JPH09255920A - Silicon-containing organic coating film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a coating film having excellent film properties such as a pencil hardness and a contact angle with water, each having at least a specific value, by coating a base material with a liq. compsn. comprising a specific silicon compd. and a specific silicone-modified acrylic copolymer, and, if necessary, heat-curing it. SOLUTION: A liq. compsn. prepd. by blending a specific silicon compd. (A) (a silicon compd. having an alkoxyl group directly bonded to the silicon atom, or its hydrolyzate) with a specific silicone-modified acrylic copolymer (B) [a copolymer of a vinyl-substituted alokoxysilane, a vinyl-substituted polysiloxane, a hydroxylated (meth)acrylic ester, and a (meth)acrylic ester as monomers] is applied on a base material and if necessary heat-cured to obtain a silicon-contg. org. coating film having a pencil hardness of at least 2H and a contact angle with water of at least 85 deg.. The coating film is also free from cracking even if bent with a SUS bar of 6mm in diameter.

Description

Detailed Description of the Invention TECHNICAL FIELD OF THE INVENTION

The present invention relates to a silicon-containing organic coating film.

[Prior art]

In recent years, a coating film having both organic and inorganic characteristics, particularly a coating film of an organic substance containing silicon has been attracting attention in various fields. For example, in addition to a coating containing a silicon component by a silyl group-containing copolymer. A coating film formed by applying a composition in which a silicon compound having a hydrolytically condensable group such as various alkoxysilanes is mixed with a resin component has been proposed.

[0003]

However, although these conventionally known silicon-containing coating films have higher hardness than organic coating films containing no silicon, they have insufficient flexibility and water repellency. . On the other hand, a coating film obtained by applying and curing a composition containing a so-called silicone resin as a main component, which has various organic group side chains such as a methyl group and a phenyl group in the Si—O main chain, is also known. In this case, the flexibility and water repellency are excellent, but the hardness is not sufficient.

[0004]

Therefore, as a result of intensive studies, the present inventors have found that a coating composition having sufficient hardness, flexibility and water repellency is formed by applying and curing a specific composition. The inventors have found that it is possible and have reached the present invention. That is, the present invention resides in a silicon-containing organic coating film having a pencil hardness of 2H or more and a contact angle with water of 85 ° or more.

Hereinafter, the present invention will be described in detail.

BEST MODE FOR CARRYING OUT THE INVENTION The silicon-containing organic coating film of the present invention comprises:
The pencil hardness is 2H. The method for measuring the pencil hardness is the method described in JIS K 5400 (1990), which is a value evaluated by scratches on the coating film using a pencil scratch tester. Further, the silicon-containing organic coating film of the present invention is characterized in that the contact angle with water is 85 ° or more. The contact angle is measured using a contact angle meter: CA-A type manufactured by Kyowa Kagaku Co., Ltd., temperature 25 ± 2 ° C., humidity 55 ± 5
%, It is a value obtained by the "droplet measuring method" for measuring the contact angle when a droplet (demineralized water) having a diameter of 2 mm is dropped on the surface of the coating film. As described above, a coating film having both high hardness, flexibility, and water repellency has never existed in the past, and it is used for outdoor coating, indoor coating, formation of antifouling coating on various substrates, and various It is very useful and can be used for various purposes.

To obtain the silicon-containing organic coating film of the present invention,
For example, the following method may be mentioned. That is, a liquid composition prepared by blending a specific silicon compound and a specific silicone-modified acrylic copolymer is applied to a substrate, and heated and cured as necessary. Here, the specific silicon compound is a silicon compound having an alkoxy group directly bonded to silicon and / or a hydrolyzate of the silicon compound.

The silicon compound having an alkoxy group directly bonded to silicon is preferably tri- or tetraalkoxysilane, more preferably tetraalkoxysilane, particularly preferably at least one monomer selected from tetraethoxysilane and tetramethoxysilane. And / or oligomers which are low condensation products. Further, it is preferable to use a hydrolyzate of these alkoxysilanes. As a hydrolysis method, 0.05 to 0.5 mol of water is added to the tetraalkoxysilane, which is 0.05 to 0.5 times the number of moles of the alkoxy groups of the tetraalkoxysilane. In addition, hydrolysis is carried out, preferably in the presence of a solvent and optionally a catalyst. Particularly when a coating film having a high hardness is intended, ultrafine silica having an inertia radius of 10 Å or less can be formed and used by the method described in detail in WO95 / 17349.

Next, the specific silicone-modified acrylic copolymer can be produced by copolymerizing the following monomers (1) to (4). (1) Vinyl group-containing alkoxysilane (2) Vinyl group-containing polysiloxane (3) Hydroxyl group-containing methacrylic acid ester and / or acrylic acid ester (4) Methacrylic acid ester and / or acrylic acid ester

Above all, in order to obtain the best coating physical properties, the use ratio of the compounds (1) and (2) at the time of producing the copolymer is 0.5 to 20% by weight of vinyl group-containing alkoxysilane,
It is preferable that the vinyl group-containing polysiloxane is 0.1 to 20% by weight, the hydroxyl group-containing acrylic acid ester or methacrylic acid ester is 10 to 30% by weight, and the methacrylic acid ester and / or the acrylic acid ester is 40 to 80% by weight. When any one or more of the amounts of the compounds (1) to (3) used are out of the above range, the properties of the obtained coating film are slightly deteriorated, and the amount of the compound (4) used is more than the above range. The same holds true, and if the amount is less than the above range, the effect of using the compound of (4) may not be sufficiently exerted in some cases.

The vinyl group-containing alkoxysilane of (1) has the general formula

[0011]

Embedded image R ² —SiX _a (R ³ ) _3-a

(In the formula, R ³ is a monovalent group selected from an alkyl group having 1 to 10 carbon atoms, an aryl group and an aralkyl group, R ² is an organic residue having a polymerizable double bond, and X is hydrolyzed. Is a silane compound represented by a functional group, a is an integer of 1 to 3). Specific groups for R ² include

[0013]

Embedded image

And the like. Further, as a specific group of X,

[0015]

Embedded image

And the like. Specific examples of the vinyl group-containing alkoxysilane (1) include methacryloxypropyltrimethoxysilane and vinyltrimethoxysilane. The vinyl group-containing polysiloxane of (2) has the general formula

[0017]

Embedded image

A polysiloxane having a vinyl group at one end represented by:

[0019]

Embedded image

[0020] is a double terminal vinyl group-containing polysiloxane represented by (R ² is same as R ² of the alkoxy silane). Specific examples of the vinyl group-containing polysiloxane (2) include vinyl dimethyl polysiloxane having both ends or one end and methacryloxypropyl dimethyl polysiloxane having both ends or one end. The viscosity range of these polysiloxanes is preferably about 5 to 1000 cP. The molecular weight is preferably 200 to 100,000.

Specific examples of the acrylic acid ester and / or methacrylic acid ester having a hydroxyl group of (3) include 2-hydroxyethyl acrylate and acrylic acid 2
-Hydroxypropyl, 2-hydroxybutyl acrylate, polyethylene glycol acrylate, polypropylene glycol acrylate, glycerol acrylate, 2-hydroxy-3-phenyloxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate , 2-hydroxybutyl methacrylate, 2-hydroxypentyl methacrylate, polyethylene glycol methacrylate, polypropylene glycol methacrylate, glycerol methacrylate and the like.

The carbon number of the ester group of the methacrylic acid ester and / or acrylic acid ester of (4) is 1 to 1
2 are preferable, and specific examples thereof include methyl acrylate, ethyl acrylate, butyl acrylate, allyl acrylate, phenyl acrylate, methyl methacrylate, butyl methacrylate, pentyl methacrylate, lauryl methacrylate, vinyl methacrylate, Examples thereof include allyl methacrylate, 2-ethylhexyl acrylate, octyl acrylate, lauryl acrylate, ethyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, and 2-ethylhexyl methacrylate. The compound (4) may be used in combination of two or more kinds.

In copolymerizing the compounds (monomers) of (1) to (4), preferably (5) an organic acid having 3 or more carbon atoms is used as a mixture for polymerization (note: compounds of (1) to (5)). 0.1 to 5% by weight of the total amount used). As a polymerization catalyst, 0.1 to 3% by weight, preferably 0.2 to 2% by weight, of a radical initiator such as benzoyl peroxide and azobisisobutyronitrile is used as a polymerization catalyst. Polymerization can be carried out by either bulk polymerization or solution polymerization,
Solution polymerization is preferred in terms of the compounding process for coating.

The organic solvent used for the solution polymerization has a certain degree of affinity for the polymer (during reaction, dilution, and viscosity adjustment), and can be selected from those having good drying properties and other properties when the curable composition is applied. Good. Examples of such a solvent include alcohols, and specific examples thereof include methanol, ethanol, isopropyl alcohol, n-butanol, isobutanol, isoamyl alcohol and the like. In addition, aromatic hydrocarbons such as toluene and xylene, esters such as ethyl acetate and butyl acetate, and ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone may be used alone or in combination.

The polymerization conditions (temperature, time) of the silicone-modified acrylic copolymer are not particularly limited, but usually 60 to 15
It can be performed at 0 ° C. for 2 to 10 hours. The method of supplying the monomers during the polymerization varies depending on the heat removal mode of the polymerization vessel or the presence or absence of a solvent or a dispersion medium, but each monomer may be individually or mixed and sequentially supplied to the polymerization vessel.

The degree of polymerization of the silicone-modified acrylic copolymer can be adjusted by the kind of the polymerization catalyst, the amount used, or the addition of a chain transfer agent with respect to the amount of the monomer. For the total amount of the quantity,
After the completion of the polymerization, the solvent is used at a constant ratio, and the above-mentioned degree of polymerization is adjusted so that the obtained coating solution has a viscosity range suitable for coating.

The silicone-modified acrylic copolymer thus obtained is blended with the above-mentioned silicon compound having an alkoxy group directly bonded to silicon and / or a hydrolyzate of the silicon compound. The amount of the silicone-modified acrylic copolymer added is 0.5 to 1900 parts by weight, preferably 1 to 80 parts by weight, based on 100 parts by weight of the silicon compound having an alkoxy group directly bonded to silicon and / or the hydrolyzate of the silicon compound.
About 0 parts by weight is suitable.

If the amount is 0.5 parts by weight or less, cracks are likely to occur in the obtained coating film. If it is 1900 parts by weight or more, the hardness of the obtained coating film tends to be low. The above silicone-modified acrylic copolymers may be used alone or in combination of two or more depending on the purpose. When used in combination, two or more kinds may be preliminarily blended, or each may be added to an aged formulation liquid.

When the silicone-modified acrylic copolymer is added to the compounding liquid, if necessary, a solvent,
A dispersion medium, a curing catalyst, and other additives can be added together or later. For example, in the case of film formation described below, particularly in the case of using a spray method or a dipping method, coating conditions, a viscosity according to the target film physical properties such as film thickness, in order to prepare a curable composition having a nonvolatile component content, these solvents or A dispersion medium can be added.

As the solvent, those having compatibility with both the compounding liquid and the silicone-modified acrylic copolymer are preferable.
For example, alcohols, glycol derivatives, hydrocarbons, esters, ketones, ethers can be used alone or in combination of two or more.

Specific examples of alcohols include methanol, ethanol, isopropyl alcohol, n-butanol, isobutanol, and octanol, and examples of glycol derivatives include ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and ethylene. Glycol mono n-propyl ether, ethylene glycol mono n-butyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, Propylene glycol monomethyl A Le acetate, propylene glycol monoethyl ether acetate, and the like.

The hydrocarbons include benzene, kerosene,
Toluene, xylene, etc. can be used, and as esters,
Methyl acetate, ethyl acetate, butyl acetate, methyl acetoacetate, ethyl acetoacetate and the like can be used. Ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and acetylacetone, and ethers such as ethyl ether, butyl ether, 2-α-methoxyethanol, 2-α-ethoxyethanol, dioxane, furan, and tetrahydrofuran can be used.

In some cases, a dispersion medium can also be used. As a dispersion medium to be used, for example, a water-surfactant system is suitable, and as the surfactant, an anionic, cationic or nonionic surfactant is generally used. As anionic surfactants, carboxylate, sulfonate,
As the cationic ones such as sulfuric acid ester salts and phosphoric acid ester salts, salts of organic or inorganic acids of primary to tertiary amines, quaternary ammonium salts, polyoxyethylene alkylamine salts and the like, and further nonionic ones Examples thereof include sorbitan dialkyl ester, sorbitan alkyl ester ethylene glycol condensate, aliphatic alcohol polyethylene glycol condensate, alkylphenol polyethylene glycol condensate, polypropylene glycol polyethylene glycol condensate, and the like.

These surfactants are generally used in an amount of 0.1 to 5% with respect to the above-mentioned compounded liquid. When dispersing (emulsifying), an appropriate amount of water is used, and a homomixer, A known method such as colloid mill or ultrasonic wave can be used.

Of these solvents and dispersion media, it is usually preferable to use a solvent because the resulting coating film has excellent physical properties and the curable composition has excellent stability. The type of solvent may be selected as appropriate for the desired characteristics of the coating film, coating conditions, etc., but generally, for example, hydrocarbons such as benzene, toluene, xylene, and ketones such as methyl ethyl ketone. In the case of using, since the solvent removal rate at the time of curing the coating film is appropriate, the surface gloss of the coating film obtained is particularly excellent and a desired film thickness can be easily obtained.

In addition, in general, it may be appropriately selected according to use conditions, desired film characteristics, and the like. Depending on the conditions of use, the type of silicone-modified acrylic copolymer, the amount used, etc., there are many functional groups, and it may be desirable to add a catalyst to improve the curing rate after film formation. ,
The catalyst added during the aging of the blended solution is sufficient. The order of addition when using these solvents and catalysts is not particularly limited, and may be added to the aged product at the same time as the silicone-modified acrylic copolymer, or may be added after mixing, mixing, leaving, etc. Good.

The liquid composition thus obtained is used as a polymer,
A base material such as metal or ceramic or a wire material is formed into a film by an impregnation method, a spin coater method, a spray method or the like. After being left as a solvent removal treatment at room temperature for 1 to 10 minutes, it can be heat-cured at 20 ° C. or higher. The heating furnace may be a general-purpose furnace such as a gas furnace or an electric furnace.

When the film is cured by drying at room temperature,
It takes a little longer than heating, but it is usually sufficient to leave it for about half a day. In addition, since the curable composition of the present invention has good recoatability, it may be dried and then recoated, depending on the application, but according to the curable composition of the present invention A film thickness of 10 μm or more can be obtained by coating.

The coating itself can be carried out by a conventional method, and the film thickness can be appropriately selected. The film thickness can be selected by a conventional method, for example, by adjusting the concentration of non-volatile components in the liquid, the viscosity of the liquid, the pulling rate in the dip method, the jetting time in the spray method, or by re-coating. Can be selected. Further, the obtained film thickness can be appropriately changed by adjusting the type of silicone-modified acrylic copolymer and the addition amount.

The silicon-containing organic coating film of the present invention can be made extremely flexible, that is, no crack will be generated even if it is bent with a SUS rod having a diameter of 6 mm.

[0041]

The present invention will be described in more detail with reference to the following examples. (Example 1) (Preparation of varnish) (Synthesis of silicone-modified acrylic copolymer) 42.5 parts by weight of methyl methacrylate (hereinafter referred to as "parts"), 2-hydroxyethyl methacrylate 18.0 parts, and methacrylate n.
-Butyl 27.5 parts, n-butyl acrylate 5.0 parts,
3-methacryloxypropyltrimethoxysilane 5.0
Parts, methacryloxypropyldimethylpolysiloxane with one terminal (Mw = 5000) 1.0 part, methacrylic acid 1.0
And 0.5 part of azobisisobutyronitrile were mixed to prepare a monomer mixture for polymerization. This mixed solution was added dropwise to 100.0 parts of isopropyl alcohol kept at 80 ° C. and reacted for 5 hours, 0.5 part of azobisisobutyronitrile was further added and reacted at 80 ° C. for 4 hours, and finally A silicone-modified acrylic resin solution having a molecular weight of about 70,000 was obtained. (Note: Resin content concentration 50% by weight) A mixed solution of isopropyl alcohol and ethyl acetate (3/1 by weight) was added to this solution to prepare a solid content concentration of 20%.

(Preparation of curable composition) "MS-51" (tetramethoxysilane oligomer) manufactured by Mitsubishi Chemical Corporation
62.4 parts of ethanol was added to 30.8 parts by weight, and then aluminum tris (acetylacetonate) 0.3 was added.
Parts and 6.57 parts of dechlorinated water were added. It was left at room temperature for one day. Next, 20 g of the copolymer obtained in (Synthesis of silicone-modified acrylic copolymer) was added and left at room temperature for 7 days to obtain a coating liquid.

(Preparation of coating film) Aluminum substrate (JIS
H 4000-88, thickness 0.1 mm) was impregnated with the obtained coating liquid and pulled up at a pulling rate of 3 mm / min. Then, it was heated and cured in an electric furnace at 150 ° C. for 2 hours. The coating thickness obtained is 1 μm and the pencil hardness is 9H.
As described above, even if the SUS304 rod having a diameter of 6 mmφ was bent at 180 ° C., no crack was generated. Contact angle with water is 96
As high as °, it has excellent stain resistance.

Example 2 Example 1 was repeated except that 80 parts of the silicone-modified acrylic copolymer was added. The obtained coating film thickness was 2 μm, the pencil hardness was 4H, and the SUS304 bar having a diameter of 6 mmφ was bent at 180 ° C., and no crack was generated. The contact angle with water is as high as 98 °, and the stain resistance is excellent.

Example 3 To 40.5 parts of tetramethoxysilane (Si (OCH ₃ ) ₄ ) was added 48.4 parts of ethanol, and then 0.3 part of maleic acid and 10.8 parts of dechlorinated water were added. 5 at room temperature
Left for days.

Then, 149 parts of the silicone-modified acrylic copolymer obtained in Example 1 (synthesis of silicone-modified acrylic copolymer) was added, and the mixture was left at room temperature for 2 days to obtain a coating liquid. Aluminum substrate (JIS H 4000
-88, thickness 0.1 mm) was impregnated with the obtained coating liquid and pulled up at a pulling rate of 3 mm / min. Then, it was heated and cured in an electric furnace at 150 ° C. for 2 hours. Even if the obtained coating film thickness was 3 μm, pencil hardness was 3H, and bending was performed at 180 ° C. with a SUS304 rod having a diameter of 3 mmφ, no crack was generated. The contact angle with water is as high as 98 °, and the stain resistance is excellent.

Example 4 62.4 parts of ethanol was added to 30.8 parts of "MS-51" manufactured by Mitsubishi Chemical Corporation, and then 0.3 parts of maleic acid and 6.57 parts of dechlorinated water were added. It was left at room temperature for 3 days.

Next, 400 parts of the silicone-modified acrylic copolymer obtained in Example 1 (synthesis of silicone-modified acrylic copolymer) was added, and the mixture was allowed to stand at room temperature for 1 day to obtain a coating liquid. Aluminum substrate (JIS H 4000
-88, thickness 0.1 mm) was applied using a 250 μm applicator. Then, it was heated and cured in an electric furnace at 150 ° C. for 2 hours. The obtained coating film thickness is 28 μm, pencil hardness is 2H, and the diameter is 3φ mm.
No cracks were generated even after bending. The contact angle with water is as high as 99 ° C, which is excellent in stain resistance.

[0049]

Industrial Applicability According to the present invention, an organic coating film having hardness, high flexibility and water repellency can be obtained, and electronic base materials, electric equipment, outdoor, indoor building materials, sliding base materials that do not like water (examples) It can also be applied to prepaid cards, etc.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takeshi Sawai 1-1 Kurosaki Shiroishi, Hachimannishi-ku, Kitakyushu City Mitsubishi Chemical Corporation Kurosaki Development Laboratory (72) Inventor Hozumi 1-1 Kurosaki Shiroishi, Hachimanishi-ku, Kitakyushu City Mitsubishi Kurosaki R & D Laboratories, Inc. (72) Inventor Nobuyuki Matsuzoe 2-5-2 Marunouchi, Chiyoda-ku, Tokyo Sanryo Chemical Co., Ltd. New Business Development Room

Claims (2)

[Claims] 1. A silicon-containing organic coating film having a pencil hardness of 2H or more and a contact angle with water of 85 ° or more. 2. The organic coating film according to claim 1, wherein cracks do not occur even when bent with a SUS rod having a diameter of 6 mm.