JP2002003775A - Coating composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating composition excellent in preservation stability, capable of forming a coating film excellent in endurance and soil resistance, and containing a fluoroethylene vinylether copolymer as a coating film-forming component. SOLUTION: This coating composition is characterized by containing an organic coating film-forming component containing the fluoroethylene vinylether copolymer, a blocked isocyanate as a curing agent and a silicate compound expressed by general formula (1) [wherein, (m) is 3-19 integer; at least one of R's is a 2-5C fluoroalkyl containing >=1 fluorine, the rest of the R's are each a 1-6C lower alkyl; the molar ratio of the fluorinated alkyl to the lower alkyl (the fluorinated alkyl/the lower alkyl) is 0.1-0.4; and the fluorine- substitution ratio in the fluoroalkyl is 50-80%].

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating composition containing a fluoroethylene vinyl ether copolymer as at least a part of a film-forming component and having excellent storage stability, durability and stain resistance. Particularly, the present invention relates to a coating composition suitable as a coating composition for a top coating.

[0002]

2. Description of the Related Art Fluorocarbon resin-based paints having superhydrophobic properties have been known as paints having excellent durability and stain resistance in applications such as construction, civil engineering, and automobile use. Such fluorocarbon resin-based paints have been conventionally used as paints that provide a tough finish and a finish that does not crack or chalk under changing weather conditions and that provide excellent durability. Such fluorocarbon resins are also recommended for building panels and the like, and have been used conventionally. Also,
Regarding the stain resistance, it has been considered that such superhydrophobic fluorocarbon resin-based paints are unlikely to be stained because water hardly adheres to the surface thereof.

However, when a coating film formed of such a superhydrophobic fluorocarbon resin-based coating material is actually exposed outdoors, there is a problem that dirt in the air easily adheres and rain streak dirt easily adheres and deposits. Was.

[0004] As a method of forming a stain-resistant coating film capable of solving such a problem, International Publication WO94 / 06 is available.
In the '870 publication, an organosilicate such as methyl silicate or ethyl silicate is compounded in a top coat,
There has been proposed a method for forming a coating film in which the surface of the coating film is subjected to an acid treatment after application of the overcoating material so that the contact angle with water is 70 ° or less. According to this method, the stain resistance is improved by making the coating film surface hydrophilic.

[0005] International Publication WO96 / 26254 proposes a topcoat composition containing an organosilicate compound having a fluoroalkyl group.

[0006]

The above-mentioned organosilicate transfers to the surface of the coating film when forming the coating film, and imparts stain resistance by forming a thin hydrophilic coating on the coating film surface. Is believed to be something. Therefore, it is considered that the hydrophilicity of the coating film surface by such an organosilicate is affected by the affinity and compatibility between the coating film forming component and the organosilicate.

However, in a fluorocarbon resin-based coating, particularly a coating containing a fluoroethylene vinyl ether copolymer (FEVE) having a high fluorine content as an organic coating film-forming component, any organosilicate compound is required to have a hydrophilic property on the coating film surface. It has not been specifically examined whether it is effective for the conversion. Furthermore, what kind of organosilicate compound having a fluoroalkyl group can specifically provide excellent effects on the storage stability of the coating material and the durability and stain resistance of the coating film has been studied. Not.

An object of the present invention is to provide a coating composition containing a fluoroethylene vinyl ether copolymer as a coating film-forming component, which can form a coating film having excellent storage stability and excellent durability and stain resistance. To provide things.

[0009]

Means for Solving the Problems The inventors of the present invention have formed a coating film which can form a coating film having excellent durability and stain resistance and which has excellent storage stability. As a result of diligent studies on organosilicate compounds to be added to paints containing a fluoroethylene vinyl ether copolymer as a component, they have found that particular silicate compounds are particularly effective, and have completed the present invention.

That is, the coating composition of the present invention is represented by the following general formula (1): an organic coating film-forming component containing a fluoroethylene vinyl ether copolymer, a blocked isocyanate or a free isocyanate as a curing agent. And a silicate compound.

[0011]

Embedded image

(Wherein, m is an integer of 3 to 19, and at least one of Rs has 2 or more carbon atoms containing at least one fluorine.)
5 to 5 fluorinated alkyl groups, and the remaining R has 1 to 1 carbon atoms.
6, wherein the molar ratio of the fluorinated alkyl group to the lower alkyl group (fluorinated alkyl group / lower alkyl group) is 0.1 to 0.4, and the fluorine substitution ratio in the fluorinated alkyl group is 50-80%. Hereinafter, the components of the present invention will be described in more detail.

The silicate compound used in the present invention is a silicate compound represented by the above general formula (1). M in the general formula (1) is an integer of 3 to 19. Therefore 3
It has a structure of a dimer to a 19-mer. More preferably, m is an integer of 9 to 15, and has a structure of 9 to 15 mer.

At least one of Rs in the general formula (1) is a C2-5 fluorinated alkyl group containing at least one fluorine. The fluorine substitution ratio in the fluorinated alkyl group is 50 to 80%. The fluorine substitution ratio is a ratio of hydrogen substituted with fluorine among all hydrogens which can be substituted with fluorine. For example, a propyl pentafluoride group is hydrogen 7 which can be substituted for fluorine in the propyl group.
Five of them are substituted with fluorine. Therefore, the fluorine substitution ratio is 5/7 = 71.4%. In the case of a butyl hexafluoride group, since six of the nine hydrogens that can be substituted for fluorine in the butyl group are substituted with fluorine, the fluorine substitution ratio is 6/9 = 66.7%. As the fluorinated alkyl group in the present invention, such a propyl pentafluoride group and a butyl hexafluoride group are preferable. By setting the fluorine substitution ratio in the fluorinated alkyl group within the above range, both storage stability and stain resistance can be achieved.

The remaining R in the general formula (1) is a lower alkyl group having 1 to 6 carbon atoms, preferably a methyl group or an ethyl group. R in the silicate compound used in the present invention is an alkyl fluoride group or a lower alkyl group, and the molar ratio of the alkyl fluoride group / the lower alkyl group is in the range of 0.1 to 0.4. The molar ratio is 0.
When it is smaller than 1, the stain resistance of the coating film decreases. If the molar ratio exceeds 0.4, the storage stability of the coating composition will decrease.

The silicate compound used in the present invention can be produced by reacting a silicate such as methyl silicate or ethyl silicate with a corresponding alcohol, ie, a fluorinated alkyl alcohol compound, and subjecting it to an alcohol exchange reaction. As a reaction substrate for such an alcohol exchange reaction, methyl silicate and / or a condensate thereof, and ethyl silicate and / or a condensate thereof can be used. It is preferable to use a condensate according to the degree of condensation of the target silicate compound.

These methyl silicates and ethyl silicates are, for example, trade names "MS-51" and "MS
-56 "(manufactured by Mitsubishi Chemical Corporation) and trade names such as" ethyl silicate 40 "," ethyl silicate 48 ", and" ethyl silicate 28 "(manufactured by Colcoat).

As described above, the silicate compound used in the present invention can be produced by reacting a corresponding alcohol compound with methyl silicates and ethyl silicates to carry out an alcohol exchange reaction. It is not limited to such a manufacturing method, and may be obtained by another manufacturing method.

Organic Film Forming Component The organic film forming component contained in the coating composition of the present invention includes a fluoroethylene vinyl ether copolymer. The fluoroethylene vinyl ether copolymer is represented by -C
A fluoroethylene structural unit represented by F ₂ —CFX— (wherein X is a fluorine atom, a chlorine atom, a hydrogen atom or a trifluoromethyl group) and a structural unit based on a vinyl ether or vinyl ester monomer It is a copolymer containing. Examples of such a fluoroethylene vinyl ether copolymer include a copolymer disclosed in JP-A-4-279612.

Examples of the curing agent the curing agent, can be used free of isocyanate and blocked isocyanate. The free isocyanate can be used in a room temperature-curable two-component mixture type coating composition. The blocked isocyanate can be used in a heat-curable coating composition. Examples of the isocyanate blocking agent include phenols such as phenol, m-cresol, xylenol and thiophenol, alcohols such as methanol, ethanol, butanol, 2-ethylhexanol, cyclohexanol and ethylene glycol monomethyl ether, caprolactam and ethyl acetoacetate. And active hydrogen-containing compounds such as diethyl malonate.

Examples of the polyisocyanate include hexamethylene diisocyanate (HMDI), trimethylhexamethylene diisocyanate, isophorone diisocyanate (IPDI), hydrogenated diphenylmethane diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate (XDI), and hydrogenated xylylene diisocyanate (hydrogenated XDI), tolylene diisocyanate (TDI), hydrogenated tolylene diisocyanate (hydrogenated TDI), lysine diisocyanate and the like.

Blending Ratio In the coating composition of the present invention, the blending ratio of the silicate compound represented by the general formula (1) is preferably 5 to 30 parts by weight based on 100 parts by weight of the resin solids in the coating composition. ,
More preferably, it is 10 to 20 parts by weight. If the compounding ratio of the silicate compound is too small, the stain resistance of the coating film becomes insufficient, and if the compounding ratio of the silicate compound is too large, on the contrary, the gloss of the coating film decreases, the coating film becomes sticky, and the alkali resistance decreases. Such a problem may occur.

Further, in the coating composition of the present invention, the mixing ratio of the curing agent is such that the NCO equivalent in the isocyanate is (based on 1 equivalent of OH group) with respect to the number of equivalents of OH group in the fluoroethylene vinyl ether copolymer. T) 0.5-1.5
It is preferable to mix them so as to be more preferably 0.8 to 1.2.

Pigments and Solvents To the coating composition of the present invention, general organic pigments and inorganic pigments used for coatings can be added.

In the coating composition of the present invention, a general solvent used in a coating system containing a fluoroethylene vinyl ether copolymer as an organic film-forming component can be used.

Coating method The coating composition of the present invention may be used according to the type of the curing agent used.
After the application, the coating can be performed by curing at room temperature or baking at a predetermined temperature. The baking temperature varies depending on the type and amount of the organic film-forming component in the coating composition, the material of the substrate covering the coating film, and the like.
It is in the range of 0 to 180 ° C.

The coating composition of the present invention can be applied by a usual coating method such as spray coating. The coating film thickness is not particularly limited, but is generally about 5
It is applied in a thickness of about 200 μm. The coating composition of the present invention is suitable as a top coating. Therefore, after coating a primer etc. on a base material, you may apply | coat the coating composition of this invention.

The substrate on which the coating composition of the present invention is applied includes:
Although not particularly limited, according to the coating composition of the present invention, since a coating film having excellent durability and stain resistance can be formed, such durability and stain resistance are required. The present invention can be applied to any substrate. Examples of such a base include an exterior panel and an interior panel used for an aluminum sash, a curtain wall, a building material, and the like. Examples of the material of the base include a metal plate such as an aluminum plate, a stainless steel plate, and a zinc copper plate.

The coating composition of the present invention has the general formula (1)
And a silicate compound represented by According to the present invention, it is possible to obtain a coating composition having good storage stability and imparting excellent durability and stain resistance to a coating film by containing such a silicate compound. The reason why excellent durability and stain resistance can be obtained by using such a silicate compound according to the present invention is not clear, but the silicate compound added to the coating composition may be used when forming a coating film. ,
By moving to the coating film surface and hydrolyzing moderately,
It is believed that silanol groups are formed, which render the coating surface moderately hydrophilic.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preparation of coating compositions (Examples 1 to 5 and Comparative Examples 1 and 2) Fluoroethylene vinyl ether copolymer (fluororesin, trade name "Zeffle GK500", manufactured by Daikin, hydroxyl value 60) 21 parts by weight were dissolved in 23 parts by weight of a mixed solvent of xylene / MIBK, and a pigment (titanium oxide, "CR9 manufactured by Ishihara Sangyo Co., Ltd.") was added thereto.
7)) Add 19 parts by weight, and disperse with an SG mill (sand grind) for 20 minutes.
16 parts by weight of a curing agent (block isocyanate, trade name "Desmodur BL4265", NCO content 12%, manufactured by Sumitomo Bayer Urethane Co., Ltd.) were added. Each coating composition was prepared by adding 4 parts by weight of a fluorinated silicate having a molar ratio (about 10 mer: m ≒ 10).

Measurement of Paint Viscosity Examples 1 to 5 and Comparative Examples 1 to 5 obtained as described above
The viscosity of the coating composition No. 2 was measured to evaluate the storage stability. The viscosity immediately after preparation and the viscosity after standing at 40 ° C. for 19 hours were measured.

Preparation of coating film for evaluation Examples 1 to 5 and Comparative Examples 1 to 5 obtained as described above
A test piece for evaluating a coating film was prepared using the coating composition of No. 2. The test piece was manufactured by aluminum plate A1100 (0.8 mm × 100 mm × 3
00 mm) by air spraying on this aluminum plate to a thickness of 25 to 35 microns.
After setting for 0 minute, it was baked and dried at 170 ° C. for 20 minutes to prepare a coating film for evaluation.

The coating films for evaluation obtained as described above were evaluated for stain resistance by the following evaluation method. 1) Measurement of Contact Angle of Coating Film to Water The contact angle was measured for the coating film for evaluation immediately after forming the coating film (initial stage) and after leaving the coating film indoors for one week (after 7 days). Using an automatic contact angle meter (manufactured by Kyowa Interface Science Co., Ltd., CA-Z), the value of the water droplet contact angle was measured by repeating the value 30 times after the water droplet was dropped five times five times, and the upper and lower numerical values were deleted. The average was determined. The smaller the value, the greater the hydrophilicity and the better the stain resistance.

2) Raindrop Contamination Test A coating film for evaluation was installed vertically, and a 30
rain from the roof of the corrugated sheet of 3 cm (three grooves with a depth of 3 mm cut at a pitch of 3 mm) to the painted surface,
After one year in Neyagawa City, Osaka Prefecture, the state of contamination was observed and visually judged according to the following criteria. ◎: Rain streaks are not formed ○: Rain streaks are slightly formed △: Rain streaks are considerably formed ×: Rain streaks are markedly formed

3) Durability Test The durability of the evaluation coating films of Examples 2 and 5 and Comparative Example 1 was evaluated. Each coating film for evaluation was placed in a carbon arc sunshine weatherometer (manufactured by Suga Test Instruments Co., Ltd.), and the gloss retention of 60 ° gloss after 6000 hours was measured. The gloss retention at the initial 60 ° gloss was 80%.

Table 1 shows the evaluation results obtained as described above.
Shown in

[0037]

[Table 1]

As is clear from the results shown in Table 1, the coating compositions of Examples 1 to 5 according to the present invention have a significantly low contact angle after 7 days, a large hydrophilicity on the surface of the coating film, and a high durability. It turns out that it is excellent in contamination property. In addition, it shows excellent resistance to raindrop contamination. Further, it can be seen that the coating compositions of Examples 1 to 5 according to the present invention show a small increase in viscosity after 19 hours at 40 ° C. and good storage stability as compared with the coating composition of Comparative Example 1.

In addition, it has good durability as well as the conventional coating film.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4J038 CD121 CD131 CD151 CE051 DG262 DL022 KA06 KA08 MA09 NA01 NA05 PA18 PB05 PC02 PC04

Claims (4)

[Claims] An organic coating film-forming component containing a fluoroethylene vinyl ether copolymer, a blocked isocyanate or a free isocyanate as a curing agent, and a silicate compound represented by the following general formula (1): A coating composition characterized by the following. Embedded image (Wherein, m is an integer of 3 to 19, at least one of R is a C2 to C5 fluorinated alkyl group containing at least one fluorine, and the remaining Rs are C1 to C6) Wherein the molar ratio of the fluorinated alkyl group to the lower alkyl group (fluorinated alkyl group / lower alkyl group) is 0.1 to
0.4, and the fluorine substitution ratio in the fluorinated alkyl group is 50 to 80%. ) 2. The coating composition according to claim 1, wherein the lower alkyl group is a methyl group or an ethyl group. 3. The coating composition according to claim 1, wherein the lower alkyl group is a methyl group, and the alkyl fluoride group is a propyl pentafluoride group and / or a butyl hexafluoride group. 4. The coating composition according to claim 1, wherein the silicate compound represented by the general formula (1) is contained in an amount of 5 to 30 parts by weight based on 100 parts by weight of the resin solid content in the coating composition. 2. The coating composition according to item 1.