JPH06182295A - Stainless steel coated article and production thereof - Google Patents

Abstract

PURPOSE:To improve corrosion resistance, adhesion property of a coating film and weather resistance, etc., by providing a silicon alkoxide-based coating layer on a stainless steel base material through a primer layer. CONSTITUTION:The silicon alkoxide-based coating layer consisting of the cured product of the silicon alkoxide-based coating material is provided on the stainless steel base material through the primer layer. The primer layer is composed of the cured product of the primer composition compounding following each component, (1) 40-60 pts.wt. silicone-modified epoxy resin, (2) 3-5 pts.wt. melamine resin, (3) 11-23 pts.wt. inorg. color pigment and extender pigment, (4) 12-44 pts.wt. org. solvent capable of dissolving (1) and (2) (the total content of the pigment of (3) (PWC) is 35-45wt.% per total solid amount of the primer composition). In this way, excellent corrosion resistance, adhesion property of a coating film and weather resistance is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stainless steel coated article having excellent corrosion resistance, coating adhesion and weather resistance, and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, in relation to building materials, metal materials such as aluminum and stainless steel have been increasing in outer walls and roof materials.
Metals generally have the drawback that the surface is corroded by environmental conditions, and even stainless steel, which is said to have excellent corrosion resistance, has not solved the problem. Therefore, there is an example of applying organic coating or fluorine coating to the surface of stainless steel. However, in the case of organic coating, the weather resistance of the coating film is poor, and in the case of fluorine coating, since the hardness of the coating film is low, there are drawbacks such as easy scratching and easy stain.

As a coating agent which does not have these drawbacks, a silicon compound type inorganic coating agent has been studied, but there is a problem that peeling is likely to occur due to insufficient adhesion of the coating film. A primer composition comprising an isocyanate prepolymer, a silicon compound having a mercapto group and an alkoxy group, an epoxy-modified silicone resin, and an organotin compound, for the purpose of improving coating adhesion of these inorganic coating agents. There is an example of using it (Japanese Patent Laid-Open No. 64-835).
No. 80).

[0004]

However, even if the primer composition described in the above-mentioned JP-A-64-83580 is used, sufficient coating film adhesion is not actually secured. Therefore, it is an object of the present invention to provide a stainless steel coated article having excellent corrosion resistance, coating film adhesion, weather resistance and the like, and a method for producing the same.

[0005]

In order to solve the above problems, a stainless coated article according to the present invention is a stainless coated article having a silicon alkoxide coating layer on the surface of a stainless substrate via a primer layer, The primer layer is a silicone-modified epoxy resin 40 to 60 parts by weight Melamine resin 3 to 5 parts by weight Inorganic color pigment and extender pigment 11 to 23 parts by weight One or more organic solvents capable of dissolving the above 12 to 12 parts by weight 44 parts by weight (however, the total content (PWC) of the above pigments is 35 to 45% by weight with respect to the total solid content of the primer composition.
Is. ) Is a cured product of a primer composition in which each component is mixed, wherein the silicon alkoxide coating layer is a cured product of the following silicon alkoxide coating agent (A) or (B). It is characterized by being.

(A) General formula: (R ¹ ) _m Si (OR ² ) _4-m (I) (In the formula, each R ¹ represents a methyl group, an ethyl group or a phenyl group, and each R ² represents a carbon atom. A silicon alkoxide-based coating agent containing a silicon compound represented by the formulas 1 to 4 and m being 0, 1 or 2, and / or a partial hydrolyzate thereof.

(B) (a) General formula: (R ³ ) _n SiX _4-n (II) (In the formula, R ³ is a substituted or unsubstituted C 1 to C 8
Represents a monovalent hydrocarbon group, X represents a hydrolyzable group,
n is an integer of 0-3. (B) a hydrolyzable organosilane represented by the formula (1) is partially hydrolyzed in colloidal silica dispersed in an organic solvent and / or water, and a silica-dispersed oligomer solution of organosilane, and (b) an average composition formula: R ⁴ ) Si (OH) _d O _{(4-cd) / 2} (III) (In the formula, R ⁴ is each a substituted or unsubstituted C 1 to C 8
Represents a monovalent hydrocarbon group, wherein c is 0.2 ≦ c ≦ 2, d is 0.0001 ≦ d ≦ 3, and c + d <4. ) A silicon alkoxide-based coating agent containing, as essential components, a polyorganosiloxane having a silanol group in the molecule thereof and (c) a curing catalyst.

The method for producing a stainless steel coated article according to the present invention is a method for producing a stainless steel coated article by sequentially forming a primer layer and a silicon alkoxide-based coating layer on the surface of a stainless base material. Formation, silicone modified epoxy resin 40 to 60 parts by weight Melamine resin 3 to 5 parts by weight Inorganic color pigment and extender pigment 11 to 23 parts by weight One or two or more kinds of organic solvents capable of dissolving the above 12 to 44 parts by weight Parts (however, the total content (PWC) of the above pigments is 35 to 45% by weight based on the total solid content of the primer composition.
Is. ) Is coated on the surface of the stainless steel substrate with a primer composition containing the respective components, and the primer composition is cured, and the silicon alkoxide coating layer is formed by the following (A). Alternatively, it is performed by applying the silicon alkoxide coating agent (B) on the primer layer and then curing the coating agent.

(A) General formula: (R ¹ ) _m Si (OR ² ) _4-m (I) (In the formula, each R ¹ represents a methyl group, an ethyl group or a phenyl group, and each R ² represents a carbon atom. A silicon alkoxide-based coating agent containing a silicon compound represented by the formulas 1 to 4 and m being 0, 1 or 2, and / or a partial hydrolyzate thereof.

(B) (a) General formula: (R ³ ) _n SiX _4-n (II) (In the formula, R ³ is a substituted or unsubstituted C 1 to C 8 group, respectively.
Represents a monovalent hydrocarbon group, X represents a hydrolyzable group,
n is an integer of 0-3. (B) a hydrolyzable organosilane represented by the formula (1) is partially hydrolyzed in colloidal silica dispersed in an organic solvent and / or water, and a silica-dispersed oligomer solution of organosilane, and (b) an average composition formula: R ⁴ ) Si (OH) _d O _{(4-cd) / 2} (III) (In the formula, R ⁴ is each a substituted or unsubstituted C 1 to C 8
Represents a monovalent hydrocarbon group, wherein c is 0.2 ≦ c ≦ 2, d is 0.0001 ≦ d ≦ 3, and c + d <4. ) A silicon alkoxide-based coating agent containing, as essential components, a polyorganosiloxane having a silanol group in the molecule thereof and (c) a curing catalyst.

The stainless steel used as the base material in the present invention is not particularly limited and may be any commercially available product. Moreover, the surface may be patterned by roll embossing. Furthermore, by welding,
It may be processed into a required shape. It is desirable that the stainless steel base material be subjected to a degreasing treatment to remove impurities adhering to the surface in consideration of the adhesion of the coating film. The degreasing treatment is not particularly limited, and may be, for example, alkali degreasing, solvent degreasing, or nitric hydrofluoric acid treatment.
Prior to applying the primer composition to the base material, the stainless base material may be subjected to chromate treatment.

The primer composition used in the present invention comprises a silicone-modified epoxy resin 40 to 60 parts by weight, a melamine resin 3 to 5 parts by weight, an inorganic color pigment and an extender pigment 11 to 23 parts by weight. 12 to 44 parts by weight of two or more organic solvents (however, the total content (PWC) of the above pigments is 35 to 45% by weight based on the total solid content of the primer composition.
Is. ) Each component is blended.

Each component of the primer composition will be described below. Examples of the silicone-modified epoxy resin is a component of the primer composition is not particularly limited, for example, silicone-modified epoxy resin was alternating structure of epoxy resins with chelate ligand functional groups: (- (epoxy) - (P _A )-(Epoxy)-(P _B )-) _{n and the} like.

The molecular weight of the silicone-modified epoxy resin is not particularly limited, but it can be 2 depending on whether it has a number average molecular weight of 5,000 to 10,000 or a number average molecular weight of 20,000 to 40,000. It is preferable to use different types together. In this invention, the excellent adhesion of the primer to the stainless steel substrate is due to the following reasons (1) and (2).

(1) Since the epoxy resin is modified to contain appropriate epoxy groups and hydroxyl groups, the hydrogen bonding force between the epoxy resin and the stainless steel substrate is strong. (2) As shown in Chemical Formula 1 below, the silicone-modified epoxy resin forms an oxane bond with the hydroxyl group on the surface of the stainless steel substrate, and at the same time imparts the property of bridging by the reaction with the resin functional group and only strengthens the initial adhesion. In addition, the secondary (evaluation after accelerated deterioration of the coating film) adhesion can also be maintained.

[0016]

[Chemical 1]

The melamine resin, which is a component of the primer composition, is used for thermal crosslinking. Examples of the melamine resin include, but are not limited to, methylrolled melamine and trimethylrolled melamine. Of the inorganic color pigments and extender pigments that are the components of the primer composition, the inorganic color pigments are not particularly limited, and examples thereof include calcined pigments such as titanium oxide. The extender pigment is not particularly limited, and examples thereof include talc; rust preventive pigments such as aluminum phosphomolybdate. However, the total content of the inorganic color pigment and the extender pigment (hereinafter referred to as "PWC") is 35 to 45% by weight based on the total solid content of the primer composition. PWC
However, if it is out of this range, problems will arise in adhesion and water resistance.

The solvent capable of dissolving the silicone-modified epoxy resin and the melamine resin, which are the components of the primer composition, is not particularly limited, but examples thereof include alcohol solvents, glycol solvents, aromatic hydrocarbon solvents and the like. Can be mentioned. More specific examples of these solvents.
It is as follows. Alcohol-based solvent: butyl alcohol, etc.

Glucol type solvent: butyl cellosolve, methoxypropanol and the like. Aromatic hydrocarbon solvent: xylene, toluene, etc. As the solvent, only one kind may be used, or two or more kinds may be used in combination. The primer composition may contain various additives as needed. The additive is not particularly limited, and examples thereof include a titanate coupling agent, an antisettling agent, a dispersant, and the like.

When the alcohol-based solvent, the glycol-based solvent and the aromatic hydrocarbon-based solvent are used in combination as the solvent and the additive is used, the composition of each component of the primer composition is not particularly limited. However, it is preferable that Silicone-modified epoxy resin 40.0 to 60.0 parts by weight Melamine resin 3.0 to 5.0 parts by weight Inorganic coloring pigment 7.0 to 13.0 parts by weight Body pigment 4.0 to 10.0 parts by weight Alcohol-based Solvent 6.0 to 10.0 parts by weight Glucol-based solvent 7.0 to 11.0 parts by weight Aromatic hydrocarbon solvent 9.0 to 13.0 parts by weight Additive 0.5 to 1.5 parts by weight Primer composition The method of coating the material on the stainless steel substrate is not particularly limited, and examples thereof include spray coating, roll coating, and dip coating.

The amount of primer applied is preferably 5 to 1
The thickness is 00 μm, more preferably 15 to 40 μm. 5μ
When it is less than m, the hiding power to the base is lost,
This is because there is a problem in adhesion, and when it exceeds 100 μm, problems such as foaming tend to occur during baking, which is not preferable. The baking and drying temperature of the primer composition is preferably in the range of 50 to 200 ° C.
It is more preferably in the range of 20 to 180 ° C.

After the primer layer is formed, a silicon alkoxide coating layer is formed as a second layer. In order to form this silicon alkoxide coating layer, the silicon alkoxide coating agent-A or silicon alkoxide coating agent-B described below is used. The silicon alkoxide coating agent-A contains a silicon compound represented by the general formula (I) and / or a partial hydrolyzate thereof as a main component. This silicon alkoxide coating agent-
A is, for example, the following components (i), (ii) and (ii)
The mixture containing i) as a main component is diluted with a suitable solvent, and a curing agent and a catalyst are added in the required amounts to cause hydrolysis and polycondensation reaction, and the weight average molecular weight Mw is 500 to 3,000 in terms of polystyrene. , And the molecular weight distribution Mw / Mn is 1.
It is preferably 1 to 3.0 (Mn is a number average molecular weight). More preferably Mw = 600 to 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 during polycondensation tends to be large, or the coating film tends to be cracked after baking. Further, when the weight average molecular weight and the molecular weight distribution are larger than the above range, the reaction is too slow to be hardened, or even when hardened, a soft coating film is formed, or the leveling property of the coating film is very poor. I tend to become.

(I): Silicon compound represented by m = 0 in the general formula (I) and colloidal silica 20 to 20
0 parts by weight. (Ii): 100 parts by weight of a silicon compound represented by m = 1 in the general formula (I). (Iii): 0 to 80 parts by weight of a silicon compound represented by m = 2 in the general formula (I).

The colloidal silica is used by dispersing a fine particle silica component in water, an organic solvent such as methanol, or a mixed solvent thereof. As long as they are colloidal, the particle size, the solvent species, etc. It is not particularly limited. The content of the colloidal silica in the component (i) is the weight part including the dispersion medium. The curing agent used as necessary in the silicon alkoxide coating agent-A is not particularly limited, and examples thereof include inorganic acids such as hydrochloric acid, phosphoric acid and sulfuric acid, and organic acids such as formic acid, acetic acid and chloroacetic acid. An acidic catalyst such as a dilute solution of 1), a basic catalyst described later, or the like can be used alone or in combination of two or more kinds. Further, when silica sol is used as the component (i), the silica sol exhibits acidity, and this serves as a catalyst, so that nothing needs to be added as a catalyst.

Silicon alkoxide type coating agent-A
Can be stably used within the above-mentioned molecular weight range by adjusting its pH value to 3.8 to 6.0. If the pH value is outside the above range, the coating agent-
The stability of A may be deteriorated and the usable period after preparation of the paint may be limited. Here, the pH value adjusting method is not particularly limited, but for example, when the pH value becomes less than 3.8 when the coating agent-A raw material is mixed, a basic reagent such as ammonia is used within the above range. The pH value may be adjusted to the above pH value. If the pH value exceeds 6.0, the pH value may be adjusted using an acidic reagent such as hydrochloric acid. Further, depending on the pH value, if the reaction does not proceed while the molecular weight remains small and it takes time to reach the molecular weight range, the coating agent-A may be heated to accelerate the reaction, or the acidic reagent may be used. The pH value may be lowered to proceed the reaction, and then the pH value may be returned to a predetermined pH value with a basic reagent.

Even if the pH value is adjusted as described above, or even if the pH value is not adjusted, until use,
Or at least at the time of use, in the coating agent-A,
By adding a basic catalyst, the condensation reaction can be promoted and the number of crosslinking points in the coating film can be increased, so that a coating film having good crack resistance can be stably obtained. Further, by promoting the crosslinking reaction, the curing time can be shortened or the curing temperature can be lowered, which is economical.

The basic catalyst used as necessary in the coating agent-A is not particularly limited, but examples thereof include amines such as triethanolamine; γ-aminopropyltriethoxysilane, N- (β-amino). Ethyl) -γ-aminopropyltriethoxysilane, N-
Aminosilanes such as (β-aminoethyl) -γ-aminopropylmethyldimethoxysilane; inorganic acids (eg hydrochloric acid, nitric acid, phosphoric acid, etc.) or organic acids (eg,
Examples thereof include salts of formic acid, acetic acid, propionic acid, etc.) such as ammonia, trimethylamine, triethylamine, n-butylamine, etc., or a metathesis salt of a salt of an inorganic acid or an organic acid with a quaternary ammonium salt. These types,
The amount added is not particularly limited.

Silicon Alkoxide Coating Agent-A
In addition to the above components, if necessary, various colorants, fillers other than the silica sol (for example, alumina sol,
One or more kinds of various additives such as an inorganic filler such as fumed silica), a diluent solvent, a thickener, a surfactant, and an ultraviolet absorber may be contained. The diluting solvent is not particularly limited, but examples thereof include alcohols such as methanol, ethanol, and isopropanol (also referred to as IPA); cellosolves such as ethylene glycol, methyl cellosolve, ethyl cellosolve, and butyl cellosolve. These may be used alone or in combination of two or more.

Silicon Alkoxide Coating Agent-A
The coating method of is not particularly limited, for example, spray coating, roll coating, flow coater coating,
Examples include dip coating. Also, the drying and baking conditions after coating are not particularly limited, but are 60 to 200 ° C.
It is preferable to carry out the process in a moderate degree. In the above composition, if 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 amount of the component (ii) exceeds 80 parts by weight, the coating film is too soft to be practical.

Next, the silicon alkoxide type coating agent-B will be described. This coating agent-B is
The following components (a), (b) and (c) are essential components. (A) General formula (R ³ ) _n SiX _4-n (II) (In the formula, R ³ is each a substituted or unsubstituted C 1 to C 8
Represents a monovalent hydrocarbon group, X represents a hydrolyzable group,
n is an integer of 0-3. ) A silica-dispersed oligomer solution of organosilane, which is obtained by partially hydrolyzing a hydrolyzable organosilane represented by the formula (4) in colloidal silica dispersed in an organic solvent and / or water.

(B) Average composition formula (R ⁴ ) Si (OH) _d O _{(4-cd) / 2} (III) (In the formula, R ⁴ is a substituted or unsubstituted C 1 to C 8 group, respectively.
Represents a monovalent hydrocarbon group, wherein c is 0.2 ≦ c ≦ 2, d is 0.0001 ≦ d ≦ 3, and c + d <4. ) A polyorganosiloxane having a silanol group in the molecule represented by the formula (1).

(C) Curing catalyst. The silica-dispersed oligomer as the component (a) used in the silicon alkoxide-based coating agent-B is the main component of the base polymer having the hydrolyzable group X, which is involved in the curing reaction during film formation. This is obtained by adding the above-mentioned general formula (II) to an organic solvent and / or water in which colloidal silica is dispersed.
With one or more of the hydrolyzable organosilanes represented by the formula (1), water in the dispersion liquid or water added separately,
It can be obtained by partially hydrolyzing this hydrolyzable organosilane.

Specific examples of R ^{3 in} the general formula (II) representing a hydrolyzable organosilane include methyl, ethyl,
Alkyl groups such as propyl, butyl, pentyl, hexyl, heptyl, octyl; cycloalkyl groups such as cyclopentyl, cyclohexyl; aralkyl groups such as 2-phenylethyl, 2-phenylpropyl, 3-phenylpropyl; aryls such as phenyl and tolyl Group: Alkenyl group such as vinyl, allyl; Halogen-substituted hydrocarbon group such as chloromethyl, γ-chloropropyl, 3,3,3-trifluoropropyl; γ-methacryloxypropyl, γ-glycidoxypropyl, 3, Substituted hydrocarbon groups such as 4-epoxycyclohexylethyl, γ-mercaptopropyl and the like can be mentioned. Among these, 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 are an alkoxyl group, an acetoxy group and an oxime group [-O-N = C (-
R ')-R], enoxy group [-OC (-R) = C (-
R ")-R '], amino group, aminoxy group [-ON"
(-R) -R '], amide group [-N (-R')-CO-
R] (wherein R, R ′ and R ″ are, for example, a hydrogen atom or a monovalent hydrocarbon group, etc.) and the like.Easy availability and easy preparation of a silica dispersion oligomer solution. Therefore, an alkoxyl group is preferable.

Examples of such hydrolyzable organosilanes are mono-, di-, tri-, and tetra-functional alkoxysilanes in which n in the general formula (II) is an integer of 0 to 3. , Acetoxysilanes, oxime silanes, enoxysilanes, aminosilanes, aminoxysilanes, amidosilanes and the like. Since it is easily available and a silica dispersion oligomer solution is easily prepared,
Alkoxysilanes are preferred.

Particularly, examples of the tetraalkoxysilane having n = 0 include tetramethoxysilane and tetraethoxysilane, and examples of the organotrialkoxysilane having n = 1 include methyltrimethoxysilane, methyltriethoxysilane and methyltriethoxysilane. Isopropoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane,
Examples include 3,3,3-trifluoropropyltrimethoxysilane and the like. Examples of the diorganodialkoxysilane with n = 2 include dimethyldimethoxysilane, dimethyldiethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, and methylphenyldimethoxysilane. Examples of the triorganoalkoxysilane with n = 3 Is trimethylmethoxysilane, trimethylethoxysilane, trimethylisopropoxysilane,
Dimethylisobutyl methoxysilane etc. can be illustrated. Furthermore, the organosilane compound generally called a silane coupling agent is also included in the alkoxysilanes.

Of the hydrolyzable organosilane represented by the general formula (II), 50 mol% or more is preferably a trifunctional one represented by n = 1, and more preferably 60 mol% or more. And most preferably 70 mol% or more. When the content of the trifunctional compound represented by n = 1 is less than 50 mol%, sufficient coating film hardness cannot be obtained and the dry curability may be poor.

The colloidal silica in the component (a) is essential for increasing the hardness of the cured coating of the silicon alkoxide coating agent-B containing the component (a). As such colloidal silica, water dispersibility,
Alternatively, non-aqueous organic solvent-dispersible colloidal silica such as alcohol can be used. Generally, such colloidal silica dispersions contain 20 to 20% silica as solids.
The content of silica is 50% by weight, and the content of silica can be determined from this value. Further, when the water-dispersible colloidal silica is used, water present as a component other than the solid content can be used for the hydrolysis of the hydrolyzable organosilane in 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 is
It can be easily prepared by replacing the 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 like the water-dispersible colloidal silica.
The type of organic solvent in which the colloidal silica is dispersed is, for example, methanol, ethanol, isopropanol,
lower aliphatic alcohols such as n-butanol and isobutanol; ethylene glycol derivatives such as ethylene glycol, ethylene glycol monobutyl ether and acetic acid ethylene glycol monoethyl ether; diethylene glycol derivatives such as diethylene glycol and diethylene glycol monobutyl ether, or diacetone alcohol Can be mentioned. These may be used alone or in combination of two or more. 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) is a colloidal silica of 5-9.
It is preferably contained in the range of 5% by weight. The range is more preferably 10 to 90% by weight, and most preferably 20 to 85% by weight. When the content is less than 5% by weight,
If the desired coating hardness cannot be obtained, and if it exceeds 95% by weight, it may be difficult to uniformly disperse the silica, which may cause inconvenience such as gelation of the component (a).

The silica-dispersed oligomer of 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 such that the hydrolyzable group (X)
0.001 to 0.5 mol of water is preferable to 1 mol.
If it 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 partial hydrolysis is not particularly limited, but it is sufficient to mix the hydrolyzable organosilane and colloidal silica and add and mix the required amount of water, at which time the partial hydrolysis reaction proceeds at room temperature. To do.
You may heat at 60-100 degreeC in order to accelerate a partial hydrolysis reaction. Furthermore, for the purpose of promoting the partial hydrolysis reaction, hydrochloric acid, acetic acid, halogenated silane, chloroacetic acid,
An organic or inorganic acid such as citric acid, benzoic acid, dimethylmalonic acid, formic acid, propionic acid, glutaric acid, glycolic acid, maleic acid, malonic acid, toluenesulfonic acid or oxalic acid may be used as a catalyst.

The component (a) has a pH value of the liquid of 2.0 to 7.0, preferably 2.5 to 6.5, and more preferably 3.0 in order to obtain stable performance for a long period of time. It is good to set it to ~ 6.0. If the pH is out of this range, especially when the amount of water used is 0.3 mol or more per 1 mol of the hydrolyzable group (X), the long-term performance deterioration of the component (a) may be remarkable. When the pH of the component (a) is outside this range, it may be adjusted by adding a basic reagent such as ammonia or ethylenediamine if it is on the acidic side of this range, and on the basic side, hydrochloric acid may be added. It may be adjusted using an acidic reagent such as nitric acid or acetic acid. However, the adjusting method is not particularly limited.

The polyorganosiloxane having a silanol group, which is the component (b), is an important component characterizing the present invention. Such component (b) has the above-mentioned average composition formula (II
It is represented by I). In formula (III), R ⁴ is represented by the above formula (I
The same as R ^{3 in} I) is exemplified, but preferably,
Alkyl group having 1 to 4 carbon atoms, phenyl group, vinyl group, γ
-Substituted hydrocarbon groups such as glycidoxypropyl group, γ-methacryloxypropyl group, γ-aminopropyl group and 3,3,3-trifluoropropyl group, more preferably methyl group or phenyl group. In the formula (III),
c and d are numbers satisfying the above relationship, and c
Is less than 0.2 or d is more than 3, there is an inconvenience such as cracking of the cured film, and c is more than 2 d
Is less than 0.0001, curing does not proceed favorably.

As such polyorganosiloxane having a silanol group, for example, one or more kinds of known compounds such as methyltrichlorosilane, dimethyldichlorosilane, phenyltrichlorosilane, diphenyldichlorosilane, and alkoxysilanes corresponding thereto are known. It can be obtained by hydrolyzing with a large amount of water according to the above method. When a polyorganosiloxane having a silanol group is hydrolyzed by a known method using an alkoxysilane, a small amount of unhydrolyzed alkoxyl group may remain. That is, a polyorganosiloxane in which a silanol group and an extremely small amount of an alkoxyl group coexist may be obtained, but in the present invention, such a polyorganosiloxane can also be used.

Silicon alkoxide type coating agent-B
The curing catalyst which is the component (c) of (1) accelerates the condensation reaction between the component (a) and the component (b) to cure the coating. Such a catalyst is not particularly limited, but examples thereof include alkyl titanate, tin octylate,
Metal salts of carboxylic acids such as dibutyltin dilaurate and dioctyltin dimaleate; amine salts such as dibutylamine-2-hexoate, dimethylamine acetate, ethanolamine acetate; carboxylic acid quaternary ammonium salts such as tetramethylammonium acetate; tetraethylene Amines such as pentamine; N-β-aminoethyl-γ
-Amine-based silane coupling agents such as aminopropyltrimethoxysilane and N-β-aminoethyl-γ-aminopropylmethyldimethoxysilane; acids such as p-toluenesulfonic acid, phthalic acid, hydrochloric acid; aluminum alkoxides, aluminum chelates, etc. Aluminum compounds of
Examples thereof include alkali metal hydroxides such as potassium hydroxide; titanium compounds such as tetraisopropyl titanate, tetrabutyl titanate and titanium tetraacetylacetonate; halogenated silanes such as methyltrichlorosilane, dimethyldichlorosilane and trimethylmonochlorosilane. However, other than these catalysts, any catalyst can be used as long as it is effective in promoting the condensation reaction between the component (a) and the component (b), and there is no particular limitation.

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

The amount of the component (c) added is 0.0001 to 10 relative to 100 parts by weight of the total of the components (a) and (b).
It is preferably part by weight, more preferably 0.00
05 to 8 parts by weight, and particularly preferably 0.0007 to
5 parts by weight. If the addition amount of the component (c) is less than 0.0001 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 component (a) and the silanol group of component (b) are
In the presence of the curing catalyst of the component (c), the condensation reaction is performed at room temperature or low temperature (for example, a temperature of 100 ° C. or less) to form a cured film. Therefore, unlike the moisture-curing type coating composition, the silicon alkoxide-based coating agent-B used in the present invention is hardly affected by humidity even when cured at room temperature. On the other hand, the heat treatment can accelerate the condensation reaction to form a cured film.

Silicon alkoxide type coating agent-B
In addition to the above components, if necessary, various colorants, fillers other than the silica sol (inorganic fillers such as alumina sol and fumed silica), diluting solvents, thickeners, surfactants, and ultraviolet absorbers. One or more kinds of various additives such as agents may be contained. The diluent solvent is not particularly limited, and examples thereof include alcohols such as methanol, ethanol, and isopropanol (also referred to as IPA); cellosolves such as ethylene glycol monomethyl ether, methyl cellosolve, ethyl cellosolve, and butyl cellosolve. These may be used alone or in combination of two or more. In combination with these hydrophilic organic solvents, toluene, xylene, ethyl acetate, butyl acetate, methyl ethyl ketone, methyl isobutyl ketone, methyl ethyl ketoxime, etc. can also be used.

Silicon alkoxide type coating agent-B
The storage method for the components is (a), (b) and (c)
It is common to take three packaging forms in which each is stored separately, but the mixed component of the component (a) and the component (c) and the component (b) are divided into two packaging forms, and both are mixed at the time of use. Alternatively, all the components may be mixed and stored in one container in one packaging form.

Silicon alkoxide type coating agent-B
Can be coated by a usual coating method, and various coating methods such as brush coating, spray coating, roll coating, flow coater coating and dip coating can be selected. The curing conditions are preferably 5 to 200 ° C., and 10 to 15
0 ° C is more preferable. If it is less than 5 ° C, it becomes difficult to cure, and if it exceeds 200 ° C, foaming may occur. The coating thickness of the second layer is preferably 3 μm or more after curing. If it is less than 3 μm, pinholes are likely to be formed, and the anticorrosion property may be deteriorated.

[0052]

When a primer layer made of a cured product of the specific primer composition and a silicon alkoxide-based coating layer made of a cured product of the specific silicon alkoxide-based coating agent are sequentially formed on the surface of the stainless steel material, The corrosion resistance and weather resistance of the stainless material are improved, and the adhesion of the primer layer and the silicon alkoxide coating layer formed on the surface of the stainless material is also high.

[0053]

EXAMPLES Examples and comparative examples of the present invention will be shown below.
The present invention is not limited to the examples below. In the following, as a general rule, “part” means “part by weight” and “%” means “% by weight”. The primer compositions P-1 to P-4 used in the following examples and comparative examples are shown below.

Primer Composition P-1 As the primer composition P-1, E-1 baking primer F-039 manufactured by Isamu Paint Co., Ltd. was used. This E-1
The baking primer F-039 was prepared by the following procedure. First, a silicone-modified epoxy resin having an alternating structure of an epoxy resin with chelate-coordinating functional groups (having a molecular weight of 5,000 to 10,000 and 20,000)
To 50 parts of 0 to 40,000 and 50 parts of melamine resin, 23 parts of a mixed solvent of butyl alcohol, butyl celloslub and xylene in a weight ratio of 8: 9: 6 is added as a solvent, and 1000 rpm by a disper. Stir for 15 minutes. After 15 minutes, 10 parts of titanium oxide as an inorganic color pigment and 7 parts of talc and aluminum phosphomolybdate as an extender pigment in total are added with further stirring. After that, stirring is continued for about 10 minutes to perform rough kneading. The liquid after the rough kneading is dispersed in a sand grind mill, and after the dispersion is completed, 5 parts of xylene is added to obtain a primer F-039.

Primer Composition P-2 As the primer composition P-2, E-1 baking primer F-0391 manufactured by Isamu Paint Co., Ltd. was used. This E-
1 Baking primer F-0391 was prepared in the same manner as in the primer composition P-1 except that the content of titanium oxide was changed to 5 parts and the total content of talc and aluminum phosphomolybdate was changed to 3.5 parts. It is the same as the preparation procedure of (E-1 baking primer F-039).

Primer Composition P-3 As the primer composition P-3, E-1 baking primer F-0392 manufactured by Isamu Paint Co., Ltd. was used. This E-
1 The procedure for preparing the baking primer F-0392 was the same as the primer composition P-1 except that the content of titanium oxide was changed to 15 parts and the total content of talc and aluminum phosphomolybdate was changed to 10.5 parts. It is the same as the preparation procedure of (E-1 baking primer F-039).

Primer Composition P-4 As the primer composition P-4, E-1 baking primer F-0393 manufactured by Isamu Paint Co., Ltd. was used. This E-
1 The procedure for preparing the baking primer F-0393 was the same as that of the primer composition P except that a commercially available epoxy resin (substantially the same as the above silicone-modified epoxy resin in terms of molecular weight) was used in place of the silicone-modified epoxy resin.
-1 (E-1 baking primer F-039) is the same as the preparation procedure.

The formulations of the primer compositions P-1 to P-4 are summarized in Table 1 below.

[0059]

[Table 1]

The silicon alkoxide-based coating agents A-1 and A-2 used in the following Examples and Comparative Examples
B-1 was prepared by the method shown below. Silicon alkoxide coating agent-A (A-1)
Preparation 100 parts of methyltrimethoxysilane, 20 parts of tetraethoxysilane, IPA organosilica sol (trade name "OS
CAL1432 ", manufactured by Catalysts & Chemicals Industry Co., Ltd., SiO ₂ content 30%) 150 parts, dimethyldimethoxysilane 40
And 100 parts of isopropyl alcohol (IPA) were mixed, and 200 parts of water was further added and stirred. By adjusting the molecular weight Mw of this to 1.200 in a constant temperature bath at 60 ° C., a silicon alkoxide-based coating agent A-
Got 1. The molecular weight is GPC (gel permeation chromatography, manufactured by Tosoh Corporation: HLC80).
20) is used to prepare a calibration curve with standard polystyrene,
It was measured.

Silicon Alkoxide Coating Agent-A
Preparation of (A-2) 100 parts of methyltrimethoxysilane, 10 parts of tetraethoxysilane, IPA organosilica sol (trade name "OS
CAL1432 ", manufactured by Catalysts & Chemicals Industry Co., Ltd., SiO ₂ content 30%) 110 parts, dimethyldimethoxysilane 20
Parts and 100 parts of isopropyl alcohol (IPA) were mixed. To this mixed solution, 1 part of 1N hydrochloric acid and 5 parts of water were added as a catalyst to prepare S-1 liquid.

To 100 parts of this S-1 solution, 7.5 parts of commercially available titanium oxide and 0.3 part of powdered silica (Aerosil R972 manufactured by Nippon Aerosil Co., Ltd.) were added. Glass beads were added to the container using a disper and dispersed at 2000 rpm for 15 minutes, and the obtained S-2 solution was tightly stoppered and stored at 25 ° C. for 3 days. At the time of use, 27 parts of water, 27 parts of IPA and 1N hydrochloric acid as a catalyst were added to 100 parts of S-2 solution.
Silicon alkoxide coating agent A-2 was prepared by adding 2 parts and stirring at 500 rpm at 25 ° C for 10 minutes.
Got

Silicon alkoxide type coating agent-B
Preparation of (B-1) Preparation of component (a) Isopropanol-dispersed colloidal silica sol IPA-ST (particle size 10 to 20 μm, solid content 30%, Nissan Chemical Co., Ltd. ) in a flask equipped with a stirrer, heating jacket, condenser and thermometer. (Manufactured by Kogyo Co., Ltd.) 100 parts, methyltrimethoxysilane 65 parts, and water 5.05 parts are added and stirred to carry out a partial hydrolysis reaction at 65 ° C. for 5 hours, and then cooled to obtain a component ( a) was obtained. This product had a solid content of 36% when left to stand at room temperature for 48 hours. The preparation conditions for this component (a) are as follows.

Mol number of water per mol of hydrolyzable group: 0.1 mol Silica content: 47.2% Mol% of hydrolyzable group-containing organosilane with n = 1: 100 mol% component Preparation of (b) A mixed solution of 220 parts (1 mol) of methyltriisopropoxysilane and 160 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, and then, 105 parts of a 1% aqueous hydrochloric acid solution was added dropwise to the above-mentioned stirred mixed solution over 30 minutes to hydrolyze methyltriisopropoxysilane. After a lapse of 40 minutes from the completion of the dropping, the stirring was stopped and the lower layer mixed solution of water and isopropyl alcohol containing a small amount of hydrochloric acid separated into two layers was separated. Then, the remaining residual hydrochloric acid in the solution containing toluene and the resin is removed by washing with water, and the toluene is further removed under reduced pressure, followed by diluting with isopropyl alcohol to give an average molecular weight of about 2
000 silanol group-containing polyorganosiloxane (polymer silanol) (component (b)) in 40% isopropyl alcohol was obtained. The molecular weight is GPC (gel permeation chromatography, Tosoh Corporation).
(Manufactured by: HLC-802UR), a calibration curve was prepared using standard polystyrene and measured.

In use, to 100 parts of the component (a) obtained above, 36 parts of titanium oxide and 3 parts of # 200 manufactured by Nippon Aerosil Co., Ltd. as fumed silica were added, and then, using a sand mill at 1000 rpm. Treated for 20 minutes. To the obtained liquid, 0.5 part of N-β-aminoethyl-γ-aminopropylmethyldimethoxysilane and 1 part of dibutyltin dilaurate were added as a curing catalyst for the component (c) to prepare a pigmented liquid A '. did. This liquid A '
And 40% isopropyl alcohol of the silanol group-containing polyorganosiloxane (component (b)) obtained above
The solution has a weight ratio of component (a) and component (b) of 50: 5.
The silicon alkoxide-based coating agent B-1 was obtained by mixing so as to be 0.

-Example 1- This example is a silicon alkoxide-based coating agent-
This is an example using A. In the implementation, SUS304 of Nisshin Steel Co., Ltd. starlight finish (roll embossed product) was used as the stainless steel substrate. The base material was degreased by performing alkaline degreasing, washing with ion-exchanged water, and then drying at 120 ° C. for 10 minutes (hereinafter, this was used for all stainless steel base materials).

P-1 was used as a primer composition, and this was spray-coated on a stainless steel substrate to give a film thickness of 20 μm.
As a result, baking was performed at 150 ° C. for 20 minutes. Then, a silicon alkoxide-based coating agent A as an undercoat paint
-2 was spray-coated to a film thickness of 25 μm, and baking was performed at 150 ° C. for 15 minutes. After that, a silicon alkoxide-based coating agent A-1 was spray-coated as a top-coat paint to a film thickness of 7 μm, and baking was performed at 180 ° C. for 30 minutes to obtain a stainless-coated article.

Example 2-A stainless steel coated article was obtained in the same manner as in Example 1 except that the silicon alkoxide coating agent A-1 was not applied. -Example 3-This example is a silicon alkoxide-based coating agent-
This is an example using B.

P-1 was used as a primer composition, and this was spray-coated on a stainless steel substrate to give a film thickness of 20 μm.
As a result, baking was performed at 150 ° C. for 20 minutes. Then, a silicon alkoxide coating agent B-1 was spray-coated to a thickness of 20 μm, and baking was performed at 60 ° C. for 30 minutes to obtain a stainless-coated article. -Comparative Examples 1 and 2-A stainless steel-coated article was obtained in the same manner as in Example 1, except that the primer compositions P-2 and P-3 were used in place of the primer composition P-1. It was
In Comparative Examples 1 and 2, the relationship between the PWC of the primer and the adhesiveness was examined.

Comparative Example 3 A stainless steel coated article was obtained in the same manner as in Example 1 except that the primer composition P-1 was used in place of the primer composition P-1. This Comparative Example 3
Shows the difference in adhesiveness due to the difference in epoxy resin used for the primer.

Comparative Examples 4 and 5-Stainless steel coating was carried out in the same manner as in Example 3 except that the primer compositions P-2 and P-3 were used in place of the primer composition P-1. I got the goods.
In Comparative Examples 1 and 2, the relationship between the PWC of the primer and the adhesiveness was examined.

Comparative Example 6 A stainless steel coated article was obtained in the same manner as in Example 3, except that the primer composition P-4 was used in place of the primer composition P-1. This Comparative Example 3
Shows the difference in adhesiveness due to the difference in epoxy resin used for the primer.

The stainless steel coated articles obtained in Examples 1 to 3 and Comparative Examples 1 to 6 were examined for coating film adhesion, corrosion resistance and weather resistance. The adhesion of the coating film was confirmed by immersing the stainless steel-coated article in boiling water for 5 hours, air-drying it, and using an adhesive tape (cellophane tape) within 3 hours. The corrosion resistance was visually evaluated after 2,000 hours from the salt spray test.

The weather resistance is an ice-par UV tester,
Set the following conditions as one cycle (8 hours + 4 hours = 12
The condition was evaluated after the test was performed up to a UV irradiation time of 1,000 hours. Test conditions Time: 8 hours 4 hours UV irradiation: Yes (100 mW / cm ² ) No Temperature: 63 ° C. 35 ° C. Humidity: 50% 90% or more (with condensation) The results are shown in Table 2 below.

[0075]

[Table 2]

As shown in Table 2, the stainless steel coated articles of Examples 1 to 3 are superior in coating adhesion, corrosion resistance and weather resistance to those of Comparative Examples 1 to 6. It was confirmed.

[0077]

The stainless coated article according to the present invention is excellent in coating film adhesion, corrosion resistance, weather resistance, and the like. According to the manufacturing method of the present invention, it is possible to obtain the above excellent stainless steel coated article.

Claims (2)

[Claims] 1. A stainless steel coated article having a silicon alkoxide coating layer on the surface of a stainless steel base material via a primer layer, wherein the primer layer is a silicone-modified epoxy resin 40 to 60 parts by weight melamine resin 3 to 5 parts by weight. Part Inorganic color pigment and extender pigment 11 to 23 parts by weight One or more organic solvents capable of dissolving the above 12 to 44 parts by weight (however, the total content of the above pigments (PWC) is the primer composition 35 to 45% by weight based on the total solid content of the product
Is. ) Is a cured product of a primer composition in which each component is mixed, wherein the silicon alkoxide coating layer is a cured product of the following silicon alkoxide coating agent (A) or (B). A stainless-painted article characterized by being. (A) General formula: (R ¹ ) _m Si (OR ² ) _4-m (I) (In the formula, each R ¹ represents a methyl group, an ethyl group or a phenyl group, and each R ² has a carbon number of 1 to 1. 4 is an alkyl group, and m is 0, 1 or 2.) A silicon alkoxide-based coating agent containing a silicon compound represented by the formula (4) and / or a partial hydrolyzate thereof as a main component. (B) (a) the general _{^{formula: (R 3) n SiX 4}} -n ... (II) ( wherein, R ³ are each a substituted or unsubstituted C 1-8
Represents a monovalent hydrocarbon group, X represents a hydrolyzable group,
n is an integer of 0-3. (B) a hydrolyzable organosilane represented by the formula (1) is partially hydrolyzed in colloidal silica dispersed in an organic solvent and / or water, and a silica-dispersed oligomer solution of organosilane, and (b) an average composition formula: R ⁴ ) Si (OH) _d O _{(4-cd) / 2} (III) (In the formula, R ⁴ is each a substituted or unsubstituted C 1 to C 8
Represents a monovalent hydrocarbon group, wherein c is 0.2 ≦ c ≦ 2, d is 0.0001 ≦ d ≦ 3, and c + d <4. ) A silicon alkoxide-based coating agent containing, as essential components, a polyorganosiloxane having a silanol group in the molecule thereof and (c) a curing catalyst. 2. A method for producing a stainless steel-coated article by sequentially forming a primer layer and a silicon alkoxide-based coating layer on the surface of a stainless steel substrate, wherein the formation of the primer layer is performed by a silicone-modified epoxy resin 40-60. Parts by weight Melamine resin 3 to 5 parts by weight Inorganic color pigment and extender pigment 11 to 23 parts by weight One or more organic solvents capable of dissolving the above 12 to 44 parts by weight (however, the total content of the above pigments The amount (PWC) is 35 to 45% by weight based on the total solid content of the primer composition.
Is. ) Is coated on the surface of the stainless steel substrate with a primer composition containing the respective components, and the primer composition is cured, and the silicon alkoxide coating layer is formed by the following (A). Alternatively, the method for producing a stainless steel coated article, which is performed by applying the silicon alkoxide-based coating agent of (B) on the primer layer and then curing the coating agent. (A) General formula: (R ¹ ) _m Si (OR ² ) _4-m (I) (In the formula, each R ¹ represents a methyl group, an ethyl group or a phenyl group, and each R ² has a carbon number of 1 to 1. 4 is an alkyl group, and m is 0, 1 or 2.) A silicon alkoxide-based coating agent containing a silicon compound represented by the formula (4) and / or a partial hydrolyzate thereof as a main component. (B) (a) the general _{^{formula: (R 3) n SiX 4}} -n ... (II) ( wherein, R ³ are each a substituted or unsubstituted C 1-8
Represents a monovalent hydrocarbon group, X represents a hydrolyzable group,
n is an integer of 0-3. (B) a hydrolyzable organosilane represented by the formula (1) is partially hydrolyzed in colloidal silica dispersed in an organic solvent and / or water, and a silica-dispersed oligomer solution of organosilane, and (b) an average composition formula: R ⁴ ) Si (OH) _d O _{(4-cd) / 2} (III) (In the formula, R ⁴ is each a substituted or unsubstituted C 1 to C 8
Represents a monovalent hydrocarbon group, wherein c is 0.2 ≦ c ≦ 2, d is 0.0001 ≦ d ≦ 3, and c + d <4. ) A silicon alkoxide-based coating agent containing, as essential components, a polyorganosiloxane having a silanol group in the molecule thereof and (c) a curing catalyst.