JPH07102211A - Composition for cold-setting coating material - Google Patents

Abstract

PURPOSE:To obtain a resin composition for use in a cold-setting fluororesin coating material having excellent smearing resistance. CONSTITUTION:An organic-solvent solution of 100 pts.wt. solvent-soluble fluorinated copolymer containing 10-20mol% hydroxylated monomer units is mixed with 5-100 pts.wt. either of a silane compound having two or more hydrolyzable groups and a low-mol. condensate thereof. Water is added to the mixture to obtain an organic-solvent solution of a silane-modified fluorinated copolymer (B). A solvent-soluble fluorinated copolymer (A) containing 3-20mol% hydroxylated monomer units and a polyisocyanate are dissolved therein to obtain the objective composition in which the weight ratio of the copolymer (B) to the copolymer (A) is 1.0 or lower.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a room temperature curing type fluororesin-based coating material having excellent weather resistance, and more specifically, a room temperature curing type coating material using a polyvalent isocyanate having significantly improved stain resistance. The present invention relates to a polymer composition for use.

[0002]

PRIOR ART AND ITS PROBLEMS Fluororesin-based paints are used in a wide range of industrial fields as highly durable paints, and even on-site construction, which was not possible with conventional dispersion-type fluororesin-based paints, This is possible with the advent of solvent-soluble fluororesin paints. For on-site construction, a room-temperature curing type coating consisting of polyisocyanate as a curing agent and a solvent-soluble fluorocarbon resin is generally used, but conventional fluorocarbon resin-based room-temperature curing coating has weather resistance. Although excellent, there was a problem with stain resistance, and there were restrictions on applications.

That is, not only in an environment with a lot of pollutants such as along a highway or in a factory area, but also on an outer wall of a building having a structure where dirt easily adheres, a curtain wall where the temperature of the painted surface easily rises, and an automobile. The conventional fluororesin-based room temperature curing type paints are contaminated remarkably with respect to coated steel sheets and the like, and improvements have been demanded. As means for improving the stain resistance of fluororesin-based paints, JP-A-4-17388 is known.
No. 1 discloses that a silane compound having a hydrolyzable group such as tetraalkoxysilane is added to an organic solvent solution of a fluorine-containing copolymer having a functional group such as a hydroxyl group or a carboxyl group to form a fluorine-containing copolymer. A silane-modified fluorinated copolymer obtained by reacting the functional group with a silane compound has been proposed.

The above-mentioned silane-modified fluorinated copolymer is a self-condensation type curable polymer that is cured by a condensation reaction of silanol groups generated by hydrolysis of a silane compound introduced therein, and is a dibutyltin laurate or the like. By heat-curing the copolymer in the presence or absence of a catalyst, a coating film having excellent mechanical strength and stain resistance can be obtained. However, the hardness of the coating film obtained by curing the silane-modified fluorinated copolymer in combination with a polyvalent isocyanate at room temperature is low and the weather resistance is also insufficient,
There is a technically unsolved problem in using the silane-modified fluorinated copolymer alone as a resin for a room temperature curable coating material.

Also, in the case of the hard coat composition disclosed in JP-A-4-211482, which comprises a fluororesin, a polyvalent isocyanate and a metal oxide sol, as will be apparent from Comparative Example 2 described later, The stain resistance was equivalent to that of the fluororesin-based paint to which no metal alkoxide such as alkoxysilane was added, and was not particularly good.

An object of the present invention is to provide a coating composition containing a fluororesin as a main component, which can be cured at room temperature with a polyvalent isocyanate and forms a coating film having high hardness and excellent stain resistance.

[0007]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that a fluorine-containing copolymer having a hydroxyl group and a silane-modified fluorine-containing copolymer obtained by a specific synthesis method are obtained. It was found that a coating film having high hardness and excellent stain resistance can be obtained by curing the mixture of (1) at room temperature with a polyvalent isocyanate, and completed the present invention.

That is, according to the present invention, a solvent-soluble fluorine-containing copolymer containing 10 to 20 mol% of a hydroxyl group-containing monomer unit is hydrolyzed per 100 parts by weight of the fluorine-containing copolymer. To the organic solvent solution of the silane-modified fluorocopolymer (B) obtained by adding 5 to 100 parts by weight of a silane compound having two or more functional groups or a low condensate thereof, and then adding water, A solvent-soluble fluorine-containing copolymer (A) containing 3 to 20 mol% of a hydroxyl group-containing monomer unit and a polyisocyanate are dissolved, and the silane-modified fluorine-containing copolymer (A) is added to the fluorine-containing copolymer (A). A room temperature curable coating composition in which the weight ratio of the polymer (B) is 1.0 or less.

The present invention will be described in detail below. First, the fluorocopolymer (A) will be described. As described above, the fluorinated copolymer (A) in the present invention is a solvent-soluble fluorinated copolymer containing 3 to 20 mol% of a hydroxyl group-containing monomer unit, and a preferable fluorinated copolymer constituting the copolymer. As the fluorine monomer, vinyl fluoride, vinylidene fluoride, trifluoroethylene, tetrafluoroethylene,
Fluoroolefins such as chlorotrifluoroethylene and hexafluoropropylene can be mentioned, more preferably tetrafluoroethylene and chlorotrifluoroethylene, and particularly preferably chlorotrifluoroethylene. The preferred ratio of the fluoroolefin monomer unit in the fluorocopolymer (A) is 35-6.
0 mol%, more preferably 40 to 55 mol%
Is. The ratio of the fluoroolefin monomer unit is 35
If it is less than mol%, the weather resistance tends to be insufficient, while if it exceeds 60 mol%, it becomes difficult to dissolve it in an organic solvent.

As the hydroxyl group-containing monomer, crotonic acid 2
-Hydroxyethyl, 3-hydroxypropyl crotonic acid, 2,2 dimethyl 3-hydroxypropyl crotonic acid, 4-hydroxybutyl crotonic acid, 5-crotonic acid 5-
Crotonic acid hydroxyalkyl esters such as hydroxypentyl and 6-hydroxyhexyl crotonic acid; 2-
Hydroxyalkyl vinyl ethers such as hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether and 4-hydroxybutyl vinyl ether; allyl such as 2-hydroxyethyl allyl ether, 3-hydroxypropyl allyl ether, 4-hydroxybutyl allyl ether and diethylene glycol monoallyl ether Ethers; methallyl ethers such as 2-hydroxyethyl methallyl ether, 3-hydroxypropyl methallyl ether, and 4-hydroxybutyl methallyl ether. When the proportion of the hydroxyl group-containing monomer unit in the fluorinated copolymer (A) is less than 3 mol%, the curing reaction with the polyvalent isocyanate becomes insufficient, resulting in poor chemical resistance and water resistance of the coating film. If it exceeds 20 mol%, the weather resistance of the coating film will be poor.

In order to obtain the fluorine-containing copolymer (A), it is preferable to use other copolymerizable monomers together with the above-mentioned fluorine-containing monomer and hydroxyl group-containing monomer. Vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, n-butyl vinyl ether and cyclohexyl vinyl ether; vinyl carboxylates such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl pivalate, vinyl caproate, vinyl versatate and vinyl stearate. Esters; acrylic acid,
Examples thereof include unsaturated carboxylic acids such as crotonic acid, maleic acid, itaconic acid and vinylacetic acid, and their anhydrides. A preferred ratio of the above-mentioned copolymerizable monomer unit in the fluorinated copolymer (A) is 20 to 62 mol%.

The above-mentioned fluorine-containing copolymer (A) can be produced by copolymerizing the above-mentioned monomers by the solution polymerization method described in, for example, JP-A-3-231906.
That is, toluene, xylene, butyl acetate or the like as a polymerization solvent, and a radical generating compound such as t-butylperoxypivalate, t-butylperoxyacetate or azobisisobutyronitrile as a polymerization initiator,
The mixture of the monomers may be polymerized at a temperature of 40 to 80 ° C. for about 5 to 20 hours.

The silane-modified fluorinated copolymer (B) is a modified polymer synthesized by the above-mentioned method, and the fluorinated copolymer used as a starting material thereof (hereinafter referred to as "modifying fluorinated copolymer"). ), As described above, is a solvent-soluble fluorine-containing copolymer containing 10 to 20 mol% of a hydroxyl group-containing monomer unit. If the proportion of the hydroxyl group-containing monomer units in the modifying fluorocopolymer is less than 10 mol%, the reactivity between the copolymer and the silane compound added is poor and the resulting coating film has stain resistance. Is insufficient.

The constitutional unit in the fluorinated copolymer for modification is a monomer unit similar to the above-mentioned fluorinated copolymer (A), and the preferable constitution of the fluorinated copolymer for modification is the whole unit amount. Based on the total amount of body units, fluoroolefin monomer units 35 to 60 mol%, hydroxyl group-containing monomer units 1
0 to 20 mol% and other copolymerizable monomer units 20
˜55 mol%. The type of the modifying fluorocopolymer used in the production of the specific coating composition may be the same as or different from the fluorocopolymer (A).

In the present invention, the above-mentioned fluorinated copolymer for modification is dissolved in an organic solvent, the silane compound described below is added to the copolymer solution, and then a small amount of water is added to the solution to give a solution in the solution. A silane-modified fluorinated copolymer (B) modified by means of hydrolyzing a part or the whole of the silane compound is used.

Examples of the organic solvent used in the above operation include ethyl acetate, butyl acetate, xylene, cyclohexanone, ethyl cellosolve acetate, methyl ethyl ketone, methyl isobutyl ketone, ethyl cellosolve, butyl cellosolve, isopropanol and cyclohexanol. Alternatively, two or more kinds may be used in combination. A more preferable organic solvent is a solvent containing 10 to 50% by weight of alcohol in that the silane-modified fluorinated copolymer (B) produced by addition of water is stably present in the solution. The preferred concentration of the modifying fluorine-containing copolymer in the organic solvent solution is 10 to 40% by weight.

In the present invention, as described above, a silane compound having two or more hydrolyzable groups or a low condensate thereof is used, but a preferred hydrolyzable group is an alkoxy group. Specific examples of the silane compound having two or more such alkoxy groups include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, and other tetraalkoxysilanes; methyltrimethoxysilane, ethyltriethoxysilane, and methyltriethoxy. Alkyltrialkoxysilanes such as silane, ethyltrimethoxysilane, propyltrimethoxysilane and butyltrimethoxysilane; and dialkyldialkoxysilanes such as dimethyldimethoxysilane, diethyldiethoxysilane, dipropyldimethoxysilane and dibutyldimethoxysilane. . Examples of the low condensate that can be used in the same manner as the silane compound include dimers, trimers, tetramers and pentamers of the above silane compounds, or a mixture thereof. Hereinafter, the low-condensation products are collectively referred to as a silane compound. More preferably,
A silane compound having a highly hydrolyzable methoxy group or ethoxy group, particularly preferably tetramethoxysilane, tetraethoxysilane silane, or a low condensate thereof.

In addition to the above silane compounds, silane compounds usable in the present invention include vinyltrimethoxysilane, vinyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, γ-chloropropyltrimethoxysilane, γ. -Aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane and γ-hydroxypropyltrimethoxysilane.

The amount of the silane compound added to the modifying fluorine-containing copolymer is 5 to 100 parts by weight of the copolymer.
It is 100 parts by weight, and more preferably 30 to 100 parts by weight. When the amount of the silane compound used exceeds 100 parts by weight, precipitation occurs in the solution and a stable silane-modified fluorinated copolymer solution cannot be obtained. On the other hand, when the amount of the silane compound used is less than 5 parts by weight, the resulting coating composition is inferior in stain resistance of the coating film. The silane compound is at room temperature to
It is preferably added to a solution of the fluorine-containing copolymer for modification maintained at 80 ° C. in an organic solvent.

Water can be added to the organic solvent solution of the modifying fluorocopolymer to which the silane compound has been added, immediately after the addition of the silane compound is completed. However, before the addition of water, hydrochloric acid, sulfuric acid, phosphorus is added. It is preferable to add an acidic compound such as an acid, acetic acid and p-toluenesulfonic acid as a catalyst for hydrolysis of the silane compound. By using the acid catalyst, hydrolysis proceeds smoothly, and a stable silane-modified fluorinated copolymer solution can be obtained. As a method of adding water, a method of gradually dropping it into a polymer solution maintained at room temperature to 80 ° C. is preferable. When water is added, the silane compound existing in the solution undergoes a condensation reaction due to hydrolysis, and part of it reacts with the hydroxyl group in the fluorinated copolymer for modification to form a side chain of the copolymer. To do.

The theoretical amount of water in the above hydrolysis reaction is
Water is 1 mol per 2 mol of the hydrolyzable group of the silane compound, but in the present invention, it is preferable to add 0.1 to 3 mol of water per 2 mol of the hydrolyzable group in the added silane compound. . If the amount of water added is less than 0.1 mol, the coating composition obtained will have poor stain resistance,
On the other hand, if it exceeds 3 mols, precipitation occurs and a stable silane-modified fluorinated copolymer solution cannot be obtained.

In the silane-modified fluorinated copolymer solution obtained by the above operation, the silane compound is chemically bonded and has a functional group derived therefrom, a silane compound condensate and unreacted silane compound. It is presumed that the modifying fluorine-containing copolymer is mixed, but in the present invention, such components are collectively referred to as a silane-modified fluorine-containing copolymer (B), and the silane-modified fluorine-containing copolymer is also included. The component derived from the silane compound and the functional group in the copolymer are collectively referred to as the introduced silane component.

As will be described later, the silane modification operation involves a hydrolysis reaction of the silane compound, that is, a reaction in which the hydrolyzable group is removed from the silane compound. Therefore, the silane introduced into the silane-modified fluorocopolymer (B) is introduced. The amount of the components is less than the weight of the silane compound added to the modifying fluorocopolymer. The content of the introduced silane component in the silane-modified fluorinated copolymer (B) is preferably 3 to 60% by weight, more preferably 15 to 6%.
It is 0% by weight.

In the present invention, by using the fluorine-containing copolymer (A) and the silane-modified fluorine-containing copolymer (B) together in a specific ratio, a coating excellent in both stain resistance and weather resistance is obtained. Thus, the weight ratio of the silane-modified fluorocopolymer (B) to the fluorocopolymer (A) is 1.0 or less. If the weight ratio of (B) to (A) exceeds 1.0, a coating having excellent weather resistance cannot be obtained.

The preferred ratio of the above (A) and (B) in the composition of the present invention varies depending on the amount of the introduced silane component in the silane-modified fluorocopolymer (B).
The ratio of the introduced silane component in the composition is 3 to 20% by weight based on the total amount of the fluorinated copolymer for modification and the fluorinated copolymer (A) used in the synthesis of the copolymer (B). In the case of using the silane-modified fluorocopolymer (B) having a content of the introduced silane component of 15 to 60% by weight, the ratio of the fluorocopolymer (A ) It is preferable to use 20 to 100 parts by weight of the silane-modified fluorinated copolymer (B) per 100 parts by weight.

In the present invention, when synthesizing the silane-modified fluorinated copolymer (B), an alkoxyaluminum such as triethoxyaluminum and tripropoxyaluminum, tetraethoxyzirconium and tetrapropoxyzirconium are used together with the above-mentioned silane compound. And other hydrolyzable metal alkoxides such as alkoxyzirconium, tetramethoxytitanium, tetraethoxytitanium, tetrapropoxytitanium, and other alkoxytitaniums. The preferable amount thereof is about 1/10 or less of the silane compound. These metal alkoxides have higher hydrolyzability than alkoxysilanes, and when used in combination with alkoxysilanes, the yield of hydrolysis of the silane and the subsequent condensation reaction is improved.

In the present invention, the polyvalent isocyanate added to the organic solvent solution of the silane-modified fluorocopolymer (B) together with the fluorocopolymer (A) is hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, isophorone diisocyanate. , Tolylene diisocyanate, xylylene diisocyanate, and 4,4′-diphenylmethane diisocyanate. Further, low-condensation products such as dimers and trimers of the above polyisocyanates, and burettes and ureas comprising the above polyisocyanates can also be used. More preferred are non-yellowing type polyisocyanates such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate and isophorone diisocyanate. The preferred amount used is the fluorine-containing copolymer (A)
5 to 25 parts by weight per 100 parts by weight of. If the amount of the polyisocyanate used is less than 5 parts by weight, the stain resistance cannot be improved because the curing is insufficient, while if it exceeds 25 parts by weight, the urethane coating is increased in the cured coating film and the weather resistance is increased. descend. A more preferable amount used is 8 to 20 parts by weight.

The coating composition of the present invention contains an organic solvent which accompanies the silane-modified fluorocopolymer (B), but in addition to this, it was used as a solvent for the fluorocopolymer (A). An organic solvent may be included, and a solvent may be added to adjust the solution viscosity. As such a solvent,
Examples thereof include toluene, xylene, ethyl acetate, butyl acetate, isobutyl acetate, acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone.

A paint is prepared by blending various additives for general paint with the composition for fluororesin paint of the present invention. As paint additives, titanium oxide, iron oxide,
Pigments such as carbon black, quinacridone red and phthalocyanine blue, UV absorbers such as benzophenone and benzotriazole, antioxidants such as hindered phenols and hindered amines, curing catalysts, surface modifiers, silane coupling agents and luster Examples include eraser.

[0030]

EXAMPLES The present invention will be described more specifically by showing Examples and Comparative Examples below. The abbreviations used in each example are as follows. CTFE: Chlorotrifluoroethylene VPr: Vinyl propionate VV-9: Veova 9 [C9 vinyl versatate manufactured by Shell Chemical Co., Ltd.] HEC: Hydroxyethyl crotonic acid EVE: Ethyl vinyl ether VPV: Vinyl pivalate HBVE: Hydroxybutyl vinyl ether VAc: vinyl acetate VCp: vinyl caproate EGMAE: ethylene glycol monoallyl ether

<Example 1> As the fluorine-containing copolymer (A), CTFE / VPr / VV-9 / HEC = 45/33.
/ 11/11 (mol%), the number average molecular weight is 12,000, the weight average molecular weight is 40,000 (both are polystyrene conversion average molecular weight by GPC), and the glass transition temperature is 35 ° C. Combined (hereinafter referred to as polymer A-1)
The polymer obtained by the following method was used as the silane-modified fluorocopolymer (B).

That is, the structure is CTFE / VPr / HE.
C = 50/32/18 (mol%), number average molecular weight; 6,000, weight average molecular weight; 17,000, and glass transition temperature of 35 ° C. used as a modifying polymer.
25 g of the polymer for modification was dissolved in a mixed solvent of xylene and butyl cellosolve (42 g of xylene + 18 g of butyl cellosolve), and the resulting solution was placed in a flask and heated to 70 ° C. in a nitrogen stream. 13 g of tetraethoxysilane and 1 of methyltriethoxysilane while stirring in the flask.
0 g and 0.01 g of p-toluenesulfonic acid were added dropwise. Furthermore, a mixed solution of 3.9 g of water and 3 g of butyl cellosolve was slowly added dropwise, and then stirring was continued for 3 hours to terminate the reaction. By the above operation, the solid content concentration is 33% by weight.
To obtain a transparent solution of the silane-modified fluorinated copolymer (hereinafter referred to as polymer B-1). The content of the solid content is 22% by weight of the fluorine-containing copolymer (the amount of the modifying polymer charged) and 11% by weight of the introduced silane component (the measured value of the solid content minus the amount of the modifying polymer charged). Met.

60% xylene solution 8 of the polymer A-1
0 g, titanium oxide [CR-97 manufactured by Ishihara Sangyo Co., Ltd.] 30
g, lubricant (manufactured by BYK, Disperbyk-10
1) 0.6 g, xylene 45 g and glass beads 80 g
Was placed in a glass bottle and dispersed and mixed by a paint shaker for 1 hour. Then, only the glass beads were separated to produce a titanium oxide dispersion liquid (hereinafter referred to as MB-1).

The above titanium oxide dispersion and polymer B-1
Using the solution, a coating composition was produced with the following formulation. Titanium oxide dispersion (MB-1) -30 g (concentration of polymer A-1; 31% by weight) Polymer B-1 solution --- 4.5 g hexamethylene diisocyanate --- 2 g [Coronate HX manufactured by Nippon Polyurethane Industry Co., Ltd.] 0.1% solution of dibutyltin dilaurate ──── 0.4 g xylene ──── 4 g Introduced silane component 5 per 100 parts by weight of the combined amount
And 20 parts by weight of polyvalent isocyanate.

The stain resistance of this paint was evaluated by the following method. This paint was applied to a chromate conversion A4 size aluminum plate by a # 50 bar coater and cured at 23 ° C. and 50% RH for 1 week. After the initial L value was measured with a color difference meter, it was exposed outdoors at a 45 ° angle on the south surface for 7 months from June to December in a place with a lot of soot and dust in the southern industrial zone of Nagoya city. After the exposure was completed, the L value was measured again, and the difference (ΔL) from the initial L value was calculated (Δ
The smaller the absolute value of L, the better the stain resistance).
The ΔL value obtained for the above paint was -3.5.

Example 2 As the silane-modified fluorine-containing copolymer (B), a polymer solution obtained by the following method was used. That is, the structure is CTFE / VAc / VCp / EG.
MAE = 45/10/30/15 (mol%),
Number average molecular weight: 9,000, weight average molecular weight: 28,000
Then, a polymer having a glass transition temperature of 30 ° C. was used as a modifying polymer, and a solution prepared by dissolving 21 g of the modifying polymer in a mixed solvent of xylene and isopropyl alcohol (42 g of xylene + 12 g of isopropyl alcohol) was charged into a flask, and a nitrogen stream was introduced. Heated to 70 ° C. in. Next, the following compound was added dropwise while stirring the inside of the flask.

Condensate of tetraethoxysilane 6.2 g [Average degree of condensation; 5, ES-40 manufactured by Tama Chemical Co., Ltd.] Methyltriethoxysilane 1.9 g Phenyltriethoxysilane 0.9 g Tetrabutoxyzirconium 0 0.5 g p-toluenesulfonic acid 0.002 g

Then, a mixed solution of 1.3 g of water and 6 g of isopropyl alcohol was slowly added dropwise, and then stirring was continued for 4 hours to terminate the reaction. By the above operation, a transparent solution of a silane-modified fluorinated copolymer (hereinafter referred to as polymer B-2) having a solid content concentration of 30% by weight was obtained. The breakdown of the solid content concentration of 30% by weight is that the fluorine-containing copolymer is 23% by weight.
The introduced silane component was 7% by weight.

The titanium oxide dispersion liquid (M
Using the solution of B-1) and the above polymer B-2, a coating material was produced with the following formulation. Titanium oxide dispersion (MB-1) -30 g (concentration of polymer A-1; 31% by weight) Polymer B-2 solution -15 g hexamethylene diisocyanate -2-g Nippon Polyurethane Industry Co., Ltd., Coronate HX] 0.1% solution of dibutyltin dilaurate ──── 0.4 g The mixing ratio of the resin component in the obtained coating composition is 100 parts by weight of the total amount of the fluorine-containing copolymer. Introduced silane component 8.
3 parts by weight and 15.8 parts by weight of polyisocyanate. The result of measuring the stain resistance of the coating film obtained from the above coating material was ΔL = −1.2.

Example 3 As the fluorine-containing copolymer (A), CTFE / EVE / VPV / HBVE = 48/30
A polymer having a composition of / 12/10 (mol%), a number average molecular weight of 15,000, a weight average molecular weight of 50,000 and a glass transition temperature of 30 ° C. (hereinafter referred to as polymer A-2). used. Using the polymer A-2, a titanium oxide dispersion liquid (hereinafter referred to as MB-2) was produced in the same manner as in Example 1.

A coating composition was prepared from the above MB-2 and the polymer B-1 solution used in Example 1 according to the following formulation. Titanium oxide dispersion (MB-2) ────30 g (polymer concentration of A-2; 31 wt%) Polymer B-1 solution ────13 g hexamethylene diisocyanate ──── 2 g [ Asahi Kasei Kogyo KK Duranate TPA-100] 0.1% solution of dibutyltin dilaurate ───── 0.4 g xylene ──── 2 g 1 silane component introduced per 100 parts by weight of total coalescence
2.1 parts by weight and 16.6 parts by weight of polyisocyanate. The result of measuring the stain resistance of the coating film obtained from the above coating material was ΔL = −2.2.

Comparative Example 1 A coating material was prepared by uniformly mixing the following materials without using the silane-modified fluorinated copolymer (B). Titanium oxide dispersion (MB-1) 30 g Hexamethylene diisocyanate 1.8 g [Coronate HX manufactured by Nippon Polyurethane Industry Co., Ltd.] 0.1% solution of dibutyltin dilaurate ─── 0 .4 g xylene ──── 5 g The stain resistance of the above paint was measured as follows: ΔL =-
It was 12.

Comparative Example 2 In the production of the silane-modified fluorinated copolymer (B) in Example 1, after mixing the fluorinated copolymer and the silane compound, water was not added,
A fluorocopolymer solution containing a silane compound was obtained. Fluorine-containing copolymer solution and titanium oxide dispersion (MB-1)
Was used to produce a coating material in the same manner as in Example 1. The measurement result of the stain resistance of the obtained paint is ΔL = -1
It was 1.

[0044]

EFFECTS OF THE INVENTION According to the present invention, it is possible to obtain a room temperature curing type fluororesin coating material which is extremely excellent in stain resistance while maintaining the high weather resistance inherent in the fluororesin coating material.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Akihito Iida 1-1 Funami-cho, Minato-ku, Nagoya, Aichi Prefecture Toagosei Chemical Industry Co., Ltd. Nagoya Research Institute (72) Inventor Hiroshi Inukai Nagoya, Aichi Prefecture 1 Touna Synthetic Chemical Industry Co., Ltd. Nagoya Research Institute, No. 1 Funami-cho, Minato-ku

Claims (1)

[Claims] 1. An organic solvent solution of a solvent-soluble fluorine-containing copolymer containing 10 to 20 mol% of a hydroxyl group-containing monomer unit contains 2 hydrolyzable groups per 100 parts by weight of the fluorine-containing copolymer. A silane compound or a low-condensate thereof having 5 or more of them is added at a ratio of 5 to 100 parts by weight, and then water is added to the organic solvent solution of the silane-modified fluorinated copolymer (B) to obtain a hydroxyl group-containing unit amount. A solvent-soluble fluorine-containing copolymer (A) containing 3 to 20 mol% of a body unit and a polyvalent isocyanate, and the fluorine-containing copolymer (A).
The weight ratio of the silane-modified fluorinated copolymer (B) to
A room temperature curable coating composition which is 1.0 or less.