JP6891366B2 - Resin composition for hydrophilic coating - Google Patents

Description

The present invention relates to a resin composition for a hydrophilic coating.

By applying the hydrophilic paint, a coating film surface having a high affinity with water can be obtained. As an example of using such a hydrophilic paint, for example, by imparting hydrophilicity to the outer wall of a building, a so-called self-cleaning function is provided in which dirt on the coating film surface to which rainwater adheres is washed away during rainfall. Examples thereof include imparting hydrophilicity to a plastic or glass base material to impart antifogging performance, and imparting hydrophilicity to heat exchanger fins of an air conditioner to prevent dew condensation.

Conventionally, hydrophilic paints include inorganic materials such as water glass, organic materials such as acrylic resins and polyacrylic acids having hydrophilic groups, polyvinyl alcohol, polyethylene glycol and celluloses, and organic-inorganic hybrid materials such as acrylic silicon resins. However, it has been used alone or in combination.

However, water glass is widely used because it has a high affinity with water, exhibits good hydrophilicity, and is low in cost, but it has poor durability over time and the hardness of the obtained coating film is low. Since it is expensive, there is a problem that cracks are likely to occur. Organic materials such as acrylic resins exhibit good hydrophilicity by introducing hydrophilic groups such as carboxyl groups and amino groups into polymer molecules. In order to improve the hydrophilicity, it is necessary to increase the content of hydrophilic groups in the polymer molecule, but increasing the hydrophilic groups lowers the durability such as water resistance of the coating film. As a method for improving durability, for example, a two-component coating using a cross-linking agent such as isocyanate is used. In this case, the hydrophilic group in the polymer molecule reacts with the cross-linking agent, resulting in a polymer. The hydrophilic group in the molecule is lost, and the hydrophilicity is reduced. Although the acrylic silicone resin exhibits good physical properties in many respects such as hydrophilicity and durability, it is generally expensive and cracks due to the gradual condensation reaction of the remaining silanol groups over time. There is a problem that occurs.

Among these materials, organic materials have advantages in terms of design freedom and cost, and are being actively studied. However, there is a trade-off relationship between hydrophilicity and durability of the coating film, and it is generally difficult to achieve both of these. For example, Patent Document 1 reports a method of improving durability while maintaining hydrophilicity by cross-linking an acrylic resin, which is a hydrophilic resin, with diglycidyl ether having a polyethylene glycol group exhibiting hydrophilicity. There is. By using a nonionic polymer activator, stain resistance is improved and hydrophilicity is maintained high, but since a bifunctional epoxy resin is used as a cross-linking agent, the cross-linking density is low and the durability is not always sufficient. The actual use was limited due to the problem that the coating film could not be obtained and the coating film whitened when it came into contact with water due to the unreacted epoxy resin. Further, as described above, since the unreacted epoxy resin in the cross-linking agent adversely affects the physical characteristics of the coating film, in the case of a two-component paint using the epoxy resin as the cross-linking agent, in order to sufficiently react each resin. There is a problem that the drying time becomes relatively long.

Japanese Unexamined Patent Publication No. 2005-232269

An object of the present invention is to provide a resin composition for a hydrophilic coating, which has high liquid stability, has water resistance and adhesion, and can form a coating film having excellent hydrophilicity.

As a result of diligent studies to solve the above problems, the present inventor has (A) a polyurethane resin having an ether group, and (B) a monofunctional monofunctional having a polyoxyalkylene group and a hydrocarbon group having 1 to 30 carbon atoms. The present invention has been completed by finding that a resin composition for a hydrophilic coating containing an epoxy compound can form a coating film having high liquid stability, water resistance and adhesion, and excellent hydrophilicity.

That is, the present invention comprises (A) 90 to 70% by weight of a polyurethane resin having an ether group, and (B) 10 to 30% by weight of a monofunctional epoxy compound having a polyoxyalkylene group and a hydrocarbon group having 1 to 30 carbon atoms. The present invention relates to a resin composition for a hydrophilic coating containing%.

The polyoxyalkylene group of the monofunctional epoxy compound (B) is preferably a polyoxyethylene group.

The hydrocarbon group of the monofunctional epoxy compound (B) is preferably a chain hydrocarbon group.

（一般式（１）中、Ｘは炭素数１〜３０の鎖状炭化水素基（ここで、炭素鎖は直鎖でも分岐鎖でもよく、炭化水素鎖の一部に不飽和結合を含んでいてもよく、炭素上の水素の一部又は全てが置換されていてもよい）、又は、炭素数３〜３０の環状構造を有する炭化水素基（ここで、環は脂環又は芳香環でもよく、単環、縮環又はスピロ環でもよく、縮環とスピロ環との両方を持つものでもよく、炭素上の水素の一部又は全てが置換されていてもよい）を表し、Ｗはエーテル結合又はエステル結合を表し、Ｙは

（一般式（２）中、Ａは炭素数１〜１０の鎖状炭化水素基（ここで、炭素上の水素の一部又は全てが置換されていてもよい）を表し、ｎは１〜３０の整数を表す。）で表されるポリオキシアルキレン鎖を表し、Ｚは

（一般式（３）中、炭素上の水素の一部又は全てが置換されていてもよい。）
を表す。）
で表される単官能エポキシ化合物であることが好ましい。 The monofunctional epoxy compound (B) has the following general formula (1).

(In the general formula (1), X is a chain hydrocarbon group having 1 to 30 carbon atoms (here, the carbon chain may be a straight chain or a branched chain, and a part of the hydrocarbon chain contains an unsaturated bond. Alternatively, some or all of the hydrogen on the carbon may be substituted) or a hydrocarbon group having a cyclic structure having 3 to 30 carbon atoms (where, the ring may be an alicyclic ring or an aromatic ring. It may be a monocycle, a fused ring or a spiro ring, it may have both a condensed ring and a spiro ring, and some or all of the hydrogen on the carbon may be substituted), and W is an ether bond or Represents an ester bond, where Y is

(In the general formula (2), A represents a chain hydrocarbon group having 1 to 10 carbon atoms (here, a part or all of hydrogen on the carbon may be substituted), and n is 1 to 30. Represents a polyoxyalkylene chain represented by), where Z represents

(In the general formula (3), a part or all of hydrogen on carbon may be substituted.)
Represents. )
It is preferably a monofunctional epoxy compound represented by.

The present invention also relates to a hydrophilic treatment member characterized by having a hydrophilic coating film formed from the hydrophilic coating resin composition on a base material.

The base material is preferably made of aluminum or an aluminum alloy.

The resin composition for hydrophilic coating of the present invention is monofunctional having (A) 90 to 70% by weight of a polyurethane resin having an ether group, and (B) a polyoxyalkylene group and a hydrocarbon group having 1 to 30 carbon atoms. Since it contains 10 to 30% by weight of the epoxy compound, the liquid stability of the composition itself is high, and the obtained coating film has excellent water resistance and adhesion and is excellent in hydrophilicity. Although the specific mechanism of hydrophilicity is not clear, the monofunctional epoxy compound (B) that has reacted with the polyurethane resin (A) is oriented in the vertical direction to form a fine uneven structure on the coating film surface. It is estimated that the wettability (hydrophilicity) will be significantly improved.

It is an observation result of AFM of the hydrophilic coating film formed from the resin composition for hydrophilic coating of Example 2. It is an observation result of AFM of the hydrophilic coating film formed from the resin composition for hydrophilic coating of Comparative Example 1.

<< Resin composition for hydrophilic coating >>
The resin composition for hydrophilic coating of the present invention is monofunctional having (A) 90 to 70% by weight of a polyurethane resin having an ether group, and (B) a polyoxyalkylene group and a hydrocarbon group having 1 to 30 carbon atoms. It is characterized by containing 10 to 30% by weight of an epoxy compound.

The polyurethane resin (A) having an ether group is a polycondensate of a compound containing an isocyanate group and a compound containing a hydroxyl group, and a compound having an ether group is always used as a monomer as a compound having a hydroxyl group.

The compound containing an isocyanate group is not particularly limited as long as it has an isocyanate group, but for example, tris such as 2,4-tolylene diisocyanate (2,4-TDI) and 2,6-tolylene diisocyanate (2,6-TDI). Diphenylmethane diisocyanate (MDI) such as range isocyanate (TDI), 4,4'-diphenylmethane diisocyanate (4,4'-MDI), 2,4'-diphenylmethane diisocyanate (2,4'-MDI), 1,4-phenylene Diisocyanate, Polymethylenepolyphenylene polyisocyanate, Xylylene diisocyanate (XDI), Tetramethylxylylene diisocyanate (TMXDI), Trizine diisocyanate (TODI), 1,5-naphthalenediocyanate (NDI), Triphenylmethane triisocyanate, Polymeric diphenylmethane diisocyanate, etc. Aromatic polyisocyanates or hydrogenated compounds thereof, ethylene diisocyanates, propylene diisocyanates, tetramethylene diisocyanates, hexamethylene diisocyanates (HDI), trimethylhexamethylene diisocyanates (TMHDI), lysine diisocyanates, norbornan diisocyanates (NBDI) and other aliphatic polyisocyanates. , Carbodiimide-modified polyisocyanate or isocyanurate-modified polyisocyanate of the above aliphatic polyisocyanate, transcyclohexane-1,4-diisocyanate, isophorone diisocyanate (IPDI), bis (isocyanatemethyl) cyclohexane (H6XDI), dicyclohexylmethane diisocyanate (H12MDI), Alicyclic polyisocyanate such as 4,4'-dicyclohexyldiisocyanate, isocyanodiisocyanate, 1,3-bis (isocyanatomethylcyclohexane), carbodiimide-modified polyisocyanate or isocyanurate-modified polyisocyanate of the above-mentioned alicyclic polyisocyanate, or , Aryl aliphatic polyisocyanate such as xylylene diisocyanate or a hydrogenated compound thereof.

The compound containing a hydroxyl group is not particularly limited as long as it has a hydroxyl group, but for example, bisphenol A, bisphenol F, bisphenol C, bisphenol K, bisphenol Z, bisphenol S, tetramethyl bisphenol A, tetramethyl bisphenol F, tetramethyl bisphenol S, tetra. Bisphenols such as methylbisphenol Z, dihydroxydiphenylsulfide, 4,4'-thiobis (3-methyl-6-tert-butylphenol), catechol, resorcin, methylresorcin, hydroquinone, monomethylhydroquinone, dimethylhydroquinone, trimethylhydroquinone, mono- Dihydroxybenzenes such as tert-butylhydroquinone and di-tert-butylhydroquinone, dihydroxynaphthalene such as dihydroxynaphthalene, dihydroxymethylnaphthalene and dihydroxydimethylnaphthalene, dihydroxyanthracenes such as dihydroxyanthracene, dihydroxymethylanthracene and dihydroxydimethylanthracene, 9 , 9'-bis (4-hydroxyphenyl) fluorene, 9,9'-bis (4-hydroxy-3-methylphenyl) fluorene and other dihydroxyfluorenes, 1,4-cyclohexanedimethanol and other alicyclic polyols , Isosorbide, Isomannide, Isoidit, Spiroglycol, 2,4: 3,5-di-O-methylene-mannitol, 2,3: 4,5-di-O-methylene-galactose and other polyols having a heterocycle. , Alibi polyols such as sorbitol, mannitol, galactose, ethylene glycol and glycol, polyether polyols such as polyethylene glycol, polypropylene glycol and polytetramethylene glycol and the like can be used. Of these compounds having a hydroxyl group, a compound having an ether group is always used. These compounds may be used alone or in combination of two or more.

The average particle size of the polyurethane resin is preferably 1000 nm or less, more preferably 500 nm or less. With such an average particle size, the storage stability of the aqueous dispersion, the water resistance and the solvent resistance of the coating film are further improved. The average particle size is preferably 10 nm or more, more preferably 100 nm or more, from the viewpoint of the viscosity characteristics and storage stability of the resin composition for hydrophilic coating. That is, the average particle size of the polyurethane resin (A) of the present invention is preferably 10 to 1000 nm, more preferably 100 to 500 nm. The polyurethane resin (A) may be used alone or in combination of two or more.

In the hydrophilic coating resin composition of the present invention, the content of the polyurethane resin (A) in the total of 100% by weight of the polyurethane resin (A) and the monofunctional epoxy compound (B) is 90 to 70% by weight. It is preferably 85 to 75% by weight. If the content of the polyurethane resin (A) is less than 70% by weight, the drying property becomes insufficient, and a long drying time or a relatively high drying temperature may be required. If the content exceeds 90% by weight, the drying property may be required. , The hydrophilicity of the coating film may be insufficient due to insufficient content of the monofunctional epoxy compound (B).

（一般式（１）中、Ｘは炭素数１〜３０の鎖状炭化水素基（ここで、炭素鎖は直鎖でも分岐鎖でもよく、炭化水素鎖の一部に不飽和結合を含んでいてもよく、炭素上の水素の一部又は全てが置換されていてもよい）、又は、炭素数３〜３０の環状構造を有する炭化水素基（ここで、環は脂環又は芳香環でもよく、単環、縮環又はスピロ環でもよく、縮環とスピロ環との両方を持つものでもよく、炭素上の水素の一部又は全てが置換されていてもよい）を表し、Ｗはエーテル結合又はエステル結合を表し、Ｙはポリオキシアルキレン鎖を表し、Ｚは

（一般式（３）中、炭素上の水素の一部又は全てが置換されていてもよい。）
を表す。）
で表される単官能エポキシ化合物が好ましい。 The monofunctional epoxy compound (B) having a polyoxyalkylene group and a hydrocarbon group having 1 to 30 carbon atoms is not particularly limited as long as it has a polyoxyalkylene group, a hydrocarbon group having 1 to 30 carbon atoms, and an epoxy group. The following general formula (1)

(In the general formula (1), X is a chain hydrocarbon group having 1 to 30 carbon atoms (here, the carbon chain may be a straight chain or a branched chain, and a part of the hydrocarbon chain contains an unsaturated bond. Alternatively, some or all of the hydrogen on the carbon may be substituted) or a hydrocarbon group having a cyclic structure having 3 to 30 carbon atoms (where, the ring may be an alicyclic ring or an aromatic ring. It may be a monocycle, a fused ring or a spiro ring, it may have both a condensed ring and a spiro ring, and some or all of the hydrogen on the carbon may be substituted), and W is an ether bond or Represents an ester bond, Y represents a polyoxyalkylene chain, Z represents a polyoxyalkylene chain

(In the general formula (3), a part or all of hydrogen on carbon may be substituted.)
Represents. )
The monofunctional epoxy compound represented by is preferable.

In the general formula (1), X is a hydrophobic group and is a chain hydrocarbon group having 1 to 30 carbon atoms, preferably 3 to 20 carbon atoms (here, the carbon chain may be a straight chain or a branched chain, and is carbonized. An unsaturated bond may be contained in a part of the hydrogen chain, and a part or all of the hydrogen on the carbon may be substituted), or the number of carbon atoms is 3 to 30, preferably 3 to 12 carbon atoms. A hydrocarbon group having a cyclic structure (here, the ring may be an alicyclic ring or an aromatic ring, a monocyclic ring, a condensed ring or a spiro ring, or one having both a condensed ring and a spiro ring, and hydrogen on carbon. Part or all of the above may be replaced). X is preferably a chain hydrocarbon group having 1 to 30 carbon atoms.

In the general formula (1), W is a bonding group and represents an ether bond or an ester bond.

In the general formula (1), Y is a hydrophilic group and represents a polyoxyalkylene group represented by the following general formula (2).

In the general formula (2), A is a chain hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 4 carbon atoms (here, a part or all of hydrogen on the carbon may be substituted). Represent. The chain hydrocarbon group having 1 to 10 carbon atoms is not particularly limited, and examples thereof include a methylene group, an ethylene group, a propylene group, a butylene group, and an isopropylene group. Among these, from the viewpoint of hydrophilicity of the coating film, an ethylene group and / or an isopropylene group is preferable, and an ethylene group is more preferable.

In the general formula (2), n is not particularly limited as long as it is an integer of 1 to 30, but is preferably an integer of 3 to 23, and more preferably an integer of 3 to 18. If n exceeds 30, the reactivity may decrease due to steric hindrance and the drying property may become insufficient.

In the general formula (1), Z represents a structure represented by the following general formula (3).

In the general formula (3), a part or all of hydrogen on carbon may be substituted.

In the present specification, when it is described that "a part or all of hydrogen on carbon may be substituted", the substituent is not particularly limited, but for example, a methyl group, an ethyl group, a propyl group, and the like. Examples thereof include an alkyl group such as an isopropyl group, an alkoxy group such as a methoxy group and an ethoxy group, and the like.

These monofunctional epoxy compounds (B) may be used alone or in combination of two or more. Further, an epoxy compound other than the monofunctional epoxy compound (B) may be optionally used in combination as long as the object of the present invention is not impaired.

In the hydrophilic coating resin composition of the present invention, the content of the compound (B) in the total 100% by weight of the polyurethane resin (A) and the monofunctional epoxy compound (B) is 10 to 30% by weight, but 15 More preferably ~ 25% by weight. If the content of the compound (B) is less than 10% by weight, the hydrophilicity of the coating film may be insufficient, and if it exceeds 30% by weight, the drying property may be insufficient.

<Curing catalyst>
A curing catalyst can also be added to the resin composition for hydrophilic coating of the present invention. The curing catalyst is not particularly limited, and conventionally known ones can be used. For example, tin compounds such as dibutyltin dilaurate and dibutyltin diacetate, bismuth compounds such as bismuth octylate, tetraoctyl titanate, and titanium ethyl can be used. Examples thereof include titanium compounds such as acetoacetate, zirconium compounds such as zirconium monoacetylacetate and zirconium tetraacetylacetate, triethylenediamine, and amines such as 1,4-diazabicyclo [2,2,2] octane (DABCO). These may be used alone or in combination of two or more.

In addition to the polyurethane resin (A) having an ether group and the monofunctional epoxy compound (B), the resin composition for hydrophilic coating of the present invention optionally contains other components as long as the object of the present invention is not impaired. It may be contained. Other components are not particularly limited, but are, for example, solvents, curing accelerators, defoaming agents, leveling agents, organic thickeners, antioxidants, light stabilizers, adhesive improvers, mold release agents, reinforcing materials. , Softeners, colorants, flame retardants, antistatic agents, wet dispersants and the like.

<Solvent>
The solvent is not particularly limited, and either an aqueous solvent or an organic solvent solvent can be preferably used. For example, aromatic hydrocarbon solvents such as toluene, ethylbenzene, trimethylbenzene and xylene, and fats such as pentane, hexane and cyclohexane are used. Group hydrocarbon solvents, ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, alcohol solvents such as methanol, ethanol, isopropanol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, methyl cellosolve, ethyl cellosolve, Examples thereof include glycol ether solvents such as butyl cellosolve, methyl diglycol, ethyl diglycol, butyl diglycol and propylene glycol monomethyl ether, ester solvents such as ethyl acetate, butyl acetate and propylene glycol monomethyl ether acetate, and water. Examples of commercially available products that can be used as an aromatic hydrocarbon solvent include Solbesso 100, Solbesso 150, and Solbesso 200. These may be used alone or in combination of two or more.

The content of the solvent may be selected depending on the coating method and the desired film thickness of the hydrophilic coating film, and is not particularly limited, but is based on 100 parts by weight of the total of the polyurethane resin (A) and the monofunctional epoxy compound (B). 10 to 2000 parts by weight is preferable, and 20 to 1000 parts by weight is more preferable. If the content is less than 10 parts by weight, the viscosity of the resin composition for hydrophilic coating becomes high and coating may become difficult, and if it exceeds 2000 parts by weight, the film thickness of the hydrophilic coating film becomes thin. The hydrophilicity of the coating film may be insufficient.

<Leveling agent>
The leveling agent is not particularly limited, but for example, polyoxyethylene alkyl ethers, polyoxyethylene aryl ethers, silicon-based surfactants, nonionic surfactants, fluorine-based surfactants, acrylic surfactants and the like. Can be mentioned. These may be used alone or in combination of two or more.

<< Hydrophilic treatment member >>
The hydrophilic treatment member of the present invention is characterized by having a hydrophilic coating film formed from the resin composition for hydrophilic coating of the present invention on a base material.

The material of the base material is not particularly limited, and examples thereof include metals such as aluminum, aluminum alloys, and steels such as stainless steel, and glass. Among these, metal is preferable because the interaction between the surface of the base material and the surface of the hydrophilic coating film and the anchoring effect on the uneven portion of the surface of the base material can be expected. Aluminum or an aluminum alloy is more preferable because of its high versatility. The base material may have a primer coating film on its surface. Specific uses of the hydrophilic treatment member include aluminum fins for heat exchangers used in air conditioners and the like, and medical devices such as surgical scalpels and tweezers.

The hydrophilic coating film is formed from the resin composition for hydrophilic coating of the present invention. The method for forming the hydrophilic coating film using the hydrophilic coating resin composition of the present invention is not particularly limited, but the hydrophilic coating resin composition of the present invention is applied to at least one surface of the substrate. After that, a method of heating and curing can be mentioned.

The method for applying the hydrophilic coating resin composition of the present invention is not particularly limited, but for example, a bar coating method, a spin coating method, a spray coating method, a dip coating method, a nozzle coating method, a gravure coating method, and a reverse roll. Coating method, die coating method, air doctor coating method, blade coating method, rod coating method, curtain coating method, knife coating method, transfer roll coating method, squeeze coating method, impregnation coating method, kiss coating method, calendar coating method, extrusion coating method. And so on.

In the method of heating and curing, the heating temperature is not particularly limited, but is preferably 60 to 300 ° C, more preferably 100 to 250 ° C. If the heating temperature is less than 60 ° C., curing may be poor, and if it exceeds 300 ° C., the shape of the base material may be impaired depending on the material of the base material. The heating time is not particularly limited, but is preferably 5 to 120 seconds, more preferably 10 to 60 seconds. If the heating time is less than 5 seconds, curing may be poor, and if it exceeds 120 seconds, the shape of the base material may be impaired depending on the material of the base material, and the time required for the process becomes long. Therefore, it is not preferable from the viewpoint of productivity.

The thickness of the hydrophilic coating film is not particularly limited, but is preferably 0.05 to 40 μm, more preferably 0.1 to 20 μm. If the thickness is less than 0.05 μm, the hydrophilicity may be insufficient, and if it exceeds 40 μm, the adhesion of the hydrophilic coating film may be insufficient.

Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to the following examples. Hereinafter, "parts" or "%" means "parts by weight" or "% by weight", respectively, unless otherwise specified.

(Material used)
In the following examples and comparative examples, the following materials were used.
<Polyurethane resin>
(A-1) Ether-based polyurethane: Superflex 130, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd. (A-2) Ether-based polyurethane: Superflex 170, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd. (A-3) Ether-based polyurethane: X -7096, manufactured by Nikka Kagaku Co., Ltd. (A-4) Polycarbonate polyurethane: HA-170 manufactured by Nikka Kagaku Co., Ltd. <monofunctional epoxy compound>
(B-1) Lauryl alcohol (EO) 15 glycidyl ether: EX-171, manufactured by Nagase ChemteX Corporation (B-2) Polyoxyethylene (23) Lauryl ether: Emargen 123P, manufactured by Kao Corporation

Examples 1 to 3 and Comparative Examples 1 to 5
Each component was mixed by the solid content weight ratio shown in Table 1 to obtain a resin composition for hydrophilic coating. The solid content concentration is 20%, and the balance is water. The obtained hydrophilic coating resin composition was applied onto an aluminum plate as a base material using a bar coater (No. 6). The applied base material was placed in a hot air dryer at 240 ° C. and heat-treated for 30 seconds to form a hydrophilic coating film. The thickness of the coating film was 1.5 μm. After drying, the base material was cooled to room temperature and used as a test piece. Using the obtained test piece, the physical properties were evaluated by the method described later. The results are shown in Table 1.

<Contact angle>
Approximately 20 μL of pure water was dropped onto the test piece, and the contact angle was measured using a contact angle measuring device (CA-D type contact angle meter manufactured by Kyowa Surface Chemistry Co., Ltd.).

<Water resistance>
The test piece immediately after preparation was immersed in running water of 3 L / min, and after 24 hours, the contact angle was measured by the method described above. In the test pieces of Comparative Examples 3 to 5, the film was roughened and the contact angle could not be measured.

<Adhesion>
According to JIS K5600, the adhesion of the hydrophilic coating film to the aluminum base material immediately after the preparation of the test piece was confirmed, and the evaluation was made in two stages according to the following criteria.
○: No peeling ×: With peeling

<Liquid stability>
The appearance of the prepared coating liquid after being left at room temperature for one week was confirmed, and the coating liquid was evaluated in two stages according to the following criteria.
○: No change ×: With sedimentation

<Observation of surface condition>
When AFM (manufactured by SII Nanotechnology, SPI3800Ne) was measured in order to observe the surface condition of the hydrophilic coating film, it is shown in FIG. 1 as compared with the composition consisting only of the polyurethane resin shown in FIG. 2 (Comparative Example 1). In Example 2, it was confirmed that the coating film formed a fine uneven structure on the surface of the base material, and the surface roughness was increased. The surface roughness was 0.90 nm in the coating film of Example 2 and 0.53 nm in the coating film of Comparative Example 1. It is known that the wettability of the surface changes due to the influence of the fine uneven structure (Wenzel's law), but the hydrophilic coating film of the present invention also has significantly improved wettability (hydrophilicity) based on this law. It is presumed that it is.

From the results in Table 1, the resin composition for hydrophilic coating of the present invention has excellent liquid stability, the obtained coating film has high water resistance and adhesion to an aluminum substrate, and the contact angle is very small to make it hydrophilic. It turns out to be excellent. Moreover, the hydrophilicity was maintained even after the water resistance test.

Claims (6)

Hydrophilicity containing (A) 90 to 70% by weight of a polyurethane resin having an ether group and (B) 10 to 30% by weight of a monofunctional epoxy compound having a polyoxyalkylene group and a hydrocarbon group having 1 to 30 carbon atoms. Resin composition for coating. The resin composition for hydrophilic coating according to claim 1, wherein the polyoxyalkylene group of the monofunctional epoxy compound (B) is a polyoxyethylene group. The resin composition for hydrophilic coating according to claim 1 or 2, wherein the hydrocarbon group of the monofunctional epoxy compound (B) is a chain hydrocarbon group. The monofunctional epoxy compound (B) has the following general formula (1).

(In the general formula (1), X is a chain hydrocarbon group having 1 to 30 carbon atoms (here, the carbon chain may be a straight chain or a branched chain, and a part of the hydrocarbon chain contains an unsaturated bond. Alternatively, some or all of the hydrogen on the carbon may be substituted) or a hydrocarbon group having a cyclic structure having 3 to 30 carbon atoms (where, the ring may be an alicyclic ring or an aromatic ring. It may be a monocycle, a fused ring or a spiro ring, it may have both a condensed ring and a spiro ring, and some or all of the hydrogen on the carbon may be substituted), and W is an ether bond or Represents an ester bond, where Y is

(In the general formula (2), A represents a chain hydrocarbon group having 1 to 10 carbon atoms (here, a part or all of hydrogen on the carbon may be substituted), and n is 1 to 30. Represents a polyoxyalkylene group represented by), where Z represents

(In the general formula (3), a part or all of hydrogen on carbon may be substituted.)
Represents. )
The resin composition for hydrophilic coating according to any one of claims 1 to 3, which is a monofunctional epoxy compound represented by. A hydrophilic treatment member having a hydrophilic coating film formed from the hydrophilic coating resin composition according to any one of claims 1 to 4 on a base material. The hydrophilic treatment member according to claim 5, wherein the base material is aluminum or an aluminum alloy.

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