JP4754545B2 - Fluorine varnish mainly composed of fluorine-containing copolymer containing double bond - Google Patents

Description

Detailed Description of the Invention

TECHNICAL FIELD OF THE INVENTION

  The present invention relates to a fluorine-containing copolymer containing a double bond, which is excellent in water and oil repellency, chemical resistance and weather resistance, and can be cured by light or heat in a single liquid, and a method for producing the same, and a fluororesin paint comprising the same , About varnish.

Conventional technology

  Solvent-soluble fluororesin coatings are generally obtained by copolymerizing hydroxyalkyl vinyl ether and fluoroolefin, and optionally alkyl vinyl ether, alkyl vinyl ester and the like. In order to obtain solubility in a general organic solvent, the coating material based on the contained fluorine copolymer contains 50% or more of a hydrocarbon monomer. Therefore, the fluorine content in the fluororesin is lowered, and the coating film properties such as water / oil repellency and stain resistance required for the fluororesin cannot be sufficiently obtained. On the other hand, water and oil repellency is improved by mixing a small amount of an organic silicon compound such as silicone oil with the fluorine-containing copolymer. However, it is difficult to maintain water and oil repellency characteristics over a long period of time. Furthermore, depending on the application, silicone oil may bleed out from the surface of the coating film, and silicone oil cannot be used. In addition, a copolymer of a fluorine-containing monomer having a perfluoro group and a monomer having a silyl group has been studied as a water / oil repellent, but has a fluorine atom in the main skeleton of the copolymer. Therefore, sufficient weather resistance is not obtained.

  Moreover, although the fluorine copolymer containing a hydroxyl group can be cured at room temperature, the two components of the main agent and the curing agent must be mixed immediately before use. This is not convenient for work, and attention must be paid to the pot life.

  The object of the present invention is to provide a fluorinated copolymer that solves the above-mentioned problems, that is, it is excellent in long-term water and oil repellency and repeated decontamination, and can be cured by light or heat in one liquid. It is to provide a novel double bond-containing fluorine-containing copolymer and a method for producing the same, and to provide a fluorine-based paint, varnish and the like mainly containing them.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the fluoroolefin and one of the general formulas (1) , (2) , (3) and (4) are selected. Reaction of hydroxyl group-containing fluorine-containing copolymer [A] having the above-mentioned organosilicon compound and the hydroxyl group-containing unsaturated ether represented by the general formula (5) as essential components and unsaturated isocyanate [B] Has found that a novel double bond-containing fluorine-containing copolymer produced by introducing a double bond into a fluorine-containing copolymer is excellent in long-term water and oil repellency and repeated decontamination .

( Where R ¹ , R ² and R ³ are each a hydrogen atom, methyl group, ethyl group, butyl group, phenyl group, —CF ₃ , —C ₂ H ₄ CF ₃ , —C (CH ₃ ) ₃ or ^{_{-OSi (CH 3) .R 1,}} R 2 and R ³ denote any of the _3, respectively, may be the same or different.)

(Here, R ⁴ represents a hydrogen atom or a methyl group , and R ⁵ represents —CO—O—, —O—, or —CH═CH—CH ₂ —O—CH ₂ —CH═CH—. shows, further, R ⁶ is an integer of. n is 0 represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, m is an integer of 0 to 200.)

(Wherein, R ⁷ represents a hydrogen atom or a methyl group, each R ^8, R ⁹ and R ¹⁰ are hydrogen atom, methyl group, ethyl group, butyl group, or -OSi (CH ₃₎ any of the _3, each one is .R ^8, R ⁹ and R ¹⁰ which indicates the, optionally the same or different .p is an integer of 0.)

(Here, R ¹¹ represents an alkylene group having 1 to 6 carbon atoms or a cyclohexylene group. R represents an integer of 0 to 10.)
That is, in the present invention, 15 to 85 mol% of a fluoroolefin and 0.001 to 30 mol% of an organosilicon compound represented by the general formulas (1), (2), (3) and (4) are used as polymerization units. 1 to 50 mol% of the hydroxyl group-containing unsaturated ether represented by the general formula (5) is an essential constituent, and is obtained by copolymerization with any other copolymerizable monomer as required. It is produced by a reaction between a hydroxyl group-containing fluorine-containing copolymer [A] and an unsaturated isocyanate [B], and is excellent in long-term water and oil repellency, repeated decontamination, chemical resistance, and weather resistance. The present invention relates to a fluorine-containing copolymer containing a heavy bond.

  In addition to the above polymerized units, the present invention includes one or more polymerized units in which the hydroxyl group-containing fluorine-containing copolymer [A] is selected from alkyl vinyl ethers, alkyl allyl ethers, methacrylic acid esters, and acrylic acid esters. The present invention relates to a double bond-containing fluorine-containing copolymer produced by a reaction between a fluorine-containing copolymer comprising and an unsaturated isocyanate [B].

  In the hydroxyl group-containing fluorine-containing copolymer [A] of the present invention, the fluoroolefin is an olefin having one or more fluorine atoms in the molecule, such as vinylidene fluoride, tetrafluoroethylene, chlorotrifluoroethylene. Hexafluoropropylene and the like are preferable. These fluoroolefins may be used alone or in combination of two or more.

  Specific examples of the organic silicon compounds represented by the general formulas (1), (2), (3) and (4) include vinyl pentamethyldisiloxane, vinylphenyldimethylsilane, vinylmethylbis (trimethylsiloxy) silane. , Vinyltriethylsilane, vinyl (trifluoromethyl) dimethylsilane, vinyl (3,3,3-trifluoropropyl) dimethylsilane, vinyltrimethylsilane, vinyltris (trimethylsiloxy) silane, vinyl-t-butyldimethylsilane, vinyldiethyl Methylsilane, (3-acryloxypropyl) methylbis (trimethylsiloxy) silane, 3-methacryloxypropylbis (trimethylsiloxy) methylsilane, (3-acryloxypropyl) tris (trimethylsiloxy) silane, methacryloxypropyl Squirrel (trimethylsiloxy) silane, methacryloxy methyl trimethoxy methyl silane, the reactive silicone oil one end is methacryl-modified, one terminal is suitable reactive silicone oil, which is acrylic-modified. These organosilicon compounds may be used alone or in combination of two or more. The molecular weight of these organosilicon compounds is preferably 100 to 6000.

  Specific examples of the hydroxyl group-containing unsaturated ether represented by the general formula (5) include hydroxymethyl vinyl ether, hydroxyethyl vinyl ether, hydroxypropyl vinyl ether, hydroxybutyl vinyl ether, ethylene glycol monoallyl ether, cyclohexyl vinyl ether, 4-hydroxy Cyclohexyl vinyl ether, 3-allyloxy-1,2-propanediol, glycerol α-monoallyl ether and the like are suitable. These hydroxyl group-containing unsaturated ethers may be used alone or in combinations of two or more.

  Furthermore, specific examples of the alkyl vinyl ether include ethyl vinyl ether, isopropyl vinyl ether, n-propyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, cyclohexyl vinyl ether, octadecyl vinyl ether and the like.

  Specific examples of the alkyl allyl ether include ethyl allyl ether, butyl allyl ether, cyclohexyl allyl ether, isobutyl allyl ether, n-propyl allyl ether, and the like.

  Specific examples of the acrylate ester include methyl acrylate, ethyl acrylate, n-butyl acrylate, t-butyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxybutyl acrylate, and the like.

  Specific examples of the methacrylic acid ester include methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, t-butyl methacrylate, glycidyl methacrylate, cyclohexyl methacrylate, 2-hydroxyethyl methacrylate, 2-methacrylic acid 2- And hydroxypropyl.

  The hydroxyl group-containing fluorine-containing copolymer [A] of the present invention can form a coating film excellent in long-term water and oil repellency, repeated decontamination, chemical resistance, and weather resistance. In addition to these units, other copolymerizable monomer units may be included within a range not exceeding 20 mol% depending on the purpose of use.

  Examples of the copolymerizable monomer include olefins such as ethylene and propylene, haloolefins such as vinyl chloride and vinylidene chloride, vinyl acetate, n-vinyl butyrate, vinyl isobutyrate, and vinyl propionate. Examples thereof include carboxylic acid vinyl esters.

  When the hydroxyl group-containing fluorine-containing copolymer [A] contains less than 15 mol% of the polymerized unit fluoroolefin, it is not preferable because sufficient stain resistance cannot be obtained when used as a coating base. Moreover, when more than 85 mol%, the solubility with respect to various solvents falls and it is not preferable. Preferably it is 30-80 mol%.

Further, when the proportion of the organosilicon compound represented by the general formulas (1), (2), (3) and (4) is less than 0.001 mol%, sufficient water and oil repellency over a long period can be obtained. Not preferable. On the other hand, when it is more than 50 mol%, sufficient chemical resistance and weather resistance cannot be obtained, which is not preferable. Preferably, it is 0.001-30 mol%, More preferably, it is 0.01-30 mol% .

  In addition, when the hydroxyl group-containing unsaturated ether represented by the general formula (5) is less than 1 mol%, the amount of double bonds decreases and sufficient curing does not occur, and the cured coating has chemical resistance and solvent resistance. It is not preferable because the properties are lowered. On the other hand, when it is more than 50 mol%, the fluorine content in the fluorine-containing copolymer is decreased, and sufficient chemical resistance and weather resistance cannot be obtained, which is not preferable.

  The hydroxyl group-containing fluorinated copolymer [A] can be produced by copolymerizing a predetermined proportion of a monomer mixture using a polymerization initiator.

  As the polymerization initiator for producing the hydroxyl group-containing fluorine-containing copolymer [A], an oil-soluble or water-soluble one is appropriately used depending on the polymerization type and the type of solvent used as desired. It is done.

  Examples of the oil-soluble initiator include peroxyester type peroxides such as t-butyl peroxyisobutyrate and t-butyl peroxyacetate, and dialkyl peroxydicarbonates such as diisopropyl peroxydicarbonate and dinormalpropyl peroxydicarbonate. Oxydicarbonate, benzoyl peroxide, azobisisobutyronitrile and the like are used.

  Examples of the water-soluble initiator include a persulfate such as potassium persulfate, hydrogen peroxide, or a redox initiator composed of a combination of these with a reducing agent such as sodium hydrogen sulfite and sodium thiosulfate. Inorganic initiators in which a small amount of iron, ferrous salt, silver nitrate, etc. coexisted, and dibasic acid organic initiators such as succinic acid peroxide, diglutaric acid peroxide, and monosuccinic acid peroxide are used. .

  The amount of these polymerization initiators to be used is appropriately selected according to the type, copolymerization reaction conditions, and the like, but is 0.005 to 5% by weight, preferably 0.1%, based on the total amount of monomers normally used. It is selected in the range of ˜2% by weight.

  Moreover, there is no restriction | limiting in particular about the polymerization method for manufacturing a hydroxyl-group containing fluorine-containing copolymer [A], For example, a block polymerization method, suspension polymerization method, emulsion polymerization method, solution polymerization method etc. can be used. A solvent such as ketones such as methyl ethyl ketone, acetates such as butyl acetate, aromatic hydrocarbons such as xylene, alcohols such as t-butanol, and halogenated saturated hydrocarbons having one or more fluorine atoms. A solution polymerization method or an emulsion polymerization method in an aqueous solvent is preferred.

  As the solvent for obtaining the hydroxyl group-containing fluorine-containing copolymer [A] of the present invention by a solution polymerization method, particularly preferred are ethyl acetate, butyl acetate, xylene, toluene and methyl ethyl ketone. When copolymerizing in an aqueous solvent, a suspension or emulsifier is usually used as a dispersion stabilizer, and a basic buffer is added, and the pH value of the reaction solution during polymerization is 4 or more, preferably 6 or more. It is desirable to make it.

The reaction temperature in each of the copolymerization reactions is appropriately selected depending on the type of the polymerization initiator and the polymerization medium, usually within a range of −30 ° C. to 150 ° C. For example, when copolymerization is performed in a solvent, it is usually selected in the range of 0 ° C to 100 ° C, preferably 10 ° C to 90 ° C. The reaction pressure is not particularly limited, but is usually selected in the range of 0.1 to 100 kg / cm ² , preferably 1 to 50 kg / cm ² . Further, the copolymerization reaction can be carried out by adding an appropriate chain transfer agent.

  The reaction between the hydroxyl group-containing fluorine-containing copolymer [A] and the unsaturated isocyanate [B] is not particularly limited, but in a solution in which the hydroxyl group-containing fluorine copolymer [A] is dissolved in a solvent, Unsaturated isocyanate [B] is preferably added dropwise while stirring.

  The reaction ratio of the hydroxyl group-containing fluorine-containing copolymer [A] and the unsaturated isocyanate [B] is selected in the range of 0.1 to 1 in terms of the ratio of isocyanate group / hydroxyl group.

  On the other hand, when the ratio of isocyanate group / hydroxyl group is smaller than 0.1, the amount of double bonds is reduced and sufficient curing does not occur, which is not preferable because the chemical resistance and solvent resistance of the cured coating film are lowered. On the other hand, when the ratio is larger than 1, unreacted unsaturated isocyanate remains, and there is a possibility of deteriorating coating film characteristics.

Specific examples of the unsaturated isocyanate include 2-isocyanate ethyl methacrylate, 2-isocyanate ethyl acrylate, 4-isocyanate butyl methacrylate, 4-isocyanate butyl acrylate, a reaction product of 1 mol of an unsaturated monoalcohol and 1 mol of a diisocyanate compound, Examples include a reaction product of 2 mol of an unsaturated monoalcohol and 1 mol of a triisocyanate compound.
Specific examples of the unsaturated monoalcohol include hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, hydroxyethyl methacrylate, hydroxybutyl methacrylate, hydroxybutyl acrylate, and allyl alcohol.

  Specific examples of the diisocyanate compound include tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, dicyclohexylmethane diisocyanate, and the like. Specific examples of the triisocyanate compound include isocyanurate-bound HDI, isocyanurate-bound IPDI, TMP-modified HDI, and TMP-modified IPDI.

  The reaction temperature at this time is selected in the range of 10 to 130 ° C, preferably 25 to 85 ° C. On the other hand, when the temperature is lower than 10 ° C, the reaction does not proceed sufficiently. When the temperature is higher than 130 ° C, gelation tends to occur during the reaction, which is not preferable.

  The solvent used in the reaction is preferably a ketone such as methyl ethyl ketone, an acetate such as butyl acetate, an aromatic hydrocarbon such as xylene. Since unsaturated isocyanate is used, if a hydroxyl group-containing solvent such as water or alcohols is used, the reaction between the hydroxyl group-containing fluorine-containing copolymer and the unsaturated isocyanate does not proceed. Group-containing solvents are not preferred.

  Further, it is preferable to use an organic tin compound such as dibutyltin dilaurate as a reaction catalyst.

  Since the double bond-containing fluorine-containing copolymer of the present invention can be cured by light irradiation, curing can be completed in a short time. Therefore, it is very useful for coating on a substrate such as plastic which cannot be heated very much. In addition, when the hydroxyl group-containing fluorine copolymer is to be cured at room temperature, a curing agent must be mixed at the time of use, which is not convenient in terms of work. In comparison, the double bond-containing fluorine-containing copolymer of the present invention is a one-component solution and can be used without mixing a curing agent, which is very useful for work.

  The double bond-containing fluorine-containing copolymer obtained by such a method can be cured by light irradiation or heat.

Examples of photocuring initiators include benzoin ether, benzophenone, 1 -hydroxy -cyclohexyl phenyl ketone, 2-methyl-1- [4- (methylthio) phenyl] -2-monfolinopropane-1,2-benzyl-2dimethyl Amino-1- (4-morpholinophenyl) -butanone-1,2,2-dimethoxy-1,2-diphenylethane-1-one and the like are used.

  As the thermosetting initiator, benzoyl peroxide, azobisisobutyronitrile, t-butylperoxy-2-ethylhexanate, t-butylperoxyisopropyl monocarbonate, or the like is used.

  Various solvents can be used for producing a curable fluororesin coating mainly composed of the double bond-containing fluorine-containing copolymer of the present invention, for example, aromatic hydrocarbons such as xylene and toluene. , Acetates such as ethyl acetate and butyl acetate, ketones such as methyl ethyl ketone and methyl isobutyl ketone, glycol ethers such as ethyl cellosolve, various commercially available thinners, etc., but ethyl acetate, butyl acetate, xylene, toluene Is particularly preferred. In addition, it is possible to add a commercially available photocurable resin or the like as necessary, and the double bond-containing fluorine-containing copolymer of the present invention is added to these other resins in the paint in an amount of 5 to 80% by weight, particularly It is preferable to use it by adjusting so as to contain 20 to 60% by weight.

  Mixing of the double bond-containing fluorine-containing copolymer of the present invention and a solvent can be performed using various equipment used for normal coating, such as a ball mill, a paint shaker, a sand mill, a three-roll mill, and a kneader. . At this time, a pigment, a dispersion stabilizer, a viscosity modifier, a leveling agent and the like can be added as necessary.

[Example]
EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.

[Example 1]
After degassing into an autoclave (withstand pressure of 100 kg / cm ² ) with a stainless steel stirrer with an internal volume of 1 L, 96 g of vinylidene fluoride (hereinafter abbreviated as VDF), 84 g of tetrafluoroethylene (hereinafter abbreviated as TFE) , ethyl vinyl ether (hereinafter referred to as EVE) 10.8 g, hydroxybutyl vinyl ether (hereinafter abbreviated as HBVE) 41.8 g, vinyl diethylmethylsilane 19.2 g, butyl acetate 400 g, and t-butyl peroxypivalate 1.3 g The temperature was raised to 60 ° C. Thereafter, the reaction was continued with stirring, the stirring was stopped for 20 hours, and the reaction was completed. The obtained copolymer was isolated by drying under reduced pressure. The copolymer yield was 234 g, and the copolymer yield was 93%. The hydroxyl group value of the obtained hydroxyl group-containing fluorine-containing copolymer (hereinafter referred to as [A-1]) measured by acetylation method with acetic anhydride was 86 mg KOH / g resin, and the fluorine content by combustion method was 48 wt%. It was.

  Next, in a 1 L round bottom three-necked flask equipped with a stirrer, a reflux condenser, a dropping funnel and a calcium chloride tower in a dark place, 600 g of the obtained 30% butyl acetate solution of [A-1] and hydroquinone monomethyl ether 0. 18 g was added. While stirring at a temperature of 40 ° C., a mixed solution containing 42.8 g of 2-isocyanatoethyl methacrylate (hereinafter referred to as [B-1]) and 18.3 g of butyl acetate was dropped little by little with a dropping funnel. After completion of dropping, stirring was continued for 2 hours to obtain a double bond-containing fluorine-containing copolymer.

The infrared absorption spectrum of the reaction solution was measured. As a result, it was confirmed that the absorption of isocyanate groups at 2,260 cm ⁻¹ disappeared completely. Thereby, it was confirmed that reaction of the hydroxyl group of [A-1] and the isocyanate group of [B-1] advanced.

The number average molecular weight measured by GPC of the obtained double bond-containing fluorine-containing copolymer was 2.0 × 10 ⁴ .

Moreover, the coating film characteristic of the cured coating film of this copolymer was investigated by the following method. The results are shown in [Table 1].
[Adhesion to Base Material] 67 g of the 30% butyl acetate solution and Ebecry 1810 [tetrafunctional polyester acrylate: product of Daicel UCB Co., Ltd.] 80 g and 2-methyl-1- [4- (methylthio) phenyl] -2 -Monfolinopropanone-1 [manufactured by Ciba Geigy Co., Ltd.] 0.3 g was added, applied onto a JISG-3141 steel plate with an applicator, dried at 80 ° C. for 3 minutes , and then irradiated with ultraviolet rays of 250 mJ / cm ^{2 in} the air. Was irradiated. The obtained 25-micrometer-thick test piece was measured by JIS-K5400 6.15 (Gobain cello tape (trademark) test).
[Pencil hardness] According to JIS-K5400 6.14 (pencil scratch test).
[Acid Resistance] Visually observe the appearance of the coating film after a 24-hour spot test using a 10% HCl solution.

A: No abnormality B: Almost no change B: Slightly attacked X: Soiled [Alkali resistance] The appearance of the coating film after a 24-hour spot test with a 10% NaOH solution is visually observed.

◎: No abnormality ○: Almost no change △: Slightly attacked ×: Soiled [Oil-based magic repellency] The surface of the paint film is painted with oil-based Magic (registered trademark) (black, red, magic ink product name) to provide repellency. evaluate. Further, this coating film is left at room temperature for 1 hour and then removed by dry wiping. The repellency of the coating film surface after repeating this 20 times is evaluated.

◎: Repels well ○: Repels △: Slightly repels ×: Does not repel at all [Repeatability of oil-based magic] Paint the surface of the coating with oil-based magic (black, red, magic ink product name), leave it at room temperature for 1 hour, and then wipe dry Remove. Furthermore, the removability of the coating film surface after repeating this 20 times is evaluated.

A: There is no trace at all. B: A trace is left. Δ: A trace is marked. X: A trace remains completely. [Water repellency] The contact angle (unit: degree) of water was evaluated.

[Example 2]
After deaeration into an autoclave with a stainless steel stirrer (withstand pressure of 100 kg / cm ² ) having an internal volume of 1 L, VDF 96 g, TFE 84 g , methyl acrylate (hereinafter abbreviated as MA) 7.8 g, EVE 8.4 g, HBVE 52.2 g, the following structure 10.5 g of methacryl-modified silicone oil represented by the formula (molecular weight: about 3500), 400 g of toluene, and 1.3 g of t-butyl peroxypivalate were added, and the internal temperature was raised to 60 ° C. while stirring.

  Thereafter, the reaction was continued with stirring, and stirring was stopped after 20 hours to complete the reaction.

  The obtained copolymer was isolated by drying under reduced pressure. The copolymer yield was 242 g, and the copolymer yield was 94%. The hydroxyl value of the obtained hydroxyl group-containing fluorine-containing copolymer (hereinafter referred to as [A-2]) measured by acetylation method with acetic anhydride was 104 mg KOH / g resin, and the fluorine content by combustion method was 47 wt%. It was.

  Next, in a 1 L round bottom three-necked flask equipped with a stirrer, reflux condenser, dropping funnel and calcium chloride tower in the dark, put 600 g of 30% butyl acetate solution of [A-2] and 0.18 g of hydroquinone monomethyl ether. It was. While stirring at a temperature of 40 ° C., a mixed solution containing 51.8 g of [B-1] and 22.2 g of toluene was dropped little by little with a dropping funnel. After completion of dropping, stirring was continued for 2 hours to obtain a double bond-containing fluorine-containing copolymer.

  The infrared absorption spectrum of the reaction solution was measured, and it was confirmed that the reaction between the hydroxyl group of [A-2] and the isocyanate group of [B-1] proceeded.

The number average molecular weight measured by GPC of the obtained double bond-containing fluorine-containing copolymer was 1.9 × 10 ⁴ .

  The cured coating film characteristics of this copolymer were examined in the same manner as in Example 1. The results are shown in [Table 1].

[Examples 3 to 7]
Using the monomers shown in [Table 1], a copolymer was produced in accordance with the operation of the above example, and these characteristics were similarly examined. The results are shown in [Table 1].

[Comparative Example 1]
The internal volume 1L stainless steel autoclave equipped with a stirrer (pressure-resistant 100kg / cm ^2), After degassing, VDF96g, TFE84g, EVE15.1g, HBVE52.2g , butyl acetate 400 g, and t- butyl peroxypivalate 1.2g The internal temperature was raised to 60 ° C. while stirring. Thereafter, the reaction was continued with stirring, the stirring was stopped for 20 hours, and the reaction was completed. The obtained copolymer was isolated by drying under reduced pressure. The copolymer yield was 230 g, and the copolymer yield was 93%. The hydroxyl group value of the obtained hydroxyl group-containing fluorine-containing copolymer (hereinafter referred to as [A-8]) measured by acetylation method with acetic anhydride was 110 mg KOH / g resin, and the fluorine content by combustion method was 49 wt%. It was.

  Next, in a 1 L round bottom three-necked flask equipped with a stirrer, reflux condenser, dropping funnel and calcium chloride tower in the dark, put 600 g of 30% butyl acetate solution of [A-8] and 0.18 g of hydroquinone monomethyl ether. It was. While stirring at a temperature of 40 ° C., a mixed solution containing 54.7 g of [B-1] and 23.4 g of butyl acetate was added dropwise little by little using a dropping funnel. After completion of dropping, stirring was continued for 2 hours to obtain a double bond-containing fluorine-containing copolymer.

The infrared absorption spectrum of the reaction solution was measured. As a result, it was confirmed that the absorption of isocyanate groups at 2,260 cm ⁻¹ disappeared completely. Thereby, it was confirmed that reaction of the hydroxyl group of [A-8] and the isocyanate group of [B-1] advanced.

The number average molecular weight measured by GPC of the obtained double bond-containing fluorine-containing copolymer was 1.9 × 10 ⁴ .

  The coating properties of the cured coating film of this copolymer were examined in the same manner as in Example 1. The results are shown in [Table 1].

[Comparative Example 2]
To the coating composition prepared in Comparative Example 1, 5% TSF410 (manufactured by Toshiba Silicone Co., Ltd.) was added to the solid content of the composition, and test pieces were prepared in the same manner as in the above Comparative Example. I investigated. The results are shown in [Table 1].

Claims (2)

15 to 85 mol% of fluoroolefin, 0.001 to 30 mol% of one or more organosilicon compounds selected from the following general formulas (1), (2), (3) and (4), and Reaction of hydroxyl group-containing fluorine-containing copolymer [A] composed of 1 to 50 mol% of a hydroxyl group-containing unsaturated ether represented by general formula (5) as a polymerization unit and unsaturated isocyanate [B] A fluorine-based varnish containing a double bond-containing fluorine-containing copolymer as a main component.

(Where R ¹ , R ² and R ³ are each a hydrogen atom, methyl group, ethyl group, butyl group, phenyl group, —CF ₃ , —C ₂ H ₄ CF ₃ , —C (CH ₃ ) ₃ or -OSi (CH ₃ ) ₃ is selected, R ¹ , R ² and R ³ may be the same or different.

(Here, R ⁴ represents a hydrogen atom or a methyl group, and R ⁵ represents —CO—O—, —O—, or —CH═CH—CH ₂ —O—CH ₂ —CH═CH—. R ⁶ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, n represents an integer of 0 to 10, and m represents an integer of 0 to 200.)

(Here, R ⁷ represents a hydrogen atom or a methyl group, and R ⁸ , R ⁹ and R ¹⁰ are each a hydrogen atom, a methyl group, an ethyl group, a butyl group, or —OSi (CH ₃ ) _3. R ⁸ , R ⁹ and R ¹⁰ may be the same or different, and p represents an integer of 0 to 10.)

(Here, R ¹¹ represents an alkylene group having 1 to 6 carbon atoms or a cyclohexylene group. R represents an integer of 0 to 10.)   The hydroxyl group-containing fluorine-containing copolymer [A] further comprises at least one polymer unit selected from alkyl vinyl ether, alkyl allyl ether, methacrylic acid ester and acrylic acid ester as a balance. The fluorinated varnish according to claim 1.