JPH09208896A - Binder for inorganic/organic composite coating agent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a binder made from a polyol component comprising a hydroxy acrylate copolymer and a fluorocopolymer and colloidal silica or a siloxane-bond-containing isocyanate. SOLUTION: This binder comprises a mixture of 95-30wt.% polyol component (A) having a hydroxyl value of 20-200mgKOH/g with 5-70wt.% colloidal silica and/or siloxane-bond-containing isocyanate compound (B). Component A, which is an organic binder, comprises a hydroxy acryl copolymer (e.g. hydroxyethyl (meth)acrylate) having a weight-average molecular weight o 10<4> to 10<5> and a fluorocopolymer comprising a fluoroolefin, cyclohexyl vinyl ether, a (hydroxy) alkyl vinyl ether or cyclohexyl vinyl ether and having a weight-average molecular weight of 2×10<4> to 2×10<5> . This is obtained by simply mixing an organic component with an inorganic component in a suitably selected mixing ratio and can form a composite coating film excellent in cracking resistance and weather resistance.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to modification of a hydroxyl group-containing acrylic copolymer or fluorine-containing copolymer, which is widely and widely used as a binder for an organic coating agent, into a binder for an inorganic / organic composite coating agent. To provide a way to
There is flexibility in the composition ratio of the inorganic and organic binder components, and a film can be formed in the temperature range from room temperature to 180 ° C. It has high gloss and hardness, hot water resistance, stain resistance, crack resistance and weather resistance. The present invention relates to a binder for an inorganic / organic composite coating agent capable of forming an excellent coating film.

[0002]

2. Description of the Related Art Conventionally, the number of carbon atoms is 1 for forming a film.
Method of using partial hydrolyzate (polyalkoxysiloxane) of alkoxysilicate having alkyl group of 4 to 4 (inorganic coating system), organosilane, hydrolyzate of organosilane, partial condensate, partial cocondensation To obtain a film-forming agent by a combination of a resin and a silyl group-containing acrylic resin, or other acrylic resin, epoxy resin, etc. (inorganic / organic coating system), a mixture of polyacetal resin and polysilicic acid, containing a carboxyl group A method using a heated mixture of an acrylic resin and an alkyl silicate as a film forming agent (inorganic / organic coating system), an acrylic resin having a hydrolyzable alkoxysilyl group in its side chain,
Alternatively, one in which a fluorine copolymer is reacted and crosslinked with a catalyst such as an organic metal to form a film (inorganic / organic coating system), a method using a fluorine-containing copolymer as a film forming agent (organic coating system)
Etc. are known.

[0003]

The above method is widely known. However, the coating is hard, and cracks are likely to occur during heating during coating formation and after coating formation, and only a thin film having a dry film thickness of about 1 μm or less can be obtained. It has the drawback of not being practical, the above method has emerged as a solution to the drawbacks of the above method, but the crack resistance improves as the amount of organic resin components increases, but the weather resistance decreases. Occurred and was insufficient to satisfy both parties. The above method is mainly a means for determining hardness and wear resistance, and has the same drawbacks as the above method.

Although the other method is excellent in weather resistance, it has a drawback that the content of the inorganic binder is small and the hardness and scratch resistance are poor. Further, as a problem common to (1) to (4), in many cases, the cross-linking reaction at the time of forming the coating film is a condensation reaction, so that the volume shrinkage is large, the residual strain is large in the formed coating film, and cracks easily occur.

The above method is not an inorganic / organic composite, but is characterized by excellent crack resistance and weather resistance. However, it has a drawback that it is inferior in terms of dyeing resistance and hardness.

In view of such a situation, the present inventors have a relatively large degree of freedom in the composition ratio of the inorganic binder component and the organic binder component, and can form a film in a temperature range from room temperature to 180 ° C. with high gloss. Moreover, it is an object of the present invention to provide a binder for an inorganic / organic composite coating agent, which is excellent in hardness, warm water resistance, stain resistance, crack resistance and weather resistance and which can form a film.

[0007]

The binder for an inorganic / organic composite agent of the present invention comprises a polyol component having a hydroxyl value of 20 to 200 mgKOH / g (relative to solid content) as an organic binder, which is an essential component, and colloidal as an inorganic component. It is characterized in that either one or both of silica and an isocyanate compound having a siloxane bond is mixed.

Hereinafter, the present invention will be described in detail.

The hydroxyl value referred to in the present invention is 20 to 200 mgK
As the OH / g (relative to solid content) polyol component, an acrylic copolymer having a —OH group at the side chain or terminal and a fluorinated copolymer are used as indexes, and they may be used alone or as a mixture of both. , And can be used as an organic binder component.

The acrylic copolymer is a copolymer containing an α, β-ethylenically unsaturated monomer having a hydroxyl group as an essential component, and has a weight average molecular weight of about 10,000 to about 10.
Those of 10,000 are preferably used.

The content of the α, β-ethylenically unsaturated monomer having a hydroxyl group is such that the copolymer has a hydroxyl value of 20 to 2
00 mg KOH / g (relative to solid content), particularly preferably 4
The amount is 0 to 150 mg KOH / g. If the hydroxyl value is less than 20, the curability of the coating film will be poor, and the hardness and stain resistance will also tend to decrease, such being undesirable. On the other hand, when the hydroxyl value is higher than 200, the flexibility of the coating film decreases, which is not preferable. Typical examples of the —OH group-containing α, β-ethylenically unsaturated monomer include 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate. Also, -OH which is copolymerizable with -OH group-containing α, β-ethylenically unsaturated monomer
Examples of the monomers other than the group-containing α, β-ethylenically unsaturated monomer are alkyl esters of (meth) acrylic acid having 1 to 12 carbon atoms, specifically, methyl (meth) acrylate, Ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate,
T-Butyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, (meth)
Examples include lauryl acrylate and the like.

In the present invention, the acrylic copolymer is
To be uniformly compatible with the fluorocopolymer referred to in the present invention,
Of these monomers, the total content of C 2-6 alkyl esters of (meth) acrylic acid is 10-80.
%, Particularly preferably 20 to 70% by weight. If the total content of the alkyl esters is less than 10% by weight, the compatibility decreases, and as a result, the transparency of the clear coating film,
It is not preferable because the gloss and the sharpness are deteriorated. On the contrary, if the total content is more than 80% by weight, the hardness of the coating film tends to decrease and the weather resistance tends to decrease though it depends on the kind of the monomer, which is not preferable. Generally, as the carbon number of the alkyl ester of (meth) acrylic acid increases, the hardness and weather resistance decrease, but those containing a large amount of monomers such as t-butyl methacrylate and cyclohexyl methacrylate , Is effective in eliminating these drawbacks.

Further, in the present invention, in order to make the acrylic copolymer to be compatible with colloidal silica uniformly, the -OH group-containing α, β-ethylenically unsaturated monomer and the carbon of (meth) acrylic acid are required. The total content of alkyl esters of several 4 or more is 50
It is preferably not less than 60% by weight, more preferably not less than 60% by weight. As the content decreases, the mixture separates,
Clear coating lacks transparency and gloss.

Further, in the acrylic copolymer, in addition to the above two kinds of monomers, monomers having an aromatic ring such as styrene, α-methylstyrene and vinyltoluene can be used together. However, since the compatibility and weather resistance of the colloidal silica and the fluorine-containing copolymer are reduced, the content thereof is 20% by weight or less, preferably 15% by weight or less.

Other copolymerizable monomers include (meth) acrylic acid, itaconic acid, fumaric acid, maleic anhydride and other acid monomers, N-dimethylaminopropyl (meth) acrylamide, Monomers having a basic nitrogen such as dimethylaminoethyl (meth) acrylamide, monomers having an epoxy group such as glycidyl (meth) acrylate, and other phosphoric acid esters of β-hydroxy (meth) acrylate, ( One or more monomers such as (meth) acrylonitrile, (meth) acrylamide, vinyl acetate and vinyl pyridine may be copolymerized.

Further, a compound having a hindered amine group having a double bond may be copolymerized for the purpose of improving the weather resistance of the acrylic copolymer. The content of these compounds is preferably 0.1 to 3% by weight.

The above acrylic copolymer may be subjected to a conventional copolymerization reaction by allowing a polymerization initiator to act in the presence of a polymerization solvent such as xylene, toluene, ethyl acetate or butyl acetate on a monomer mixture in a predetermined ratio. Can be manufactured by

The fluorine-containing copolymer having a hydroxyl group used in the present invention is preferably JP-A-57-3.
The fluorine-containing copolymer described in Japanese Patent No. 4107 may be mentioned.

The fluorine-containing copolymer contains fluoro-olefin, cyclohexyl vinyl ether, alkyl vinyl ether and cycloxyalkyl vinyl ether as essential components, and 30 to 70% by weight, 5 to 60% by weight and 3 to 3% by weight, respectively.
It is contained in a proportion of 50% by weight and 3 to 20% by weight, and has a weight average molecular weight of about 20,000 to about 100,000.
A fluorine-containing copolymer of 0 is preferable.

If the content of the fluoroolefin is too low, the weather resistance is lowered, and if it is too high, the production is difficult. If the cyclohexyl vinyl ether content is too low, the flexibility will decrease.

Further, it is particularly important that the content of the hydroxyalkyl vinyl ether is within the above range because the curability is improved without impairing various useful properties as a paint base. That is, if the hydroxyalkyl vinyl ether content is too high, not only the solubility of the copolymer in an organic solvent is reduced, but also the flexibility of the coating film is reduced, and conversely if it is too low, the durability of the coating film, Adhesion decreases.

In the fluorine-containing copolymer, the fluoroolefin is preferably a perhaloolefin, particularly chlorotrifluoroethylene or tetrafluoroethylene.

Further, as the alkyl vinyl ether, those containing a linear or branched alkyl group having 2 to 8 carbon atoms can be usefully used, but particularly 4 to 8 is preferable in view of compatibility with colloidal silica. Are preferred.

Further, the above-mentioned fluorine-containing copolymer may contain other comonomer other than the above-mentioned four essential constituent components within a range not exceeding 20% by weight. Typical examples of such copolymers include ethylene, propylene, isobutylene, vinyl chloride, vinylidene chloride, methyl methacrylate, butyl acetate and the like.

The above-mentioned fluorine-containing copolymer is allowed to undergo a copolymerization reaction by allowing a polymerization initiator or a polymerization initiator such as ionizing radiation to act on a monomer mixture in a predetermined ratio in the presence or absence of a polymerization medium. It can be manufactured by

In the polyol component, when the acrylic copolymer and the fluorine-containing copolymer are mixed and used, the mixing ratio is not specified, but as the ratio of the acrylic copolymer becomes higher, the dryness is increased. Good property, and the weather resistance tends to decrease. Further, although the drying property decreases as the ratio of the fluorine-containing copolymer increases, the flexibility at low temperature is good and the weather resistance performance is improved.

The colloidal silica used in the present invention is a colloidal solution prepared by dispersing silica having a particle diameter in the range of 10 to 100 nm in an organic solvent. The present colloidal silica is usefully used as the inorganic binder component of the present invention, and the mixing ratio of the polyol component (solid content) and the colloidal silica (solid content) is 0 to 100 with respect to 100 parts by weight of the polyol component. Parts by weight. When the amount of colloidal silica mixed is small, the amount of inorganic components in the binder decreases, and hardness and scratch resistance decrease.As the amount increases, stain resistance improves but flexibility and water resistance decrease. It Preferably, the compounding amount of colloidal silica is 10 to 60 parts by weight.

Further, as a dispersion medium of colloidal silica,
Alcohols such as methyl alcohol and isopropyl alcohol, glycols such as ethylene glycol and ethylene glycol monopropyl ether, amino compounds such as dimethylacetamide, ketones such as methyl butyl ketone, mixed solvents such as xylene and n-butyl alcohol, etc. It is usefully used.

The isocyanate compound having a siloxane bond used in the present invention is typically represented by the following formula.

[0030]

Embedded image

[0031]

Embedded image

[0032]

Embedded image This component causes an addition reaction with a hydroxyl group of a polyol component as an organic component, introduces an inorganic component into an organic binder component, and is usefully used for improving hardness, scratch resistance, and weather resistance. Further, a monofunctional isocyanate compound represented by the following formula may be used as an auxiliary material.

[0033]

Embedded image In addition to the above-mentioned siloxane-bonded isocyanates, cyanurate compounds starting from hexamethylene diisocyanate, isophorone diisocyanate, hydrogenated xylene diisocyanate, lysine diisocyanate, etc., TMP
Isocyanate compounds for urethane coatings that are usually used for outdoor applications such as adducts may be used in combination.

The isocyanate compound may be blocked isocyanates masked with phenols, alcohols, oximes, lactams, amines, carboxylic acids and the like.

Next, in the present invention, in the method of curing the coating film, the polyol component and the colloidal silica mixture are crosslinked with an ordinary isocyanate compound. In this method, a predetermined amount of an isocyanate compound is mixed immediately before use in a two-pack method, a coating type method in which forced drying is performed by heating from room temperature to a relatively low temperature, and a predetermined amount of an isocyanate compound masked with a blocking agent is mixed in advance. It is possible to use a coating forming method of heating and curing in the one-pack type.

If necessary, a polyol component containing colloidal silica (which may or may not be contained) is added to a predetermined amount of an isocyanate compound having a siloxane bond or a mixture of the isocyanate compound and an ordinary isocyanate compound in a two-pack type. Alternatively, it is possible to use a coating type method in which, in addition to the one-pack type, the room temperature crosslinking is followed by heat curing.

The aminoplast compound is mixed with a mixture of a polyol component and colloidal silica, and the mixture is heated and cured in a one-pack type. The aminoplast compound is a compound obtained by further etherifying a condensation product of an aldehyde compound with an amino compound such as melamine, urea, benzoguanamine and acetoguanamine.

The polyol component (mixed with colloidal silica as required) and the isocyanate compound having a siloxane bond are pre-reacted at a ratio of 50% equivalent or less, preferably 45% equivalent or less of the hydroxyl group of the polyol component, and then the isocyanate compound is reacted. A two-liquid type in which a predetermined amount of the above is mixed immediately before use or a method in which a blocked isocyanate compound or an aminoplast compound is mixed and used in a one-liquid type and heat-cured from room temperature can be usefully used. Here, the amount of the siloxane compound to be preliminarily reacted is limited to 50 equivalent% or less of the hydroxyl group of the polyol component, preferably 45 equivalent% or less. This is because the occurrence etc. will occur.

Further, the mixing ratio of the polyol component of the present invention and the polyvalent isocyanate compound curing agent component is such that the equivalent ratio (NCO / OH) of the isocyanate group of the isocyanate compound to the hydroxyl group of the polyol component is 0.6 / 1 to 1.5 / 1,
The range of 0.7 / 1 to 1.2 / 1 is particularly preferable, and the original resin characteristics can be exhibited in this range.

If the isocyanate group is more than the above range, the free isocyanate group reacts with moisture in the air and the like, and the weather resistance is lowered. On the contrary, if it is too small, satisfactory curability cannot be obtained and the crosslinking density is low. Therefore, the dissolution resistance, stain resistance, chemical resistance, weather resistance and the like are deteriorated, which are all unfavorable.

In the present invention, an aminoplast compound can also be used as a curing agent as described above.

The mixing ratio (weight basis) of the polyol component and the aminoplast compound curing agent component is 95: 5 to 60: 4.
0, particularly preferably 90:10 to 70:30,
In this range, the original resin characteristics can be exhibited. If the amount of aminoplast compound is more than the above range, the reaction between aminoplast compounds easily occurs, and the flexibility and chemical resistance of the coating film decrease, and if it is too small, satisfactory curability cannot be obtained and crosslinking occurs. Since the density is low, the solvent resistance, stain resistance and the like are deteriorated, which is not preferable.

Further, in the composite of the inorganic binder component and the organic binder component of the present invention, the conventional inorganic / organic composite type binder makes the inorganic binder component and the organic binder component react with each other in advance (at the stage of resin synthesis) to make them compatible with each other. On the other hand, since it is simply constituted by mixing, it has a feature that the mixing ratio of the inorganic binder component and the organic binder component can be selected relatively easily. The mixing ratio of the organic binder and the inorganic binder is 100 parts by weight of the former and 5 of the latter.
70 parts by weight.

The inorganic / organic composite coating agent binder thus obtained is dissolved or dispersed in a solvent for use and cross-linked and cured in a temperature range from room temperature to 180 ° C.

As the solvent, aromatic compounds such as toluene and xylene, methanol, ethanol, isopropanol,
Examples thereof include alcohol solvents such as butanol, glycol monoethyl ether and glycol monobutyl ether, ester solvents such as ethyl acetate, butyl acetate and cellosolve acetate, and ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone. These solvents are 80 to 5 relative to 100 parts by weight of the solid content of the binder.
It can be used in the range of 00 parts by weight.

Further, by dispersing a pigment or the like in the binder,
The material may be concealed, aesthetics may be imparted, and various patterning materials may be protected. In particular, when a proper amount of a coloring pigment is blended, a high gloss coating film can be obtained.

Examples of pigments include various inorganic pigments such as titanium oxide, carbon black, iron oxide, and lead oxides (nickel titanium type, chromium titanium type, bismuth vanadium type), quinacridone, diketopyrrolopyrrole, and benzimidazo. Representative examples thereof include various organic pigments such as ron, isoindolinone, anthrapyrimidine, phthalocyanine, threne, and dioxazine. or,
Various extender pigments such as talc, mica, calcium carbonate, barium sulfate, silicon oxide, aluminum oxide and kaolin, or plastic beads, fibrous pigments, pearl pigments, metal powder, ceramic powder and the like can be mentioned. These pigments are used in an amount of 10 parts by weight per 100 parts by weight of the solid content of the binder.
It can be used in the range of up to 400 parts by weight.

As other additives and modifiers, precipitation inhibitors, surface modifiers, reaction accelerators, UV absorbers, pigment dispersants, etc. can be used as appropriate, and these have a solid content of 100% of the binder. It can be used in the range of 0.1 to 10 parts by weight with respect to parts by weight.

The coating material thus obtained using the binder can be coated by a known coating method such as a brush, a spray, a flow coater, a roll coater or an electrostatic coating machine.

[0050]

EFFECT OF THE INVENTION According to the present invention, the degree of freedom of the composition ratio of the inorganic binder component and the organic binder component is relatively large, and a film can be formed in a temperature range from room temperature to 180 ° C. with high gloss and hardness. It is possible to obtain an inorganic / organic composite coating binder that is excellent in stain resistance / crack resistance and weather resistance and that can form a film.

Next, the present invention will be described more specifically with reference to production examples, examples and comparative examples. Here, all "parts" and "%" are based on weight unless otherwise specified.

[0052]

【Example】

(Undercoat paint) methyl methacrylate / butyl acrylate / 2-hydroxymethyl acrylate = 70/20 /
Acrylic copolymer consisting of 10: 10 parts, hexamethylene diisocyanate trimethylolpropane adduct:
4 parts, tolylene diisocyanate trimer body: 3 parts, titanium white: 15 parts, kaolin: 8 parts, mica: 8 parts, barium sulfate: 4 parts, butyl acetate: 20 parts and xylene: 2
A composition consisting of 8 parts.

(Intermediate paint) Acrylic copolymer consisting of methyl methacrylate / cyclohexyl acrylate / 2-hydroxymethyl acrylate = 70/20/10:
13 parts, titanium white: 20 parts, kaolin: 5 parts, barium sulfate: 15 parts, butyl acetate: 13 parts, toluene: 25
Parts, hexamethylene diisocyanate trimer body: 4 parts.

(Topcoat) The composition of the topcoat is shown in Table 1.

[0055]

[Table 1] Note 1) Acrylic copolymer t-butyl methacrylate 56.0 Styrene 15.0 n-Butyl methacrylate 15.0 2-Hydroxyethyl methacrylate 13.0 Methacrylic acid 1.0 Xylene 60.0 MiBK 40.0 Heating residue 48 Viscosity (25 ° C.) 1465 Acid value (Solid) 8.5 OH value (Solid) 57.7 mgKOH / g Molecular weight (weight average) About 35,000 Note 2) Fluorine-containing copolymer varnish 57-3410
No. 7 publication) Lumiflon LF200 (trade name of Asahi Glass Co., Ltd.) Heating residue 59.0 to 61.5% Viscosity (25 ° C Stokes) 20 ± 3 Acid value (mgKOH / g) 0 OH value (mgKOH / g) 31 ± 3 Note 3) Colloidal silica Organocierikasol IPA-ST (trade name, manufactured by Nissan Chemical Industries, Ltd.) Note 4) Non-yellowing isocyanate (normal isocyanate compound without siloxane bond) Nippon Polyurethane, trade name NCO-containing 20 0.5 to 22.0 wt% The NCO / OH equivalent ratio when using Coronate HX (when EFKA88 is not used) is preferably in the range of 0.5 to 1.5.

Note 5) EFKA88 siloxane-containing isocyanate (manufactured by EFKA) (R ₁ is an NCO group, n is an integer of 0 to 80)

[0057]

[Table 2] Test method <Adhesion> A 4 mm pitch scoring cut scratch is made on a coated plate, a cellophane tape is attached, and it is rapidly peeled off.

○: Number of remaining goggles / cutting goggles 48/50 <△: 〃 30/50 <×: 〃 25/50><Hardness> Pencil hardness measured by JIS-K-5400 <Mirror reflectance > Measurement according to JIS-K-5400 <Warm water resistance> The test piece was immersed in warm water at 60 ° C for 5 days to visually observe the abnormality of the coating film. ◯: No change Δ: Minor change such as whitening Yes ×: Large change such as whitening <Cooling heat resistance> Test piece was frozen at -20 ° C for 2 hours,
Then, it was left to stand in hot air at 80 ° C. for 2 hours. This was set as 1 cycle and 30 cycles were performed to visually judge the abnormality of the coating film. ◯: No crack was generated. Δ: Minor crack generation or partial peeling of the coating film. ×: Significant crack, peeling of coating film. <Contamination resistance> For exhaust gas carbon Make a paste by adding a small amount of kerosene and water. Rub this on the coated surface, then wash with water. Repeat this operation 3 times to observe the contamination status. ○: Almost no contamination △: Minor contamination x: Significant contamination <Frost resistance> Measured by ASTM-C-666A method (cycle is 150 cycles) ○: Crack generation None △: Minor crack generation or partial peeling of coating film ×: Marked crack, peeling of coating film <Weather resistance> Sunshine weatherometer (test time 3000H) ◯: No change in coating appearance, 90% gloss retention Above Δ: slight change in coating appearance, gloss retention of 70% or more ×: significant change in coating, gloss retention of 50% or more

[0059]

[Table 3]

As is clear from the results shown in Table 3, Examples 1 to 6 using the binder of the present invention have good hardness and stain resistance, but an isocyanate having a colloidal silica or siloxane bond. Comparative Example 1 containing no compound had poor hardness and stain resistance.
Further, the equivalent ratio (NCO / OH) of the isocyanate group of the isocyanate compound to the hydroxyl group of the polyol component is 1.6.
In Comparative Example 2 in the range other than the range of / 1 to 1.5 / 1, both hardness and stain resistance were poor.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C09D 201/02 PDN C09D 201/02 PDN 201/06 PDJ 201/06 PDJ 201/10 PDP 201/10 PDP

Claims (5)

[Claims] 1. A hydroxyl value of 20 to 200 mg KOH / g
95-30% by weight of polyol component having (solid content ratio)
And a binder mixture of 5 to 70% by weight of an isocyanate compound having a colloidal silica and / or siloxane bond, and a binder for an inorganic-organic composite coating agent. 2. The polyol component has a side chain or terminal-
2. At least one selected from the group consisting of an acrylic copolymer having an OH group and a fluorine-containing copolymer.
Binder for the inorganic / organic composite coating agent described. 3. The mixing ratio of the polyol component and the isocyanate compound having a siloxane bond is such that the equivalent ratio (NCO / OH) of the isocyanate group of the isocyanate compound to the hydroxyl group of the polyol component is 0.6 / 1 to 1.5 /.
The binder for an inorganic / organic composite coating agent according to claim 1, which is 1. 4. The acrylic copolymer is a copolymer having an α, β-ethylenically unsaturated monomer having a hydroxyl group as an essential component and a weight average molecular weight of about 10,000 to about 100,000. The binder for an inorganic / organic composite coating agent according to claim 2. 5. The fluorocopolymer contains fluoroolefin, cyclohexyl vinyl ether, alkyl vinyl ether and hydroxyalkyl vinyl ether as essential components and has a weight average molecular weight of about 20,000 to about 10.
The binder for an inorganic / organic composite coating material according to claim 2, which is a copolymer of 10,000.