JPH0860099A - Coating composition - Google Patents

Abstract

PURPOSE: To obtain a coating composition capable of forming a transparent or translucent tough film which is excellent in adhesion to various inactivated metal surfaces and has antistatic properties. CONSTITUTION: The composition comprises as major components 10-35 pts.wt. organoalkoxysilane (a) represented by the formula R<1> Si (OR<2> )3 (wherein R<1> is a 1-8C organic group and R<2> s each is a 1-5C alkyl or a 1-4C acyl), 1-8 pts.wt. poly(vinyl butyral) (b), 1-11 pts.wt. (in terms of alumina) colloidal and/or ultrafine particles of alumina (c), 10-75 pts.wt. hydrophilic organic solvent (d), and 4-40 pts.wt. water (e), the sum of (a), (b), (c), (d), and (e) being 100 pts.wt. It has a solid content of 10-35wt.%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating composition, and more specifically to the surface of iron, stainless steel, aluminum and other metals, ceramics, glass, plastics, paper and other products, or an organic coating film. When it is applied to the surface of and cured at room temperature or under heating, it is transparent or translucent, has good adhesion, wear resistance, impact resistance, flexibility, chemical resistance, stain resistance, and antistatic property. The present invention relates to a coating composition for forming a coating film having excellent toughness and high hardness.

[0002]

2. Description of the Related Art Conventionally, various coating compositions for forming a cured coating film on a substrate surface have been proposed for the purpose of improving the weather resistance, hardness, chemical resistance, abrasion resistance, etc. of the substrate surface. ing.

For example, the following (a) and (b) are known as organoalkoxysilane-based coating compositions. (A) An organoalkoxysilane represented by RSi (OR ') ₃ (wherein R and R'represent an alkyl group or an aryl group) or a hydrolyzate thereof, and Si (OR ") ₄
(Wherein R ″ represents an alkyl group) and a composition thereof with a tetraalkoxylane or a hydrolyzate thereof (Japanese Patent Publication Nos. 55-4148, 55-40631, and 55-41273). (B) A composition containing an organoalkoxysilane represented by RSi (OR ') ₃ (wherein R and R'represent an alkyl group or an aryl group) or a hydrolyzate thereof and colloidal silica. (Japanese Patent Application Laid-Open No. 55-94971, Japanese Patent Application Laid-Open No. 5
9-68377, etc.).

However, there is no coating composition showing good adhesion to only various anticorrosion-treated iron and aluminum, which are difficult to adhere to, stainless steel, copper and various alloys of the base material, only by degreasing treatment.

[0005]

DISCLOSURE OF THE INVENTION The present invention is directed to an organoalkoxysilane-based coating composition which is nonflammable and forms a film excellent in weather resistance, heat resistance, acid resistance, organic chemical resistance, hardness, etc. A butyral resin which has excellent adhesion to glass and which is used in a wash primer and the like, and a coating composition in which colloidal or ultrafine particle alumina having a higher positive charge and becoming transparent or translucent is arranged, Excellent adhesion to various metals that are difficult to adhere to, transparent, semi-transparent, and tough coating with excellent wear resistance, impact resistance, flexibility, chemical resistance, stain resistance, antistatic properties, and hardness. It is an object to provide a coating composition capable of forming a film.

[0006]

The present invention provides (a) R ¹ S
i (OR ² ) ₃ (wherein R ¹ is an organic group having 1 to 8 carbon atoms,
R ² represents an alkyl group having 1 to 5 carbon atoms and / or an acyl group having 1 to 4 carbon atoms), 10 to 35 parts by weight of organoalkoxysilane, (b) 1 to 8 parts by weight of polyvinyl butyral, c) 1 to 11 parts by weight of colloidal and / or ultrafine particle alumina in terms of alumina,
(D) 10 to 75 parts by weight of hydrophilic organic solvent, and (e) 4 to 40 parts by weight of water [(a) + (b) +
(C) + (d) + (e) = 100 parts by weight] and has a solid content concentration of 10 to 35% by weight.

Regarding the coating composition of the present invention,
Hereinafter, each component will be described. (A) Organoalkoxysilane The organoalkoxysilane used in the present invention is hydrolyzed and polycondensed in the presence or absence of an acid or an alkali in the presence of water to give a high molecular weight. It cures under heating or at room temperature. Furthermore, in the coating composition of the present invention, the organic (b)
It acts as a coupling agent for improving the affinity between the component and (c) colloidal alumina and / or ultrafine particle-shaped alumina and a dispersant for uniformly dispersing alumina in the composition.

In the above organoalkoxysilane, R ¹ in the above formula is an organic group having 1 to 8 carbon atoms, for example, a methyl group,
Alkyl groups such as ethyl group and n-propyl group, as well as γ-chloropropyl group, vinyl group, 3,3,3-trifluoropropyl group, γ-glycidoxypropyl group, γ-methacryloxypropyl group, γ- A mercaptopropyl group, a phenyl group, a 3,4-epoxycyclohexylethyl group, a γ-aminopropyl group and the like, and R in the formula
² is an alkyl group having 1 to 5 carbon atoms and / or an acyl group having 1 to 4 carbon atoms, for example, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, sec-butyl group, An organic silane compound having a t-butyl group, an acetyl group, or the like.

Specific examples of these organoalkoxysilanes include methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, n-propyltrimethoxysilane, and n-propyltrimethoxysilane.
Propyltriethoxysilane, i-propyltrimethoxysilane, i-propyltriethoxysilane, γ-chloropropyltrimethoxysilane, γ-chloropropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 3,3,3 -Trifluoropropyltrimethoxysilane, 3,3,3-trifluoropropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-
Mercaptopropyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, 3,4
-Epoxycyclohexylethylmethoxysilane, 3,
4-epoxycyclohexylethylethoxysilane, γ
Examples include -aminopropylmethoxysilane and γ-aminopropylethoxysilane.

These organoalkoxysilanes have 1
They may be used alone or in combination of two or more. Further, it is also possible to use a hydrolyzate obtained by previously hydrolyzing such an organoalkoxysilane in the presence or absence of an acid or an alkali, and a partial condensate obtained by further aging the hydrolyzate and polycondensing it.

The mixing ratio of the component (a) in the total 100 parts by weight of the coating compositions (a) to (e) is 10 to 35 parts by weight, preferably 15 to 25 parts by weight in terms of organoalkoxysilane. . If the blending ratio of the component (a) is less than 10 parts by weight, the hardness of the cured coating film will be insufficient, while 3
If the amount exceeds 5 parts by weight, the hardness of the coating film increases, but cracks are likely to occur, and impact resistance, flex resistance, etc. are greatly reduced, which is not preferable.

(B) Polyvinyl butyral The polyvinyl butyral which constitutes the component (b) is generally called butyral resin, which is tough and excellent in flexibility and has a hydroxyl group in the molecule, so that it adheres to glass or metal. It is a resin that has the property of being rich in properties. Adhesiveness is
Although it depends on the degree of polymerization and the composition, for example, the lower the degree of polymerization or the higher the number of acetyl groups, the greater the adhesiveness. In addition, it is well soluble in a wide range of organic solvents such as alcohols and ketones, especially solvents containing a small amount of water, and also has good compatibility with various resins and is easy to crosslink, so it is used in various paints and adhesives. Has been done. In the present invention, it is an essential component as the component (b), and is copolymerized with the organopolysiloxane produced by the polycondensation of the organoalkoxysilane (a) to form a coating film having high hardness and flexibility. And improve the adhesion to the surface of the inert base material.

The mixing ratio of the component (b) in the total 100 parts by weight of the coating compositions (a) to (e) is 1
-8 parts by weight, preferably 2-6 parts by weight. When the blending ratio of the component (b) is less than 1 part by weight, sufficient adhesion and impact resistance of the coating film cannot be obtained, while when it exceeds 8 parts by weight, the surface hardness, heat resistance, weather resistance and the like of the coating film are deteriorated. It is not preferable because it significantly decreases.

A mixture of polyvinyl butyral and a thermosetting resin can be used as the component (b).
The thermosetting resin that may constitute the component (b) has at least two functional groups in the molecular chain and is three-dimensionally cross-linked and polymerized by heating to be cured, and the cured product exhibits thermoplasticity. It is a resin that does not exist, and is cured by heating in the presence or absence of a curing agent or standing at room temperature.
In the present invention, (a) an organopolysiloxane produced by polycondensation of an organoalkoxysilane is copolymerized to form a cured coating film having high hardness and flexibility, and the organic base surface of the cured coating film. Improve adhesion to.

Examples of such thermosetting resins include amino resins such as urea resins and melamine resins, phenol resins, urethane resins, epoxy resins such as bisphenol A type epoxy resins and bisphenol F type epoxy resins, alkyd resins and unsaturated resins. Polyester resin, for example, maleic acid type unsaturated polyester, diallyl phthalate type unsaturated polyester, thermosetting acrylic resin,
Examples of the epoxy-modified polyamide resin and polyurethane resin include (d) in the present invention.
What is soluble in a hydrophilic organic solvent is used as a varnish dissolved in the solvent. These thermosetting resins may be used alone or in combination of two or more.

(C) Colloidal and / or ultrafine particles
Alumina colloidal alumina is an alumina sol having a pH of 2.5 to 6 using water and / or lower alcohols as a dispersion medium, contains 5 to 25% by weight of alumina, and contains nitric acid, hydrochloric acid, acetic acid, etc. as a stabilizer. An acid is used, and the ultrafine particle alumina is an alumina produced by a high temperature hydrolysis method of a purified aluminum salt (a specific example; manufactured by Degussa).

In the present invention, since such alumina has a high positive charge, the antistatic property of the coating film is improved,
As a result, the antifouling property of the coating film is improved. Alumina also improves the adhesion and heat emissivity of the coating film. In addition, it is possible to prevent the formation of spots on the coating film.

The colloidal or ultrafine particles of alumina have an average particle size or average thickness of 5 to 50 mμ.
Granules or feathers are preferred. The mixing ratio of the component (c) in the total 100 parts by weight of the coating compositions (a) to (e) is 1 to 11 parts by weight, preferably 3 to 9 parts by weight, in terms of alumina. If the mixing ratio of the component (c) is less than 1 part by weight, a sufficient antistatic effect cannot be obtained, while if it exceeds 10 parts by weight, the coating composition thickens, which is not preferable.

(D) Hydrophilic Organic Solvent The (d) hydrophilic organic solvent used in the present invention is
(B) An organic solvent that dissolves polyvinyl butyral and is compatible with water, a solid concentration and viscosity modifier for the coating composition other than the component (b), and (a) an organoalkoxysilane. It is used as a hydrolysis regulator.

The hydrophilic organic solvent (d) used in the present invention is alcohols, glycols, esters, ethers, ketones and the like. Examples of alcohols include aliphatic alcohols having 1 to 8 carbon atoms, such as methanol, ethanol, n-propanol, i-propanol, and n-.
Butanol, sec-butanol, t-butanol, n
-Pentanol, n-hexanol, 4-methyl-2-
Pentanol, 4-methyl-n-pentanol and the like can be mentioned. Examples of glycols include ethylene glycol and propylene glycol. Examples of the esters include esters of the alcohols and glycols such as formic acid, acetic acid and propionic acid, specifically, methyl formate, ethyl formate, butyl formate, methyl acetate, ethyl acetate, butyl acetate, ethyl propionate and the like. it can.

The ethers include alkyl ethers of alcohols and glycols, such as dimethyl ether, diethyl ether, dibutyl ether, methyl ethyl ether, ethyl butyl ether, ethylene glycol monobutyl ether, acetic acid ethylene glycol monoethyl ether, propylene. Examples thereof include glycol monoethyl ether. As the ketones, acetone, diethyl ketone, methyl ethyl ketone,
Examples include acetophenone.

Such a hydrophilic organic solvent can be used alone or as a mixed solvent of two or more kinds. In the present invention, i-propanol, n-butanol, ethylene glycol monobutyl ether, methyl ethyl ketone, ethyl acetate alone or A mixed solvent of two or more of them is preferably used.

The mixing ratio of the component (d) in the total 100 parts by weight of the coating compositions (a) to (e) is 1
It is 0 to 75 parts by weight, preferably 25 to 60 parts by weight.
When the blending ratio of the component (d) is less than 10 parts by weight, the viscosity of the coating composition is excessively increased and the storage stability is lowered, while when it exceeds 75 parts by weight, the storage stability is improved, but for coating. It is not preferable because the solid content concentration in the composition becomes small, the thickness of the obtained coating film becomes too thin, and the blending ratio of water (e) described later becomes relatively small. When the colloidal alumina (c) is alcoholic, this alcohol is also included in the hydrophilic organic solvent.

[0024] In (e) water present invention, water is an essential component as a hydrolysis agent of (a) an organoalkoxysilane. As this water, tap water, distilled water, or ion-exchanged water can be used. Note that (a) water produced by hydrolysis of the organoalkoxysilane and water as a dispersion medium for the colloidal alumina of the component (c) are also included.

The mixing ratio of the component (e) in the total 100 parts by weight of the coating compositions (a) to (e) is 4
-40 parts by weight, preferably 8-30 parts by weight.
When the blending ratio of the component (e) is less than 4 parts by weight, hydrolysis of the (a) organoalkoxysilane is difficult to sufficiently occur,
On the other hand, if the amount exceeds 40 parts by weight, the stability of the coating composition decreases, which is not preferable.

The coating composition of the present invention contains, in addition to the components (a) to (e), a surfactant, if necessary.
Additives such as acids, aluminum acetylacetonate, pigments and ultrafine silica can be included.

The coating composition of the present invention is a liquid composition comprising the components (a) to (e) and having a solid content concentration of 10 to 35% by weight in an acidic region of pH 7 or less. If the solid content concentration is less than 10% by weight, a coating film having a sufficient thickness cannot be obtained by one coating, resulting in poor workability.
If it exceeds 5% by weight, the coating film is cracked and powdery, which is not preferable.

The coating composition of the present invention comprises (b)
Polyvinyl butyral is dissolved in (d) a hydrophilic organic solvent to prepare a varnish, and component (c) colloidal or ultrafine particle alumina, (e) water and, if necessary, an additive are added thereto, and a roll mill, a ball mill, Alumina is sufficiently dispersed using a stirrer or the like. It can be prepared by adding (a) organoalkoxysilane to this and stirring sufficiently.

Substrates to be coated with the coating composition of the present invention include metals such as iron, stainless steel and aluminum, inorganic substrates such as cement, concrete, glass and ceramics, plastic, paper and wood. In addition to the organic base materials, the surface of organic and inorganic coating films.

For coating the substrate with the coating composition, a coating means such as brush coating, spraying, dipping, roll coating, spin coating, or printing can be used. A coating film having a dry film thickness of 0.1 to 15 μm can be formed by coating once, and the coating can be repeated 2 to 4 times. Further, in the case of multiple coating, the curing treatment may be performed once.

When the coating composition of the present invention is coated on a substrate, the organoalkoxysilane component (a) is hydrolyzed at a temperature of room temperature to 60 ° C. and, at the same time, a polycondensation reaction is caused to form a sol. The reaction proceeds further to form a gel, that is, an organopolysiloxane compound. Leave it at room temperature for 1-10 days or 8
By heating at 0 to 200 ° C. for 3 to 60 minutes, the organopolysiloxane compound and (b) are volatilized with the solvent.
Polyvinyl butyral which is a component is copolymerized to further form a cured coating film in which component (c) alumina is composited. However, the reaction temperature and the standing time or heating time are not limited to the above, because they vary depending on the type and mixing ratio of each component used.

[0032]

In the cured coating film formed by the coating composition of the present invention, the organopolysiloxane exhibits excellent adhesion to various base materials in combination with the adhesive force of polyvinyl butyral, and particularly, the organopolysiloxane. It became possible to adhere even to an inactivated rust-treated metal surface or resin surface, which hardly adheres only with polysiloxane, by using it together with polyvinyl butyral.

As for the surface hardness of the cured coating film, a high hardness close to that of an inorganic substance is obtained by the combination of organopolysiloxane and alumina, and polyvinyl butyral is used as a buffer material to interpolate the decrease in impact resistance and flexibility due to the high hardness. Therefore, mechanical properties such as impact resistance and flex resistance are extremely excellent.

Further, by compounding alumina, not only the adhesion is improved, but also the chargeability is prevented by the positive charge of alumina, and as a result, the antifouling property is improved and the heat radiation property and the antistatic property are improved. And a cured coating film excellent in stain resistance can be obtained.

In addition to the above, organopolysiloxane and polyvinyl butyral interpolate with each other to give weather resistance, heat resistance, acid resistance, alkali resistance, organic chemical resistance, corrosion resistance,
A cured coating film having excellent wear resistance and electrical insulation can be obtained. The coating composition of the present invention is extremely excellent in workability because various coating means can be adopted, and is also excellent in repairability because it can be repeatedly coated.

[0036]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples. In addition, "part" and "%" in the examples are based on weight unless otherwise specified.

Examples 1 to 6 and Comparative Examples 1 to 6 (1) Preparation of Coating Composition A varnish prepared by dissolving the component (b) in the component (d) was prepared by using the following components, and the components (c) and ( After stirring for 30 minutes using a high-speed stirrer with or without addition of the component e) and additives, the component (a) is added and stirred at a low speed for 10 minutes,
This was aged at room temperature for 3 hours to prepare coating compositions A to F (Examples 1 to 6) and coating compositions G to L (Comparative Examples 1 to 6) having the compounding ratios shown in Table 1.

(A) Organoalkoxysilane (a) -1: Methyltrimethoxysilane (a) -2: Methyltriethoxysilane (b) Component (b): Butyral resin; Solid content concentration 98%

(C) Colloidal or ultrafine aluminum
Na (c) -1: aqueous colloidal alumina; alumina 20
%, PH 3.5 (c) -2: ultrafine particulate alumina; average particle size 15 mμ (d) hydrophilic organic solvent (d) -1: butanol (d) -2: butyl cellosolve (d) -3: isopropanol (e ) ) Water water

(F) Additive (f) -1: amino resin; solid content concentration 60% (f) -2: cationic surfactant (f) -3: aluminum acetylacetonate (f) -4: acetic acid (F) -5: pigment; iron oxide (brown)

[0041]

[Table 1]

[0042]

[Table 2]

(2) Preparation of test piece for evaluation test For the evaluation test, the coating compositions shown in Tables 1 and 2 prepared in the above item (1) were applied to various substrates shown in Table 3 and cured. Test pieces TP1-24 were prepared. Among the substrates to be coated, a steel plate, a steel container and a stainless steel container were alkali degreased, an aluminum plate was degreased with toluene, and others were cleaned as a base treatment before the coating composition was applied. An air spray gun was used for applying the coating composition, and an electric oven was used for heating. The coating compositions were used within 8 hours after preparation. The number of times the coating composition was applied and the curing conditions are shown in Tables 4-5.

[0044]

[Table 3]

[0045]

[Table 4]

[0046]

[Table 5]

(3) Evaluation test After the test piece prepared in the item (2) was kept indoors for 7 days, the following evaluation test was carried out. Adhesiveness JIS K-5400-6.15 based on a cross cut test. Adhesion cold / heat cycle test piece (used)
It was based on the K-5400-6.15 cross cut test. Hardness It was based on JIS K-5400-6.14 pencil scratch test. Impact resistance Based on JIS K-5400-6.13.2.

After holding the test piece at 200 ° C. for 8 hours in a heat-resistant electric furnace, it was naturally cooled and the appearance of the coating film was observed. Boil-resistant aqueous solution Hold the test piece in boiling water for 8 hours and allow it to cool.
After repeating 0 times, the appearance of the coating film was observed. After maintaining the test piece in warm water having a hot water resistance of 60 ° C. for 20 days, the appearance of the coating film was observed.

After maintaining the test piece in 4% saline water resistant saline for 20 days, the appearance of the coating film was observed. Salt sprayability 4% saline was continuously sprayed on the test piece for 480 hours, and then the appearance of the coating film was observed. Solvent resistance The test piece was immersed in a mixed solvent of acetone / cellosolve / ethyl acetate / hydrous alcohol for industrial use / toluene = 3/2/2/1/2 (weight ratio) for 20 days, and then the appearance of the coating film was observed.

A 10% aqueous solution of caustic soda was dropped on the alkali resistance test piece, and after holding for 8 hours, the appearance of the coating film was observed. A 20% hydrochloric acid aqueous solution was dropped on the acid- resistant test piece, and after holding for 8 hours, the appearance of the coating film was observed. The test piece was kept at 200 ° C. for 30 minutes in a cold-heat cycle electric furnace and naturally cooled. After repeating this operation 8 times, the appearance of the coating film was observed. After strongly rubbing the test piece with steel wool of abrasion resistance # 0000, the appearance of the coating film was observed to determine the presence or absence of scratches.

Weather resistance A test piece was exposed for 2000 hours by a sunshine carbon arc lamp weather resistance tester according to JIS K-5701, and then the appearance of the coating film was observed. Measured value (Ωcm) at a volume resistance of 50% relative humidity and 23 ° C. Antistatic property According to the method A half-life measurement method of JIS L1094-1980 electrostatic measurement method. As the measuring method, a test piece was set in a half-life measuring device, an applied voltage of +10 kV was applied for 30 seconds, the voltage after the applied voltage was cut off was measured with time, and the half-life was obtained. The unit is seconds. The evaluation of the appearance observation result of the coating film was as follows. O mark: No peeling of the coating film was observed and the appearance was not changed. X: Peeling, cracking or melting damage is observed on part or all of the coating film. -Mark: Tables 6 to 8 show the results of non-evaluation tests.

[0052]

[Table 6]

[0053]

[Table 7]

[0054]

[Table 8]

[0055]

EFFECTS OF THE INVENTION By using the coating composition of the present invention, a transparent or translucent cured coating film having excellent chemical properties, mechanical properties and electrical properties, as shown in the above-mentioned examples, can be formed on a metal. It can be formed on any base material such as a base material, an inorganic base material and an organic base material, and the cured coating film has excellent adhesion even to a base material that is difficult to adhere to. Further, by adjusting the composition of the coating composition, a cured coating film can be formed according to the material of the base material and the purpose of the coating. Furthermore, in coating, various known coating means can be adopted, so that workability is excellent, and since recoating can be performed, repairability is also excellent. Since the present invention provides such a very excellent coating film, its industrial significance is extremely large.

Claims (1)

[Claims] 1. (a) R ¹ Si (OR ² ) ₃ (wherein R ^1
1 represents an organic group having 1 to 8 carbon atoms, R ² represents an alkyl group having 1 to 5 carbon atoms and / or an acyl group having 1 to 4 carbon atoms)
10 to 35 parts by weight of organoalkoxysilane represented by, (b) 1 to 8 parts by weight of polyvinyl butyral, (c) 1 to 11 parts by weight of colloidal and / or ultrafine particle alumina in terms of alumina, (d) 10 to 75 parts by weight of hydrophilic organic solvent, and 4 to 40 parts by weight of (e) water [where (a) + (b) + (c) + (d) + (e) =
100 parts by weight] as a main component and has a solid content concentration of 10 to
35% by weight of the coating composition.