents an anion such as a halide ion such as a chloride ion or a bromide ion, or an organic acid ion such as an alkyl sulfate ion having from 1 to 3 carbon atoms, an acetate ion, a lactate ion, a benzoate ion, an adipate ion, a formate ion, a malate ion, or a glycolate ion. Of these, a lactate ion is preferred.

Examples of quaternary ammonium cation-modified silicones include silicone quaternium-1, silicone quaternium-2, silicone quaternium-3, silicone quaternium-4, silicone quaternium-5, silicone quaternium-6, silicone quaternium-7, silicone quaternium-8, silicone quaternium-9, silicone quaternium-10, silicone quaternium-11, silicone quaternium-12, silicone quaternium-15, silicone quaternium-16, silicone quaternium-17, silicone quaternium-18, silicone quaternium-20, silicone quaternium-21, silicone quaternium-22, quaternium-80, silicone quaternium-2 panthenol succinate, and silicone quaternium-16/glycidyl dimethicone crosspolymer.

Examples of commercially available cationic polymers of the cationic compound (B) include the following:
(2-(dimethylamino)ethyl methacrylate diethyl sulfate/vinylpyrrolidone copolymer)
Polyquaternium-11: For example, Gafcut 734 (manufactured by ISP Japan), Gafcut 755N (manufactured by ISP Japan), etc. (2-(dimethylamino)ethyl diethyl methacrylate sulfate/N,N-dimethylacrylamide/polyethylene glycol dimethacrylate copolymer)
Polyquaternium-52: For example, SOFCARE KG-101W-E: cation charge density (literature value) 0.8 meq/g (manufactured by Kao Corporation) (polydiallyldimethylammonium chloride)
Polyquaternium-6: for example, MERQUAT 100: cation charge density (literature value) 6.2 meq/g (manufactured by Lubrizol Advanced Materials) (diallyldimethylammonium chloride/acrylic acid copolymer)
Polyquaternium-22: For example, MERQUAT 280: cationic charge density: 2.2 meq/g, MERQUAT 295: cationic charge density: 5.7 meq/g (all manufactured by Lubrizol Advanced Materials), etc. (diallyldimethylammonium chloride/acrylamide copolymer)
Polyquaternium-7: for example, MERQUAT 550: cation charge density (literature value) 3.1 meq/g (manufactured by Lubrizol Advanced Materials) (diallyldimethylammonium chloride/acrylic acid/acrylamide copolymer)
Polyquaternium-39: for example, MERQUAT3331PR: cation charge density 0.42 meq/g (manufactured by Lubrizol Advanced Materials) (quaternary ammonium cation-modified silicone)
Quaternium-80: for example, ABIL QUAT 3272 (manufactured by Evonik) (cationized polyvinyl alcohol)
Gohsenex K-434 (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), CM318: cation charge density 0.35 meq/g (manufactured by Kuraray Co., Ltd.), etc. (cationized guar gum)
Jaguar Excel: cationic charge density 1.1 meq/g (manufactured by Solvay (Novecare)) etc. (cationized tara gum)
Catinal CTR-100: cationic charge density 1.3 meq/g (manufactured by Toho Chemical Industry Co., Ltd.) or the like (cationized locust bean gum)
Catinal CLB-100 (manufactured by Toho Chemical Industry Co., Ltd.) and the like (cationized hydroxyethyl cellulose)
Polyquaternium-10 (o-[2-hydroxy-3-(trimethylammonio)propyl]hydroxyethyl cellulose chloride): for example, U-Care Polymer JR-400: cation charge density 1.3 meq/g (manufactured by The Dow Chemical Company), Poise C-60H: cation charge density 1.1 to 1.8 meq/g (manufactured by Kao Corporation), Poise C-150L: cation charge density 0.7 to 1.1 meq/g (manufactured by Kao Corporation), Poise C-80M: cation charge density 0.9 to 1.2 meq/g (manufactured by Kao Corporation).
(cationized hydroxypropyl cellulose)
SOFCARE C-HP2: cation charge density 0.5 meq/g (manufactured by Kao Corporation), etc.

The cationic charge density of the cationic compound (B) is, from the viewpoint of enhancing the modifying effect imparted to the target surface by manifesting cation-π interactions and enhancing the hydrophilizing effect imparted to the target surface, preferably 0.01 meq/g or more, more preferably 0.05 meq/g or more, even more preferably 0.1 meq/g or more, still more preferably 0.15 meq/g or more, and is preferably 1.0 meq/g or less, more preferably 0.8 meq/g or less, even more preferably 0.6 meq/g or less, still more preferably 0.4 meq/g or less, and still more preferably 0.2 meq/g or less.
The cationic compound (B) is a compound that exhibits cationicity as a whole, but may contain anionic groups within the compound as long as the effects of the present invention are not impaired. When the cationic compound (B) contains anionic groups, the cationic charge density of the cationic compound (B) refers to the value obtained by subtracting the number of moles of the anionic groups in the compound (B)/g×1000 (anionic charge density; meq/g) from the number of moles of the cationic groups in the compound (B)/g×1000 (cationic charge density; meq/g).
The cationic compound (B) may be a mixture of two or more compounds that exhibit cationic properties as a whole. In this case, the cationic charge density can be determined by calculating a weighted average of the cationic charge densities of the individual compounds and their blending amounts.
When the cationic compound (B) is a cationic vinyl polymer (BI), the cationic charge density of the cationic vinyl polymer (BI) can be calculated from the types and molar ratios of the structural units constituting the polymer. The types and molar ratios of the structural units constituting the polymer can be measured by analysis such as NMR.

The content or blending amount of compound (B) in the treatment agent according to the present invention is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, even more preferably 0.1% by mass or more, even more preferably 0.3% by mass or more, even more preferably 0.5% by mass or more, even more preferably 0.7% by mass or more, from the viewpoints of enhancing the modifying effect imparted to the target surface by manifesting cation-π interactions, enhancing the hydrophilic effect imparted to the target surface, and blend stability and adsorption. It is preferably 30% by mass or less, more preferably 20% by mass or less, even more preferably 15% by mass or less, even more preferably 10% by mass or less, even more preferably 5% by mass or less, even more preferably 3% by mass or less, even more preferably 2% by mass or less, and even more preferably 1.5% by mass or less.

(Other ingredients)
The treatment agent according to the present invention may contain other components in addition to the compound (B) to the extent that the effects of the present invention are not impaired. The other components may be appropriately selected and used depending on the intended modification effect, for example, from amphoteric surfactants, antioxidants, silicones, aromatic alcohols, polymers other than cationic polymers, oils, vitamins, disinfectants, anti-inflammatory agents, antidandruff agents, preservatives, chelating agents, moisturizers, pearlescent agents, ceramides, fragrances, ultraviolet absorbers, etc.

[Electrolyte]
The treatment agent according to the present invention preferably further contains an electrolyte. It is believed that the inclusion of an electrolyte can improve the blend stability of the cationic compound (B) in the treatment agent.
In the present invention, the term "electrolyte" refers to a compound that undergoes ion dissociation in water.
Examples of the electrolyte include organic acids, inorganic acids, organic bases, inorganic bases, and salts thereof, from the viewpoint of improving the compounding stability of the cationic compound (B) in the treatment agent.
Examples of organic acids include monocarboxylic acids such as formic acid, acetic acid, propionic acid, and benzoic acid; dicarboxylic acids such as malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid, and phthalic acid; polycarboxylic acids such as polyglutamic acid; hydroxycarboxylic acids such as glycolic acid, lactic acid, hydroxyacrylic acid, glyceric acid, malic acid, tartaric acid, and citric acid; acidic amino acids such as glutamic acid and aspartic acid; sulfonic acids such as methanesulfonic acid, N-methyltaurine, sulfamic acid, xylenesulfonic acid, p-toluenesulfonic acid, and benzenesulfonic acid; sulfates such as lauryl sulfate; and organic phosphates such as methyl phosphate and ethyl phosphate.
Examples of inorganic acids include hydrochloric acid, sulfuric acid, nitric acid, perchloric acid, carbonic acid, thiocyanic acid, and phosphoric acid.
Examples of the organic base include alkanolamines such as monoethanolamine, diethanolamine, and triethanolamine.
Examples of inorganic bases include hydroxides of alkali metals such as potassium, sodium, and lithium. Ammonia may also be used as the inorganic base.
Examples of salts include sodium chloride, potassium chloride, magnesium chloride, sodium citrate, potassium benzoate, ammonium chloride, sodium carbonate, dipotassium phosphate, and monoethanolamine sulfate.
These may be used alone or in combination of two or more.
When producing the treatment agent, the electrolyte may be formed into a salt in the treatment agent by blending the above organic acid or inorganic acid with an organic base or inorganic base.

Among these, from the viewpoint of formulation stability, the electrolyte is preferably a salt, more preferably a water-soluble inorganic salt, even more preferably one or more selected from alkali metal salts and metal salts of Group 2 elements, still more preferably one or more selected from sodium chloride, potassium chloride, and magnesium chloride, still more preferably one or more selected from sodium chloride and potassium chloride, and still more preferably sodium chloride.
The solubility of the water-soluble inorganic salt in 100 g of water at 20° C. is preferably 10 g or more, more preferably 20 g or more, and even more preferably 30 g or more.

From the viewpoint of formulation stability, the content or blending amount of electrolyte in the treatment agent according to the present invention is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, even more preferably 0.3% by mass or more, still more preferably 0.5% by mass or more, and even more preferably 0.7% by mass or more. From the viewpoint of enhancing the modifying effect imparted to the target surface, enhancing the hydrophilic effect imparted to the target surface, and adsorption properties, it is preferably 15% by mass or less, more preferably 10% by mass or less, even more preferably 7% by mass or less, still more preferably 5% by mass or less, still more preferably 3% by mass or less, still more preferably 2% by mass or less, and even more preferably 1.5% by mass or less.

(aqueous medium)
The treatment agent according to the present invention preferably further contains an aqueous medium, such as water, lower alcohols such as ethanol and isopropyl alcohol, and low-molecular-weight diols and triols having 6 or less carbon atoms, such as 1,3-butylene glycol, glycerin, ethylene glycol, and propylene glycol.
As mentioned above, when the polymer of compound (A) containing a benzene ring has a crosslinked structure and is insoluble in a solvent that dissolves compound (A), the aqueous medium of the treatment agent is preferably one that does not dissolve the polymer of compound (A). This allows the treatment agent containing cationic compound (B) to be applied in step 1 while the polymer of compound (A) is formed on the target surface without being removed from the target surface, and compound (B) can be efficiently adsorbed to the target surface via the polymer of compound (A), thereby enhancing the modifying effect due to the properties of compound (B). From this perspective, the aqueous medium is preferably one or more selected from water and lower alcohols, more preferably contains at least water, and even more preferably is water.
When water is used as the aqueous medium, the content or blending amount of the aqueous medium in the treatment agent according to the present invention is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, still more preferably 80% by mass or more, still more preferably 85% by mass or more, still more preferably 90% by mass or more, still more preferably 95% by mass or more, and preferably 99% by mass or less, from the viewpoint of enhancing the modifying effect imparted to the target surface, enhancing the hydrophilizing effect imparted to the target surface, and adsorption properties.

The treatment agent according to the present invention can be prepared, for example, by blending compound (B), an aqueous medium, and, if necessary, other components such as an electrolyte, and mixing them using a known stirring device or the like.

The method for applying the treating agent to the target surface on which the polymer of compound (A) has been formed in step 1 is not particularly limited, and examples thereof include the following methods (i) to (iii).
(i) A method of immersing a target surface on which a polymer of compound (A) has been formed in a treatment agent. (ii) A method of spraying or applying a treatment agent to a target surface on which a polymer of compound (A) has been formed. (iii) A method of cleaning a target surface on which a polymer of compound (A) has been formed using a treatment agent in a conventional manner. The ambient temperature when applying the treatment agent to a target surface on which a polymer of compound (A) has been formed is preferably 5°C or higher, more preferably 10°C or higher, even more preferably 15°C or higher, from the viewpoints of enhancing the modifying effect imparted to the target surface, enhancing the hydrophilic effect imparted to the target surface, adsorption, and ease of work, and is preferably 50°C or lower, more preferably 40°C or lower, even more preferably 30°C or lower.
The application time of the treatment agent in step 1 is preferably 0.1 minutes or more, more preferably 0.3 minutes or more, even more preferably 0.4 minutes or more, from the viewpoint of enhancing the modifying effect imparted to the target surface, enhancing the hydrophilizing effect imparted to the target surface, and from the viewpoint of economy, and is preferably 60 minutes or less, more preferably 30 minutes or less, even more preferably 10 minutes or less, still more preferably 5 minutes or less, and still more preferably 3 minutes or less.
The spraying or application method in the method (ii) can be appropriately selected depending on the size (area) of the surface to be treated, etc. After spraying, the solution may be thinly spread using a sponge or the like.
The amount of the treatment agent applied to the target surface on which a polymer of compound (A) has been formed in step 1 depends on the content or blending amount of compound (B) in the treatment agent. For example, when the target surface is a hydrophobic surface, the amount is preferably 20 ^mL or more and 50,000 mL or less, more preferably 100 mL or more and 30,000 mL or less, and even more preferably 1,000 mL or more and 10,000 mL or less per 1 m2 of the target surface.

In step 1, after the treatment agent is applied to the target surface on which the polymer of compound (A) is formed, a treatment may be carried out in which excess treatment agent on the surface to which the treatment agent has been applied is removed using an aqueous medium.
The method for removing excess treatment agent is not particularly limited, and examples thereof include a method of immersing the surface to which the treatment agent has been applied in an aqueous medium, a method of spraying or applying the aqueous medium to the surface to which the treatment agent has been applied, and a method of rinsing the surface to which the treatment agent has been applied with an aqueous medium in accordance with a conventional method.
Examples of aqueous media used in the method for removing excess treatment agent include water; lower alcohols such as ethanol and isopropyl alcohol; and low-molecular-weight diols and triols having 6 or less carbon atoms such as 1,3-butylene glycol, glycerin, ethylene glycol, and propylene glycol. Of these, those containing water are preferred.
The water used as the aqueous medium in the method for removing excess treatment agent is not particularly limited, and tap water, distilled water, ion-exchanged water, hard water, soft water, ultrapure water, etc. can be used.
The water content in the aqueous medium used in the method for removing excess treatment agent is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and still more preferably 95% by mass or more, with the upper limit being 100% by mass.

The present invention will be described below using examples, but the present invention is not limited to these examples. Various measurements were performed using the following methods.

(Weight-average molecular weight of cationic vinyl polymer (BI))
Measurement was carried out using gel permeation chromatography under the following measurement conditions.
[Measurement conditions]
Column: Two "TSKgel α-M" (manufactured by Tosoh Corporation) connected in series Column temperature: 40°C
Eluent: 0.15 mol/L Na ₂ SO ₄ /1 mass% CH ₃ COOH aqueous solution Flow rate: 1.0 mL/min
Detector: Differential refractive index detector Sample size: 5 mg/mL
Standard substance: pullulan

Production Example 1 (Production of Cationic Betaine Polymer B1)
(Step a)
A 1000 mL four-neck flask was charged with 126.30 g of ethanol (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.), and the temperature was raised to 78 ° C and refluxed. A solution containing 181.12 g of 2-(dimethylamino)ethyl methacrylate (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.), 23.60 g of a 90% aqueous solution of 2-(dimethylamino)ethyl methacrylate diethyl sulfate, and 53.20 g of ethanol, and a solution containing 5.83 g of 2,2'-azobis(2-methylbutyronitrile) (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.) and 10.00 g of ethanol were each added dropwise over 2 hours to carry out the reaction. After completion of the addition, the mixture was aged at 78 ° C for 4 hours and then cooled to obtain a polymer solution.
The 90% aqueous solution of 2-(dimethylamino)ethyl methacrylate diethyl sulfate was obtained by mixing 2-(dimethylamino)ethyl methacrylate (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.) and diethyl sulfate (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.) in a molar ratio of 1:1.
(Step b)
94.70 g of the polymer solution obtained in step a, 3.15 g of sodium hydrogen carbonate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and 150.00 g of water were added to a 1000 mL four-neck flask, and the temperature was raised to 50° C. 38.70 g of 1,3-propane sultone (manufactured by Tokyo Chemical Industry Co., Ltd.) was added dropwise over 1 hour to carry out a reaction. After completion of the dropwise addition, the mixture was aged at 50°C for 3 hours and then heated under reduced pressure at 90°C/20 kPa for 2 hours to distill off the ethanol, thereby obtaining an aqueous solution containing cationic betaine polymer B1 (methacrylic acid 2-(dimethylamino)ethyl diethyl sulfate/N-(3-sulfopropyl)-N-methacryloyloxyethyl-N,N-dimethylammonium betaine copolymer) (content of structural units derived from 2-(dimethylamino)ethyl diethyl methacrylate sulfate: 5 mol %, content of structural units derived from N-(3-sulfopropyl)-N-methacryloyloxyethyl-N,N-dimethylammonium betaine: 95 mol %, weight average molecular weight: 65,000, cationic charge density: 0.18 meq/g).

Preparation Example 1-1 (Preparation of Pretreatment Agent I-1)
A 200 mM aqueous solution of 2-amino-2-hydroxymethyl-1,3-propanediol (TRIS) was prepared as an alkaline agent, and then a 1 mass % solution of 5,6-dihydroxyindole as compound (A) was added in an amount equal to the mass of the TRIS aqueous solution to prepare pretreatment agent I-1.

Preparation Example 2-1 (Preparation of Treatment Agent II-1)
According to the formulation shown in Table 1, an aqueous solution containing the cationic betaine polymer B1 obtained in Production Example 1 as compound (B), sodium chloride as an electrolyte, and water were blended and mixed to prepare Treatment Agent II-1.

Examples 1 to 7 and Comparative Examples 1 to 7
Using the prepared pre-treatment agent and treatment agent, a modification treatment was carried out by the following method.
In Comparative Examples 1 to 7, water was used as the pretreatment agent I-C1 and the treatment agent II-C1.
(Step 1-1)
180 mL of the pretreatment agent shown in Table 1 was added to a dyeing vat with an internal volume of approximately 200 mL, and a substrate (70 to 75 mm long x 25 mm wide x 1 mm thick) shown in Table 1 was immersed in the pretreatment agent at room temperature (25°C) for 24 hours to polymerize compound (A) and form a polymer of compound (A) on the surface of the substrate. The substrate was then removed from the pretreatment agent and rinsed with ion-exchanged water for 20 seconds to remove excess pretreatment agent, and then dried by blowing nitrogen gas over it, yielding a substrate on which a polymer of compound (A) had been formed.
(Step 1)
Next, 10 mL of the treatment agent shown in Table 1 was applied to the surface of the substrate obtained in step 1-1 on which the polymer of compound (A) had been formed, and the treatment agent was applied by leaving it to stand for 30 seconds.
Next, the substrate to which the treatment agent had been applied was rinsed with ion-exchanged water for 20 seconds to remove excess treatment agent, and then dried by blowing nitrogen gas onto it, thereby obtaining a substrate that had been hydrophilically treated with cationic betaine polymer B1 as compound (B).

(Evaluation of modification effect)
Each substrate that had been hydrophilically treated in the Examples and Comparative Examples was placed on the stage of a fully automatic contact angle measuring meter ("DM-701" manufactured by Kyowa Interface Science Co., Ltd.), and 1 μL of ultrapure water was applied, and the contact angle after 5 seconds was determined using the θ/2 method. The smaller the contact angle value, the higher the degree of hydrophilicity and the greater the modification effect. The results are shown in Table 1.

The details of the substrates shown in Table 1 are as follows:
PP: Polypropylene (manufactured by Nippon Test Panel Co., Ltd., product name "Standard Test Plate PP")
PVC: Polyvinyl chloride (manufactured by Engineering Test Services Co., Ltd., product name "Test Piece PVC")
ABS: acrylonitrile/butadiene/styrene copolymer (manufactured by Engineering Test Services Co., Ltd., product name "Test Piece ABS")
PE: Polyethylene (manufactured by Engineering Test Services Co., Ltd., product name "Test Piece PE")
PET: Polyethylene terephthalate (manufactured by Nippon Test Panel Co., Ltd., product name "Standard Test Plate PET")
PTFE: Polytetrafluoroethylene (manufactured by Engineering Test Services Co., Ltd., product name "Test Piece PTFE")
SUS: Stainless steel (manufactured by Engineering Test Services Co., Ltd., product name "Test piece SUS304")

Table 1 shows that Examples 1 to 7 have smaller contact angles, a higher degree of hydrophilicity, and a greater modification effect than Comparative Examples 1 to 7.

The method of the present invention can impart a high modification effect to the target surface and is particularly suitable as a surface hydrophilization method. Therefore, the surface modification treatment agent set of the present invention is useful, for example, as a surface hydrophilization treatment agent set.

Claims (6)

A surface modification method for modifying a target surface, comprising:
Step 1: applying a treatment agent containing a cationic compound (B) to a polymer of a compound (A) containing a benzene ring on a target surface,
the benzene ring-containing compound (A) is 5,6-dihydroxyindole,
the cationic compound (B) is a cationic betaine polymer containing a structural unit (b1) having a cationic group and a structural unit (b2) having a betaine group,
the structural unit (b1) is a structural unit derived from at least one selected from the group consisting of a quaternized product of 2-(dimethylamino)ethyl (meth)acrylate, a quaternized product of 2-(diethylamino)ethyl (meth)acrylate, and a quaternized product of 3-(dimethylamino)propyl (meth)acrylate;
A surface modification method, wherein the structural unit (b2) is a structural unit derived from at least one selected from the group consisting of N-(3-sulfopropyl)-N-(meth)acryloyloxyethyl-N,N-dimethylammonium betaine and N-(3-sulfopropyl)-N-(meth)acryloylamidopropyl-N,N-dimethylammonium betaine . 2. The surface modification method according to claim 1, wherein the structural unit (b1) is a structural unit derived from (meth)acrylic acid 2-(diethylamino)ethyl sulfate. The surface modification method according to claim 1 or 2, wherein the structural unit (b2) is a structural unit derived from N-(3-sulfopropyl)-N-(meth)acryloyloxyethyl-N,N-dimethylammonium betaine. The surface modification method according to any one of claims 1 to 3 , comprising the following step 1-1 before step 1:
Step 1-1: A step of applying a pretreatment agent containing a compound (A) having a benzene ring to a target surface, and then forming a polymer of the compound (A). The surface modification method according to any one of claims 1 to 4 , wherein the surface modification method is a surface hydrophilization method. a pretreatment agent containing a compound (A) containing a benzene ring and a treatment agent containing a cationic compound (B);
the benzene ring-containing compound (A) is 5,6-dihydroxyindole,
the cationic compound (B) is a cationic betaine polymer containing a structural unit (b1) having a cationic group and a structural unit (b2) having a betaine group,
the structural unit (b1) is a structural unit derived from at least one selected from the group consisting of a quaternized product of 2-(dimethylamino)ethyl (meth)acrylate, a quaternized product of 2-(diethylamino)ethyl (meth)acrylate, and a quaternized product of 3-(dimethylamino)propyl (meth)acrylate;
The surface modification treatment agent set includes the structural unit (b2) derived from at least one structural unit selected from the group consisting of N-(3-sulfopropyl)-N-(meth)acryloyloxyethyl-N,N-dimethylammonium betaine and N-(3-sulfopropyl)-N-(meth)acryloylamidopropyl-N,N-dimethylammonium betaine .