JPH0841416A - Fluororesin coating composition - Google Patents

Abstract

PURPOSE:To obtain the composition as a film-forming component of coatings capable of providing coating film developing no deterioration/discoloration even under long-term outdoor exposure on buildings and outdoor structures and excellent in weathering resistance and contamination resistance with no rain traces developed. CONSTITUTION:This coating composition is obtained by incorporating (A) 100 pts.wt. of a fluorocopolymer 100-350mgKOH/g in hydroxyl value produced by copolymerization of a monomer mixture comprising 40-65mol% of chlorotrifluoroethylene, 14-50mol% of a copolymerizable vinyl compound, 16-28mol% of a hydroxyl-contg. polymerizable compound and 0.1-3mol% of a carboxyl-contg. polymerizable compound with (B) 0.05-15 pts.wt. of a water-soluble polyether-modified silicone oil having in the molecule at least dimethylsiloxane structural unit and ethylene oxide structural unit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluororesin coating composition having stain resistance.

[0002]

2. Description of the Related Art Conventionally, fluororesin paints utilizing the excellent weather resistance of fluorocopolymers have been industrialized. Particularly recently, solvent-soluble fluorine-based copolymers having a curing site have been synthesized (for example, JP-A-57-34107 and JP-A-61-57609), and are used for construction, automobiles, and chemistry. It is widely applied as a weather resistant paint in the industrial field. In addition, water-based and powder-type paints, which place importance on the environment and suppress the emission of organic solvents, have been put into practical use. The main components of these coating resins are fluorine-based raw materials such as chlorotrifluoroethylene, tetrafluoroethylene, or vinylidene fluoride, and the use of hydrocarbon-based monomers such as vinyl esters and vinyl ethers as copolymerization components makes them It has increased solubility.

However, these solvent-soluble fluororesin coatings have the drawback of being easily soiled although they are excellent in weather resistance. As a solution to this, an attempt to increase the surface hardness by increasing the glass transition point of the resin and an attempt to increase the soil release by creating a hydrophilic / water-repellent surface (monthly building finishing technology, VO
L19, No219, 74 (1993)) and so on. Fluorocarbon resin paints with increased surface hardness show stain resistance effects in carbon black adhesion tests and stain tests with magic ink, but in actual exposure tests they are still susceptible to stains, and to improve clear stain resistance. I haven't arrived.

[0004]

DISCLOSURE OF THE INVENTION The present invention is excellent in weather resistance and stain resistance without deterioration or discoloration of a coating film even after long-term outdoor exposure to buildings, outdoor structures, etc. Provided is a composition for a fluororesin paint, which is a film forming component of a paint capable of forming a coated film.

[0005]

The inventors of the present invention have conducted detailed stain tests on various coated fluororesin coating films, and as a result, at least hydrocarbon compounds such as chlorotrifluoroethylene, vinyl ester and vinyl ether have been used. A compound, a hydroxy group-containing polymerizable compound, and a fluorine-containing copolymer (A) having a specific OH value obtained by copolymerizing a carboxyl group-containing polymerizable compound as an essential monomer,
The present inventors have found that a coating composition comprising a polyether-modified silicone oil (B) having at least a dimethyl siloxane structural unit and an ethylene oxide structural unit in the molecule thereof exhibits excellent stain resistance and weather resistance. It was

That is, in the present invention, at least 40 to 65 mol% of chlorotrifluoroethylene, 14 to 50 mol% of one or more copolymerizable vinyl compounds selected from vinyl esters, vinyl ethers and allyl ethers. The resin OH value obtained by copolymerizing a monomer mixture containing 16 to 30 mol% of a hydroxy group-containing polymerizable compound and 0.1 to 3 mol% of a carboxyl group-containing polymerizable compound is 100 to Polyether-modified silicone oil (B) 0.05 to 100 parts by weight of a fluorocopolymer (A) of 350 mgKOH / g, at least a dimethylsiloxane structural unit and an ethylene oxide structural unit in the molecule, and a water-soluble polyether-modified silicone oil (B) It is a composition for a fluororesin coating material, which contains 15 parts by weight.

The present invention will be described in detail below. In the fluorine-based copolymer (A) according to the present invention, chlorotrifluoroethylene accounts for 40 to 65 mol% of all monomers. If it is 40 mol% or less, the weather resistance is poor and 65 mol%
The above is not preferable because the solubility in the solvent decreases.

The copolymerizable vinyl compound used in the fluorocopolymer (A) according to the present invention is not particularly limited, but vinyl esters, vinyl ethers, allyl ethers and the like can be preferably used. .
The vinyl ester is a polymerizable ester compound having a carbonyl group in the molecule, for example, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl pivalate, vinyl caproate, vinyl caprylate, vinyl laurate, myristin. Examples thereof include vinyl acid salt, vinyl palmitate, vinyl stearate, versatic vinyl octoate, vinyl versatate 10 and vinyl benzoate. Examples of vinyl ethers include methyl vinyl ether, ethyl vinyl ether, butyl vinyl ether, cyclohexyl vinyl ether and the like.
As the allyl ethers, for example, ethyl allyl ether, butyl allyl ether, benzyl allyl ether, allyl glycidyl ether, cyclohexyl allyl ether, etc. are used. Further, (meth) acrylic acid ester-based compounds, vinylsilane-based compounds and the like can also be used. The composition ratio of these monomers is 1 of all monomers.
It is 4 to 50 mol%. There is a relationship with other copolymerization components, but if it is less than 14 mol%, the solubility of the fluorine-based copolymer (A) in a solvent may be poor, and if it exceeds 50 mol%, the weather resistance of the coating film may be poor. May be impaired, which is not preferable.

As the hydroxy group-containing polymerizable compound used in the fluorocopolymer (A) according to the present invention, allyl ethers, vinyl ethers or crotonic acid modified compounds having a hydroxy group in the molecule can be used. . For example, ethylene glycol monoallyl ether, propylene glycol monoallyl ether, diethylene glycol monoallyl ether, polyethylene glycol monoallyl ether, alkylene glycol monoallyl ethers such as hydroxybutyl allyl ether, hydroxymethyl vinyl ether, hydroxyethyl vinyl ether, hydroxybutyl vinyl ether, hydroxy Preferable examples include hydroxyalkyl vinyl ethers such as pentyl vinyl ether and hydroxyhexyl vinyl ether, polyethylene glycol monovinyl ethers such as diethylene glycol monovinyl ether, and crotonic acid-modified compounds such as hydroxyethyl crotonate. Further, glycerin monoallyl ether having two OH groups in the molecule is also suitably used as a component which can obtain a high OH value with a small number of moles used. The amount of glycerin monoallyl ether used is preferably 0.1 to 30 mol% of all monomers.

The composition ratio of these hydroxy group-containing polymerizable compounds is 16 to 30 mol% of all monomers,
The fluorine-based copolymer (A) obtained at that time preferably has a relatively high OH value of 100 to 350 mgKOH / g. When the OH value is less than 100, the compatibility with the polyether-modified silicone oil (B) decreases and the coating surface does not become smooth. When it exceeds 350, the solubility in the solvent decreases and the compatibility with the curing agent. It is not preferable because defects such as a decrease occur.

The carboxylic group-containing polymerizable compound used in the fluorocopolymer (A) according to the present invention is not particularly limited, but vinyl acetic acid, decenoic acid, undecylenic acid, crotonic acid, etc. may be mentioned. You can
The carboxyl group-containing polymerizable compound is useful for improving, for example, pigment dispersibility and pot life,
If it is 0.1 mol% or less, no effect is obtained, and if it is 3 mol% or more, the pot life becomes short, which is not preferable.

The polyether-modified silicone oil (B) used in the present invention has at least a dimethylsiloxane structural unit and an ethylene oxide structural unit in the molecule and is water-soluble. The degree of polymerization thereof is not particularly limited as long as it is water-soluble, but the viscosity at 25 ° C. is 2
0 to 10000 cps, 50 to 300
It is preferably about 0 cps.

The polyether-modified silicone oil (B) according to the present invention has a polyalkylene oxide structure introduced into one end, both ends or side chains of polydimethylsiloxane. As the polyalkylene oxide structure, an ethylene oxide structural unit is essential, and in addition, one or more oxyalkylene structural units having 3 to 8 carbon atoms can be optionally combined. When two or more alkylene oxide structural units are used together, each structural unit may be randomly polymerized or block polymerized.

In the polyether-modified silicone oil (B) according to the present invention, the terminal group of the polyalkylene oxide introduced into the terminal or side chain of the polydimethylsiloxane is not particularly limited, but it is cured like an -OH group. It may be a functional group involved in, and these can also be suitably used.

The polyether-modified silicone oil (B) used in the present invention is not particularly limited as long as it meets the above-mentioned conditions, but specifically, the following general formula (1)
Or the thing represented by (2) is mentioned as a suitable example.

[0016]

Embedded image

(PAG is a polyalkylene oxide chain containing an ethylene oxide structural unit, Me is a methyl group, R is an alkylene group, and n, X and Y are integers.) Polyether-modified according to the present invention When silicone oils are listed as commercially available products without limitation, SF8427, BY16-005, and B are represented by the general formula (1).
Y16-006, BY6-007, BY16-008,
As represented by the general formula (2), SH3746, S
F8428, SH3771, BY16-036, BY1
6-027, BY16-038, SH8400, SH3
749, SH3748, SF8410 (these are products of Toray Dow Corning Silicone Co., Ltd.). Needless to say, other companies' products corresponding to these products also have similar effects.

In the fluororesin coating composition of the present invention, it is preferable to add 0.05 to 15 parts by weight of the polyether-modified silicone oil (B) to 100 parts by weight of the fluorocopolymer (A). If it is less than 0.05 parts by weight, sufficient stain resistance will not be exhibited, and if it exceeds 15 parts by weight, the weather resistance will be poor, such being undesirable.

As a method for polymerizing the fluorine-based copolymer (A), which is the main component of the present invention, an ordinary radical polymerization method can be adopted in the production thereof, and the polymerization form can be solution polymerization,
Suspension polymerization and emulsion polymerization are possible. The temperature of the polymerization step depends on the radical polymerization initiator used, but is usually 0 to 1
It is 30 ° C. Examples of the solvent include water, alcohols such as t-butanol and ethyl alcohol, saturated hydrocarbons such as n-hexane and n-heptane, aromatic hydrocarbons such as toluene and xylene, trichlorotrifluoroethane, dichlorotetra. Fluorine such as fluoroethane, ketone such as acetone, methyl ethyl ketone and methyl isobutyl ketone, ester such as ethyl acetate and butyl acetate can be used alone or in a mixture.
Examples of the radical initiator include dicarbonates such as diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate and di-2-ethylhexyl peroxydicarbonate, or n-heptafluorobutyric peroxide, lauroyl. Diacyl peroxides such as peroxypivalate and t-butyloxy neodecanoate, alkyl peroxides such as di-t-butyl peroxide and t-butylcumyl peroxide, t-butylperoxypivalate and t-
Conventional radical initiators such as peroxyesters such as butyl peroxy neodecanoate can be used.

The molecular weight of the fluorocopolymer (A) polymerized in this manner is not particularly limited, but it is in the range of 1,000 to 30,000 (number average molecular weight; polystyrene conversion) depending on the required strength and flexibility of the coating film. It is desirable to use it, and more preferably about 3000 to 18000. When it is 1000 or less, the weather resistance and flexibility of the coating film are deteriorated, and when it is 30,000 or more, it becomes a high viscosity when it is made into a coating material, which causes a drawback of being difficult to handle.

The solvent for these fluorine-containing copolymer compositions may be a solvent, such as an aromatic solvent, an ester solvent, an ether solvent, a ketone solvent, or an alcohol solvent, which is generally used in the field of paints or may be a mixed solvent. is there. In any case, it can be made into a paint like an ordinary paint, and a pigment or a dye can be appropriately added.

Further, other additives such as an ultraviolet absorber, a light stabilizer, a rust preventive, a dispersant and the like can be added depending on the use. The composition for a fluororesin coating produced as described above, as a curing agent, includes a usual urethane-based or polyvalent isocyanate-based curing agent,
A melamine-based curing agent, a blocked isocyanate-based curing agent, etc. can be used without any particular limitation. For example, when an isocyanate-based curing agent is used, NCO / OH = 0.3 to
A range of 1.0 is preferred. In addition, the resin OH value is 10
In the case of 0-350 mgKOH / g NCO / OH = 0.4
It is preferably in the range of 0.7. The reason for this is N
It is considered that CO is deficient and some of the hydroxy groups remain on the surface of the coating film without participating in the curing reaction to form a hydrophilic surface, and as a result, rain is less likely to form rain streaks.

The present invention will be described in detail below with reference to examples.

[0024]

【Example】

Synthesis Examples 1 to 6 145 g (26 mol%) of vinyl acetate, 152 g (23 mol%) of ethylene glycol monoallyl ether, 12 g (1 mol%) of undecylenic acid, and xylene were added to a SUS autoclave having an internal capacity of 2 liters and equipped with a magnetic stirrer. Two
40 g and t-butyl peroxypivalate (manufactured by NOF CORPORATION) were charged, and deaeration and replacement with nitrogen gas was repeated 3 times to degas, and then chlorotrifluoroethylene 377 g
(50 mol%) was charged, and polymerization was carried out at 55 ° C. for 20 hours in the presence of 1.4 g of sodium carbonate (Synthesis Example 1).

Similarly, polymerization was carried out with the composition shown in Table 1 (Synthesis Examples 2 to 6). In each case, after the polymerization was completed, the contents were taken out and filtered to obtain a varnish of the fluorocopolymer (A). Table 1 shows the OH value, acid value and molecular weight (styrene equivalent, number average) of these resins.

[0026]

[Table 1]

CTFE: Chlorotrifluoroethylene VAc: Vinyl acetate EVE: Ethyl vinyl ether V-9: Versatic vinyl octoate EGMAE: Ethylene glycol monoallyl ether GMAE: Glycerin monoallyl ether UA: Undecylenic acid Examples 1 to 7 Synthesis Example 1 The compound (B) was added at a ratio shown in Table 2 to 100 parts of the solid content of the varnish of the fluorocopolymer (A) produced in any one of Examples 1 to 3 to prepare a base varnish for the fluororesin. The compound (B) used was Toray Dow Corning
Polyether-modified silicone SF manufactured by Silicone Co., Ltd.
8427, SH3746, and polyether-modified silicone BYK333 manufactured by Big Chemie. These are water-soluble silicones having at least a dimethylsiloxane structural unit and an ethylene oxide structural unit in the molecule.

Next, 100 parts of titanium oxide was uniformly mixed in a dispersion mill with 100 parts of the resin of the main agent varnish consisting of the mixture of (A) and (B) to prepare a main agent of white paint. Coronate HX (Nippon Polyurethane Industry Co., Ltd.) premixed 1: 1 with the main agent of this white paint
(Manufactured by Mitsui Chemicals Co., Ltd.) / Xylene was added so that the ratio of NCO / OH was as shown in Table 2, and the resulting mixture was uniformly mixed, spray-coated on an aluminum plate to a thickness of about 40 microns, and dried and cured at room temperature for 2 days.

Using the coated plate produced as described above,
A static contact angle of water, a soil test for 6 months of outdoor exposure, and a weather resistance test were conducted. The stain was judged by the color difference of the part without the rain streak and the generation condition of the rain streak. The results are shown in Table 2. Here, (A) and (B)
After mixing, the pigment is added to form a paint. However, when the pigment is added to (A) alone to form a paint, a curing agent is also added.
The results did not differ from the results for the different procedures in Table 2.

Comparative Examples 1 to 3 The compound (B) was added at a ratio shown in Table 2 to 100 parts of the solid content of the varnish of the fluorocopolymer (A) produced in Synthesis Examples 4 and 5, respectively. It was dried and cured. Used as the main varnish for fluorine-based paint. The compound (B) used is the same as in the example.

Subsequently, a white paint was formed by the same procedure as in Example 1, the same Coronate HX / xylene mixed solution as in Example 1 was added as a curing agent, and the same was applied to an aluminum plate as in Example 1, and after coating. Dried.

Using the coated plate produced as described above,
A static contact angle of water, a soil test for 6 months of outdoor exposure, and a weather resistance test were conducted. The results are shown in Table 2.

[0033]

[Table 2]

<Evaluation method> ・ Stain resistance ΔE: Color difference before and after exposure (J
(IS-Z8730) was measured in a portion where there are no rain stripes (exposed place, Kawagoe City, Saitama Prefecture).

Rain streaks: ⊚ not attached, ∘ not attached but not noticeable, Δ when attached but relatively thin, and X when conspicuous with thick lines. -Weather resistance: Accelerated test by sunshine weatherometer 4000 hours (60-degree gloss retention before and after the test).

[0036]

EFFECT OF THE INVENTION A coating material comprising the composition for a fluororesin coating material of the present invention does not cause deterioration of the coating film in a weather resistance test corresponding to long-term outdoor exposure as shown in Examples, and
Since it is clear that even in an actual long-term outdoor exposure test, the coating film does not discolor and does not have rain streaks, it exhibits excellent weather resistance and stain resistance. It is extremely useful as a film-forming component for paints used on objects.

Claims (3)

[Claims] 1. At least chlorotrifluoroethylene 4
0-65 mol%, copolymerizable vinyl compound 14-5
0 to 30% by mol of a hydroxy group-containing polymerizable compound 16 to 30
Mol%, carboxyl group-containing polymerizable compound 0.1 to 3
100 parts by weight of a fluorine-based copolymer (A) having an OH value of 100 to 350 mgKOH / g, which is obtained by copolymerizing a monomer mixture containing 100% by mole, and at least a dimethylsiloxane structural unit in the molecule. A fluororesin coating composition containing 0.05 to 15 parts by weight of a water-soluble polyether-modified silicone oil (B) having an ethylene oxide structural unit. 2. The fluororesin coating composition according to claim 1, wherein the copolymerizable vinyl compound is at least one monomer selected from vinyl esters, vinyl ethers and allyl ethers. 3. The fluororesin coating composition according to claim 1, wherein the hydroxy group-containing polymerizable compound contains at least 0.1 to 30 mol% of glycerin monoallyl ether in the monomer mixture.