JPH0670102B2 - Fluorine-containing copolymer and fluororesin paint - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel fluorine-containing copolymer and a room temperature curable fluororesin coating material containing the novel copolymer as a main component.

[Prior Art] Conventionally, a fluororesin paint containing a carboxylic acid vinyl ester having about 10 carbon atoms and a polymer containing a fluoroolefin as a main component and which does not require high temperature baking is known in the art (US Patent No. 3,449,305 and JP-A-5
9-102962 reference). The above-mentioned conventional fluororesin paint is used mainly for the purpose of protecting the base material and improving its weather resistance. However, these do not have a curing site, or even if they are present, they have poor copolymerizability due to the use of hydroxyethyl methacrylate, etc. The coating film obtained by coating has insufficient solvent resistance and lacks gloss, and the appearance of the coated object may be improved. Further, even if the gloss is good immediately after coating, the weather resistance is not sufficient, so that the gloss immediately deteriorates, and the aesthetic appearance of the coated object cannot be maintained for a long time.

[Object of the Invention]

The present inventors have earnestly studied a room temperature curable fluororesin coating material which can provide a coating film that retains high gloss for a long period of time and is excellent in curability. As a result, a perhaloolefin, a carboxylic acid vinyl ester having a specific structure The present inventors have found that a fluorine-containing copolymer composed of a vinyl ether having a hydroxyl group and a vinyl ether having a hydroxyl group (particularly by the latter two methods) is suitable for this material, and thus reached the present invention.

An object of the present invention is to provide a novel fluorine-containing copolymer and a room temperature curable fluororesin coating material containing this as a main component.

[Structure of Invention]

The present invention has the formula: (In the formula, X represents a chlorine atom or a fluorine atom.) 35 to 65 mol% of a structural unit represented by the formula: (In the formula, R ¹ , R ² and R ³ are the same or different and each represents an alkyl group having 1 to 10 carbon atoms.) 5 to 50 mol% of the structural unit represented by the formula: (In the formula, R ⁴ represents an alkylene group having 2 to 5 carbon atoms.) A fluorine-containing copolymer having a number average molecular weight of 10,000 to 100,000 (provided that the number of carbon atoms is 1 to 30 mol% represented by A fluororesin coating composition containing 5 to 70 mol% of a unit based on a vinyl ether having an alkyl group of 1 to 8) and a fluorine-containing copolymer as a main component. And the existence of (ii) and (iii) is especially important for achieving the purpose.

The number average molecular weight (by gel permeation method) of the copolymer used in the fluororesin coating material of the present invention is usually 10,0.
It is 100 to 100,000.

When the content of the structural unit (i) in the copolymer is more than the above range, the solvent solubility of the copolymer and the gloss of a coating film obtained from a coating composition containing the copolymer are insufficient and small. And the weather resistance of the coating film is not good. The preferable range of the structural unit (i) is 40 to 60 mol%.

When the content of the structural unit (ii) in the copolymer is more than the above range, the weather resistance of the coating film is small, and when the content is small, the glossiness (initial glossiness and gloss retention rate) is not sufficient. The preferred range of structural unit (ii) is 10 to 45 mol%.

When the content of the structural unit (iii) in the copolymer is more than the above range, the copolymer is easily cross-linked and the storage stability of the coating composition containing the copolymer is deteriorated. The curability of the composition, and eventually the solvent resistance of the coating film, deteriorates. The preferable range of the structural unit (iii) is 5 to 25 mol%.

The polymer has the formula: (In the formula, X is the same as the above.) Formula: (In the formula, R ¹ , R ² and R ³ are the same as the above.) And the formula: (In the formula, R ⁴ is the same as the above.) It can be obtained by copolymerizing the monomer.

Typical perhaloolefins (i ')
CTFE may be mentioned, and other perhaloolefins such as tetrafluoroethylene may be usually mixed in an amount of 25% by weight or less.

The monomers represented by the formulas (ii ′) and (iii ′) may also be a mixture of those included in the above formula. The above formula (i
Specific examples of the monomer of i ′) include vinyl pivalate,
Examples thereof include vinyl versatate, and vinyl versatate is used because it is easily available. The monomer (iii ′) is specified as the hydroxyalkyl vinyl ether having the above structure in terms of curability. The improvement in curability contributes to the solvent resistance of the coating film. Specific examples include 2-hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether, 4-hydroxybutyl vinyl ether and 5-hydroxypentyl vinyl ether. 4-Hydroxybutyl vinyl ether is usually used because of its ready availability.

The polymerization method is not particularly limited as long as it is a method capable of polymerizing a conventionally known vinyl monomer, but a solution polymerization method which can be immediately used as a paint after polymerization is preferable.

The solvent in the solution polymerization method is ketones such as methyl ethyl ketone, carboxylic acid esters such as ethyl acetate and butyl acetate, and the like. The polymerization initiator is an azo compound such as azobisisobutylnitrile, a peracid compound such as isobutyryl peroxide, di-iso-propylperoxy-dicarbonate, or the like. The polymerization temperature is usually 0 to 150 ° C., preferably 5 to 95 ° C., and the polymerization pressure is usually 1 to 50 kg / cm ² G.
The polymerization is usually carried out until the concentration of the produced copolymer reaches 30 to 60% by weight.

The above-prepared copolymer can be used as a lacquer type coating as it is, but it is used by adding a compound (curing agent) having two or more groups capable of reacting with the hydroxyl group contained in the copolymer. can do. Examples of the curing agent include isocyanates such as hexamethylene-di-isocyanate trimer, tolylene-di-isocyanate, and acid halides such as hexamethylene-di-carbonyl chloride. The curing agent is usually used in an amount of 0.5 to 2.0 equivalents based on 1 equivalent of hydroxyl groups of the copolymer. When using a hardening agent, dibutyltin laurate etc. can be used as a hardening accelerator. The curing accelerator is
Usually, 0.001 to 0.1 part by weight is used per 100 parts by weight of the curing agent.

The coating composition containing the fluorine-containing copolymer of the present invention,
For the purpose of adjusting the viscosity and the like, a solvent other than the above, for example, an ether compound such as tetrahydrofuran, an amide compound such as N-dimethylformamide, an aromatic compound such as toluene and xylene can be added. In addition, pigments, viscosity modifiers, leveling agents, anti-gelling agents, which are usually used in paints,
It is also possible to add an anti-skin agent, an ultraviolet absorber and the like. The crosslinking agent is usually mixed just before the coating material prepared from the material of the present invention is applied to the substrate.

The coating composition containing the fluorine-containing copolymer of the present invention can be applied to metal, wood, concrete, glass, plastic and the like by the same method as in the case of using the above-mentioned known fluororesin coating.

〔Example〕

Example 1 Butyl acetate 27 in a 1000 ml autoclave equipped with a stirrer
0g, ethyl acetate 100g, Versatic vinylate (Veor 10, Shell Petrochemical Co., Ltd., VA) 227g
And 4-hydroxybutyl vinyl ether (hereinafter HB
After charging 34 g of VE) and replacing the space with nitrogen gas, chlorotrifluoroethylene (hereinafter referred to as CTFE)
168g was added and the autoclave was heated to 65 ° C. Then, 35m of a mixed solvent of 1/1 by weight of butyl acetate and ethyl acetate
A solution of 3.3 g of azobisisobutyronitrile dissolved in 1 was added to initiate polymerization. The mixture was stirred for 16 hours while maintaining the temperature. The pressure of the autoclave before polymerization is 4.4 kg / cm ² G,
After that time it was 1.7 g / cm ² G. 750 g of transparent varnish of copolymer was obtained.

A part of the varnish was taken and the number average molecular weight of the copolymer was measured, elemental analysis, nuclear magnetic resonance analysis ( ¹ H and ¹³ F), glass transition temperature and thermal decomposition temperature were measured. The results are shown below.

Number average molecular weight (gel permeation method, polystyrene standard): 31,000.

Elemental analysis: 55.0% by weight carbon, 9.9% by weight chlorine and 16% by weight fluorine.

Nuclear magnetic resonance analysis: ¹ H, δ; 0.7 to 2.0 ppm (side chain methyl and methine hydrogen), 2.0 to 3.0 ppm (backbone methyl group hydrogen) and 5.0 to 6.4 ppm (backbone methine) Group hydrogen), and ¹³ F, δ; 37-48 ppm (main chain fluorine).

Glass transition temperature (Differential scanning calorimeter heated in nitrogen stream at 20 ° C / min): 17 ° C Thermal decomposition temperature (Differential heat, thermogravimetric device heated in air at 10 ° C / min): 201 ° C From the elemental analysis, it was found that the copolymer prepared in this example was composed of 44 mol% CTFE, 47 mol% VA and 9 mol% HBVE.

To 100 g of the varnish obtained above, 40 g of rutin-type titanium oxide and 20 g of xylene were added, and mixed with a paint shaker for 1 hour. Hexamethylene diisocyanate trimer (Nihon Polyurethane Co., Ltd., Coronate EH) was added to the obtained mixture.
5.2 g of dibutyltin laurate and 2 mg of dibutyltin laurate were mixed, and 45 g of xylene was added to adjust the viscosity to 300 centipoise.

The obtained mixture was applied to an aluminum plate (manufactured by Japan Test Panel Co., BT-712 treatment) with a brush and dried at 25 ° C. for 7 days,
Cured. A coating film having an average thickness of 35 μm was obtained.

The following tests were conducted using the aluminum plate having the above coating film as a sample. The results are shown in the table below.

Pencil hardness test: Performed by the method described in JIS K 5400.

Gloss retention test: JIS Z 8741 6 of the sample immediately after the above preparation
0 ° -60 ° specular gloss and the sample was measured using a sunshine weather meter (Suga Test Instruments Co., Ltd., rain cycle 18 minutes / 1
The glossiness was measured after exposure treatment for 20 minutes, humidity 60%, black panel temperature 63 ° C) for 4000 hours. The table shows initial glossiness and gloss retention rate (post-treatment glossiness x 100 / initial glossiness)
Indicates. The higher the gloss retention rate, the better the weather resistance.

Examples 2 and 3 In place of the monomer of Example 1, in Example 2, 340 g of CTFE, 177 g of VA and 32.4 g of HBVE were used in the autoclave.
In Example 3, a copolymer was prepared by the same procedure as in Example 1 except that CTFE185g, VA171g and HBVE67g were initially charged and used. In Example 2, 738 g and in Example 3 783 g of transparent varnish were obtained.

The glass transition temperatures of the copolymers of Examples 2 and 3 were 33, respectively.
℃ and 25 ℃, the thermal decomposition temperature was 223 ℃ and 218 ℃ respectively.

The elemental analysis value of the copolymer of Example 2 was 47.9% by weight of carbon,
At 14.2 wt% chlorine and 22.2 wt% fluorine, that of the copolymer of Example 3 was 50.3 wt% carbon, 12.4 wt% chlorine and 19.4 wt% fluorine. From these values, the copolymer of Example 2 was found to have CTFE 56 mol%, VA 33 mol% and HBVE
11 mol%, the copolymer of Example 3 is CTFE49 mol%, VA32
It was found to consist of mol% and HBVE 19 mol%.

To 100 g of each varnish obtained above, 40 g of rutile type titanium oxide and 20 g of xylene were added and mixed with a paint shaker for 1 hour. The mixture of Example 2 contains 6.6 g of hexamethylesiisocyanate trimer and 3 mg of dibutyltin laurate, and the mixture of Example 3 contains 1 of hexamethylethylisocyanate trimer.
1.5 g of dibutyltin laurate and 1 mg of dibutyltin laurate were mixed, and 50 g of xylene was added to adjust the viscosity to 300 centipoise.

The obtained mixture was applied to an aluminum plate of the same type as in Example 1 with a brush, dried at 25 ° C. for 7 days and cured.

The results of the same tests as in Example 1 measured using the aluminum plate having the above coating film as a sample are shown in the table below.

Example 4 In place of the monomer of Example 1, 133 g of CTFE, 30 g of tetrafluoroethylene (hereinafter referred to as TFE), 135 g of vinyl pivalate (hereinafter referred to as VA-4) and 34 g of HBVE were initially charged in an autoclave and used. A copolymer was prepared in the same manner as in Example 1 to obtain 695 g of a transparent varnish.

Copolymer glass transition temperature 35 ℃, thermal decomposition temperature 245 ℃
Met.

The elemental analysis value of the copolymer is 44.7% by weight of carbon,
It was 11.9% by weight and fluorine 25.0% by weight. From these values, it was found that the copolymer composition was composed of CTFE 39 mol%, TFE 10 mol%, VA-441 mol%, and HBVE 10 mol%.

The number average molecular weight (gel permeation method, polystyrene standard) was 12,000.

The varnish obtained above was made into a paint with the same formulation as in Example 1,
The sample was tested by brushing onto an aluminum plate, drying at 25 ° C. for 7 days and curing.

The results of the same tests as in Example 1 measured using the aluminum plate having the above coating film as a sample are shown in the table below.

Comparative Example 1 300 g of a 1/1 toluene / methyl isobutyl ketone mixture by weight was placed in the same autoclave as in Example 1, the space was replaced with nitrogen, 90 g of CTFE was added, and the mixture was heated until the temperature reached 60 ° C. VA154g, methyl methacrylate (hereinafter,
A mixture of 135 g of MMA), 20 g of β-hydroxyethyl methacrylate and 6.7 g of azobisvaleronitrile was charged with a high-pressure constant-flow micropump for 4.5 hours. Then, the temperature was maintained while stirring for 30 hours. 614 g of a cloudy varnish was obtained.

To 100 g of each varnish obtained above, 40 g of rutile type titanium oxide and 20 g of xylene were added and mixed with a paint shaker for 1 hour. 4 g of hexamethylene diisocyanate trimer and 5 mg of dibutyltin laurate were mixed with the obtained mixture, and 30 g of xylene was further added to adjust the viscosity to 300 centipoise.

The obtained mixture was applied to an aluminum plate of the same type as in Example 1 with a brush, dried at 25 ° C. for 7 days and cured.

The results of the same tests as in Example 1 measured using the aluminum plate having the above coating film as a sample are shown in the table below.

Comparative Example 2 250 g of a 1/1 toluene / methyl isobutyl ketone mixture by weight was placed in the same autoclave as in Example 1, and after replacing the space with nitrogen, 135 g of CTFE was added and heated to a temperature of 60 ° C. A mixture of 100 g of VA, 85 g of MMA, 17 g of allyl glycidyl ether and 6.7 g of azobisvaleronitrile was charged with a high-pressure constant-flow micropump for 4.5 hours.
Then, the temperature was maintained while stirring for 26 hours. I got 462g of varnish.

40 g of rutile type titanium oxide and 20 g of xylene were added to 100 g of the varnish obtained above and mixed for 1 hour with a paint shaker. 3 g of a polycarboxylic acid having a molar ratio of trimellitic acid and ε-caprolactone of 1/6 was mixed with the obtained mixture. The obtained mixture was applied to an aluminum plate of the same type as in Example 1 with a brush and heated at 170 ° C for 20 minutes.

Example 1 Using the aluminum plate having the above coating film as a sample
The same test was conducted. The results are shown in the table below.

Comparative Example 3 Polymerization was carried out for 16 hours in the same procedure as in Example 1 except that the amounts of butyl acetate, ethyl acetate, CTFE, VA and HBVE used were changed to 220 g, 80 g, 54 g, 320 g and 26 g, respectively, and 682 g of transparent I got a varnish. The result of the elemental analysis of the copolymer is carbon 6
5.7%, chlorine 3.8% and fluorine 5.8%, copolymer is CTF
It consisted of 18 mol% E, 72 mol% VA and 10 mol% HBVE.

40 g of rutile type titanium oxide and 20 g of xylene were added to 100 g of the varnish obtained above, and the mixture was stirred for 1 hour with a paint shaker. 5.3 g of hexamethylene diisocyanate trimer and 2 mg of dibutyltin laurate were mixed with this mixture, and 100 g of xylene was further added to adjust the viscosity to 300 centipoise.

The obtained mixture was applied to an aluminum plate of the same kind as in Example 1 with a brush, dried at 25 ° C. for 7 days, and cured. The results of the same tests as in Example 1 measured using this aluminum plate as a sample are shown in the table below.

[Effects of the Invention] A coating film obtained from the fluororesin coating material of the present invention is obtained from a coating material containing a conventionally known copolymer composed of chlorotrifluoroethylene, vinyl versatate, methyl methacrylate and the like as a main component. Compared with other coatings, the gloss is good immediately after coating, and this gloss can be maintained for a long time.

Continuation of front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display area // (C08F 214/24 218: 10 216: 14) (C08F 214/26 218: 10 216: 14)

Claims (2)

[Claims] 1. A formula: (In the formula, X represents a chlorine atom or a fluorine atom.) 35 to 65 mol% of a structural unit represented by the formula: (In the formula, R ¹ , R ² and R ³ are the same or different and each represents an alkyl group having 1 to 10 carbon atoms.) 5 to 50 mol% of a structural unit represented by the formula: (In the formula, R ⁴ represents an alkylene group having 2 to 5 carbon atoms.) A fluorine-containing copolymer having a number average molecular weight of 10,000 to 100,000 composed of 1 to 30 mol% of a structural unit (provided that
Excluding those containing 5 to 70 mol% of a unit based on a vinyl ether having an alkyl group having 1 to 8 carbon atoms. ). 2. The formula: (In the formula, X represents a chlorine atom or a fluorine atom.) 35 to 65 mol% of a structural unit represented by the formula: (In the formula, R ¹ , R ² and R ³ are the same or different and each represents an alkyl group having 1 to 10 carbon atoms.) 5 to 50 mol% of a structural unit represented by the formula: (In the formula, R ⁴ represents an alkylene group having 2 to 5 carbon atoms.) A fluorine-containing copolymer composed of 1 to 30 mol% of structural units (provided that the alkyl group has 1 to 8 carbon atoms). Fluorine resin paint containing as a main component 5 to 70 mol% based on vinyl ether having