JP2005002350A - Hydrophilizing treatment agent, its production process and method for hydrophilization of coated film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydrophilizing treatment agent capable to simply hydrophilize surface by a simple and effective coating such as spraying. <P>SOLUTION: The hydrophilizing treatment agent contains a hydrolyzate of silicate compounds shown by formula (1), a nonionic surfactant, water and a hydrophilic organic solvent. The above mentioned nonionic surfactant has an alkylene oxide unit with an HLB of 10-15 and 0.02-10 mass% to the amount of water wherein n represents an integer of 1-30, R<SP>1</SP>s may represent different optionally substituted 1-8C alkyl groups. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a hydrophilizing agent, a method for producing the same, and a method for hydrophilizing a coating film.

In many cases, various pollutants adhere to the coating film installed outdoors, and the appearance is impaired. For this reason, the stain resistance of the coating film has been improved by adding a silicate compound to make the coating film surface hydrophilic.
For example, Japanese Patent Application Laid-Open No. 10-140077 discloses an automotive top coating in which a low-condensation product (silicate low-condensation product) having a condensation degree of 2 to 10 of tetramethyl silicate and / or tetraethyl silicate is blended with an acid epoxy curing coating. It is disclosed. The coating film obtained from this paint may not have sufficient initial stain resistance depending on the environment in which it is placed. Furthermore, the surface of the coating film is polished and lost in hydrophilicity during repair in the painting line, and as a result, only the repaired part has a problem of poor appearance due to a decrease in contamination resistance.

On the other hand, Japanese Patent Application Laid-Open No. 2000-256619 discloses a silicon compound or a hydrolysis condensate thereof (a) or a mixture of (a) and a catalyst capable of hydrolyzing a silicon compound and / or an organic solvent on the top coating film. A method for antifouling treatment of a top coat film applied to the surface is disclosed. However, since the coating film formed on the surface by this stain-resistant treatment method is hydrophilized by rainfall, the initial stain resistance is insufficient.

Furthermore, International Publication No. 95/17349 discloses a hard coat composition obtained by blending tetramethoxysilane with water. Although this composition can form a film by an impregnation method, it has a problem that the film is broken by a spray method. Moreover, there is no description about the objective of hydrophilizing the surface with this composition.

An object of the present invention is to provide a hydrophilizing agent capable of easily hydrophilizing the surface by simple and efficient application such as spraying.

The present invention includes a hydrolyzate of a silicate compound represented by the following formula (1), a nonionic surfactant, water and a hydrophilic organic solvent, and the nonionic surfactant has an alkylene oxide unit. The hydrophilizing agent has an HLB of 10 to 15 and an amount of 0.02 to 10% by mass relative to the water.

(Wherein n represents an integer of 1 to 30; R ¹ may represent a different one, and represents a C 1-8 alkyl group having a substituent or not having a substituent) It is preferable that content of the hydrolyzate of a silicate compound is 0.05-10 mass%.

The present invention also hydrolyzes a silicate compound represented by the following formula (1) in a mixed solution of water and a hydrophilic organic solvent, and has an alkylene oxide unit, and its HLB is 10-15. It is a method for producing a hydrophilizing agent characterized by adding a nonionic surfactant.

(Wherein n represents an integer of 1 to 30; R ¹ may represent a different one, and represents a C 1-8 alkyl group having a substituent or not having a substituent) The addition of the nonionic surfactant may be performed before the hydrolysis, or may be performed after the hydrolysis.
The present invention is also a method for hydrophilizing a coating film characterized by applying the above-described hydrophilic treatment agent to the coating film surface.

The hydrophilic treatment agent of the present invention contains a hydrolyzate of a silicate compound, a nonionic surfactant, water and a hydrophilic organic solvent.
The hydrolyzate of the silicate compound is obtained by hydrolyzing the silicate compound represented by the above formula (1).

In said formula (1), n represents the integer of 1-30. When it exceeds 30, the particle property of a silicate compound will become high and a malfunction will arise in an external appearance, such as a coating film becoming cloudy. From the viewpoint of setting the hydrolyzate of the silicate compound to an appropriate viscosity, 1 to 25 is preferable, and 5 to 25 is more preferable.

In the above formula (1), R ¹ may represent a different one and represents a C 1-8 alkyl group having a substituent or not having a substituent. If the number of carbon atoms exceeds 8, the hydrolyzability is lowered, which is not preferable. A C1-C4 alkyl group is still more preferable, and a C1-C2 alkyl group is especially preferable. Most preferred is a methyl group.

Examples of the alkyl group having 1 to 8 carbon atoms having a substituent or not having a substituent include, for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, and a tert-butyl group. Examples thereof include linear or branched groups such as a group, n-amyl group, isoamyl group, neoamyl group, hexyl group, heptyl group, octyl group and 2-ethylhexyl group. Among these, a methyl group, an ethyl group, a propyl group, an isopropyl group, and an n-butyl group are preferable. More preferred are a methyl group and an ethyl group, and particularly preferred is a methyl group.
Examples of the substituent for the alkyl group include, but are not limited to, halogens such as chloro and bromo; alkoxy groups such as methoxy and ethoxy; cyano groups and dimethylamino groups. Even if it has the said substituent, it is preferable that carbon number of an alkyl group is 1-8.

Specific examples of the silicate compound in which R ¹ has a substituent or is an alkyl group having 1 to 8 carbon atoms that has no substituent include tetramethoxysilane, tetraethoxysilane, tetra-n-propoxysilane, tetra- iso-propoxysilane, tetra-n-butoxysilane, tetra-sec-butoxysilane, tetra-tert-butoxysilane, tetra-n-pentoxysilane, tetra-iso-pentoxysilane, tetraneopentoxysilane, etc .; 1 type, or 2 or more types of condensates. Preferred is methyl silicate and / or a condensate thereof, or ethyl silicate and / or a condensate thereof, and most preferred is a condensate of methyl silicate.

Examples of the methyl silicate condensate include commercially available products such as “MKC silicate MS51”, “MKC silicate MS56”, and “MKC silicate MS60” (all trade names, manufactured by Mitsubishi Chemical Corporation).
Examples of the ethyl silicate condensate include commercially available products such as “ethyl silicate 28”, “ethyl silicate 40”, and “ethyl silicate 48” (both trade names, manufactured by Colcoat).

The hydrolyzate can be obtained by reacting the alkoxysilyl group of the silicate compound with an equivalent amount or more of water and the silicate compound. The reaction proceeds at room temperature, but can be heated if necessary. Preferably, the silicate compound hydrolyzate can be obtained by adding the silicate compound to a large excess amount of water containing the catalyst and leaving it to stand. As said catalyst, what is generally used for a hydrolysis reaction can be used. For example, inorganic acids such as hydrochloric acid, acetic acid, nitric acid, formic acid, sulfuric acid, phosphoric acid; organic acids such as formic acid, acetic acid, propionic acid, oxalic acid, p-toluenesulfonic acid, benzoic acid, phthalic acid, maleic acid; potassium hydroxide Alkali catalysts such as sodium hydroxide, calcium hydroxide and ammonia; organometallics; metal alkoxides, eg organotin compounds such as dibutyltin dilaurate, dibutyltin dioctiate, dibutyltin diacetate, aluminum tris (acetylacetonate), titanium Tetrakis (acetylacetonate), Titanium bis (butoxy) bis (acetylacetonate), Titanium bis (isopropoxy) bis (acetylacetonate), Zirconium tetrakis (acetylacetonate), Zirconium bis (butoxy) bis ( Cetyl acetonate) and zirconium bis (isopropoxy) bis (acetylacetonate) metal chelate compounds such as boron butoxide, may be mentioned boron compounds such as boric acid. The amount of the catalyst is not particularly limited, but can usually be 0.1 to 5% by mass with respect to the silicate compound.

Moreover, since the said silicate compound is not sufficiently soluble in water, it is preferable to make the system uniform by adding a hydrophilic organic solvent in order to proceed the hydrolysis reaction efficiently. Such hydrophilic organic solvents are preferably those that are freely miscible in water, such as methanol, ethanol, isopropyl alcohol, etc. as alcohols; ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl as glycol derivatives; Ether, ethylene glycol mono n-propyl ether, ethylene glycol mono n-butyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, etc .; ketones such as acetone and methyl ethyl ketone; dioxane, tetrahydrofuran Etc. can be used. The amount of the hydrophilic organic solvent added is not particularly limited as long as it is at least an amount capable of dissolving the silicate compound.

The hydrolyzate can confirm that the peak based on the alkoxysilyl group has disappeared by measuring the IR spectrum. That is, the hydrolyzate of the silicate compound is considered to have a structure in which the alkoxysilyl group in the above formula (1) is hydrolyzed to a silanol group. By having this silanol group, it is considered that hydrophilicity appears immediately after coating. However, in the hydrolyzate, all alkoxysilyl groups may not be hydrolyzed to silanol groups. Usually, in a homogeneous system containing a catalyst, the desired hydrolyzate can be obtained by leaving it to stand at room temperature for 12 hours or more.
Since the hydrolyzate obtained in this way may be subjected to a condensation reaction between the hydrolysates when it is isolated, it may be used as a solution obtained by hydrolysis. preferable.

The content of the hydrolyzate of the silicate compound in the hydrophilizing agent is preferably an amount corresponding to 0.05 to 10% by mass as the silicate compound before hydrolysis. If it is less than 0.05% by mass, sufficient hydrophilicity cannot be imparted, and if it exceeds 10% by mass, the appearance of the resulting film may be deteriorated. More preferably, it is 0.1-5 mass%, Most preferably, it is 0.1-3 mass%.

The said nonionic surfactant contained in the hydrophilization treatment agent of this invention makes the uniform application | coating of a hydrophilization treatment agent independent of an application means by reducing the surface tension of water. On the other hand, in the case of a cationic surfactant or an anionic surfactant, the stability of the hydrophilizing agent may be lowered or uniform coating may not be possible.

As said nonionic surfactant, what has an alkylene oxide unit as a hydrophilic group is used. As such, polyalkylene glycol monoalkyl ether is preferable. HLB which is a parameter | index of the balance of the hydrophilic property of the said nonionic surfactant and hydrophobicity is 10-15. Outside these ranges, it may not be possible to apply uniformly. The HLB is a value obtained by multiplying the value obtained by dividing the molecular weight of the entire nonionic surfactant by the molecular weight of the alkylene oxide unit part by 20 times.

Examples of the alkylene oxide unit include ethylene oxide, propylene oxide, and tetramethylene oxide. Among these, ethylene oxide and propylene oxide are preferable. Moreover, it is preferable that the repeating number of the said alkylene oxide unit is 7-10. Moreover, it is preferable that carbon number of the alkyl group of alkyl ether is 12-18.

Content in the hydrophilization processing agent of the said nonionic surfactant is 0.02-10 mass% with respect to the water contained in a hydrophilization processing agent. If it is less than 0.02% by mass, the hydrophilic treatment agent cannot be applied uniformly, and if it exceeds 10% by mass, no improvement in the effect is observed and the coating film performance may be inferior. More preferably, it is 0.1 to 5% by weight.

The hydrophilic treatment agent of the present invention contains water and a hydrophilic organic solvent as a solvent. As the hydrophilic organic solvent, those mentioned above can be used, but methanol, ethanol and isopropyl alcohol are particularly preferable in consideration of volatility and solubility. Although the mass ratio of water and a hydrophilic organic solvent is not specifically limited, For example, it can be set to 5 / 95-95 / 5.

The hydrophilizing agent can be obtained by mixing each of the above components. A predetermined amount of nonionic surfactant is added to a solution obtained by hydrolysis of the silicate compound or a solution before hydrolysis. It can also be obtained by a method of adding an agent.
In these cases, it is preferable to blend each component so as to have a predetermined concentration, but by diluting with water and / or a hydrophilic organic solvent, the solution obtained by hydrolyzing the silicate compound, It can also be adjusted to a predetermined concentration. In addition, the hydrophilization treatment agent obtained by this method contains the above catalyst used for hydrolysis.

The hydrophilic treatment agent can be applied to various substrates as long as the surface is not eroded. In particular, by applying on the coating film, the surface can be hydrophilized and the coating film can be imparted with stain resistance.
The method for hydrophilizing a coating film according to the present invention is characterized in that the hydrophilic treatment agent is applied to the surface of the coating film. The coating film to be applied is not particularly limited, and generally includes a top coating film in various fields such as architectural use, automobile use, and industrial use. These top coat films can be formed by various paints such as solvent-based, water-based, powder, and UV curable systems. Moreover, since stain resistance is provided by application | coating, it is preferable that it is a coating film formed on the articles | goods used outdoors. More preferably, it is a top coat film for automobile bodies. The topcoat coating film may be a hydrophilic or hydrophilic coating film or a normal coating film. When the top coat film is a hydrophilic or hydrophilizable paint film, the method of hydrophilizing the paint film is an auxiliary means for imparting hydrophilicity, while the top coat film is a normal paint film. In this case, the method for hydrophilizing the coating film becomes a new function imparting means to the coating film. The application to the top coat film is preferably performed at the time of repairing on the line or outside the line.

The application method is not particularly limited, and examples thereof include spray coating, roll coater method, brush coating, dip coating, and wipe coating. As a drying method after the above coating, it may be left to dry at room temperature, or may be performed by heating at 40 to 100 ° C. for about 1 to 30 minutes.
As a dry film thickness of the said hydrophilic treatment agent, 0.01-10 micrometers is preferable. When the thickness is less than 0.01 μm, the stain resistance may not be obtained over a long period of time. When the thickness exceeds 10 μm, the transparency of the coating film may be inferior or cracking may occur. More preferably, it is 0.01-5 micrometers.

Since the hydrophilic treatment agent of the present invention has the above-described configuration, the surface can be easily hydrophilized by simple and efficient application such as spraying.
The method for producing a hydrophilic treatment agent of the present invention can easily obtain a desired hydrophilic treatment agent.
The method for hydrophilizing a coating film of the present invention can easily impart hydrophilicity to a coating film that does not have hydrophilicity to form a stain-resistant coating film.

Example 1 Production of Hydrophilization Treatment Agent “MKC Silicate MS51” (Mitsubishi Chemical Methyl Silicate Condensate, SiO ₂ Content 51%; n in Formula (1) is 5 as an Average Value) Tris (2 , 4-Pentandionate) 2.5 g of an aluminum 10% ethanol solution was added and dissolved. To 1.5 g of this mixed solution, 0.0114 g (0.02% by mass with respect to water) of polyethylene glycol monolauryl ether (repetition number of ethylene oxide unit: 10; HLB14.1) was added and dissolved in 41 g of ethanol. Subsequently, 57 g of water was gradually added and stirred, and left overnight at room temperature to obtain a hydrophilic treatment agent A.

Examples 2 to 7 and Comparative Examples 1 to 4 Production of hydrophilization treatment agent In Example 1, as the nonionic surfactant, the types and amounts shown in Table 1 were used in the same manner, and the hydrophilic treatment agent was used. Treatment agents B to G and comparative hydrophilization treatment agents a to d were obtained.

Example 8 Production of hydrophilization treatment agent In Example 1, instead of “MKC silicate MS51”, “MKC silicate MS60” (Mitsubishi Chemical's methyl silicate condensate, SiO ₂ content 60%; formula (1) N is an average value of 26) 100 g, and the hydrophilic treatment agent H is obtained in the same manner except that the amount of polyethylene glycol monolauryl ether is 0.318 g (0.56% by mass with respect to water). It was.

Examples 9 to 16, Comparative Examples 5 to 9 Hydrophilization method of coating film Unipon 400HK Taxi Yellow (manufactured by Nippon Paint Co., Ltd., acrylic / polyester polyol / isocyanate curing system) on a polished steel plate so that the dry film thickness is 45 to 55 μm. Spray coating was performed and baking was performed at 90 ° C. for 20 minutes to obtain a cured coating film. On this coating film, the hydrophilic treatment agents A to H and a to d obtained in Examples 1 to 8 and Comparative Examples 1 to 4 are sprayed to a dry film thickness of 0.1 to 0.5 μm. After coating in this manner, it was dried at 60 ° C. for 5 minutes. About the obtained coating-film surface, while observing visually and finger touch, the water contact angle was measured using the Kyowa Interface Science company CA-A type | mold contact angle measuring apparatus. In addition, the thing which does not apply | coat a hydrophilic treatment agent was made into the comparative example 9. The results are shown in Table 2.

On the surface of the coating film to which the hydrophilizing agent of the present invention is applied, a transparent and uniform film with no finger touch is formed, and the water contact angle is less than 50 degrees, at which contamination resistance is good. Met. On the other hand, in the comparative example using the nonionic surfactant and the amount thereof deviating from the scope of the present invention, the entire coating film cannot be coated due to the occurrence of film breakage, or the nonionic surfactant Satisfactory results could not be obtained, for example, when the surfactant surfaced.

Claims (6)

A hydrolyzate of a silicate compound represented by the following formula (1), a nonionic surfactant, water and a hydrophilic organic solvent,
The hydrophilization agent whose said nonionic surfactant has an alkylene oxide unit, the HLB is 10-15, and the quantity with respect to the said water is 0.02-10 mass%.

(In the formula, n represents an integer of 1 to 30; R ¹ may represent a different one, and represents a C 1-8 alkyl group having a substituent or not having a substituent) The hydrophilizing agent according to claim 1, wherein the content of the hydrolyzate of the silicate compound is 0.05 to 10% by mass. A silicate compound represented by the following formula (1) is hydrolyzed in a mixed solution of water and a hydrophilic organic solvent, has an alkylene oxide unit, and has a nonionic surface activity of 10 to 15 in HLB. A method for producing a hydrophilic treatment agent, comprising adding an agent.

(In the formula, n represents an integer of 1 to 30; R ¹ may represent a different one, and represents a C 1-8 alkyl group having a substituent or not having a substituent) The method for producing a hydrophilic treatment agent according to claim 3, wherein the addition of the nonionic surfactant is performed before the hydrolysis. The method for producing a hydrophilic treatment agent according to claim 3, wherein the addition of the nonionic surfactant is performed after the hydrolysis. A method for hydrophilizing a coating film, comprising applying the hydrophilic treatment agent according to claim 1 or 2 to the coating film surface.