JP2608666B2 - Painted metal article and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a maintenance-free coated metal article which retains the feel of a metal base material, secures corrosion resistance, weather resistance and stain resistance for a long period of time, and is maintenance-free. .

[0002]

2. Description of the Related Art Conventionally, steel plates such as stainless steel,
As a coated article of a non-ferrous metal such as aluminum, an article formed by forming an organic coating on a metal surface and an article formed by forming a water glass coating are known. However, most have a colored layer.

[0003] Recently, there has been a demand for a coated article which has a metallic appearance and overcomes the disadvantage of corroding metals. Reflecting the needs, some are coated with a stainless steel base material or water glass based coating agent with fluorine clear coating,
It is not enough in terms of long-term durability.

Therefore, use of a transparent coating agent mainly composed of a silicon compound has been studied. However, it is difficult for this film to directly adhere to a substrate such as stainless steel or aluminum for a long period of time. Usually, a primer is used. However, if the material texture of the substrate is left (clear coating film), There is a disadvantage that the primer is exposed to ultraviolet rays and deteriorates.

On the other hand, a chemical conversion treatment method for a metal substrate (Japanese Patent Application No. 3-246306) has been proposed, and a certain degree of performance has been ensured. However, in the chemical conversion treatment, the long-term adhesion of a transparent coating agent mainly composed of a metal and a silicon compound is insufficient, and since the chemical conversion treatment itself is colored, the appearance is limited. receive.

[0006]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems, uses a transparent primer composition which is resistant to ultraviolet rays, retains the appearance of a metal base material even in appearance, and protects against corrosion for a long period of time. It is an object of the present invention to provide a maintenance-free coated metal article which secures resistance, weather resistance, and stain resistance, and a method for manufacturing the same.

[0007]

Means for Solving the Problems As a result of intensive studies on the method of solving the above problems, the present inventors have found that the first layer is made of a silicone resin, a curing catalyst, and an organic solvent, and is strong against ultraviolet rays. And, after coating and curing a transparent primer composition having excellent adhesion, the second layer is coated and cured with a coating agent obtained by hydrolytic condensation polymerization of alkoxysilane in a colloidal silica dispersion, It has been found that the problem can be solved by coating and curing a coating agent comprising a silica-dispersed oligomer obtained by partially hydrolyzing an organosilane in a colloidal silica dispersion, a polyorganosiloxane having a silanol group, and a catalyst, and complete the present invention. Reached.

That is, according to the present invention, (1) (a) average composition formula (R ¹ ) _a SiO _{(4-ab) / 2} (OR ² ) _b (I) (wherein R ¹ is Substituted or unsubstituted carbon number 1-8
R ² represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, a is 0.6 to 1.8, and b is a hydroxyl group or an alkoxyl group bonded to a silicon atom. Represents a number of 1 or more groups in one molecule, and a + b
<4) polyorganosiloxane (b)
A coating film comprising a transparent primer layer obtained by curing a plyomer composition containing an organic titanate and / or a partial hydrolyzate thereof; (2) On the coating film, (A) Formula (R ³ ) _m Si (OR ⁴ ) _4-m (II) wherein R ³ represents a methyl group, an ethyl group or a phenyl group, R ⁴ represents an alkyl group having 1 to 4 carbon atoms,
m is the hydrolysis of the alkoxysilane represented by 0, 1 or 2), polycondensates and colloidal silica silicon alkoxide transparent film -1 was cured comprises or, (B) (a) Formula (R ⁵ ) _n SiX _4-n (III) (wherein, each of R ⁵ is a substituted or unsubstituted C 1-8)
Represents a monovalent hydrocarbon group, X represents a hydrolyzable group,
n is from 0 to 3), a silica-dispersed oligomer containing a hydrolyzable and condensed product of a hydrolyzable organosilane represented by the following formula: (b) an average composition formula (R ⁶ ) _c Si (OH) _d O _{(4-cd) / 2} (IV) (wherein, R ⁶ is a substituted or unsubstituted C 1-8
Wherein c is 0.2 ≦ c ≦ 2, d is 0.0001 ≦ d ≦ 3, and c + d <4), and contains a silanol group-containing polyorganosiloxane represented by the formula: A coated metal article having a silicon alkoxide-based transparent coating -2,

Further, according to the present invention, (1) (a) an average composition formula (R ¹ ) _a SiO _{(4-ab) / 2} (OR ² ) _b (I) wherein R ¹ is Substituted or unsubstituted carbon number 1-8
R ² represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, a is 0.6 to 1.8, and b is a hydroxyl group or an alkoxyl group bonded to a silicon atom. Represents a number of 1 or more groups in one molecule, and a + b
<4) polyorganosiloxane 100 represented by the formula:
After applying and curing a primer composition containing (b) 0.1 to 100 parts by weight of an organic titanate and / or a partial hydrolyzate thereof and (c) an organic solvent with respect to parts by weight, ) Then, (A) Formula (R ³ ) _m Si (OR ⁴ ) _4-m (II) (wherein R ³ represents a methyl group, an ethyl group or a phenyl group, respectively, and R ⁴ represents a carbon atom of 1 to 1 Represents an alkyl group of 4,
m is 0, 1 or 2), by hydrolyzing and polycondensing an alkoxysilane represented by the following formula (1) in a colloidal silica dispersion, and applying a silicon alkoxide-based coating agent-1; or (B) (a) Formula (R ⁵ ) _n SiX _4-n (III) (wherein, R ⁵ represents a substituted or unsubstituted monovalent hydrocarbon group, X represents a hydrolyzable group, and n represents 0 to 3) (B) a silica-dispersed oligomer obtained by partially hydrolyzing and condensing a hydrolyzable organosilane represented by the formula (1) in a colloidal silica dispersion: (b) an average composition formula (R ⁶ ) _c Si (OH) _d O _{(4- cd) / 2} (IV) (wherein R ⁶ is a substituted or unsubstituted C 1-8
Wherein c is 0.2 ≦ c ≦ 2, d is 0.0001 ≦ d ≦ 3, and c + d <4), and a silanol group-containing polyorganoshiroquine represented by c) A method for producing a coated metal article, which comprises applying a silicon alkoxide-based coating agent-2 containing a curing catalyst to form a transparent film on a primer layer.

Hereinafter, the present invention will be described in detail.

The polyorganosiloxane of component (a) used in the primer composition of the first layer in the present invention is a component which is a main component of the primer composition of the present invention, and has an adhesive property to the primer composition of the present invention. In particular, in order to impart water-resistant adhesion, one molecule has one or more hydroxyl groups or alkoxyl groups, and is represented by the average composition formula (I). In the formula, R ¹ represents a substituted or unsubstituted monovalent hydrocarbon group, and specific examples thereof include methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, tert-butyl and the like. alkyl group having 1 to 4 carbon atoms; vinyl, alkenyl, such as allyl; phenyl, aryl groups such as tolyl; or a halogen atom their hydrogen atoms, but include those substituted with a cyano group, among all the R ^1, It is preferable to contain an alkyl group having 1 to 4 carbon atoms in an amount of 40 mol% or more. R
² is a hydrogen atom or methyl, ethyl, n-propyl, iso
-Propyl, n-butyl, iso-butyl, represents an alkyl group having 1 to 4 carbon atoms such as tert-butyl, a is 0.6 to
1.8, b is the number of one or more hydroxyl groups or alkoxyl groups bonded to a silicon atom in one molecule, and a + b <4.

The polyorganosiloxane (I) having a hydroxyl group or an alkoxyl group has the general formula (R ¹ ) _p SiY
_4-p (wherein R ¹ is the same as above, and Y is Cl or OR
² wherein R ² is the same as above, and p is 0,
Chlorosilane or alkoxysilane having a substituted or unsubstituted monovalent hydrocarbon group represented by formula (1), (2) or (3), in the presence of an organic solvent in a usual manner. Hydrochloric acid that is hydrolyzed and by-produced,
Obtained by removing alcohol and the like.

The component (b), an organic titanate and / or a partial hydrolyzate thereof, functions as a catalyst for curing a polyorganosiloxane (a) having a hydroxyl group or an alkoxyl group. It is also a component for obtaining good adhesion of the primer composition to the substrate. Examples of the organic titanate include tetraethyl titanate, tetra (n-propyl) titanate, tetraisopropyl titanate, tetra (n-butyl) titanate, tetra (2-ethylhexyl) titanate, and the like. Can also be used.

The amount of component (b) used is 100 parts (a).
It is in the range of 0.1 to 100 parts by weight based on parts by weight. If the amount of the component (b) is less than 0.1 part by weight, not only the curing of the coating film is delayed, but also the water-resistant adhesiveness is reduced. Conversely, if it exceeds 100 parts by weight, the water-resistant adhesiveness decreases and the coating becomes brittle.

The organic solvent of the component (c) is a component for uniformly coating a film of an appropriate thickness on the surface of the base material with good workability. These organic solvents (c) include alcohols such as methanol, ethanol, and isopropanol; aromatic hydrocarbons such as toluene and xylene; aliphatic hydrocarbons such as normal hexane and gasoline; and ethyl acetate and butyl acetate. Carboxylic acid esters; ketones such as acetone and methyl ethyl ketone; ethers such as dimethyl ether and tetrahydrofuran;
7 cyclic polydimethylsiloxanes, preferably hexamethylcyclopolysiloxane, octamethylcyclopolysiloxane, decamethylcyclopolysiloxane, etc .; having 2 to 2 silicon atoms capped with trimethylsiloxy groups
And 20 chain polydimethylsiloxanes.
These solvents may be used alone or in combination.

The primer composition used in the present invention (1)
In addition to the above components, one or more kinds of colloidal silica, which will be described in detail later, can be blended.

The coating method of the primer composition (1) is as follows.
For example, spray coating, roll coating, dip coating and the like are mentioned, and there is no particular limitation. The baking drying temperature of the primer composition is preferably in the range of 50 to 250 ° C,
More preferably, the temperature is in the range of 100 to 250 ° C. The preferred thickness of the primer layer is 0.1 to 10 μm.

After forming the primer layer, a silicon alkoxide-based coating layer is applied as a second layer. The silicon alkoxide-based coating agent used in the present invention includes the following two types.

The first silicon alkoxide-based coating agent-1 is obtained by hydrolyzing and condensation-polymerizing a silicon compound represented by the above general formula (II) in a colloidal silica dispersion and obtaining a silanol-terminated prepolymer obtained by condensation. It is an essential component. The silicon alkoxide-based coating agent-1 is prepared by, for example, diluting a mixture mainly containing the following components (i), (ii) and (iii) with an appropriate solvent, and adding a necessary amount of a curing agent and a catalyst. The weight average molecular weight Mw obtained by hydrolysis and polycondensation reaction is 500 to 3,000 in terms of polystyrene, and the molecular weight distribution Mw / Mn is 1.
Those having 0 to 3.0 (Mn is a number average molecular weight) are preferred. More preferably, Mw = 600-3,000, and Mw
/Mn=1.2 to 1.8. When the weight average molecular weight and the molecular weight distribution are smaller than the above ranges, the curing shrinkage at the time of polycondensation tends to increase, and the coating film tends to crack after baking. On the other hand, when the ratio is larger than the above range, the reaction is too slow to be hardened, or the cured film tends to be soft, or the leveling property of the coated film tends to be very poor.

(I) 20 to 200 parts by weight of a silicon compound represented by m = 0 in the general formula (II) and 100 to 200 parts by weight of a colloidal silica (ii) 100 parts by weight of a silicon compound represented by m = 1 in the general formula (II) ( iii) 0 to 80 parts by weight of a silicon compound represented by m = 2 in the general formula (II)

Further, in the above composition, when the proportion of the component (i) is less than 20 parts by weight or more than 200 parts by weight, there is a problem that crack resistance is poor. When the above component (iii) is 8
If it exceeds 0 parts by weight, the coating film is too soft and not practical.

The above-mentioned colloidal silica is used by dispersing a particulate silica component in an organic solvent such as water or methanol or a mixed solvent thereof. It is not limited. In addition, the mixing ratio of the colloidal silica of the component (i) is part by weight including the dispersion medium. As the above curing agent,
For example, water is used, and the amount is not particularly limited, but is preferably 45% or less, more preferably 25% or less, by weight in the coating composition.

The catalyst is not particularly restricted but includes, for example, inorganic acids such as hydrochloric acid, phosphoric acid and sulfuric acid, formic acid, acetic acid and the like.
An acidic catalyst such as a dilute solution of an organic acid such as chloroacetic acid, a basic catalyst described later, or the like can be used alone or in combination of two or more. Further, when an acidic colloidal silica dispersion (acidic silica sol) is used as the component (i), it does not need to be used as a catalyst since this is used instead of the catalyst.

Silicon alkoxide coating agent-1
Can be used stably within the above-mentioned molecular weight range by adjusting the pH value to 3.8 to 6.0. If the pH value is outside the above range, the stability of the coating composition is poor, so that the usable period after preparation of the paint may be limited. Here, the method of adjusting the pH value is not particularly limited. For example, when the pH value becomes less than 3.8 at the time of mixing the raw materials of the coating agent, the pH value is adjusted within the above range using a basic reagent such as ammonia. The pH may be adjusted to a pH of 6.0. Even when the pH value exceeds 6.0, the pH may be adjusted using an acidic reagent such as hydrochloric acid. In addition, depending on the pH, when the reaction does not proceed with a low molecular weight and it takes time to reach the above molecular weight range, the coating agent may be heated to accelerate the reaction, or the pH value may be adjusted with an acidic reagent. After the reaction is advanced by lowering the pH, the pH value may be returned to a predetermined value with a basic reagent.

Even when the pH is adjusted as described above or without pH adjustment, a condensation catalyst is promoted by adding a basic catalyst to the coating agent until the use or at least during the use, Since the number of crosslinking points in the coating film can be increased, a coating film having good crack resistance can be obtained stably.

Further, by accelerating the crosslinking reaction,
Since the curing time can be shortened or the curing temperature can be lowered, it is economical and has an effect that it can be applied to a substrate that can only be baked at a low temperature. Examples of the basic catalyst include amines (for example, triethanolamine and the like),
Aminosilanes (for example, γ-aminopropyltriethoxysilane, N- (β-aminoethyl) -γ-aminopropyltriethoxysilane, N- (β-aminoethyl)
-Γ-aminopropylmethyldimethoxysilane),
Salts of inorganic acids (eg, hydrochloric acid, nitric acid, phosphoric acid, etc.) or organic acids (eg, formic acid, acetic acid, propionic acid, etc.) such as ammonia, trimethylamine, triethylamine, n-butylamine, or salts of inorganic acids or organic acids. And the fourth
Examples thereof include a double decomposition salt with a quaternary ammonium salt, but the kind and the amount of addition are not particularly limited.

The silicon alkoxide-based coating agent-1 prepared by the above-mentioned production method contains, in addition to the above components,
If necessary, various colorants, fillers other than the above colloidal silica dispersion (silica sol) (for example, inorganic fillers such as alumina sol and fumed silica), a diluting solvent,
Various additives such as thickeners, surfactants, and UV absorbers
More than one species may be added.

Examples of the diluting solvent include alcohols such as methanol, ethanol, and isopropanol (also referred to as IPA); and cellosolves such as ethylene glycol, methyl cellosolve, ethyl cellosolve, and butyl cellosolve. .

The coating method of the silicon alkoxide-based coating agent-1 in the present invention includes, for example, spray coating, roll coating, flow coater coating, dip coating, and is not particularly limited. The conditions for drying and baking after painting are also not particularly limited, but may be 60 to 20.
It is preferable to carry out at about 0 ° C.

Next, the silicon alkoxide-based coating agent-2 will be described. This coating agent contains the following components (a), (b) and (c) as essential components. (A) an organic solvent in which a hydrolyzable organosilane represented by the general formula (R ⁵ ) _n SiX _4-n (III) (wherein R ⁵ , X and n are the same as described above) is dispersed in colloidal silica; And / or a silica-dispersed oligomer solution of organosilane obtained by partial hydrolysis in water. (B) Average composition formula (R ⁶ ) _c Si (OH) _d O _{(4-cd) / 2} (IV) R ⁶ , c and d are the same as defined above), and a polyorganosiloxane having a silanol group (c) curing catalyst

The silica-dispersed oligomer of the component (a) used in the present invention is a main component of a base polymer having a hydrolyzable group (X) which participates in a curing reaction when forming a film.
This is achieved by adding one or more hydrolyzable organosilanes represented by the general formula (III) to an organic solvent and / or water in which colloidal silica is dispersed, and adding water or water separately added to the dispersion. The hydrolyzable organosilane is obtained by partial hydrolysis.

R ⁵ in the general formula (III) representing a hydrolyzable organosilane represents a substituted or unsubstituted monovalent hydrocarbon group having 1 to 8 carbon atoms, for example, methyl, ethyl, propyl, butyl, Alkyl groups such as pentyl, hexyl, heptyl and octyl; cycloalkyl groups such as cyclopentyl and cyclohexyl; aralkyl groups such as 2-phenylethyl, 2-phenylpropyl and 3-phenylpropyl; aryl groups such as phenyl and tolyl; Alkenyl groups such as vinyl, allyl and the like; chloromethyl,
halogen-substituted hydrocarbon groups such as γ-chloropropyl, 3,3,3-trifluoropropyl and the like; or γ-methacryloxypropyl, γ-glycidoxypropyl,
Examples thereof include substituted hydrocarbon groups such as 3,4-epoxycyclohexylethyl and γ-mercaptopropyl. Among them, an alkyl group having 1 to 4 carbon atoms or a phenyl group is preferable from the viewpoint of ease of synthesis and availability.

Examples of the hydrolyzable group X include an alkoxyl group, an acetoxy group and an oxime group [—ON—C (—R
') -R], an enoxy group [-OC (-R) = C (-
R ")-R '], an amino group, an aminoxy group [-ON
(-R) -R '], an amide group [-N (-R')-CO-
R] (where R, R ′ and R ″ are, for example, hydrogen or monovalent hydrocarbon groups, etc.), etc., because they are readily available and easy to prepare silica-dispersed oligomer solutions. Alkoxyl groups are preferred.

Examples of such hydrolyzable organosilanes include mono-, di-, tri- and tetra-functional alkoxysilanes wherein n in the general formula (III) is an integer of 0 to 3; Acetoxysilanes, oxime silanes, enoxysilanes, aminosilanes, aminoxysilanes,
Amidosilanes and the like. Alkoxysilanes are preferred because they are easily available and easy to prepare a silica-dispersed organosilane oligomer solution.

Particularly, tetramethoxysilane and tetraethoxysilane can be exemplified as the n = 0 tetraalkoxysilane, and methyltrimethoxysilane, methyltriethoxysilane, methyltriisosilane as the organotrialkoxysilane having n = 1. Propoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane,
3,3,3-trifluoropropyltrimethoxysilane and the like can be exemplified. Examples of the diorganodialkoxysilane having n = 2 include dimethyldimethoxysilane, dimethyldiethoxysilane, diphenyldimethoxysilane,
Examples include diphenyldiethoxysilane and methylphenyldimethoxysilane. Examples of the triorganoalkoxysilane having n = 3 include trimethylmethoxysilane, trimethylethoxysilane, trimethylisopropoxysilane, and dimethylisobutylmethoxysilane. Further, an organosilane compound generally called a silane coupling agent is also included in the alkoxysilanes.

5 of the hydrolyzable organosilane (III)
It is preferable that 0 mol% or more is a trifunctional compound represented by n = 1, more preferably 60 mol% or more, and most preferably 70 mol% or more. This is 50
If less than mol%, sufficient coating film hardness cannot be obtained,
Dry curability may be poor.

The colloidal silica in the component (a) is essential for increasing the hardness of the cured film of the silicon alkoxide-based coating agent-2 used in the present invention. As such colloidal silica, water-dispersible or non-aqueous organic solvent-dispersible colloidal silica such as alcohol can be used. Generally, such a colloidal silica dispersion contains 20 to 50% by weight of silica as a solid content, and the amount of silica can be determined from this value. When water-dispersible colloidal silica is used, water present as a component other than the solid content can be used for hydrolysis of the hydrolyzable organosilane of the component (a). These are usually made from water glass, but such colloidal silica dispersions are readily available commercially.

The organic solvent-dispersed colloidal silica can be easily prepared by replacing water of the water-dispersible colloidal silica with an organic solvent. Such an organic solvent-dispersed colloidal silica can be easily obtained as a commercial product, similarly to the water-dispersed colloidal silica. Examples of the organic solvent in which the colloidal silica is dispersed include, for example, lower aliphatic alcohols such as methanol, ethanol, isopropanol, n-butanol and isobutanol; ethylene glycol, ethylene glycol monobutyl ether, and ethylene glycol monoethyl acetate. And the like. Diethylene glycol derivatives such as diethylene glycol and diethylene glycol monobutyl ether; diacetone alcohol; and the like, and one or more of these can be used. In combination with these hydrophilic organic solvents, toluene, xylene, ethyl acetate, butyl acetate, methyl ethyl ketone, methyl isobutyl ketone, methyl ethyl ketoxime and the like can also be used.

Component (a) comprises colloidal silica of 5-95
It is preferable to contain it in the range of weight%. More preferably 10-90% by weight, most preferably 20-85% by weight
Range. If the content is less than 5% by weight, a desired film hardness cannot be obtained, and if it exceeds 95% by weight, it is difficult to uniformly disperse the silica, and the component (a) may cause inconvenience such as gelation. .

The silica-dispersed oligomer of the component (a) can be usually obtained by partially hydrolyzing a hydrolyzable organosilane in water-dispersed colloidal silica or organic solvent-dispersed colloidal silica. The amount of water used relative to the hydrolyzable organosilane is preferably 0.001 to 0.5 mol of water per 1 mol of the hydrolyzable group (X). If the amount is less than 0.001 mol, a sufficient partial hydrolyzate cannot be obtained, and if it exceeds 0.5 mol, the stability of the partial hydrolyzate may deteriorate. The method of performing the partial hydrolysis is not particularly limited, and the hydrolyzable organosilane and the colloidal silica dispersion may be mixed and a necessary amount of water may be added and blended. At this time, the partial hydrolysis reaction proceeds at room temperature. . You may heat to 60-100 degreeC in order to accelerate a partial hydrolysis reaction. For the purpose of further promoting the partial hydrolysis reaction, hydrochloric acid, acetic acid, halogenated silane, chloroacetic acid, citric acid, benzoic acid, dimethylmalonic acid, formic acid, propionic acid, glutaric acid, glycolic acid, maleic acid, malonic acid, toluene Sulfonic acid,
An organic acid such as oxalic acid or an inorganic acid may be used as the catalyst.

In order to obtain stable performance over a long period of time, component (a) should have a pH of 2.0 to 7.0, preferably 2.5 to 7.0.
-6.5, more preferably 3.0-6.0. If the pH is out of this range, the long-term deterioration of the performance of the component (a) may be remarkable particularly when the amount of water used is 0.3 mol or more per 1 mol of X. When the pH of the component (a) is out of this range, it may be adjusted by adding a basic reagent such as ammonia or ethylenediamine if it is more acidic than this range, and hydrochloric acid, nitric acid, It may be adjusted using an acidic reagent such as acetic acid. However, the adjustment method is not particularly limited.

The polyorganosiloxane having a silanol group of the component (b) is an important component that characterizes the present invention. Such a component (b) is obtained by the above average composition formula (IV)
Indicated by

In the formula, R ^{6 is the same} as R ⁵ in the above formula (III).
The same is exemplified, but preferably, it has 1 to 4 carbon atoms.
Alkyl group, phenyl group, vinyl group, γ-glycidoxypropyl group, γ-methacryloxypropyl group, γ-aminopropyl group, substituted hydrocarbon group such as 3,3,3-trifluoropropyl group, more preferably Is a methyl group or a phenyl group. Further, in the formula, a and b are numbers satisfying the above relation, respectively. If c is less than 0.2 or d exceeds 3, there is a disadvantage that cracks occur in the cured film, and c is 2 If it exceeds or d is less than 0.0001, curing does not preferably proceed.

The polyorganosiloxane having such a silanol group is, for example, methyltrichlorosilane,
Dimethyldichlorosilane, phenyltrichlorosilane,
It can be obtained by hydrolyzing one or a mixture of two or more of diphenyldichlorosilanes or corresponding alkoxysilanes with a large amount of water by a known method.
When a polyorganosiloxane having a silanol group is hydrolyzed by a known method using alkoxysilane, a small amount of an unhydrolyzed alkoxyl group may remain. That is, a polyorganosiloxane in which a silanol group and a trace amount of an alkoxyl group coexist may be obtained. In the present invention, such a polyorganosiloxane can be used.

The curing catalyst which is the component (c) of the present invention promotes the condensation reaction between the components (a) and (b) to cure the coating. Examples of such a catalyst include metal salts of carboxylic acids such as alkyl titanates, tin octylates, dibutyltin dilaurate, dioctyltin dimaleate; dibutylamine-2-hexoate;
Amine salts such as dimethylamine acetate and ethanolamine acetate; quaternary ammonium salts of carboxylic acids such as tetramethylammonium acetate; amines such as tetraethylenepentamine; N-β-aminoethyl-γ-aminopropyltrimethoxysilane Silane coupling agents such as N-β-aminoethyl-γ-aminopropylmethyldimethoxysilane; acids such as p-toluenesulfonic acid, phthalic acid and hydrochloric acid; aluminum compounds such as aluminum alkoxide and aluminum chelate; Alkali metal hydroxides such as potassium; Titanium compounds such as tetraisopropyl titanate, tetrabutyl titanate, and titanium tetraacetylacetonate; methyltrichlorosilane, dimethyldichlorosilane, trimethylmonochlorosiloxane There are halogenated silanes such as down, not particularly limited as long as effective a condensation reaction with components (a) and (b) In addition to these catalysts.

The mixing ratio of component (a) and component (b) is
Assuming that the total amount of the component (a) and the component (b) is 100 parts by weight, the component (b) 99 is added to the component (a) 1 to 99 parts by weight.
To 1 part by weight, and more preferably 5 to 95 parts of component (a).
95 to 5 parts by weight of component (b) relative to parts by weight, particularly preferably 10 to 90 parts by weight of component (b) 9
0 to 10 parts by weight. If the amount of the component (a) is less than 1 part by weight, the curability at room temperature is inferior and sufficient film hardness cannot be obtained. On the other hand, when component (a) exceeds 99 parts by weight, the curability is unstable and a good coating film may not be obtained.

The amount of the component (c) added depends on the amount of the component (a).
0.0001 to the total of 100 parts by weight of
It is preferably from 10 to 10 parts by weight, more preferably from 0.0005 to 8 parts by weight, particularly preferably from 0.005 to 8 parts by weight.
007 to 5 parts by weight. The amount of component (c) added is 0.0
If it is less than 001 parts by weight, it may not be cured at room temperature, and if it exceeds 10 parts by weight, heat resistance and weather resistance may be deteriorated.

The hydrolyzable group contained in the silica-dispersed oligomer of the component (a) and the silanol group of the component (b)
In the presence of the curing catalyst of component (c), a condensation reaction is carried out at room temperature or at a low temperature (for example, at a temperature of 100 ° C. or lower) to form a cured film. Therefore, like the moisture-curable coating composition, the silicon alkoxide-based coating agent-2 used in the present invention is hardly affected by humidity even when cured at room temperature. On the other hand, a heat treatment can promote a condensation reaction to form a cured film.

The silicon alkoxide-based coating agent-2 prepared by the above-mentioned production method may contain, in addition to the above-mentioned components, various coloring agents and fillers (alumina sol, silica sol) other than the above-mentioned colloidal silica dispersion (silica sol). One or more kinds of various additives such as an inorganic filler such as fumed silica, a diluting solvent, a thickener, a surfactant, and an ultraviolet absorber may be added.

Examples of the diluent include alcohols such as methanol, ethanol, and isopropanol; and cellosolves such as ethyl cellosolve, butyl cellosolve, and ethylene glycol monomethyl ether. These may be used alone or in combination. Further, in combination with these hydrophilic organic solvents, toluene, xylene, ethyl acetate, butyl acetate, methyl ethyl ketone, methyl isobutyl ketone,
Methyl ethyl ketoxime and the like can also be used.

As a method of preserving the silicon alkoxide-based coating agent-2, it is general to take three packaging forms in which the components (a), (b) and (c) are separately stored. a) and a mixture of component (c) and component (b) are divided into two packaging forms, and both are mixed at the time of use, or all components are mixed and stored in one container in one packaging form. Is also possible.

Silicon alkoxide coating agent-2
Can be coated by an ordinary application method, and for example, various application methods such as brushing, spraying, dipping, and flow can be selected. The curing conditions are preferably from 5 to 200 ° C, more preferably from 10 to 150 ° C. If it is lower than 5 ° C., it is difficult to cure, and if it is higher than 200 ° C., foaming may occur.

Silicon alkoxide coating agent-1
It is preferable that the coating thickness of the second layer according to (1) and (2) is 3 μm or more and about 30 μm or less after curing. When the thickness is less than 3 μm, pinholes are easily formed and the anticorrosion property may be deteriorated. On the other hand, if it exceeds 30 μm, there is a disadvantage that the crack resistance is poor.

The coated article of the present invention or the coated article obtained by the manufacturing method of the present invention retains the material feeling of a steel plate such as stainless steel, a non-ferrous metal such as aluminum, and has a long-term corrosion resistance, weather resistance, and stain resistance. It is maintenance free. For this reason, such a coated article is used, for example, as a member for an exterior wall material, a roof material, a rain gutter, or the like.

[0055]

By forming a transparent layer consisting of a primer layer as a first layer on the surface of a metal substrate and a silicon alkoxide-based coating agent-1 or -2 as a second layer thereon, corrosion resistance and weather resistance are obtained. Performance, contamination resistance, etc.
It can be maintenance-free. In addition, the underlying metal can be seen through the transparent film, so that a metallic feel can be obtained.

[0056]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to specific examples, but the present invention is not limited to these examples. Hereinafter, “parts” and “%” represent “parts by weight” and “% by weight”.

Reference Example 1: Silicone resin solution (S-1)
Preparation of 70 parts of methyltrichlorosilane, 6 parts of dimethyldichlorosilane and 3 parts of tetrachlorosilane were mixed with 85 parts of toluene, and this was mixed with 200 parts of water and 50 parts of n-butanol in a container equipped with a reflux condenser. The temperature was kept at 50 ° C. or lower, and the mixture was added dropwise with stirring to effect hydrolysis and condensation.

The produced polymethylsiloxane was washed with water to remove by-product hydrogen chloride. This was heated under pressure to remove water remaining as a part of the solvent, and the concentration was adjusted to 50.
% Of a silicone resin toluene solution (S-1).

Reference Example 2: Silicone resin solution (S-2)
Preparation of 33 parts of methyltrichlorosilane, 28 parts of dimethyldichlorosilane, and 75 parts of phenyltrichlorosilane were mixed with 130 parts of toluene, and this was mixed with 150 parts of water and 70 parts of acetone in a container equipped with a reflux condenser. Temperature 50
The solution was kept at a temperature of not more than 0 ° C. and added dropwise with stirring to effect hydrolysis and condensation.

The produced polymethylphenylsiloxane was washed with water to remove by-product hydrogen chloride. This is heated under pressure to remove water remaining as part of the solvent,
A 50% concentration silicone resin toluene solution (S-2) was obtained.

Reference Example 3: Preparation of primer composition (a) Silicone resin toluene solution (S-1) or (S
The primer compositions (P-1) to (P-7) were prepared by adding the titanate (b) and / or the organic solvent (c) shown in Table 1 to -2).

[0062]

[Table 1]

Reference Example 4: Preparation of silicon alkoxide-based coating agent-1 (C-1) 100 parts of methyltrimethoxysilane, 20 parts of tetraethoxysilane, isopropyl alcohol (IPA) -dispersed colloidal silica sol (trade name "OSCAL1432",
150 parts of an SiO ₂ content of 30% (produced by Catalyst Kasei Co., Ltd.), 40 parts of dimethyldimethoxysilane and 100 parts of isopropyl alcohol (IPA) were mixed, and 200 parts of water was further added and stirred. This was adjusted to a molecular weight Mw of 1,200 in a thermostat at 60 ° C. This liquid is referred to as (C-1). The molecular weight was measured by using GPC (gel permeation chromatography, manufactured by Tosoh Corporation: HLC8020) to prepare a calibration curve with standard polystyrene.

Reference Example 5 Preparation of Silicon Alkoxide Coating Agent-1 (C-2) Fumed silica (trade name "Aerosil # 200", manufactured by Nippon Aerosil Co., Ltd.) as a filler per 100 parts of (C-1) 3) was added and dispersed with a Glen Mill to obtain a coating liquid (C-2).

Reference Example 6 Preparation of Components (a) and (b) of Silicon Alkoxide Coating Agent-2 (C-3) IPA- was placed in a flask equipped with a stirrer, a heating jacket, a condenser and a thermometer. ST (trade name, isopropyl alcohol-dispersed colloidal silica sol; particle size 10
100 parts), 100 parts of methyltrimethoxysilane, 18 parts of dimethyldimethoxysilane, 2.7 parts of water, and 0.1 part of acetic anhydride. A partial hydrolysis reaction was carried out at a temperature of 80 ° C. for about 3 hours while being charged and stirred, followed by cooling to obtain a component (a) of (C-3). This had a solid content of 36% when left at room temperature for 48 hours.

<Preparation Conditions for Component (a)> Molar number of water per mole of hydrolyzable group: 1 × 10 ⁻¹ Silica content of component (a): 40.2% Mol% of hydrolyzable organosilane ... 77 mol%

A mixture of 220 parts (1 mol) of methyltriisopropoxysilane and 150 parts of toluene was weighed and placed in a flask equipped with a stirrer, a heating jacket, a condenser, a dropping funnel and a thermometer. 108 parts of the aqueous solution was dropped into the above mixed solution in 20 minutes to hydrolyze methyltriisopropoxysilane. After 40 minutes from the dropping, stirring was stopped, and a mixed solution of lower layer water and isopropyl alcohol containing a small amount of hydrochloric acid separated into two layers was separated, and then the remaining hydrochloric acid of the resin solution of toluene was removed by washing with water. After the toluene was removed under reduced pressure, the residue was diluted with isopropyl alcohol to obtain a component (b) of (C-3) as a 40% solution of a silanol group-containing organopolysiloxane having an average molecular weight of about 2,000 in isopropyl alcohol.

Reference Example 7: (C-4) A fluorine clear (Lumiflon-based) (trade name "V Freon # 2000 Clear") manufactured by Dainippon Paint Co., Ltd. is designated as (C-4).

Reference Example 8: (C-5) Water glass ceramic coating agent (CRM-700)
(S) Stock solution pH = 12.0, manufactured by Okuno Pharmaceutical Co., Ltd.
5).

Reference Example 9: (C-6) Fluorine clear (Kyner system) (trade name “Precolor No. 8300 Clear”) manufactured by NOF Corporation is designated as (C-6).

Examples 1 to 8 A primer was used for the first layer, and a silicon alkoxide-based coating agent-1 was used for the second layer. In implementation, the substrate is:
A stainless steel substrate (SUS304) with a hairline finish manufactured by Nissin Steel Co., Ltd. was used after alkaline degreasing.

The primer composition shown in Table 2 was applied to this substrate so as to have a film thickness of 1 to 3 μm, kept for 5 minutes for setting time, baked at 150 ° C. for 30 minutes, cooled to room temperature, and then cooled to (C). -1) or (C-2) A coating agent was applied by spraying to a film thickness of 7 to 10 μm, and after setting for 5 minutes, baking was performed at 180 ° C. for 20 minutes to prepare a test body.

The coated article thus obtained was examined for adhesion, corrosion resistance and weather resistance. The results are shown in Table 2.

The adhesion was confirmed by dipping in boiling water for 10 hours, air-drying, and using an adhesive tape (cellophane tape) within 3 hours.

The anticorrosion property was determined by a salt spray test of 2,000.
The situation after the time was visually evaluated.

The weather resistance was measured using an ice-par UV tester.
The following table shows one cycle (8 hours + 4 hours = 12 hours as one cycle), and the situation after performing the UV irradiation time up to 1,000 hours was evaluated. Test conditions Time 8 hours 4 hours UV irradiation Yes (100mW / cm ² ) No Temperature 63 ℃ 35 ℃ Humidity 50% 90% or more (with condensation)

[0077]

[Table 2]

Examples 9 to 12 A primer was used for the first layer, and a silicon alkoxide coating agent-2 was used for the second layer. As the silicon alkoxide-based coating agent-2, component (a) and component (b) of (C-3) were used, and 65 parts of component (a) and 35 parts of component (b) were used as catalysts for component (c). N-β-aminoethyl-γ
-Aminopropylmethyldimethoxysilane was prepared by mixing 3 parts.

The silicon alkoxide-based coating agent-2 was spray-coated on a substrate treated in the same manner as in Examples 1 to 8, the applied film thickness was 7 to 10 μm, and after setting for 5 minutes, 60 ° C. For 20 minutes to obtain a coated metal article. Table 2 shows the results.

Comparative Examples 1-3 As primers (P-5), (P-6) and (P-
Except having used each of 7), it implemented similarly to Examples 1-8. Table 2 shows the results.

Comparative Example 4 The procedure of Example 1 was repeated, except that no primer was used. Table 2 shows the results.

Comparative Examples 5 to 7 The base material was subjected to a chemical conversion treatment after alkali degreasing, and a silicon alkoxide-based coating agent shown in Table 2 was used.
It carried out similarly to Examples 1-8. Table 2 shows the results. The chemical conversion treatment solution used had the composition shown in Table 3.

[0083]

[Table 3]

COMPARATIVE EXAMPLE 8 Instead of (C-1), the coating agent of (C-4) was applied by spraying so as to have a thickness of 25 μm, set for 5 minutes, and then set at 200 ° C. for 10 minutes. Was carried out in the same manner as in Comparative Examples 5 to 7, except that baking was performed. Table 2 shows the results.

Comparative Example 9 A substrate subjected to a chemical conversion treatment was subjected to a preliminary heat treatment (230 ° C., 30
), The coating agent of (C-5) is applied by spraying so as to have a thickness of 20 μm,
The same operation as in Comparative Examples 5 to 7 was performed except that the baking was performed for 5 minutes. Table 2 shows the results.

Comparative Example 10 Instead of (C-1), the coating agent of (C-6) was applied by spraying so as to have a film thickness of 20 μm, set for 5 minutes, and then at 240 ° C. for 10 minutes. Was carried out in the same manner as in Comparative Examples 5 to 7, except that baking was performed. Table 2 shows the results.

As shown in Table 2, the primer layer as the first layer and the coating film comprising the silicon alkoxide-based coating agent-1 or -2 as the second layer were formed on the metal base material. A coated article excellent in all of adhesion, corrosion resistance and weather resistance can be obtained, but if the primer layer is not formed or the coating film composed of the silicon alkoxide-based coating agent is not formed, these three properties are obtained. One or more is inferior.

[0088]

According to the present invention, there is provided a maintenance-free coated metal article which retains the texture of the metal base material, secures corrosion resistance, weather resistance, stain resistance and the like for a long period of time.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location B05D 7/24 303 B05D 7/24 303B B32B 15/08 B32B 15/08 G (72) Inventor Toba Kumi 6-31 Roppongi, Minato-ku, Tokyo Toshiba Silicone Co., Ltd. (72) Inventor Takashi Urabe 6-2-31 Roppongi, Minato-ku, Tokyo Toshiba Silicone Co., Ltd. (56) References JP 3 −242268 (JP, A)

Claims (2)

(57) [Claims] (1) (a) an average composition formula (R ¹ ) _a SiO _{(4-ab) / 2} (OR ² ) _b (I) wherein R ¹ is substituted or unsubstituted Substituted carbon number 1-8
R ² represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, a is 0.6 to 1.8, and b is a hydroxyl group or an alkoxyl group bonded to a silicon atom. Represents a number of 1 or more groups in one molecule, and a + b
<4) polyorganosiloxane (b)
Organic titanate and / or a partial hydrolyzate comprising a transparent primer layer a primer composition was cured containing coating, on the (2) coating film, (A) formula (R ³⁾ _m Si (OR ⁴ ) _4-m (II) wherein R ³ represents a methyl group, an ethyl group or a phenyl group, R ⁴ represents an alkyl group having 1 to 4 carbon atoms,
m is the hydrolysis of the alkoxysilane represented by 0, 1 or 2), polycondensates and colloidal silica silicon alkoxide transparent film -1 was cured comprises or, (B) (a) Formula (R ⁵ ) _n SiX _4-n (III) (wherein, each of R ⁵ is a substituted or unsubstituted C 1-8)
Represents a monovalent hydrocarbon group, X represents a hydrolyzable group,
n is 0 to 3), a silica-dispersed oligomer containing a hydrolyzable organopolysilane represented by the following formula, a condensation polymer and colloidal silica: (b) an average composition formula (R ⁶ ) _c Si (OH) _d O _{(4-cd) / 2} (IV) (wherein, R ⁶ is a substituted or unsubstituted C 1-8
Wherein c is 0.2 ≦ c ≦ 2, d is 0.0001 ≦ d ≦ 3, and c + d <4), and includes a silanol group-containing polyorganosiloxane represented by the formula: A coated metal article having a silicon alkoxide-based transparent coating-2 formed thereon. 2. The method according to claim 1, wherein (1) (a) an average composition formula (R ¹ ) _a SiO _{(4-ab) / 2} (OR ² ) _b (I) wherein R ¹ is substituted or unsubstituted Substituted carbon number 1-8
R ² represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, a is 0.6 to 1.8, and b is a hydroxyl group or an alkoxyl group bonded to a silicon atom. Represents a number of 1 or more groups in one molecule, and a + b
<4) polyorganosiloxane 100 represented by the formula:
After applying and curing a primer composition containing (b) 0.1 to 100 parts by weight of an organic titanate and / or a partial hydrolyzate thereof and (c) an organic solvent with respect to parts by weight, ) Then, (A) Formula (R ³ ) _m Si (OR ⁴ ) _4-m (II) (wherein, R ³ represents a methyl group, an ethyl group or a phenyl group, respectively, and R ⁴ each represents 1 to 1 carbon atoms) Represents an alkyl group of 4,
m is 0, 1 or 2), by hydrolyzing and polycondensing an alkoxysilane represented by the following formula (1) in a colloidal silica dispersion, and applying a silicon alkoxide-based coating agent-1; or (B) (a) Formula (R ⁵ ) _n SiX _4-n (III) (wherein, R ⁵ represents a substituted or unsubstituted monovalent hydrocarbon group, X represents a hydrolyzable group, and n represents 0 to 3) (B) a silica-dispersed oligomer obtained by partially hydrolyzing and condensing a hydrolyzable organosilane represented by the formula (1) in a colloidal silica dispersion: (b) an average composition formula (R ⁶ ) _c Si (OH) _d O _{(4- cd) / 2} (IV) (wherein R ⁶ is a substituted or unsubstituted C 1-8
Wherein c is 0.2 ≦ c ≦ 2, d is 0.0001 ≦ d ≦ 3, and c + d <4), and a silanol group-containing polyorganoshiroquine represented by c) A method for producing a coated metal article, comprising applying a silicon alkoxide-based coating agent-2 containing a curing catalyst to form a transparent film on the primer layer.