JP2000230150A - Composition for coating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily obtain an inorganic coating composition at a low cost, capable of forming a coating film through a low-temperature baking treatment at <=150 deg.C, giving high surface hardness to the coating film, excellent in properties such as scratch-resisting property when washed by a brush, boil-resisting, solvent-resisting, corrosion-resisting, water-resisting, chemical-resisting and crack- resisting properties (flexibility), and useful as a one-pack type composition having a wide tolerance range to be mixed with water and good aging stability for a long period. SOLUTION: This coating composition comprises (a) an akloxysilane expressed by the formula A: RnSi(OR')4-n [R is a 1-8C organic radical; R' is methyl or ethyl; (n) is 0-2], (b) a solvent soluble-type fluorine resin mainly having hydroxyl groups, (c) a solvent dispersible-type colloidal silica, and (d) a metal alkoxide, excluding silicon alkoxides and expressed by the formula B: M(OR")m [R" is a 1-4C alkyl; M is Ti, Zr or Al; (m) is 3 or 4].

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a coating composition, and more particularly to a composition suitable for use as a surface coating for various product base materials such as a calcium silicate ceramic base material and a metal base material such as SUS and aluminum. Coating compositions that can be made.

[0002]

2. Description of the Related Art In recent years, low-temperature baking treatment at a coating film forming temperature of 150 ° C. or less has been conducted with the aim of reducing the coating processing cost of an object to be coated and environmental measures. There are demands for inorganic coating compositions that have excellent corrosion resistance, solvent resistance, boiling water resistance, water resistance, chemical resistance, etc., and also have a flexible coating film and a high thickness limit. Various compositions have been proposed to satisfy the needs.

As a coating composition containing a hydroxyl group-containing vinyl resin as a component, for example, Japanese Patent Publication No. 7-9 / 1995
No. 1511 reports an inorganic paint having high chemical resistance, in which a silicone resin and / or a solvent-soluble fluororesin is blended with an alkoxysilane hydrolyzed condensate to increase the thick film limit. However, in this composition, the cross-linking reaction between the alkoxysilane hydrolyzed condensate and the organic resin does not occur, so that the hybrid effect is not sufficiently exhibited, and the coating film properties such as boiling resistance and water resistance are reduced to those of organic paints and water glass. Is significantly weaker than inorganic coatings using an alkali silicate as a binder, and the coating film forming temperature is 180 ° C to 200 ° C.
Because it is near, there are restrictions on construction such as baking temperature,
There is a drawback that the productivity of the coated product deteriorates.

[0004] Also, in Japanese Patent No. 2709281,
A mixture of an alkoxysilane hydrolysis condensate and a solvent-soluble fluororesin having a specific hydroxyl value, a filler such as an epoxy group-containing silane coupling agent, a catalyst, and an inorganic pigment are blended to provide high surface hardness and boiling resistance. Although an excellent composition is disclosed, the solvent resistance of the coating film, the corrosion resistance is weak, especially when the coating film forming temperature is low-temperature baking conditions of 150 ° C. or less,
There is a problem that it is difficult to obtain desired coating film performance.

Further, Japanese Patent Application Laid-Open No. Hei 5-163463 discloses that a filler is dispersed in a binder composed of an alkoxysilane hydrolyzed condensate and colloidal silica and / or colloidal alumina. There has been proposed a coating composition which is excellent in chemical properties, stain resistance, etc., and can form a glossy coating film which can be easily colored. However, this composition has a low thick film limit, and since the main constituent components are separately synthesized and then mixed at the time of use, it is necessary to manage the pot life of the composition itself, and control may be complicated.

On the other hand, JP-A-4-275379 discloses that an isocyanate compound or a melamine resin is prepared by blending an alkoxysilane or a hydrolytic condensate of a different metal alkoxide with a fluorine-containing copolymer having a hydroxyl value and an acid value. It has been reported that a coating film having high surface hardness and excellent acid resistance, which is difficult to cure with, is obtained. However, when a one-component composition having a high content of silica sol and / or metal alkoxide sol having high surface activity is used, there is a problem that storage stability is reduced.

[0007] Also, in Japanese Patent Application Laid-Open No. 5-25422,
To disperse the filler such as an inorganic pigment and a fluoropolymer having curing reactivity, an organoalkoxysilane having a functional group having high reactivity with -OH group such as isocyanate group is blended, and the pigment dispersibility is improved. A good coating film having high chemical or physical resistance is obtained. However, isocyanate group-containing silane coupling agents are difficult to handle from the viewpoint of stability, and are expensive at tens of thousands of yen / kg.

Further, as a coating composition containing a hydrolyzable and / or silyl group-containing vinyl resin as a component, for example, JP-A-64-1769 discloses an alkoxysilane hydrolyzed condensate, zirconium A composition comprising a compound and a silyl group-containing vinyl resin is disclosed. In this composition, the zirconium compound acts on the cross-linking site between the alkoxysilane hydrolyzed condensate and the silyl group-containing vinyl resin to form a copolymer, and a coating film having high gloss is obtained. However, there is a problem that it is difficult to obtain an excellent coating film.

JP-A-10-273623 discloses an invention relating to a coating composition comprising a Si-alkoxide and a vinyl resin having a hydrolyzable and / or silyl group having a silicon atom bonded to a hydroxyl group. However, in order to increase the hardness and the adhesion, it is necessary to carry out the reaction under high hydrolysis conditions, and it is described that a considerable amount of a chelating agent is contained for stabilizing the solution.

However, since a considerable amount of a chelating agent, which is an alkoxy group stabilizer, is contained, the coating film curing speed is reduced,
In addition, the yellowing easily occurs when the film is thick. In addition, 140 ℃ ~ 150
Under baking conditions below ℃, unless a curing agent is added at the time of use, it is difficult to obtain a coating film with excellent surface hardness, boiling resistance, chemical resistance, solvent resistance, etc., so that the storage stability after adding the curing agent There is a problem.

JP-A-10-225404 discloses a partially hydrolyzed condensate of tetramethoxysilane containing a silanol group and a methoxysilyl group and having a specific weight average molecular weight, a film-forming resin (A) and The invention discloses a coating film containing at least one inorganic binder (B) having an alkoxysilyl group as a curing reactive group and having a specific dynamic retraction tension of water, but discloses a partially hydrolyzed condensate of tetramethoxysilane. Are mixed during the synthesis of the base polymer or at the time of coating, and are not added during the reaction. In particular, when a thermosetting type is used as (A) / (B), a two-part type is used. It is something that becomes. The coating has a low surface hardness.

[0012]

SUMMARY OF THE INVENTION According to the present invention, a coating film can be formed by a low-temperature baking treatment at 150 ° C. or less, which is a problem from the prior art. Scratch resistance, boiling resistance, solvent resistance,
Corrosion resistance, water resistance, chemical resistance, crack resistance (flexibility)
It is another object of the present invention to provide an inorganic coating composition that is excellent in the above-mentioned properties, is one-pack type, has a wide allowable range of water contamination, is stable, and has good long-term storage properties.

[0013]

The coating composition of the present invention has the general formula (A) R _n Si (OR ')
_4-n (wherein, R represents an organic group having 1 to 8 carbon atoms, R ′ represents a methyl group or an ethyl group, and n is an integer of 0 to 2) (a ), A solvent-soluble fluororesin having a hydroxyl group (b), a colloidal silica dispersed in a solvent (c), and a general formula (B) M (OR ″) _m
(Wherein, R ″ is an alkyl group having 1 to 4 carbon atoms, M represents a metal selected from titanium, zirconium, or aluminum, and m is an integer of 3 or 4.) d).

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The coating composition of the present invention will be described in detail below for each component. First, the alkoxysilane (a) represented by the general formula (A) R _n Si (OR ′) _4-n in the present invention is used for introducing a siloxane bond that is chemically stable in a coating film matrix. It mainly plays a role in improving the surface hardness of the coating film and as a binder.

R in the general formula (A) has 1 to 1 carbon atoms.
8, an alkyl group such as a methyl group, an ethyl group, and an n-propyl group, a phenyl group, a vinyl group, a γ-methacryloxypropyl group, a γ-mercaptopropyl group, and a γ
-Glycidoxypropyl group, 3,4-epoxycyclohexylethyl group, γ-aminopropyl group and the like. R ′ represented by the general formula (A) is a methyl group or an ethyl group.

Specific examples of the alkoxysilane (a) represented by the general formula (A) include tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane. Silane, n-propyltrimethoxysilane, n-propyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diethyldimethoxysilane, diethyldiethoxysilane,
Phenyltrimethoxysilane, phenyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-
Mercaptopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, β-3,4-epoxycyclohexylethyltrimethoxysilane, β-3,4-epoxycyclohexyltriethoxysilane And γ-aminopropyltrimethoxysilane.
Among these, it is desirable to select methyltrimethoxysilane and methyltriethoxysilane from the viewpoint of ease of reaction and handling properties. It is also possible to use one of these alkoxysilanes alone or as a mixture of two or more.

Further, among the alkoxysilanes (a) represented by the general formula (A), the chemical resistance, crack resistance,
To improve the water repellency, adhesion, etc., specify a tetraalkoxysilane such as tetramethoxysilane, a dialkyldialkoxysilane such as dimethyldimethoxysilane, and a γ-glycidoxypropyl group and a 3,4-epoxycyclohexylethyl group. The organoalkoxysilane having a cross-linking reactive functional group may be mixed at a fixed ratio and subjected to a co-hydrolysis reaction, or after adjusting the composition as described below,
You may mix and add. The mixing ratio is at most 80 mol%, preferably at most 20 mol%, in the alkoxysilane (a) component.

The alkoxysilane (a) undergoes a hydrolysis reaction by adding water adjusted to the acidic side, and at the same time, a hydrolysis condensation product by polycondensation reaction (hereinafter, alkoxysilane hydrolysis condensation product (hereinafter referred to as alkoxysilane hydrolysis condensation product). a ′)). At this time, the amount of water is preferably added in the range of 0.5 mol to 1.5 mol per 1 mol of the alkoxysilane (a).

Next, the hydroxyl group (-) used in the present invention is mainly used.
The solvent-soluble fluororesin (b) having an OH group) is capable of causing a crosslinking reaction with the alkoxysilane hydrolysis-condensation product (a ′), and is capable of forming a phase via a polar solvent such as alcohol. Those having solubility are preferred.

The solvent-soluble fluororesin (b) has a hydroxyl group concentration of 40 mg KOH / g in OHV value (polymer value).
~ 200mgKOH / g, preferably 80 ~ 120mg
It is preferable to select one having a KOH / g range and a weight average molecular weight (Mw) in terms of polystyrene of 3,000 to 100,000, preferably 10,000 to 50,000. If the OHV value is less than 40 mgKOH / g, it is difficult to obtain the effect of the hybrid of the target inorganic component and the organic component, and if it exceeds 200 mgKOH / g,
The storage stability of the entire composition is deteriorated, and cracks are easily generated at the time of curing. When the weight average molecular weight (Mw) is smaller than 3000, the water resistance, chemical resistance and solvent resistance of the obtained coating film are reduced, and it is difficult to make the coating film thicker. , The adhesion and leveling of the coating film are reduced.

As the solvent-soluble fluororesin (b), for example, a fluoroolefin such as tetrafluoroethylene or chlorotrifluoroethylene is copolymerized with a hydroxyl group-containing monomer such as hydroxyalkyl vinyl ether or hydroxyalkyl allyl ether. Alternatively, it is obtained by copolymerizing a monomer such as a carboxylic acid ester of fluoroolefin and vinyl alcohol, and then hydrolyzing it. Commercially available products include, for example, "Lumiflon" (trade name, solid content concentration 65% by weight, acid value 1 mg KOH / g, OH value 70 mg KOH / g, manufactured by Asahi Glass Co., Ltd.), "Sefural Coat" (trade name, solid A concentration of 55% by weight, an OH value of 35 mg KOH / g, manufactured by Central Glass Co., Ltd.) and "Fluonate" (trade name, manufactured by Dainippon Ink Co., Ltd.).

The solvent-soluble fluororesin (b) having a hydroxyl group may be used alone, but may be a resin containing a hydroxyl group, such as a vinyl resin, a silicone resin, a saturated or unsaturated polyester. You may use together with resin, alkyd resin, epoxy resin, epoxy silicone resin, acrylic silicone resin, etc.

The hydroxyl group-containing vinyl resin is prepared by, for example, copolymerizing a hydroxyl group-containing vinyl monomer with another vinyl monomer copolymerizable with the monomer, or a homopolymer of vinyl acetate. Or by hydrolyzing a copolymer. Examples of the hydroxyl group-containing vinyl monomer include hydroxyalkyl esters of (meth) acrylic acid such as 2-hydroxyethyl (meth) acrylate and N-methylol (meth) acrylamide. Examples of other vinyl monomers copolymerizable with these hydroxyl group-containing vinyl monomers include, for example, (meth) acryl such as methyl (meth) acrylate, cyclohexyl (meth) acrylate, and benzyl (meth) acrylate. Acid esters, fumaric acid, maleic acid and other dibasic monoalkyl and dialkyl esters, styrene, aromatic vinyl compounds such as vinyltoluene, vinyl acetate, vinyl chloride, (meth) acrylonitrile, (meth) Acrylic acid, maleic anhydride, maleic acid, (meth) acrylamide and the like can be mentioned. These hydroxyl group-containing vinyl resins are usually obtained by a known production method such as solution radical polymerization. The following can be mentioned as those which can be suitably used in the present invention and can be easily obtained. As a hydroxyl group-containing vinyl resin,
For example, Acrydic, an acrylic polyol
(Trade name, solid content concentration 50% by weight, acid value 3mgKOH /
g, OH value 50 mg KOH / g, manufactured by Dainippon Ink and Chemicals, Inc., “Nipporan” (trade name, solid content concentration 10
0% by weight, acid value 2 mg KOH / g or less, OH value 45 mg
KOH / g, manufactured by Nippon Polyurethane Industry Co., Ltd.), "Orestar" (trade name, manufactured by Mitsui Chemicals, Inc.) and the like.

In the silicone resin, the side chain group is a linear or branched alkyl group such as a methyl group or an ethyl group, or an aryl group such as a phenyl group. The hydroxyl group concentration may be 30 mgKOH / g to 500 mgKOH in OHV value.
/ G, preferably 60 mg KOH / g to 300 mg KO
H / g and a weight average molecular weight (Mw) of 1
000 to 50,000, preferably 3000 to 15000
It is better to select a value within the range. OHV value is 30m
If it is less than gKOH / g, the adhesion and curing speed of the obtained coating film will be reduced, and if it exceeds 500, the storage stability of the composition will be poor and the coating film will crack. When the weight average molecular weight (Mw) is less than 1000, the adhesion and moisture resistance of the obtained coating film are reduced, and it is difficult to form a thick film.
If it exceeds 50,000, the storage stability of the composition, the sharpness of the coating film, and the curing speed decrease. Examples of these silicone resins include KR-220L and K-220L manufactured by Shin-Etsu Chemical Co., Ltd.
R-242A, KR-2610B (all are trade names) and the like.

The composition according to the present invention has a storage stability and a pigment when cold-blended with the alkoxysilane hydrolyzed condensate (a ') and the above-mentioned solvent-soluble fluororesin (b) alone or in combination. Dispersibility may decrease, and gelation of the composition and decrease in gloss value of the coating film may occur, which is not preferable. Therefore, the alkoxysilane (a) is partially co-hydrolyzed with the solvent-soluble fluororesin (b) alone or in combination in the alkoxysilane (a), and the reaction product (hereinafter, referred to as It is desirable to obtain a modified organopolysiloxane (A)). The mixing ratio of the alkoxysilane (a) and the solvent-soluble fluororesin (b) alone or in combination is such that the solvent-soluble fluororesin (b) alone or 10 parts by weight to 100 parts by weight, preferably 20 parts by weight
80 parts by weight.

Next, the solvent-dispersed colloidal silica (c) in the composition of the present invention will be described.

The solvent-dispersed colloidal silica (c) is an essential component for improving the storage stability, surface hardness, solvent resistance, and corrosion resistance of the modified organopolysiloxane (A).
Further, it plays an important role at a low coating film forming temperature of the composition, and is mainly mixed and added during the partial co-hydrolysis reaction of the modified organopolysiloxane (A) to form a reaction containing colloidal silica. It is used for the purpose of obtaining a product (hereinafter, referred to as a modified organopolysiloxane (B)).

The solvent-dispersed colloidal silica (c) used in the present invention is a solution of anhydrous silica adjusted to a high purity so that the sodium content is 0.05% by weight or less, water and / or alcohol, glycol or the like. Is dispersed in a solution containing a hydrophilic solvent, having an average particle size of 5 nm to
It is 50 nm, preferably 10 nm to 20 nm. Generally, the silica solid content of the component (c) is 10% by weight to 50% by weight.

Colloidal silica containing only water as a dispersion solvent (hereinafter referred to as water-dispersible colloidal silica)
Is selected from those having a pH of 1 to 6, preferably 2 to 4. Examples of such a solvent-dispersed colloidal silica (c) include “Snowtex” (trade name, manufactured by Nissan Chemical Industry Co., Ltd.); “Cataroid” (trade name, manufactured by Catalyst Kasei Kogyo Co., Ltd.); "Adelite AT" (trade name, manufactured by Asahi Denka Kogyo Co., Ltd.); "Ludox" (trade name, manufactured by Dupont, USA); "Syton" (trade name, manufactured by Monsanto Co., USA) and the like can be mentioned.

The mixing ratio of the component (c) in the composition is 1 to 100 parts by weight of the alkoxysilane (a).
5 parts by weight to 50 parts by weight, and based on 100 parts by weight of the modified organopolysiloxane (A), 2 parts by weight to 20 parts by weight, preferably 2 parts by weight, in terms of the silica solid content in the component (c). 10 parts by weight. Beyond this range,
The storage stability of the composition is lowered, and desired coating film properties cannot be obtained during low-temperature curing, which is the object of the present invention. (C)
When water-dispersible colloidal silica is used as a component, the pH is adjusted by adding an acid as necessary, and the content of water is 0.5 mol to 1.5 mol per 1 mol of the component (a).
It is preferable to mix and add after adjusting to the molar range. p
Examples of the acid used for adjusting H include inorganic acids such as hydrochloric acid, nitric acid, sulfuric acid, benzoic acid, acetic acid, formic acid, maleic acid, and toluenesulfonic acid, and organic acids.

The solvent-dispersed colloidal silica (c) is not particularly limited, but is prepared by using water-dispersible colloidal silica and adjusting the composition to form a clear coat film. This is not preferred because the transparency of the clear film may decrease. Therefore, when the modified organopolysiloxane (B) is obtained, a non-aqueous solvent-dispersed colloidal silica (hereinafter, referred to as colloidal silica (c ′)) having a polar solvent such as an alcohol and / or a non-polar solvent such as xylene as a main dispersion solvent is used. It is preferable to select These colloidal silicas (c ') include "methanol silica sol: MT-ST", "isopropanol silica sol: IPA-ST", and "xylene.
n-butanol silica sol: XBA-ST "(trade name,
Nissan Chemical Industry Co., Ltd.); "Oscar" (trade name, manufactured by Catalyst Chemical Industry Co., Ltd.) and the like.

Further, as colloidal silica (c '),
The tetraalkoxysilane represented by the general formula (C) Si (OR ') ₄ (wherein R' represents a methyl group or an ethyl group), and the partially hydrolyzed sol are further hydrolyzed by adding water. A decomposition / polycondensation reaction is performed, and the particle size of the silica sol, which is a reaction product, is adjusted to 5 to 50 nm.

When the modified organopolysiloxane (B) prepared as described above is used alone for coating, the coating has good film properties when the aging period is within 30 minutes to 24 hours, but outside the period, When the curing speed of the composition is low, and particularly when the coating film forming temperature is 150 ° C. or lower, the adhesion to the substrate, the surface hardness, the solvent resistance and the like are inferior to those of the organic coating film.

Next, the heterometallic alkoxide (d) in the present invention will be described. In the present composition, the role of the heterometallic alkoxide (d) represented by the general formula (B) M (OR ″) _m is that the composition is coated at a coating temperature of 150 ° C. or less after storage for a long period of time. With the aim of obtaining a high coating film physical property, and good coating film physical properties,
It is to be compounded with the modified organopolysiloxane (B).

The heterometal alkoxide (d) represented by the general formula (B) M (OR ″) _m is Ti (OR ″)
₄ , Zr (OR ") ₄ , Al (OR") _{3 and the} like, wherein R "is an alkyl group having 1 to 4 carbon atoms,
Examples include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group and the like.

Specific examples of the heterometallic alkoxide (d) represented by the general formula (B) include titanium tetraethoxide, titanium tetraisopropoxide, titanium tetra-n-butoxide, zirconium tetraethoxide, and zirconium. Examples thereof include tetraisopropoxide, zirconium tetra-n-butoxide, aluminum trimethoxide, aluminum triethoxide, aluminum triisopropoxide, and aluminum tri-n-butoxide. These metal alkoxides are used alone or in combination of two or more.

Further, the modified organopolysiloxane (B)
And the mixing ratio of the different metal alkoxide is from 3 parts by weight to 100 parts by weight of the modified organopolysiloxane (B).
The amount is 30 parts by weight, preferably 5 to 20 parts by weight, particularly preferably 7 to 10 parts by weight. When the amount is less than 3 parts by weight, the curing speed of the composition is slow, and when it is more than 30 parts by weight, the storage stability is obtained. However, even when the obtained composition is used for coating, the adhesion of the coating film is poor.

As described above, the coating composition of the present invention is described in detail for each component, and the composition of the present invention contains the above (a) to (d) as essential components. The film formation temperature is 140 ° C. to 150 ° C. and 20
Minutes to 30 minutes.

After the modified organopolysiloxane (B) and the different metal alkoxide (d) are compounded, a crosslinking reaction between the functional groups in the inorganic and / or organic components of the composition during heat curing. To further promote
It is also possible to add an internal catalyst (e).

The internal catalyst (e) may be used between specific crosslinking reactive functional groups such as an alkoxy group, a silanol group and a γ-glycidoxypropyl group in the component (a), or
A heterocyclic amine compound having an effective effect for promoting a crosslinking reaction between different components such as components (a), (b), (c) and (d), for example, a heterocyclic amine compound containing a nitrogen atom as a different atom And metal acetylacetate compounds.

Preferred examples of component (e) include heterocyclic amine compounds such as piperazine, imidazoles, and boron trifluoride complexes of these amines. Examples of metal acetyl acetate compounds include aluminum acetyl. Acetate, chromium acetyl acetate, titanyl acetyl acetate and the like can be mentioned. The mixing ratio is 0.01 to 3 parts by weight, preferably 0.05 to 1 part by weight, based on 100 parts by weight of the coating composition. If the ratio is outside this range, the compatibility is reduced, the coating film performance such as opacity and adhesion of the coating film is reduced, and further, the storage stability of the composition itself is reduced. The time of adding the component (e) to the composition is preferably after the compounding of the heterometallic alkoxide (d).

To the composition of the present invention, a solvent such as alcohol can be added for the purpose of preventing gelation and improving the coating (painting) property. These suitable solvents include alcohols, glycols, ketones, esters, cellosolves, cyclic ethers, aromatic hydrocarbon compounds and the like. For alcohol, methanol, ethanol, n
-Propanol, i-propanol, n-butanol,
Lower alcohols such as i-butanol, glycols include ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, and ketones include acetone and methyl ethyl ketone. Methyl isobutyl ketone, ethyl acetate, butyl acetate for esters, methyl cellosolve, ethyl cellosolve, butyl cellosolve for cellosolve, tetrahydrofuran, 1,4-dioxane for cyclic ethers, toluene and xylene for aromatic hydrocarbon compounds, and the like. It is possible to use one kind alone or as a mixed solvent of two or more kinds. Further, among these solvents, alcohol which is a by-product of a partial co-hydrolysis reaction or a polycondensation reaction of the alkoxysilane (a) component or the like is also included.

The solids concentration of the composition in these solvents can be arbitrarily adjusted according to the purpose, but is generally used as a coating composition of 30% by weight to 70% by weight. In particular, when the composition is used as a varnish for an inorganic coating, the solid content concentration is preferably adjusted to a range of 30% by weight to 55% by weight. Hereinafter, an example of a method for preparing the composition of the present invention will be described.

The alkoxysilane (a) / solvent-soluble fluororesin (b) is mixed at a predetermined composition ratio in a reaction vessel equipped with a reflux condenser, a heating jacket and a stirring device, and then one kind is used alone or two kinds. A homogeneous solution adjusted to an arbitrary concentration using at least one kind of solvent.

Next, while stirring, the solvent-dispersed colloidal silica (c) and / or distilled water adjusted to pH 2 are added dropwise to initiate partial co-hydrolysis and simultaneously carry out a polycondensation reaction to obtain a modified organopolysiloxane ( B) was obtained. Further, one kind or two or more kinds of different metal alkoxides such as Ti, Zr and Al are added and reacted to obtain a composition.
If necessary, it can be prepared by adding an organoalkoxysilane having a crosslinking reactive functional group such as a γ-glycidoxypropyl group, an internal catalyst (e), a solvent and the like. However, the partial co-hydrolysis reaction or the like of these compositions is usually performed at room temperature, but when it is necessary to shorten the synthesis time or replace the solvent, and increase the degree of condensation of the composition to increase the viscosity, , 80 ° C. as the upper limit.

The prepared coating composition can be used as it is as an inorganic clear, but may be mixed with a suitable filler such as an inorganic or organic pigment, a paint additive, or the like.
It can be dispersed to form an inorganic coating composition. As these fillers, for example, titanium oxide, zinc white, zinc sulfate, lead white, antimony oxide, carbon black, graphite,
Zinc yellow, barium chromate, calcium plumbate, red iron oxide, iron oxide, lead red, cerulean blue, calcium carbonate, barium sulfate, alumina, silica, clay, talc, mica, zinc dust, silicon nitride, silicon carbide, aluminum, bentonite , Zirconium oxide, slaked lime, potassium whisker, magnesium carbonate, zirconia, zinc chromate, calcium leadate, barium carbonate, calcium silicate, glass wool, titanium yellow, cobalt blue, cobalt aluminum blue, copper chrome black And the like. The mixing ratio of these fillers is as follows:
6 parts by weight to 500 parts by weight, preferably 30 parts by weight to 300 parts by weight, more preferably 60 parts by weight to 150 parts by weight with respect to 00 parts by weight. If the amount is less than 6 parts by weight, the strain stress of the coating film is large and cracks occur. Also, 50
If the amount exceeds 0 parts by weight, the filler becomes rich, gloss, chemical resistance, stain resistance and the like are reduced, and the original coating film performance is hardly obtained.

Further, as a paint additive, a pigment dispersant,
There are wetting agents, thickeners, leveling agents, antifoaming agents, ultraviolet shielding agents, heat stabilizers, organic resin elastic fine particles, etc., and these can be used by appropriately selecting those used for ordinary paints. it can.

The coating composition of the present invention can be usually used as a one-pack type as long as the stability of the whole system is not impaired. For the purpose of shortening the curing time, it is also possible to add a known curing accelerator together at the time of use. These curing accelerators include, for example, metal salt compounds of carboxylic acids such as tin octylate, dibutyltin dilaurate, and dioctyltin dimaleate; acidic compounds such as phosphoric acid, p-toluenesulfonic acid, phthalic acid, and hydrochloric acid; and dibutylamine-2-. Amines such as hexoate, dimethylamine acetate and ethanolamine acetate; aliphatic polyamines such as diethylenetriamine, triethylenetetramine and tetraethylenepentamine; quaternary such as tetramethylammonium chloride, tetramethylammonium hydroxide and tetramethylammonium acetate Ammonium salt compounds, sodium hydroxide, alkaline compounds such as potassium hydroxide, γ-aminopropyltriethoxysilane, γ-
Examples include amine silane coupling agents such as (2-aminoethyl) -aminopropyltrimethoxysilane and γ- (2-aminoethyl) -aminopropylmethyldimethoxysilane. In general, the mixing ratio of the curing accelerator is from 1 part by weight to 100 parts by weight of the composition.
15 parts by weight, preferably 3 parts by weight to 10 parts by weight.

As the object to be coated in the coating composition of the present invention, nonmetallic materials such as inorganic building material boards, metals and plastics can be selected, and the same coating methods as those for ordinary coatings, ie, air spray, The coating can be performed by any method such as airless spraying, dipping, and brush coating. Hereinafter, the composition of the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.

[0050]

EXAMPLES In this example, the compositions were prepared at the compounding ratios shown in Tables 1 to 3 of the Examples according to the method for preparing the above-mentioned composition. All numbers in the table are shown in parts by weight. In the table, the component (a) with an asterisk (*) was added after mixing the different metal alkoxide. In Examples 9 and 10, after the compositions were adjusted, they were dispersed using a sand mill for 40 minutes to obtain inorganic enamel paints.

The obtained composition was applied to various coated substrates shown in Tables 1 to 3 by air spray at a film forming temperature shown in Tables 1 to 3 so that the film thickness after drying was 30 μm. And cured. The coating properties of the various coated substrates coated were evaluated by the following items, and the results are shown in Tables 4 to 6.

(1) The base material to be applied is an aluminum plate A5052P (hereinafter referred to as a base material A) which has been subjected to a primer treatment (baking type epoxy resin paint: 180 ° C. for 20 minutes), and a calcium silicate decorative plate (“Grasal”,
After washing the surface of a trade name (manufactured by Toray Grasal Co., Ltd.) with water, a calcical plate (hereinafter, referred to as a base material B) from which water was removed by heating was used.

(2) The coating film forming temperature is the substrate temperature. As shown in the table, the base material A was heated at 120 ° C. for 15 minutes or at 150 ° C. for 2 minutes.
Substrate B was performed at 120 ° C. for 15 minutes for 0 minutes.

(3) The initial adhesion is JIS-K540
It was evaluated by a cross cut tape peel test according to 0, and 10
The points were marked with a circle.

(4) The surface hardness is JIS-K5400
Was evaluated by the flaw method according to the above.

(5) The acid resistance was evaluated by dropping 2 ml of sulfuric acid having a concentration of 5% on the coating film, covering with a petri dish for 24 hours, washing away with water, and observing and evaluating.も の indicates that there was no abnormality in the coating film, and △ indicates that there was a trace.

(6) For alkali resistance, 2 ml of 5% caustic soda was dropped on the coating film, covered with a petri dish and covered.
After standing for a time, the sample was washed with water and observed and evaluated.塗膜 indicates that the coating film had no abnormality, Δ indicates that there was a trace, and X indicates that the coating film was dissolved.

(7) The solvent resistance was evaluated by impregnating methyl ethyl ketone (MEK) into gauze, rubbing the coating film a certain number of times under a load of 1 kg, and then observing and evaluating. Rubbing 100
The sample was evaluated as 回 when there was no abnormality in the coating film after the rubbing, and was evaluated as x when the gloss of the coating film was reduced or dissolved after 50 rubbings.

(8) Boiling resistance was evaluated by observing the state of the coating film after boiling in tap water for 24 hours.異常 indicates that the coating film had no abnormality, and X indicates that the coating film had cracks or the surface layer was cohesively broken.

(9) As for the corrosion resistance, the composition was applied to an aluminum plate A1050P having been degreased with acetone at a coating film forming temperature shown in the table so that the film thickness after drying was 20 μm. After that, CA according to JIS-H8681
An S (hole corrosion) test was performed to observe and evaluate the state of the coating film.
After the start of the test, ○ indicates that no abnormality was observed in the coating film for 500 hours or more, Δ indicates that no abnormality was observed for 200 hours or more, and X indicates that corrosion occurred within 16 hours.

(10) The storage stability was as follows. After adjusting each composition, the composition was allowed to stand at room temperature for 3 months, and the viscosity change rate was 150%.
Less than O was evaluated as 、, and at least 150% or gelation was evaluated as ×.

The raw materials used in the examples are methyltrimethoxysilane and dimethyldimethoxysilane are KBM-403 (γ-glycidoxypropyltrimethoxysilane) and KBM-303 manufactured by Tama Chemical Industry Co., Ltd. (Β-
3,4-Epoxycyclohexyl) ethyltrimethoxysilane is a solvent-soluble fluororesin (trade name: Lumiflon, manufactured by Shin-Etsu Chemical Co., Ltd., solid content concentration: 65% by weight, acid value: 1 mgKOH / g, OH Value 70 mgKOH /
g) is manufactured by Asahi Glass Co., Ltd .; Snowtex O (silica concentration: 20% by weight; pH 3) is manufactured by Nissan Chemical Industries, Ltd .;
PA-ST (silica concentration 30% by weight, i-propanol 70% by weight) was manufactured by Nissan Chemical Industries, Ltd., XBA-ST.
(Silica concentration 30% by weight, xylene 45% by weight, n-butanol 25% by weight) are manufactured by Nissan Chemical Industries, Ltd., and titanium alkoxide (“trade name: A-1”) is manufactured by Nippon Soda Co., Ltd. Zirconium alkoxide (trade name: HZ-
OB) is manufactured by Hokuko Chemical Co., Ltd., and rutile-type titanium oxide (“trade name: JR-603”) is manufactured by Teika Co., Ltd., and γ-aminopropyltriethoxysilane (“trade name: KBE-9”)
03 ”) is manufactured by Shin-Etsu Chemical Co., Ltd.

[0063]

[Table 1]

[0064]

[Table 2]

[0065]

[Table 3]

[0066]

[Table 4]

[0067]

[Table 5]

[0068]

[Table 6]

[0069]

According to the present invention, a coating film can be formed by a low-temperature baking treatment at a temperature of 150 ° C. or less, the surface hardness of the coating film is high, scratch resistance during brush cleaning, boiling resistance, and solvent resistance. sex,
Corrosion resistance, water resistance, chemical resistance, crack resistance (flexibility)
In addition, it is possible to easily and inexpensively provide an inorganic coating composition which is one-pack type, has a wide allowable range of water mixing, is stable and has good long-term storage properties.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kazunari Murakami 2-1-1 Otemachi, Chiyoda-ku, Tokyo Shinagawa White Brick Co., Ltd. F-term (reference) 4J038 CD091 CD121 CE051 GA03 HA446 JA23 JC32 PC02 PC03

Claims (1)

[Claims] 1. Formula (A) R _n Si (OR ′)
_4-n (wherein, R represents an organic group having 1 to 8 carbon atoms, R ′ represents a methyl group or an ethyl group, and n is an integer of 0 to 2) (a ), A solvent-soluble fluororesin (b) mainly having a hydroxyl group, a solvent-dispersed colloidal silica (c), a general formula (B) M (OR ″) _m (wherein, R ″ has 1 to 4 carbon atoms) Where M is titanium, zirconium,
Or a metal selected from aluminum, and m is an integer of 3 or 4).