JP3065282B2 - Composition for paint - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a coating composition.

[0002]

2. Description of the Related Art It has been known that a homopolymer of vinylidene fluoride has excellent properties as a weather-resistant paint. However, since the coating has to be performed by high-temperature baking, it cannot be applied locally, and is limited to use as a factory-coated product such as a precoat.

[0003] In recent years, fluoroolefin / vinyl ether copolymers for room temperature curing coatings have been used for the purpose of overcoming the above restrictions. However, this is a two-pack type, and it is necessary to mix a main agent (varnish) and a curing agent (isocyanate) in a prescribed ratio at the time of application on site. If these mixing ratios are out of the specified range, strict mixing must be performed in order to obtain the required performance.However, such a strict operation is required at the coating site. There is a problem in practical use.

[0004] Attempts have been made to develop a paint that can be applied at room temperature by increasing the solubility in an organic solvent by using vinylidene fluoride as a copolymer with another fluoroolefin. For example, a copolymer of vinylidene fluoride and tetrafluoroethylene (for example, trademark “VT-100”, manufactured by Daikin Industries, Ltd., trademark “Kainer SL”, manufactured by Penwald), vinylidene fluoride and tetrafluoride Copolymers of ethylene and propylene hexafluoride (trade name “Kyner ADS”, manufactured by Penwald) have been developed.

[0005] However, in the former case, the type of the organic solvent which is still soluble is small and the solution viscosity is large, so that coating is difficult. In the case of the latter, the coating film obtained is close to the fluororubber composition, so that the coating is soft and easily scratched, and the usable temperature is lower than that of the conventional homopolymer of vinylidene fluoride because the melting point of the copolymer is low. There are problems such as.

[0006]

The present invention alleviates the above-mentioned problems by improving the solubility of a fluorine-based copolymer in an organic solvent, makes the coating less likely to be scratched, and improves weather resistance and coating properties. An object of the present invention is to provide an excellent coating composition.

According to the study of the present inventors, the structural unit a)-
_{CH 2 -CF 2 -, b)} -CF 2 -CF 2 -, c) -CF 2
-CFCl- and d) trifluoroethylene (T
rFE), vinyl fluoride (VF), propylene hexafluoride (HFP) and perfluoro (alkyl vinyl ether) (PAVE). It has high solubility in organic solvents and dissolves in various kinds of organic solvents, and has been found to be suitable for a coating material. Further, it has been found that the fluorine-based copolymer has excellent compatibility with the acrylic resin.

That is, the present invention provides: a) a structural unit represented by the formula —CH ₂ —CF ₂ —
0 mol%, b) formula -CF ₂ -CF ₂ - structure units 5-30 represented by
Mol%, c) structural units 5 represented by formula -CF ₂ -CFCl-
30 mol% and d) trifluoroethylene, vinyl fluoride, propylene hexafluoride and perfluoro (alkyl vinyl ether)
A structural unit composed of a fluoroolefin selected from
The present invention relates to a coating composition obtained by dissolving 1 to 10 mol% of a fluorine-based copolymer in an organic solvent.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In a fluorine-based copolymer having the structural units a) to d), the proportion of the structural units a) to d) in the copolymer is as follows: a) 50 to 9
0 mol%, b) 5-30 mol%, c) 5-30 mol% and d) 0.1-10 mol%, more preferably a) 70-
It is preferably 85 mol%, b) 10 to 20 mol%, c) 5 to 15 mol% and d) 0.1 to 10 mol%.

D) trifluoroethylene in the copolymer,
If the proportion of the structural unit composed of a fluoroolefin selected from vinyl fluoride, propylene hexafluoride and perfluoro (alkyl vinyl ether) exceeds 10 mol%, the solubility of the copolymer in an organic solvent may decrease, or The surface of the coating film to be softened is easily scratched.

[0011] These fluorine-based copolymers are usually prepared by emulsification, suspension or solution polymerization methods, by vinylidene fluoride, ethylene tetrafluoride, ethylene trifluoride chloride, or vinylidene fluoride, tetrafluoroethylene, trifluoride chloride. It is prepared by copolymerizing ethylene and fluoroolefin. The polymerization temperature is usually about 0 to 150 ° C, preferably about 5 to 95 ° C in any of the polymerization methods. The polymerization pressure is usually about 1 to 50 kg / cm ² G in any polymerization method. The polymerization medium is water in the emulsion polymerization method, for example, water in the suspension polymerization method,
Chlorofluorohydrocarbons such as 1,1,2-trichloro-1,2,2-trifluoroethane, 1,2-dichloro-1,1,2,2-tetrafluoroethane or a mixture thereof; In the legal case, it is ethyl acetate, butyl acetate or a mixture thereof. The emulsifier in the emulsion polymerization method,
For example, C ₇ F ₁₅ COONH ₄ , H (CF ₂ ) ₈ COON
H ₄ , H (CF ₂ ) ₆ COONH ₄ and C ₇ F ₁₅ COONa. In the emulsion polymerization, the polymerization initiator includes a redox initiator comprising an oxidizing agent (eg, ammonium persulfate, potassium persulfate, etc.), a reducing agent (eg, sodium sulfite, etc.) and a transition metal salt (eg, iron sulfate, etc.), suspension and solution weight. In the legal method, it is an azo compound or an organic peroxide (for example, azobisisobutyronitrile, isobutyryl peroxide, octanoyl peroxide, di-iso-propylperoxydicarbonate, etc.).

The molecular weight of the thus-prepared fluorocopolymer is preferably about 0.15 to 0.80 as an intrinsic viscosity [η] at 35 ° C. in dimethylformamide (DMF). By doing so, the film strength and solubility become excellent.

The organic solvent in the present invention is not particularly limited, but it has a boiling point of 60 to 250 ° C. in terms of solubility.
About ketones or esters are preferable, for example, acetone, methyl ethyl ketone, methyl isobutyl ketone,
Examples thereof include cyclohexanone, ethyl acetate, n-butyl acetate, and methyl cellosolve, and one or more of these can be used. Besides these, tetrahydrofuran, dimethylformamide, dimethylacetamide and the like can also be used. If necessary, a small amount of aromatics such as toluene and xylene and alcohols may be added.

These solvents can dissolve the above-mentioned fluorine-containing polymer satisfactorily to obtain a coating composition in a wide concentration range from a low concentration to a high concentration, and the resulting coating film has excellent gloss and weather resistance. It will be.

The mixing ratio of the resin such as a fluorine-based copolymer and the organic solvent in the present invention is not particularly limited, and the solids concentration of the resin is usually about 5 to 50% by weight, preferably 3% by weight.
It is preferable that the content be about 0 to 50% by weight. The mixing method is not particularly limited, and any conventional method may be used. For example, the mixing may be sufficiently performed using a ball mill, a paint shaker, a sand mill, or the like. At the time of mixing, known additives used in paints such as pigments, viscosity modifiers, leveling agents, ultraviolet absorbers, anti-burr agents, dispersants, and defoamers can be added as needed.

The coating composition of the present invention is applied to a substrate and then dried at 10 to 200 ° C., preferably 20 to 50 ° C. for several hours to several days, and has excellent weather resistance and is hardly scratched. Form a strong coating. Applicable substrates include metals such as aluminum, iron, and stainless steel, inorganic materials such as glass, cement, concrete, and ceramics; resins such as polyester, polypropylene, acrylic, vinyl chloride, polycarbonate, and polyethylene; and other wood materials. ,
An example is paper. The composition may be applied directly to these, or one or more layers of a normal primer such as wash primer, rust preventive paint, epoxy resin paint, acrylic, polyester resin paint, etc. It can be easily applied in any case and has excellent coatability.

[0017]

【Example】

Preparation Example 1 (Preparation of fluorinated copolymer) 700 g of water and 1,2-dichloro-1,1,2,2-tetrafluoroethane 1180 were placed in a 3.5 L autoclave.
g and 5 g of ethyl acetate as a transfer agent, and the space in the autoclave was replaced with nitrogen.
dF) 75.2 g, tetrafluoroethylene (TFE)
6 g, chlorotrifluoroethylene (CTFE) 1.5
g. After heating the autoclave to 40 ° C. and stirring sufficiently, diisopropyl peroxydicarbonate was used.
5 g was added to initiate polymerization. Polymerization pressure is 8.0 kg / cm
VdF / TFE / CTFE = 80/1 so as to be ² G
Polymerization was carried out for 12 hours while supplying a mixture of 5/5 (mol%). Thereafter, the produced copolymer was fractionated, and the temperature was 80 ° C.
And dried under reduced pressure to obtain 200 g of a copolymer. This copolymer was analyzed by NMR to find that VdF / TFE / CTF
E = 81/14/5, melting point (Tm) 125 ° C.,
[Η] = 0.79 (DMF, 35 ° C.).

Preparation Examples 2 to 11 Copolymers having the compositions shown in Table 1 were prepared in the same procedure as in Preparation Example 1.

[0019]

[Table 1]

Preparation Example 12 In a 3 L autoclave, 1500 g of water and "Unidyne DS-101" as an emulsifier (manufactured by Daikin Industries, Ltd.)
After adding 3 g and degassing and replacing with nitrogen, VdF / TFE / CTF
A mixed monomer of E = 73/14/13 (mol%) was charged and pressurized at 39 ° C. to 20 kg / cm ² G. 2. Add diisopropyl peroxydicarbonate with stirring.
5 g was added to initiate polymerization. Polymerization pressure is 20 kg / cm ² G
The polymerization was carried out for 8 hours while continuously supplying the mixed monomer such that The obtained dispersion was freeze-coagulated, washed with water to remove the emulsifier, and dried at 80 ° C. under reduced pressure to obtain 270 g of a copolymer. As a result of elemental analysis, this copolymer was found to have VdF / TFE / CTFE = 74/14/12, a melting point (Tm) of 108 ° C., and [η] = 0.690 (D
MF, 35 ° C).

[Solubility Test] The copolymers obtained in Preparation Examples 1 to 11 were dissolved in the following organic solvents by heating at 60 ° C. for 3 hours so that the copolymer content became 50% by weight. After standing at room temperature for a week, the state of the solution was observed. The evaluation was as follows: ○: Dissolved and left for one week, and the solution was fluid. Δ: Dissolved but 1
After standing for a week, the solution became a gel without fluidity. X: Not dissolved. Table 2 shows the results.

[0022]

[Table 2]

[Compatibility test with acrylic resin] 1 part by weight of a MIBK solution of 20% by weight of the following acrylic resin and 20% by weight of MEK of the copolymer obtained in Preparation Examples 1, 2, 5 to 11
Mix the solution, polyethylene terephthalate (PET)
The film was cast on a sheet and visually observed whether the coating film was whitened (cloudy). The evaluation was as follows: ：: A clear coating film was obtained, Δ: A slightly turbid coating film was obtained, and X: A significantly turbid coating film was obtained. Table 3 shows the results.

Acrylic resin No. Composition (molar ratio) Tg ° C. [η] 1 PMMA 105 0.240 2 MMA / EMA (93/7) 100 0.264 3 MMA / EA (67/33) 60 0.288 4 MMA / BMA (50/50) 50 0.187 5 EMA / MA (43/57) 40 0.294 6 PIBMA 50 0.163

[0025]

[Table 3]

Comparative Preparation Examples 1-2 Copolymers having the compositions shown in Table 4 were prepared in the same procedure as in Preparation Example 1.

[0027]

[Table 4]

Examples 1 to 3 20% M of the fluorinated copolymer obtained in Preparation Examples 4, 9 and 10
An IBK solution was obtained, and an aluminum plate (BT71 manufactured by Nippon Test Panel Co., Ltd.) coated with an undercoat (“Hypon 20 Ace” manufactured by Nippon Paint Co., Ltd., coating film 45 μm)
2 treatment), and dried at 25 ° C. for 1 day to obtain a coating film having a thickness of 25 μm. These were subjected to the following performance tests as samples (test plates). Table 5 shows the results.

Comparative Example 1 A 20% MIBK solution of the copolymer obtained in Comparative Preparation Example 1 was prepared, but did not dissolve.

A coating film was obtained in the same manner as in Examples 1 to 3 using a 20% acetone solution of this copolymer, but the coating film was whitened.

Comparative Example 2 A coating film was obtained from the copolymer obtained in Comparative Preparation Example 2 in the same manner as in Examples 1 to 3. This was used as a sample (test plate) for the following performance test. Table 5 shows the results.

[Performance test] Pencil hardness : Performed according to the method described in JIS K5400.

Adhesion : 1 mm square with a knife on the coating 1
00 pieces were cut and adhered and peeled ten times with a cellophane adhesive tape, and the number of remaining squares was determined.

Gloss : 6 described in JIS K 5400
The 0 degree specular gloss was measured.

Gloss retention rate : Rain cycle 1 using a sunshine weatherometer (manufactured by Suga Test Instruments Co., Ltd.)
8 minutes / 120 minutes, humidity 60% and black panel temperature 6
Exposure was performed for 4000 hours at 3 ° C., and the gloss retention was determined from the gloss before and after exposure.

Antifouling property : A test plate was stuck on a wall beside a road where a large amount of automobile traffic was passed, and left for three months. Thereafter, the test plate was removed, and after washing with water, the degree of contamination was visually observed. Evaluation is ○:
Stain is not noticeable, Δ: Slightly noticeable, X: Considerably dirty.

[0037]

[Table 5]

[0038]

EFFECTS OF THE INVENTION The coating composition of the present invention reduces the problems of the prior art by improving the solubility of the fluorine-based copolymer in an organic solvent. Excellent workability.

Continuation of the front page (56) References JP-A-61-159410 (JP, A) JP-A-2-123152 (JP, A) JP-A-4-173855 (JP, A) (58) Fields investigated (Int) .Cl. ⁷ , DB name) C09D 127/16 C08F 214/22 CA (STN) CAOLD (STN) REGISTRY (STN)

Claims (1)

(57) [Claims] 1. A a) formula -CH ₂ -CF ₂ - structural units from 50 to 90 mol% represented by, b) formula -CF ₂ -CF ₂ - structural unit represented by 5-30
Mol%, c) structural units 5 represented by formula -CF ₂ -CFCl-
30 mol% and d) trifluoroethylene, vinyl fluoride, propylene hexafluoride and perfluoro (alkyl vinyl ether)
A structural unit composed of a fluoroolefin selected from
A coating composition obtained by dissolving 1 to 10 mol% of a fluorine-based copolymer in an organic solvent.