JP3244297B2 - Two-part fluorine-containing coating composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-part fluorine-containing paint composition, and more particularly to a two-part fluorine-containing paint composition having excellent weather resistance which is suitably used for automobiles, building exterior materials, roofing materials, plastics and the like. The present invention relates to a fluorine-containing polyurethane coating composition.

[0002]

2. Description of the Related Art A two-pack type polyurethane coating composition comprising an acrylic polyol or a polyester polyol as a main component and a non-yellowing type polyisocyanate obtained from an aliphatic organic polyisocyanate compound as a curing agent is used as a weathering agent. It has excellent properties and abrasion resistance, and is widely used in, for example, repair of automobiles, building exteriors, plastics and the like.

In recent years, however, the required physical properties of coatings in these fields are becoming increasingly severe. To meet such requirements, for example, JP-A-57-34107 and JP-A-58-34866. As described in Japanese Patent Application Laid-Open Publication No. H10-163, a two-pack type polyurethane paint using a fluorine-containing polyol as a main component and a polyisocyanate as a curing agent has been proposed as having excellent weather resistance. However, conventionally, in such paints, the compatibility between the polyisocyanate and the fluorine-containing polyol is insufficient, so that the polyisocyanate and the fluorine-containing polyol which can be used are variously restricted.

Japanese Patent Application Laid-Open No. 63-265970 discloses a trimerization reaction of hexamethylene diisocyanate.
That is, it has been proposed to use a relatively low molecular weight polyisocyanate obtained by an isocyanuration reaction as a curing agent. Such a polyisocyanate is compared with a conventionally known adduct of a low-molecular-weight polyol and a diisocyanate compound, a biuret body obtained by reacting a diisocyanate compound with water and / or a tertiary alcohol, and the like. Although the compatibility with the fluorine-containing polyol has been relatively improved, it cannot be said that it has yet reached a satisfactory level.In particular, in order to improve the stain resistance, the fluorine content was increased and the solubility was increased. Fluorine-containing polyols with reduced parameters have extremely poor compatibility and are not practical.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems in a conventional weather-resistant two-pack type polyurethane coating composition using a fluorine-containing polyol as a main component and a polyisocyanate as a curing agent. The polyisocyanate as a curing agent has a high degree of compatibility with various fluorine-containing polyols, including a fluorine-containing polyol having a high fluorine content, and has excellent weather resistance. It is an object of the present invention to provide a two-component polyurethane coating composition which gives a coating film.

[0006]

According to the present invention, two molecules are contained in one molecule.
In a two-pack type fluorine-containing coating composition comprising a fluorine-containing polyol having two or more hydroxyl groups and a polyisocyanate, the polyisocyanate may be an aliphatic alcohol or an alicyclic alcohol.
Alcohol and araliphatic having 1 to 10 carbon atoms selected from an alcohol monoalcohols and aliphatic organic polyisocyanates obtained Yotsute the reaction of a compound Arofuane <br/> preparative group Arofuaneto isocyanurate groups with group / Lee
It is characterized by containing a polyisocyanate having a ratio of 4/1 to 1/10 in terms of a soocyanurate group molar ratio .

As is already known, polyisocyanates having allophanate groups can be obtained by various methods. Such methods include , for example,
UK Patent No. 994,890 and U.S. Patent No. 4,177,342
No. 4,160,080, 3,769,318, 4,810,820, JP-B-46-1711, JP-B-49-40860, and the like.
Things are known . However, the polyisocyanate having an allophanate group obtained by such a known method has a problem that the final product obtained by using the polyisocyanate may be discolored. The polyisocyanate having an allophanate group obtained from a monoalcohol and a polyisocyanate is bifunctional,
Using only such a polyisocyanate as a curing agent,
In order to obtain a coating composition having a sufficient crosslinking density and curing rate, it is necessary to increase the hydroxyl group content of the fluorine-containing polyol which is the main component, and the production restrictions of the fluorine-containing polyol increase.

[0008] Therefore, according to the present invention, in order to solve the above problems, to the extent that does not affect the compatibility of the fluorine-containing polyol, the polyisocyanate component as a curing agent, in addition to Arofuaneto group, Furthermore, Ru allowed Yes isocyanurate groups. The polyisocyanate component in the present invention is used in the first method as described in detail below.
Te is reacted with an excess amount of aliphatic organic polyisocyanate compound monoalcohol having 1 to 10 carbon atoms, Arofua
An allophanate group was obtained by performing a
Separately, the same polyisocyanate isocyanurate
Polyisocyanate having isocyanurate groups
To obtain a mixture. Second
As a method, an allophanatized anti-
Reaction and isocyanuration reaction simultaneously
To form an allophanate group and an isocyanurate group.
Can be obtained.

That is, according to the present invention, the polyisocyanate-containing polyisocyanate component is contained only by containing a polyisocyanate having an isocyanurate group together with an allophanate group obtained from a monoalcohol and an organic polyisocyanate compound. Compatibility with hydrogen polyol can be dramatically improved. This is an effect that cannot be expected from the conventionally known fact that polyisocyanates having polar groups such as urethane groups, urea groups, and biuret groups have poor compatibility with fluorine-containing polyols.

As described above, according to the present invention, the polyisocyanate is excellent in compatibility with the fluorine-containing polyol, so that various organic polyisocyanate compounds can be used as raw materials without being restricted by the conventional compatibility. The polyisocyanate to be used can be used as a curing agent, and thus, in the two-component fluorine-containing polyurethane coating composition, the design and setting of the curability and physical properties of the coating film can be made more freely than before.

In the present invention, the aliphatic organic polyisocyanate compound is an aliphatic, alicyclic or araliphatic polyisocyanate, and preferably has the general formula (I) R (NCO) _x (wherein R is an aliphatic hydrocarbon group having 2 to 20 carbon atoms, preferably 6 to 10 carbon atoms, and 4 to 20 carbon atoms, preferably 6 to 15 carbon atoms.
Or an alicyclic hydrocarbon group having 8 to 14, preferably 8 to 12, carbon atoms, and x represents a number of 2 to 4. )).

Examples of such organic polyisocyanate compounds include ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, undecamethylene diisocyanate, 2,2,4- or
2,4,4-trimethyl-1,6-diisocyanatohexane,
Isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, 1,3-diisocyanatocyclobutane, 1,4-diisocyanatocyclohexane, 4,4′-diisocyanatodicyclohexylmethane, 1,2-bis (isocyanate Natomethyl) cyclobutane, trimethylhexane-
1,6-diisocyanate, 1,11-diisocyanatoundecane, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, 4,4′-cyclohexane diisocyanate, isopropylidenebis (4-cyclohexyl) isocyanate, 1 3,3-bis (isocyanatomethyl) cyclobutane, bis (isocyanatomethyl) norbornane (mixture of isomers), 3 (4), 8 (9) -diisocyanatomethyltricyclo (5,2,1,2,6 ) Decane, m- or p
-Xylylene diisocyanate, tetramethyl xylylene diisocyanate, 4,4-bis (isocyanatomethyl) diphenylmethane, 1,12-dodecane diisocyanate, lysine diisocyanate (C ₁ -C ₈ alkyl ester), 1,3-diisocyanato cyclohexane , 1,3-
Or 1,4-diisocyanatomethylcyclohexane, 1-
Isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate)
And the like.

[0013] Among these organic polyisocyanate compounds, in the present invention, hexamethylene diisocyanate, 1,3-diisocyanatomethylcyclohexane or isophorone diisocyanate is preferable. Particularly, from the viewpoint of coating workability, low viscosity polyisocyanate is preferred. Hexamethylene diisocyanate which gives isocyanate is most preferably used.

As the monoalcohol having 1 to 10 carbon atoms, aliphatic alcohol, alicyclic alcohol or araliphatic alcohol is used. Specifically, for example, methanol, ethanol, n-propanol, isopropanol, isomer butanols, allyl alcohol, pentanol, hexanol, heptanol, 2-ethylhexanol, n-octanol, nonanol, n-decanol, cyclopentanol , include cyclohexanol, furfuryl alcohol, benzyl alcohol, etc.
Can be.

In the present invention, among these, a polyisocyanate having a high isocyanate group content and a low viscosity can be obtained.
4 aliphatic monoalcohols are preferably used. However, in the present invention, a monoalcohol having more than 10 carbon atoms can be used in combination with the above-mentioned monoalcohol having 1 to 10 carbon atoms. In addition, a small amount of a polyfunctional alcohol such as a dialcohol or a trialcohol can be used in combination with the above-mentioned monoalcohol having 1 to 10 carbon atoms. Further, in addition to these, active hydrogen compounds such as thiols, oximes, lactams, phenols, and β-diketones can also be used as monoalcohols, if necessary.

As described above, the polyisocyanate component which can be particularly preferably used in the present invention has an isocyanurate group in addition to the allophanate group. It can be obtained by a method. That is,
As a first method, a polyisocyanate having an allophanate group obtained by the above-described method and an isocyanurate group obtained by performing an isocyanuration reaction in the presence of a catalyst using the same raw material The method of mixing with a polyisocyanate can be mentioned. In this method, the unreacted organic polyisocyanate compound is removed before or after mixing the polyisocyanate having an allophanate group and the polyisocyanate having an isocyanurate group. In the second method, after performing an allophanation reaction and an isocyanuration reaction in the presence of a catalyst using the above-described raw materials,
It removes unreacted organic polyisocyanate compounds.

Such a polyisocyanate component has an allophanate group and an isocyanurate group, but contains substantially no thermally unstable dimer, and is substantially colorless. In particular, according to the present invention, the polyisocyanate obtained by the second method is preferably used as a curing agent from the viewpoints of production efficiency and quality stability of the polyisocyanate.

The above-mentioned organic polyisocyanate compound and monoalcohol are subjected to a pre-reaction of a part or all of the hydroxyl groups of the monoalcohol with a part of the isocyanate groups present in the polyisocyanate before the allophanatization and / or isocyanuration reaction. As a result, a urethane group may be generated. The use ratio of the organic polyisocyanate compound and the monoalcohol in the present invention is preferably about 5 to 10 in terms of the molar ratio of isocyanate groups present in the organic polyisocyanate compound to the hydroxyl groups of the monoalcohol.
The range is about 0, more preferably about 10 to 50. When the isocyanate group / hydroxyl group molar ratio is less than 5, the content of the polyisocyanate whose terminals are all blocked by urethane bonds increases, which may result in a decrease in the number of functional groups in the final product. , 1
When it exceeds 00, the content of the allophanate group is low, and the compatibility with the fluorine-containing polyol may be low.

In the reaction between the monoalcohol and the organic polyisocyanate compound, a solvent may or may not be used. When a solvent is used, it is necessary that the solvent has no reaction activity for isocyanate groups. As the catalyst used for the reaction between the monoalcohol and the organic polyisocyanate compound, a catalyst which is easy to control the reaction, has little coloring of the final product, and has little generation of a dimer having poor thermal stability is used. Such catalysts include, for example, tetraalkylammonium hydroxides such as tetramethylammonium, tetraethylammonium, tetrabutylammonium, trimethylbenzylammonium and organic weak acid salts, trimethylhydroxypropylammonium, trimethylhydroxyethylammonium, triethylhydroxypropylammonium , Trialkylhydroxyalkylammonium hydroxides and organic weak acid salts such as triethylhydroxyethylammonium, etc., alkali metal salts of alkylcarboxylic acids such as acetic acid, caproic acid, octylic acid, myristic acid, tin and zinc of the above alkylcarboxylic acids Metal such as lead, β-diketone such as aluminum acetylacetone, lithium acetylacetone, etc. Examples include chelate compounds, Friedel-Crafts catalysts such as aluminum chloride and boron trifluoride, various organic metal compounds such as titanium tetrabutylate and tributylantimony oxide, and compounds containing an aminosilyl group such as hexamethylsilazane. . Among these,
A quaternary ammonium compound such as a tetraalkylammonium hydroxide or an organic weak acid salt is preferably used.

Such a catalyst varies depending on the kind, reaction temperature and the like, but is usually used in a range of about 0.0001 to 1% based on the organic polyisocyanate compound.
In the present invention, the allophanate-forming reaction and the isocyanurate-forming reaction are usually carried out in a temperature range of about 20 to 160 ° C, preferably about 40 to 100 ° C.

In the present invention, the conversion rate of the above-mentioned allophanatization reaction and isocyanuration reaction is about 10 to 60% by weight, preferably about 15% by weight, based on the total charged amount of the organic polyisocyanate compound and the monoalcohol. The range is preferably about 40% by weight. Conversion rate is about 6
If it exceeds 0%, the molecular weight of the resulting polyisocyanate is too high, and the compatibility with the fluorine-containing polyol may be low, and the content of the isocyanate group may be low.

When the reaction reaches the desired conversion, the catalyst is deactivated by adding an acidic substance such as phosphoric acid, benzoyl chloride, monochloroacetic acid or dodecylbenzenesulfonic acid to the reaction mixture as a terminator. For example, by removing unreacted organic polyisocyanate compound (and solvent) by means such as thin film distillation or solvent extraction, polyisocyanate having an allophanate group which can be preferably used in the present invention is obtained. Obtainable.

In particular, according to the present invention, in the polyisocyanate having an allophanate group and an isocyanurate group, the allophanate group / isocyanurate group molar ratio is preferably in the range of 4/1 to 1/10. Allophanate group / isocyanurate group molar ratio
It is preferably in the range of 2/1 to 1/2 .

In the polyisocyanate having an allophanate group and an isocyanurate group, when the molar ratio of the allophanate group / isocyanurate group is smaller than 1/10, the polyisocyanate may have poor compatibility with the fluorine-containing polyol. If the allophanate group / isocyanurate group molar ratio exceeds 4/1, the polyisocyanate is excellent in compatibility with the fluorine-containing polyol, but the number of functional groups in the polyisocyanate is reduced, so that the curability of the paint is reduced. And physical properties of the coating may be insufficient.

As described above, the polyisocyanate having an allophanate group and an isocyanurate group is well compatible with any of the fluorine-containing polyols, and has a fluorine content which has heretofore been difficult to use due to restrictions on compatibility. It can be used as an effective curing agent even for a room temperature-curable fluorine-containing polyol having a high content.

In particular, in the present invention, the polyisocyanate having an allophanate group and an isocyanurate group obtained from hexamethylene diisocyanate and an aliphatic alcohol having 1 to 10 carbon atoms is substantially free from a free organic polyisocyanate compound and a solvent. In the state not including
The viscosity at 25 ° C. can be less than 500 centipoise, preferably less than 300 centipoise, so that such polyisocyanates can themselves be used as curing agents without dilution with solvents. . Therefore, in the present invention, such a polyisocyanate is particularly preferably used as a curing agent from the viewpoint of workability.

In the present invention, fluorine-containing polyols having two or more hydroxyl groups in one molecule include, for example, JP-A-57-34107, JP-A-57-34108, and JP-A-61-34108. JP-A-200145, JP-A-61-2
No. 75311, JP-A-61-272212,
JP-A-59-189108, JP-A-60-284
No. 58, Japanese Patent Application Laid-Open No. 60-67517, Japanese Patent Application Laid-Open
JP-A-1-51045, JP-A-61-176620, JP-A-62-7767, JP-A-4-2870
No. 7, as described in JP-A-59-413, for example, those containing fluoroolefin as a constituent component.
JP-A-21, JP-A-59-96177 and JP-A-6-197177
JP-A-137950, JP-A-61-36374, JP-A-61-118466, and JP-A-60-1
No. 267, for example, those obtained by further modifying a fluorine-containing polyol containing the above-mentioned fluoroolefin as a constituent component, for example, as described in JP-A-58-34866 and the like. Includes polyols that are soluble in organic solvents such as those using unsaturated monomers having a fluorine-containing group in the side chain as constituent components and modified products thereof. As the fluorine-containing polyol, commercially available products can be used. For example, Lumiflon LF-100, LF manufactured by Asahi Glass Co., Ltd.
-200, LF-300, LF-601, and K-700, K-701, manufactured by Dainippon Ink and Chemicals, Inc.

In the present invention, the mixing ratio of the polyisocyanate and the fluorine-containing polyol in the coating composition is as follows:
The isocyanate group / hydroxyl equivalent ratio is preferably in the range of about 1/5 to 2/1. When the equivalent ratio is smaller than 1/5, the resulting coating film may be inferior in weather resistance and solvent resistance, and when it exceeds 2/1, the drying property may be slow.

Further, according to the present invention, the coating composition may contain additives commonly used in polyurethane coatings, such as a curing accelerator, an ultraviolet absorber, an antioxidant, and a leveling agent.

[0030]

The present invention relates to a cold-setting, weather-resistant, two-pack polyurethane coating composition using a fluorine-containing polyol as a main component and a polyisocyanate as a curing agent, wherein the polyisocyanate is a monoalcohol having 1 to 10 carbon atoms. Of isocyanurate groups together with allophanate groups obtained by the reaction of the compound with the aliphatic organic polyisocyanate compound and the molar ratio of allophanate groups / isocyanurate groups
In the range of 4/1 to 1/10 . In the urethane coating composition according to the present invention, particularly, since the polyisocyanate component has a high degree of compatibility with the fluorine-containing polyol,
In addition to forming a coating film that is uniform and transparent and has excellent weather resistance, it has a wide selection of workability and physical properties such as viscosity, drying properties, curability, and flexibility of the cured coating film.

[0031]

EXAMPLES The present invention will be described below with reference to examples.
The present invention is not limited by these examples. In the following, unless otherwise specified,% is
% By weight.

Reference Example 1 (Production of Polyisocyanate Having Allophanate Group and Isocyanurate Group) A 500 ml four-necked flask equipped with a stirrer, a thermometer, a nitrogen gas inlet tube and a Dimroth condenser tube was charged under a nitrogen gas atmosphere. 490 g of 6,6-hexamethylene diisocyanate (hereinafter abbreviated as HDI)
And 10 g of methanol, heated to 80 ° C. and maintained for 2 hours, and then 0.03 g of trimethyl-N-2-hydroxypropylammonium 2-ethylhexanoate was added as a catalyst.

While adjusting the reaction temperature to 80 ± 5 ° C.,
After the reaction was continued for an hour, 0.05 g of benzoyl chloride was added to deactivate the catalyst, and the reaction was stopped. The obtained reaction solution was treated with a thin-film distillation apparatus (vacuum degree: 0.5 mmHg, temperature: 140 ° C.) to remove unreacted HDI to obtain 135 g (27% conversion) of pale yellow transparent polyisocyanate. Was.
This polyisocyanate has a color number APHA of 20 to 30,
The viscosity at 25 ° C. (BL type viscometer) was 250 centipoise, the isocyanate group content was 21.6%, and the free HDI content was 0.2%. As a result of NMR measurement, there were almost no urethane groups and allophanate groups / isocyanate. The molar ratio of the nurate groups was about 5/4. Hereinafter, this polyisocyanate is referred to as PI-1.

REFERENCE EXAMPLE 2 (Production of polyisocyanate having allophanate group and isocyanurate group) A pale yellow, transparent yellow transparent compound was prepared in the same manner as in Reference Example 1, except that 479 g of HDI and 21 g of isobutanol were used in place of methanol. 150 g of product (30% conversion) were obtained.

The polyisocyanate composition has a color number A
PHA30, viscosity at 25 ° C. 260 centipoise,
Isocyanate group content 20.1%, free HDI content 0.
As a result of NMR measurement, there was almost no urethane group, and the molar ratio of allophanate group / isocyanurate group was about 1/1. Hereinafter, this polyisocyanate is referred to as PI-2.

Reference Example 3 (Production of polyisocyanate having allophanate group and isocyanurate group) A pale yellow, transparent yellowish transparent compound was prepared in the same manner as in Reference Example 1 except that 470 g of HDI and 30 g of benzyl alcohol were used instead of methanol. 170 g (34% conversion) of polyisocyanate were obtained.

This polyisocyanate has a color number of APHA.
The viscosity at 20, 25 ° C. was 440 centipoise, the isocyanate group content was 18.9%, and the free HDI content was 0.1%. As a result of NMR measurement, there was almost no urethane group, and the molar ratio of allophanate group / isocyanurate group was found. Was about 1/1. Hereinafter, this polyisocyanate is referred to as PI
-3.

Reference Example 4 (Production of Polyisocyanate Having Allophanate Group and Isocyanurate Group) A 500 ml four-necked flask equipped with a stirrer, a thermometer, a nitrogen gas inlet tube and a Dimroth condenser was placed under a nitrogen gas atmosphere. , 3-Diisocyanatomethylcyclohexane (hereinafter abbreviated as HXDI) 4
92 g and 8 g of methanol were charged and heated to 80 ° C.
After holding for 2 hours, trimethyl-N-2-
0.05 g of hydroxypropyl ammonium 2-ethylhexanoate was added.

While adjusting the reaction temperature to 85 ± 5 ° C.,
After the reaction was continued for an hour, 0.05 g of benzoyl chloride was added to deactivate the catalyst, and the reaction was stopped. The obtained reaction solution was treated with a thin-film distillation apparatus (vacuum degree: 0.5 mmHg, temperature: 150 ° C.) to remove unreacted HXDI, and 140 g of a viscous, pale yellow, transparent product (conversion rate: 28%) ) Got.

The molar ratio of allophanate groups / isocyanurate groups in this product was about 4/3. This product was diluted with ethyl acetate to a solid content of 75% to prepare a solution. The solution had a color number APHA of 30, a viscosity at 25 ° C. of 30 centipoise, and an isocyanate group content of 14.5.
%, Free HXDI content 0.3%. Hereinafter, this polyisocyanate is referred to as PI-4.

Reference Example 5 (Production of Polyisocyanate Having Allophanate Group and Isocyanurate Group) Isophorone was placed in a 500 ml capacity four-necked flask equipped with a stirrer, thermometer, nitrogen gas inlet tube and Dimroth condenser tube under a nitrogen gas atmosphere. 483 g of diisocyanate (hereinafter abbreviated as IPDI) and 17 g of isobutanol were charged, heated to 85 ° C. and maintained for 3 hours, and then trimethyl-N-2-hydroxypropylammonium 2-ethylhexanoate 0 was used as a catalyst. .
1 g was added.

While adjusting the reaction temperature to 90 ± 5 ° C., 3
After continuing the reaction for 0.1 hour, 0.1 g of benzoyl chloride was added,
The catalyst was deactivated and the reaction was stopped. The resulting reaction solution was treated with a thin film distillation apparatus (vacuum degree: 0.5 mmHg, temperature: 170 ° C.) to remove unreacted IPDI, and 140 g of a pale yellow transparent product having no fluidity at room temperature (conversion) 28%).

The mole ratio of allophanate groups / isocyanurate groups in this product was about 3/2. A solution prepared by diluting this product to a solid content of 75% with ethyl acetate has a color number APHA of 80, a viscosity of 100 centipoise at 25 ° C., an isocyanate group content of 11.6%, and a free I
The PDI content was 0.4%. Hereinafter, this polyisocyanate is referred to as PI-5.

[0044]

[0045]

Comparative Reference Example 1 (Production of Polyisocyanate Having Isocyanurate Group) 500 g of HDI was placed in a 500 ml four-necked flask equipped with a stirrer, a thermometer, a nitrogen gas inlet tube and a Dimroth condenser tube under a nitrogen gas atmosphere. And trimethylbenzylammonium hydroxide 0.1 as a catalyst
g was added. After adjusting the reaction temperature to 70 ± 5 ° C. and reacting for 3 hours, 0.1 g of benzoyl chloride was added to deactivate the catalyst, and the reaction was stopped. The obtained reaction solution was treated with a thin film distillation apparatus (vacuum degree: 0.5 mmHg, temperature: 140 ° C.) to remove unreacted HDI, and to obtain 105 g of pale yellow transparent isocyanurated polyisocyanate (conversion rate: 21%). ) Got.

This polyisocyanate has a color number of APHA.
60, viscosity 1350 centipoise at 25 ° C, isocyanate group content 23.3%, free HDI content 0.2%
It was. Hereinafter, this polyisocyanate is referred to as PI-R1
That.

COMPARATIVE REFERENCE EXAMPLE 2 (Production of adduct-type polyisocyanate) 50 equipped with a stirrer, a thermometer, a nitrogen gas inlet tube and a Dimroth condenser tube.
HDI in a four-neck flask with a capacity of 0 ml
Was added, and the temperature was raised to 70 ° C., then, 48 g of trimethylolpropane (TMP) was added dropwise over 1 hour, and further reacted at 80 ° C. for 2 hours.

The obtained reaction solution was purified using a thin-film distillation apparatus in the same manner as in Example 1. 210 g of a pale yellow transparent adduct-type polyisocyanate having no fluidity at room temperature
(Conversion 42%). A solution prepared by diluting this polyisocyanate to 75% solids with ethyl acetate is:
The viscosity at 25 ° C was 260 centipoise, the isocyanate group content was 12.5%, and the free HDI content was 0.3%. Hereinafter, this polyisocyanate is referred to as PI-R2.

Comparative Reference Example 3 (Production of Biuret-Type Polyisocyanate) A sample equipped with a stirrer, a thermometer, a nitrogen gas introducing tube and a Dimroth cooling tube was prepared.
HD in a four-necked flask with a capacity of 00 ml under a nitrogen gas atmosphere.
382 g of I and 4 g of water were reacted at 150 ° C. for 2 hours using 114 g of methyl cellosolve acetate as a solvent.

The obtained reaction solution was purified in the same manner as in Example 1 using a thin film distillation apparatus. This biuret type polyisocyanate has a viscosity of 1300 centipoise at 25 ° C., an isocyanate group content of 23.5%, and free HDI.
The content was 0.2%. Hereinafter, this polyisocyanate is referred to as PI-R3.

Reference Example 6 (Production of Fluorine-Containing Polyol) In a 1-liter autoclave with a stainless steel stirrer, 400 ml of ethyl acetate as a reaction solvent, 0.8 g of vinyl pivalate (hereinafter referred to as VPI) and 4-hydroxybutyl were used. Vinyl ether (hereinafter referred to as HBVE)
After charging 7 g, degassing and purging with nitrogen, 17.5 g of tetrafluoroethylene (hereinafter referred to as TFE) and 133.0 g of vinylidene fluoride (hereinafter referred to as VDF) were charged and heated to 40 ° C.

0.6 g of diisopropyl peroxycarbonate (hereinafter referred to as IPP) was charged and polymerization was started. With the pressure drop, 50.2 g of a VDF / TFE mixture (90/10 molar ratio) and an HBVE / VPI mixture ( (Molar ratio 1/1) 24.5 g was charged, and polymerization was carried out while appropriately adding 2.5 g of IPP. After 18 hours from the start of the polymerization, the mixture was cooled, the reaction was stopped, and the unreacted monomers were expelled. Then, the polymerization liquid was precipitated in hexane. This was washed and dried to obtain 100.3 g of a fluorine-containing polyol as a copolymer.

[0054] The GPC method of fluorine-containing polyol (polystyrene standard) by weight-average molecular weight is 12000 der connexion, ¹⁹ from the measurement of the F-NMR and ¹ H-NMR, the composition of the fluorine-containing polyol, VDF / TFE / VPI / H
The BVE molar ratio was 75/11/7/7. This fluorine-containing polyol is dissolved in ethyl acetate, and the solid content is 50%.
Of a two-component paint having a hydroxyl value of 26.

Example 1 The polyisocyanate obtained in Reference Example 1 and the fluorine-containing polyol of Reference Example 7 were blended at an isocyanate group / hydroxyl equivalent ratio of 1, applied to a dry film thickness of 100 μm, and dried by touch. Observation of the transparency of the coating film after and after curing and drying revealed that the coating film was uniform and transparent without fogging in each case.

Examples 2 to 5 In the same manner as in Example 1, each of the polyisocyanates obtained in Reference Examples 2 to 5 was mixed with the fluorine-containing polyol obtained in Reference Example 6, and the mixture was dried to the touch. And the transparency of the coating film after curing and drying were observed. Table 1 shows the results.

Comparative Examples 1 to 3 In the same manner as in Example 1, the polyisocyanates obtained in Comparative Reference Examples 1 to 3 were each mixed with the fluorine-containing polyol obtained in Reference Example 6, and dried by touch. The transparency of the coating film after and after curing and drying was observed. Table 1 shows the results.

[0058]

[Table 1]

Examples 6 to 10 For Examples 1 to 5 in which a transparent coating film was obtained, the curability and physical properties of the coating film were examined. Table 2 shows the results. Here, the curability and coating film performance were determined by spraying a coating on a zinc phosphate-treated steel sheet to an average film thickness of 40 ± 5 μm, at a temperature of 25 ° C.
The temperature was measured after drying for 7 days at 60 ° C. and a relative humidity of 60%.

[0060]

[Table 2]

From the results shown in Table 2, it is clear that the coating film of the coating composition of the present invention has sufficient strength and curability, and that a wide range of properties can be imparted by changing the composition of the polyisocyanate used. It is understood that can be.

Claims (2)

(57) [Claims] 1. A two-pack type fluorine-containing coating composition comprising a fluorine-containing polyol having two or more hydroxyl groups in one molecule and a polyisocyanate, wherein the polyisocyanate is a fatty acid.
Aliphatic alcohols, alicyclic alcohols and araliphatic alcohols
Allophanate groups obtained by the reaction of a monoalcohol having 1 to 10 carbon atoms selected from coal with an aliphatic organic polyisocyanate compound are combined with isocyanurate groups in a molar ratio of allophanate groups / isocyanurate groups of 4 /
A two-part type fluorine-containing coating composition comprising a polyisocyanate having a ratio of 1 to 1/10 . 2. A polyisocyanate having an isocyanurate group together with an allophanate group obtained by reacting a monoalcohol having 1 to 10 carbon atoms with hexamethylene diisocyanate, wherein the polyisocyanate has a free organic polyisocyanate compound and a solvent. 2. The two-part fluorine-containing coating composition according to claim 1, which is a polyisocyanate having a viscosity of not more than 500 centipoise at 25.degree.