WO2018008421A1 - Powder coating composition, coating film, and coated article - Google Patents

Abstract

Provided is a powder coating composition which generates no bubbles during coating-film formation and is capable of forming coating films having excellent adhesion to the substrates. The powder coating composition is characterized by containing a polymer that includes a vinylidene fluoride unit and has, at a main-chain terminal, at least one terminal group selected from the group consisting of -CONH₂ and -COOH groups.

Description

Powder paint, coating film and coated article

The present invention relates to a powder coating material, a coating film, and a coated article.

The fluororesin is excellent in heat resistance, chemical resistance, and weather resistance, and has excellent properties such that the surface of the molded product or coating film is non-adhesive and has a small coefficient of friction. On the other hand, since it is difficult to adhere to other materials, attempts have been made to improve adhesiveness by introducing a functional group into the fluororesin.

For example, Patent Document 1 discloses a cyclic hydrocarbon monomer having a repeating unit (a) based on tetrafluoroethylene and / or chlorotrifluoroethylene, a dicarboxylic anhydride group, and a polymerizable unsaturated group in the ring. Containing a repeating unit (b) based on the repeating unit (b) and other monomer (excluding tetrafluoroethylene, chlorotrifluoroethylene and the cyclic hydrocarbon monomer), the repeating unit (a) and the repeating unit The repeating unit (a) is 50 to 99.89 mol% and the repeating unit (b) is 0.01 to 5 mol% based on the total molar amount of (b) and the repeating unit (c). a unit (c) is from 0.1 to 49.99 mol%, the fluorine-containing, wherein the volume flow rate is 0.1 ~ 1000 mm ³ / sec Polymers have been described.

Patent Document 2 discloses a fluorine-containing ethylene having a carbonate group or a carboxylic acid halide group at a polymer chain terminal or a side chain, and the number of these groups is 150 or more with respect to 1 × 10 ⁶ carbon atoms in the main chain. A fluorine-containing adhesive material made of a conductive polymer is described.

Patent Document 3 discloses a binder containing a fluorine-containing polymer, wherein the fluorine-containing polymer is a polymer unit based on vinylidene fluoride and an amide group (—CO—NRR ′ (R and R ′ are the same). Or differently, each represents a hydrogen atom or an optionally substituted alkyl group.)) Or an amide bond (—CO—NR ″ — (R ″ represents a hydrogen atom, an optionally substituted alkyl). A binder having a polymerization unit based on a monomer having a group or a substituent, and having a solution viscosity of 10 to 20,000 mPa · s. Is described.

Patent Document 4 contains a repeating unit (A) based on tetrafluoroethylene, a repeating unit (B) based on ethylene, and a repeating unit (C2) based on a monomer having an acid anhydride group and a polymerizable unsaturated bond. Reactive fluorine-containing polymer containing powder (X) made of reactive fluorine-containing polymer, powder (Y) made of adhesive resin, and fluorine-containing dispersion medium (Z) having a boiling point of 50 to 200 ° C. Fluorine-containing dispersion medium having a powder (Y) content of 1 to 30 parts by mass and a boiling point of 50 to 200 ° C. (100 parts by mass of the polymer powder (X)) A primer composition is described in which the content of Z) is 20 to 500 mass.

JP 2006-152234 A International Publication No. 99/45044 JP 2013-2119016 A JP2015-134865A

An object of this invention is to provide the powder coating material which does not produce foam at the time of coating-film formation, and can form the coating film excellent in adhesiveness with a base material. In addition, the present invention provides a coated film having a good appearance and excellent adhesion of the substrate, and a coated article having a good appearance of the coated film and having the substrate and the coated film firmly adhered to each other. The purpose is to do.

The present invention relates to a powder coating material comprising a polymer containing vinylidene fluoride units and having at least one terminal group selected from the group consisting of —CONH ₂ groups and —COOH groups at the ends of the main chain. It is.

The polymer preferably has 50 or more end groups per 10 ⁶ main chain carbon atoms of the polymer.

The polymer contains a vinylidene fluoride unit and a tetrafluoroethylene unit, the vinylidene fluoride unit is 10.0 to 98.0 mol% of the total monomer units constituting the polymer, and the tetrafluoroethylene unit is the above It is preferably 2.0 to 90.0 mol% of all monomer units constituting the polymer.

This invention is also a coating film characterized by being formed from the above-mentioned powder coating material.

The present invention is also a coated article comprising a substrate and a coating film of the above-described powder coating material provided on the substrate.

The powder coating material of the present invention does not cause foaming when forming a coating film, and can form a coating film having excellent adhesion to a substrate. The coating film of the present invention has a good appearance and high adhesion to the substrate. The coated article of the present invention has a good appearance of the coating film, and the substrate and the coating film are firmly adhered.

Hereinafter, the present invention will be specifically described.

The powder coating material of the present invention comprises a polymer containing vinylidene fluoride units and having at least one terminal group selected from the group consisting of —CONH ₂ group and —COOH group at the main chain terminal. To do. The relationship between the presence of these end groups and the adhesion of the polymer containing the vinylidene fluoride unit is a finding found by the present inventors. In the case of a polymer that does not contain vinylidene fluoride units, even if these end groups are included, no significant improvement in adhesion as in the case of polymers containing vinylidene fluoride units is observed.

When —CONH ₂ group is present at the end of the main chain, a peak derived from —NHH of —CONH ₂ group appears at an absorption wavelength of 3400 to 3470 cm ⁻¹ in the infrared spectrum of the polymer obtained by infrared absorption spectrum analysis. . By confirming the presence of this peak, it can be confirmed that a —CONH ₂ group is present at the end of the main chain.

Further, when a —COOH group is present at the end of the main chain, a peak derived from C═O of the —COOH group appears at an absorption wavelength of 1700 to 1780 cm ⁻¹ in the infrared spectrum of the polymer obtained by infrared absorption spectrum analysis. . By confirming the presence of this peak, it can be confirmed that a —COOH group is present at the end of the main chain.

The polymer preferably has 50 or more end groups per 10 ⁶ main chain carbon atoms of the polymer. The number of end groups is more preferably 80 or more. The upper limit is not particularly limited, and all of the ends of the main chain may be the above-mentioned end groups, but may be 10,000, preferably 1000.

Among the terminal groups, the number of —CONH ₂ groups appears at 2900 to 3100 cm ⁻¹ due to CH ₂ groups of the main chain in the infrared absorption spectrum obtained by performing infrared spectrum analysis on a film having a thickness of 200 μm. The absorbance of the peak is normalized to 1.0, and the absorbance A of the peak due to the NH bond of the terminal NH ₂ group appearing in the vicinity of 3400 to 3470 cm ^{−1 of the} spectrum is obtained and calculated by the following formula. In the present specification, when a peak due to an NH bond is not detected, it is assumed that the polymer does not have a —CONH ₂ group.
Number of —CONH ₂ groups per 10 ⁶ main chain carbon atoms = 4258 × A

Of the above terminal groups, the number of —COOH groups is 2900 to 3100 cm ⁻¹ due to the CH ₂ group of the main chain in the obtained infrared absorption spectrum by performing infrared spectrum analysis on a film having a thickness of 200 μm. The absorbance of the peak that appears is normalized to 1.0, and the absorbance A of the peak due to the C═O bond of the terminal COOH group that appears in the vicinity of 1700 to 1780 cm ^{−1 of the} spectrum is obtained and calculated by the following equation. In the present specification, when a peak due to a C═O bond is not detected, it is assumed that the polymer does not have a —COOH group.
Number of —COOH groups per 10 ⁶ main chain carbon atoms = 4057 × A

In order to obtain good adhesion, the polymer preferably has 0 to 40 —OCOOR groups at the end of the main chain per 10 ⁶ main chain carbon atoms, more preferably 0 to 20 units. 0 is more preferable.

R in the —OCOOR group is preferably a linear or branched alkyl group, and the alkyl group may have 1 to 15 carbon atoms.

The number of —OCOOR groups was determined by performing infrared spectrum analysis on a film having a thickness of 200 μm, and measuring the absorbance of a peak appearing at 2900-3100 cm ⁻¹ due to the CH ₂ group of the main chain in the obtained infrared absorption spectrum at 1.0 The absorbance A of the peak (1780 to 1830 cm ⁻¹ ) due to the —OCOOR group appearing in the spectrum is obtained, and calculated by the following formula.
Number of —OCOOR groups per 10 ⁶ main chain carbon atoms = 1265 × A

The polymer contains vinylidene fluoride units. In the above polymer, the vinylidene fluoride unit is preferably 10.0 to 100 mol%, more preferably 10.0 to 98.0 mol% of the total monomer units constituting the fluororesin, More preferably, it is 0.0 to 95.0 mol%.

Since the said polymer can form the coating film which is excellent in heat resistance, it is preferable that a tetrafluoroethylene unit is included further. In this case, vinylidene fluoride units are 10.0 to 98.0 mol% of all monomer units constituting the polymer, and tetrafluoroethylene units are 2.0 to 90% of all monomer units constituting the polymer. It is preferably 0.0 mol%. More preferably, the vinylidene fluoride unit is 15.0 to 95.0 mol% of all monomer units constituting the polymer, and the tetrafluoroethylene unit is 5.0 to 5.0% of all monomer units constituting the polymer. 85.0 mol%.

The polymer further includes a tetrafluoroethylene unit and at least one ethylenically unsaturated monomer unit selected from the group consisting of ethylenically unsaturated monomers represented by formula (1) and formula (2). It is preferable.
The polymer is at least one ethylenically unsaturated group selected from the group consisting of vinylidene fluoride units, tetrafluoroethylene units, and ethylenically unsaturated monomers represented by formula (1) and formula (2). A monomer unit, the vinylidene fluoride unit is 10.0 to 98.0 mol% of the total monomer unit constituting the polymer, and the tetrafluoroethylene unit is 2.0% of the total monomer unit constituting the polymer. The ethylenically unsaturated monomer unit may be 0 to 5.0 mol% of the total monomer units constituting the polymer.
More preferably, the vinylidene fluoride unit is 15.0 to 90.0 mol% of all monomer units constituting the polymer, and the tetrafluoroethylene unit is 5.0 to 9% of all monomer units constituting the polymer. 85.0 mol%, and the ethylenically unsaturated monomer unit is 0 to 5.0 mol% of the total monomer units constituting the polymer.

Formula (1): CX ¹¹ X ¹² = CX ¹³ (CX ¹⁴ X ¹⁵ ) _n11 X ¹⁶
(Wherein X ¹¹ to X ¹⁶ are the same or different and each represents H, F or Cl, and n11 represents an integer of 0 to 8, except for tetrafluoroethylene and vinylidene fluoride)

Formula (2): CX ²¹ X ²² = CX ²³ -O (CX ²⁴ X ²⁵ ) _n21 X ²⁶
(Wherein X ²¹ to X ²⁶ are the same or different and each represents H, F or Cl, and n21 represents an integer of 0 to 8)

Examples of the ethylenically unsaturated monomer represented by the formula (1) include CF ₂ = CFCl, CF ₂ = CFCF ₃ , and the following formula (3):
CH ₂ = CF- (CF ₂ ) _n11 X ¹⁶ (3)
(Wherein X ¹⁶ and n11 are the same as above) and the following formula (4):
CH ₂ = CH- (CF ₂ ) _n11 X ¹⁶ (4)
(In the formula, X ¹⁶ and n 11 are the same as above.)
It is preferably at least one selected from the group consisting of: CF ₂ = CFCl, CH ₂ = CFCF ₃ , CH ₂ = CH-C ₄ F ₉ , CH ₂ = CH-C ₆ F ₁₃ , CH ₂ = More preferably, it is at least one selected from the group consisting of CF—C ₃ F ₆ H and CF ₂ ═CFCF ₃ , CF ₂ ═CFCl, CH ₂ ═CH—C ₆ F ₁₃ , CH ₂ ═CF— More preferably, it is at least one selected from C ₃ F ₆ H and CH ₂ ═CFCF ₃ .

The ethylenically unsaturated monomer represented by the formula _(2), the group consisting of _{CF 2 = CF-OCF 3,} CF 2 = CF-OCF 2 CF 3 and _{CF 2 = CF-OCF 2 CF} 2 CF 3 It is preferable that it is at least one selected from more.

When the polymer further has a tetrafluoroethylene unit and the ethylenically unsaturated monomer, the vinylidene fluoride unit is 10.0 to 97.9 mol% of the total monomer units constituting the polymer, and the tetrafluoroethylene The unit is 2.0 to 89.9 mol% of the total monomer unit constituting the polymer, and the ethylenically unsaturated monomer unit is 0.1 to 5.0 mol% of the total monomer unit constituting the polymer. It may be. Preferably, vinylidene fluoride units are 10.0 to 49.9 mol% of all monomer units constituting the polymer, and tetrafluoroethylene units are 50.0 to 85% of all monomer units constituting the polymer. 0.0 mol%, and the ethylenically unsaturated monomer unit is 0.1 to 5.0 mol% of the total monomer units constituting the polymer. More preferably, the vinylidene fluoride unit is 15.0 to 49.9 mol% of the total monomer units constituting the polymer, and the tetrafluoroethylene unit is 50.0% to the total monomer units of the polymer. 70.0 mol%, and the ethylenically unsaturated monomer unit is 0.1 to 5.0 mol% of the total monomer units constituting the polymer.

The polymer is
55.0-90.0 mol% tetrafluoroethylene,
5.0 to 49.9 mol% vinylidene fluoride, and
0.1 to 10.0 mol% of an ethylenically unsaturated monomer represented by the formula (1),
It is preferable that the polymer contains a copolymer unit.

More preferably,
55.0-85.0 mol% tetrafluoroethylene,
10.0-44.9 mol% vinylidene fluoride, and
0.1 to 5.0 mol% of an ethylenically unsaturated monomer represented by the formula (1),
It is a polymer containing the copolymerization unit.

More preferably,
55.0-85.0 mol% tetrafluoroethylene,
13.0-44.9 mol% vinylidene fluoride, and
0.1 to 2.0 mol% of an ethylenically unsaturated monomer represented by the formula (1),
It is a polymer containing the copolymerization unit.

In addition to improving the mechanical strength of the polymer at a high temperature, the low permeability of the polymer is particularly excellent, so that the ethylenically unsaturated monomer represented by the formula (1) is CH ₂ = It is preferably at least one monomer selected from the group consisting of CH—C ₄ F ₉ , CH ₂ ═CH—C ₆ F ₁₃ and CH ₂ ═CF—C ₃ F ₆ H. More preferably, the ethylenically unsaturated monomer represented by formula (1) is CH ₂ ═CH—C ₄ F ₉ , CH ₂ ═CH—C ₆ F ₁₃ and CH ₂ ═CF—C ₃ F ₆ H. And at least one monomer selected from the group consisting of:
55.0-80.0 mol% tetrafluoroethylene,
19.5 to 44.9 mol% vinylidene fluoride, and
0.1 to 0.6 mol% of an ethylenically unsaturated monomer represented by the formula (1),
It is a polymer containing the copolymerization unit of.

The above polymer contains 58.0 to 85.0 mol% tetrafluoroethylene,
10.0-41.9 mol% vinylidene fluoride, and
0.1 to 5.0 mol% of an ethylenically unsaturated monomer represented by the formula (1),
It may be a polymer containing the copolymerized unit.

The polymer is
55.0-90.0 mol% tetrafluoroethylene,
9.2-44.2 mol% vinylidene fluoride, and
A polymer containing 0.1 to 0.8 mol% of an ethylenically unsaturated monomer represented by the formula (2) and a copolymer unit is also preferred.

More preferably,
58.0-85.0 mol% tetrafluoroethylene,
14.5 to 39.9 mol% vinylidene fluoride, and
0.1 to 0.5 mol% of an ethylenically unsaturated monomer represented by the formula (2),
It is a polymer containing the copolymerization unit.

The polymer is
55.0-90.0 mol% tetrafluoroethylene,
5.0-44.8 mol% vinylidene fluoride,
0.1 to 10.0 mol% of an ethylenically unsaturated monomer represented by the formula (1), and
0.1 to 0.8 mol% of an ethylenically unsaturated monomer represented by the formula (2),
It is also preferable that the polymer contains a copolymer unit.

More preferably,
55.0-85.0 mol% tetrafluoroethylene,
9.5 to 44.8 mol% vinylidene fluoride,
0.1 to 5.0 mol% of an ethylenically unsaturated monomer represented by the formula (1), and
0.1 to 0.5 mol% of an ethylenically unsaturated monomer represented by the formula (2),
It is a polymer containing the copolymerization unit.

More preferably 55.0-80.0 mol% tetrafluoroethylene,
19.8-44.8 mol% vinylidene fluoride,
0.1 to 2.0 mol% of an ethylenically unsaturated monomer represented by the formula (1), and
0.1 to 0.3 mol% of an ethylenically unsaturated monomer represented by the formula (2),
It is a polymer containing the copolymerization unit. When the polymer has this composition, it is particularly excellent in low permeability.

The polymer is
58.0-85.0 mol% tetrafluoroethylene,
9.5-39.8 mol% vinylidene fluoride,
0.1 to 5.0 mol% of an ethylenically unsaturated monomer represented by the formula (1), and
0.1 to 0.5 mol% of an ethylenically unsaturated monomer represented by the formula (2),
It may be a polymer containing the copolymerized unit.

When the content of each monomer is within the above range, the polymer is excellent in mechanical strength, chemical resistance and low permeability at high temperatures. The low permeability at a high temperature is, for example, low permeability to methane, hydrogen sulfide, CO ₂ , methanol, hydrochloric acid and the like.

The content of each monomer in the polymer can be calculated by appropriately combining NMR and elemental analysis depending on the type of monomer.

The polymer preferably has a melt flow rate (MFR) of 0.1 to 100 g / 10 min, and more preferably 1 to 50 g / 10 min since higher adhesion can be obtained. More preferably, it is / 10 min.

The above MFR is based on ASTM D3307-01, using a melt indexer (manufactured by Toyo Seiki Co., Ltd.), and the mass (g / 10 min) of the polymer flowing out per 10 minutes from a nozzle having an inner diameter of 2 mm and a length of 8 mm. is there. The temperature and load at the time of measurement can be selected according to the melting point of the polymer.
In particular, the MFR is a value measured at 265 ° C. under a 5 kg load when the melting point of the polymer is 200 ° C. or higher.
In particular, the MFR is a value measured under a load of 230 ° C. and 2.16 kg when the melting point of the polymer is 140 ° C. or higher and lower than 200 ° C.

The polymer is preferably a fluororesin. The polymer preferably has a melting point of 140 ° C. or higher, and the upper limit may be 290 ° C. A more preferred lower limit is 150 ° C., and an upper limit is 270 ° C.

The melting point is measured by using a differential scanning calorimeter RDC220 (manufactured by Seiko Instruments) according to ASTM D-4591 at a heating rate of 10 ° C./min, and the temperature corresponding to the peak of the endothermic curve obtained is measured. The melting point.

The polymer preferably has a thermal decomposition starting temperature (1% mass loss temperature) of 360 ° C. or higher. A more preferred lower limit is 370 ° C., and a more preferred lower limit is 380 ° C. If the said thermal decomposition start temperature is in the said range, an upper limit can be 410 degreeC, for example.

The thermal decomposition starting temperature is a temperature at which 1% by mass of the polymer subjected to the heating test is decomposed, and the mass of the polymer subjected to the heating test using a differential thermal / thermogravimetric measuring apparatus [TG-DTA] is This is a value obtained by measuring the temperature when the mass decreases by 1% by mass.

The polymer can be produced by a production method including a step of obtaining a polymer by polymerizing vinylidene fluoride in the presence of a polymerization initiator and a step of amidating the polymer. This production method is suitable for producing a polymer having a —CONH ₂ group at the end of the main chain.

The amidation treatment can be performed by bringing the polymer obtained by polymerization into contact with ammonia water, ammonia gas, or a nitrogen compound capable of generating ammonia.

By adding ammonia water to the polymer obtained by polymerization, the polymer before treatment can be brought into contact with ammonia water. As the ammonia water, one having an ammonia concentration of 0.01 to 28% by mass can be used, and the contact time can be 1 minute to 24 hours. The number of —CONH ₂ groups can be adjusted by adjusting the concentration of ammonia water and the contact time.

Examples of the method for bringing the polymer before treatment into contact with ammonia gas include a method in which the polymer before treatment is placed in a reaction vessel and ammonia gas is supplied into the reaction vessel. The supply of ammonia gas into the reaction vessel may be performed after mixing with a gas inert to amidation to form a mixed gas.

The gas inert to the amidation is not particularly limited, and examples thereof include nitrogen gas, argon gas, and helium gas. The ammonia gas is preferably 1% by mass or more of the mixed gas, more preferably 10% by mass or more, and may be 80% by mass or less as long as it is within the above range.

The amidation treatment is preferably performed at 0 ° C. or more and 100 ° C. or less, more preferably 5 ° C. or more, further preferably 10 ° C. or more, more preferably 90 ° C. or less, and further preferably 80 ° C. or less. It is. If the temperature is too high, the polymer may be decomposed or fused, and if it is too low, the treatment may take a long time, which is not preferable in terms of productivity.

The duration of the amidation treatment is usually about 1 minute to 24 hours, although it depends on the amount of polymer.

The amidation treatment is preferably carried out so that the ratio of the —CONH ₂ group of the polymer after the amidation treatment to the —OCOOR group of the polymer before the amidation treatment is 25% or more. . The ratio is more preferably 50% or more, further preferably 60% or more, particularly preferably 80% or more, and may be 100%.

The polymer can also be produced by a production method comprising a step of obtaining a polymer by polymerizing vinylidene fluoride in the presence of a polymerization initiator and a step of bringing the polymer into contact with sodium hydroxide. This production method is suitable for producing a polymer having a —COOH group at the end of the main chain.

By adding an aqueous sodium hydroxide solution to the polymer obtained by polymerization, the polymer before treatment can be brought into contact with sodium hydroxide. As the sodium hydroxide aqueous solution, one having a sodium hydroxide concentration of 1 mol% can be used, and the contact time may be 1 minute to 12 hours. The number of —COOH groups can be adjusted by adjusting the concentration of sodium hydroxide aqueous solution and the contact time.

The contact with the sodium hydroxide is preferably performed at 0 ° C. or more and 200 ° C. or less, more preferably 5 ° C. or more, still more preferably 10 ° C. or more, more preferably 90 ° C. or less, still more preferably It is 80 degrees C or less. If the temperature is too high, the polymer may be decomposed or fused, and if it is too low, the treatment may take a long time, which is not preferable in terms of productivity.

The treatment with sodium hydroxide is preferably carried out so that the ratio of the —COOH group of the polymer after the treatment to the —OCOOR group of the polymer before the treatment is 25% or more. The ratio is more preferably 50% or more, further preferably 60% or more, particularly preferably 80% or more, and may be 100%.

The polymerization of the vinylidene fluoride may be solution polymerization, bulk polymerization, emulsion polymerization, suspension polymerization, etc., but emulsion polymerization or suspension polymerization is preferable from the viewpoint of easy industrial implementation, and suspension polymerization. Is more preferable.

As the polymerization initiator, an oil-soluble radical polymerization initiator or a water-soluble radical polymerization initiator can be used, but an oil-soluble radical polymerization initiator is preferable.

The oil-soluble radical polymerization initiator may be a known oil-soluble peroxide such as dialkyl peroxydicarbonate, di-n-propylperoxydicarbonate, disec-butylperoxydicarbonate, etc. Peroxycarbonates, peroxyesters such as t-butylperoxyisobutyrate and t-butylperoxypivalate, dialkyl peroxides such as di-t-butylperoxide, and the like are also used as di (ω-hydro -Dodecafluoroheptanoyl) peroxide, di (ω-hydro-tetradecafluoroheptanoyl) peroxide, di (ω-hydro-hexadecafluorononanoyl) peroxide, di (perfluorobutyryl) peroxide, di (Perful Valeryl) Par Xide, di (perfluorohexanoyl) peroxide, di (perfluoroheptanoyl) peroxide, di (perfluorooctanoyl) peroxide, di (perfluorononanoyl) peroxide, di (ω-chloro-hexafluoro) Butyryl) peroxide, di (ω-chloro-decafluorohexanoyl) peroxide, di (ω-chloro-tetradecafluorooctanoyl) peroxide, ω-hydro-dodecafluoroheptanoyl-ω-hydrohexadecafluoro Nonanoyl-peroxide, ω-chloro-hexafluorobutyryl-ω-chloro-decafluorohexanoyl-peroxide, ω-hydrododecafluoroheptanoyl-perfluorobutyryl-peroxide, di (dichloropentafluorobutanoy ) Peroxide, di (trichlorooctafluorohexanoyl) peroxide, di (tetrachloroundecafluorooctanoyl) peroxide, di (pentachlorotetradecafluorodecanoyl) peroxide, di (undecachlorodotriacontafluoro) Representative examples include di [perfluoro (or fluorochloro) acyl] peroxides of docosanoyl) peroxide.

The water-soluble radical polymerization initiator may be a known water-soluble peroxide, for example, ammonium salts such as persulfuric acid, perboric acid, perchloric acid, perphosphoric acid, percarbonate, potassium salts, sodium salts. , T-butyl permalate, t-butyl hydroperoxide and the like. A reducing agent such as sulfites and sulfites may be used in combination with the peroxide, and the amount used may be 0.1 to 20 times that of the peroxide.

The oil-soluble radical polymerization initiator is preferably a dialkyl peroxycarbonate, and is selected from the group consisting of diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, and disec-butyl peroxydicarbonate. At least one is preferred.

In the above polymerization, a surfactant, a chain transfer agent, and a solvent can be used, and conventionally known ones can be used.

As the surfactant, a known surfactant can be used. For example, a nonionic surfactant, an anionic surfactant, a cationic surfactant, or the like can be used. Of these, fluorine-containing anionic surfactants are preferred, and may contain ether-bonded oxygen (that is, oxygen atoms may be inserted between carbon atoms), or are linear or branched having 4 to 20 carbon atoms. A fluorine-containing anionic surfactant is more preferable. The addition amount (with respect to polymerization water) is preferably 50 to 5000 ppm.

Examples of the chain transfer agent include hydrocarbons such as ethane, isopentane, n-hexane, and cyclohexane; aromatics such as toluene and xylene; ketones such as acetone; acetates such as ethyl acetate and butyl acetate; Examples include alcohols such as methanol and ethanol; mercaptans such as methyl mercaptan; halogenated hydrocarbons such as carbon tetrachloride, chloroform, methylene chloride, and methyl chloride. The addition amount may vary depending on the size of the chain transfer constant of the compound used, but is usually used in the range of 0.01 to 20% by mass with respect to the polymerization solvent.

Examples of the solvent include water, a mixed solvent of water and alcohol, and the like.

In the suspension polymerization, a fluorine-based solvent may be used in addition to water. Examples of the fluorine-based solvent include hydrochlorofluoroalkanes such as CH ₃ CClF ₂ , CH ₃ CCl ₂ F, CF ₃ CF ₂ CCl ₂ H, CF ₂ ClCF ₂ CFHCl; CF ₂ ClCFClCF ₂ CF ₃ , CF ₃ CFClCFClCF _3, etc. Perfluoroalkanes such as perfluorocyclobutane, CF ₃ CF ₂ CF ₂ CF ₃ , CF ₃ CF ₂ CF ₂ CF ₂ CF ₃ , CF ₃ CF ₂ CF ₂ CF ₂ CF ₂ CF ₃ , etc. Among them, perfluoroalkanes are preferable. The amount of the fluorine-based solvent used is preferably 10 to 100% by mass with respect to the aqueous medium from the viewpoint of suspendability and economy.

The polymerization temperature is not particularly limited, and may be 0 to 100 ° C. The polymerization pressure is appropriately determined according to other polymerization conditions such as the type, amount and vapor pressure of the solvent to be used, and the polymerization temperature, but it may usually be 0 to 9.8 MPaG.

The powder coating is densified under the condition that the specific gravity of 90% or more of the true specific gravity (specific gravity of the melt-formed product) is obtained by using a roll or the like with the raw powder of the polymer obtained by the polymerization method. After pulverization, fine particles and fibrous particles in the range of 3 to 40% by mass of the entire particle size distribution of the pulverized product are removed by airflow classification, and coarse particles of 1 to 20% by mass of the entire particle size distribution of the pulverized product are further classified. It is desirable to manufacture by the method of removing. Further, it is more desirable to heat-treat at a temperature higher than the melting start temperature of the polymer after classification of the coarse particles.

First, the raw powder of the polymer is compressed into a sheet using a roll or the like under a condition that 90% or more, preferably 95 to 99% of the true specific gravity is obtained. When the specific gravity after compression is less than 90% of the true specific gravity, the apparent density of the particles obtained after pulverization is low and the fluidity is poor. When the specific gravity after compression exceeds 99% of the true specific gravity, the particles obtained after pulverization have a non-uniform shape, and the apparent density is low and the fluidity is poor.

In forming a sheet with a roll, the sheet thickness is set to 0.05 to 5 mm, preferably 0.1 to 3 mm. The roll to be used is preferably one in which two or more rolls are arranged in a vertical type, an inverted L type, a Z type, and the like, and specifically includes a calendar roll, a mixing roll, a roller compactor, and the like. When such a roll is used, a strong shearing force is applied to the polymer bulk powder during sheeting, and pores and bubbles present in the bulk powder can be removed to obtain a uniform sheet. . It is preferable to produce the sheet under the condition of milky white or transparent at a temperature of 0 to 250 ° C., preferably 5 to 150 ° C.

In general, the sheet is pulverized by a pulverizer after pulverizing so that the average particle diameter becomes 0.1 to 10 mm by a pulverizer.

Crushing is performed by fixing a screen or a mesh having a hole having a size of a pulverized particle size and crushing it, or by crushing by passing several rolls having grooves or undulations, and averaging. The particle size is preferably 0.1 to 10 mm.

The pulverization is generally performed by a mechanical pulverizer. The mechanical pulverizer includes an impact type such as a cutter mill, a hammer mill, a pin mill, and a jet mill, and a grinding type in which the rotary blade and the outer peripheral stator are pulverized by a shearing force caused by unevenness. As the pulverizer, a high shearing method is preferable from the viewpoint of pulverization efficiency. The grinding temperature is -200 to 100 ° C. In the freeze pulverization, the temperature is usually -200 to -100 ° C, but may be pulverized at room temperature (10 to 30 ° C). Liquid nitrogen is generally used for freeze pulverization, but the equipment is enormous and the pulverization cost is high. It is appropriate to grind at room temperature (10 ° C.) to 100 ° C., preferably at a temperature close to room temperature (10 ° C. to 30 ° C.) in that the process becomes simple and the grinding cost can be reduced. The obtained powder particles are not in a non-uniform form such as fine particle aggregates or pellets, but have a uniform particle size distribution, and the average particle size is 5 to 100 μm.

Fine particles and fibrous particles may be removed by classification, and coarse particles may be further removed by classification.

Airflow classification may be used for classification. In the airflow classification, the pulverized particles are sent to a cylindrical classification chamber by reduced-pressure air, dispersed by a swirling airflow in the room, and fine particles are classified by centrifugal force. The fine particles are collected from the center to a cyclone and a bag filter and formed into a sheet again. In the classification chamber, a rotating body such as a conical cone or a rotor is installed so that the pulverized particles and the air can perform a swirl motion uniformly.

A classification cone may be used for classification. When using a classification cone, the classification point is adjusted by adjusting the air volume of the secondary air and the gap between the classification cones. When using a rotor, adjust the air volume in the classification chamber according to the number of rotations of the rotor. The wind pressure of the blower is 0.1 to 1 MPa, preferably 0.3 to 0.6 MPa. The classification range is 3 to 40% by mass, preferably 5 to 30% by mass, and 3 to 40% by mass of fine particles and fibrous particles are removed. When the fine particles to be removed are less than 3% by mass, the fluidity of the powder cannot be improved, and the leveling property of the formed film is inferior because the particle size distribution is extremely wide. On the other hand, if the fine particles to be removed exceed 40% by mass, it is not suitable in terms of cost.

Examples of the method for removing coarse particles include airflow classification, vibration sieve, ultrasonic sieve, and the like. The classification range depending on the particle size is 1 to 20% by mass, preferably 2 to 10% by mass of the entire particle size distribution of the pulverized product, and coarse particles in this range are removed.

Fine particles and fibrous particles recovered in the airflow classification can be formed into a sheet again in the same manner as the raw powder. The coarse particles classified in the airflow classification or the vibration sieve can be returned to the pulverizer and pulverized again.

When the classified powder is momentarily brought into contact with an air flow that is equal to or higher than the melting start temperature of the above polymer using a continuous air flow heating dryer, the powder particle surface becomes rounded, the apparent density and the powder flow The properties can be further improved, and a preferable powder coating can be obtained.

The contact temperature of continuous air flow type heat drying is 1000 ° C. or less, preferably 200 to 800 ° C., and the contact time is 0.1 to 10 seconds. As the heat source, gas heating is preferable in terms of energy saving. The heat-treated powder can be further removed by classifying coarse particles with an air flow sieve or a vibrating sieve to obtain a powder coating material having a narrow particle size distribution.

The powder coating material preferably has an average particle size of powder particles of 10 to 1000 μm. When the thickness is less than 10 μm, electrostatic coating tends to be difficult, and when it exceeds 1000 μm, the smoothness when used in rotrining tends to deteriorate. The average particle size of the powder particles is determined by the purpose, and is generally 20 to 40 μm in the case of a thin coating powder coating having a dry film thickness of 100 μm or less. In the case of a thick coating powder coating 40 to 80 μm is preferable, and in the case of a powder coating for lotioning, 200 to 500 μm is preferable. The average particle diameter is a value obtained by measurement with a laser diffraction particle size distribution measuring apparatus. As the average particle diameter, a volume-based median diameter measurement value can be cited using a Microtrac MT3300EXII particle size analyzer manufactured by Nikkiso Co., Ltd.

The powder coating material of this invention may contain other resins other than the said polymer as needed. The other resins are not particularly limited as long as they can be used for powder coatings, and may be either thermoplastic resins or thermosetting resins. The other resin is preferably a heat-resistant resin, and more preferably one that does not decompose at the heating temperature when the powder coating material is applied. Examples of the heat resistant resin include silicone resin, fluorosilicone resin, polyamide resin, polyamideimide resin, polyimide resin, polyester resin, epoxy resin, polyphenylene sulfide resin, phenol resin, acrylic resin, and polyethersulfone resin. . One or more of the other resins may be used.

The powder coating material of this invention may contain an additive etc. with the said polymer as needed. The additive is not particularly limited as long as it is added to a general powder coating material. For example, for the purpose of coloring, coloring pigments such as titanium oxide and cobalt oxide; Other pigments such as pigments and calcined pigments; for the purpose of reducing the shrinkage rate of the film, and for improving the hardness of the film and improving the scratch resistance, such as carbon fiber, glass fiber, glass flake, mica, etc. Filler; For the purpose of imparting conductivity, a conductivity imparting material such as conductive carbon may be used. The additive may also be a leveling agent, antistatic agent, ultraviolet absorber, radical scavenger and the like.

This invention is also a coating film characterized by being formed from the above-mentioned powder coating material. Since the said coating film is formed from the above-mentioned powder coating material, it shows very excellent adhesion.

The present invention is also a coated article comprising a substrate and a coating film of the above-described powder coating material provided on the substrate. A primer layer may be provided between the base material and the coating film. However, since the coating film is excellent in adhesion, the base material and the coating film can be directly adhered with sufficient adhesion. Is possible.

The substrate is preferably made of metal, ceramic, resin or glass.

The metal is not particularly limited, and examples thereof include iron; stainless steel such as SUS304, SUS316L, and SUS403; aluminum; plated steel plate that has been subjected to zinc plating, aluminum plating, and the like. The ceramic is not particularly limited as long as it has heat resistance, and examples thereof include ceramics, porcelain, alumina material, zirconia material, and silicon oxide material. Examples of the resin include silicone resin, fluorosilicone resin, polyamide resin, polyamideimide resin, polyimide resin, polyester resin, epoxy resin, polyphenylene sulfide resin, phenol resin, acrylic resin, and polyethersulfone resin.

The base material is not particularly limited as long as it is generally desired to form a lining with a polymer. For example, a base material that is desired to impart corrosion resistance is suitable. Such substrates include, for example, tanks, vessels, towers, valves, pumps, fittings, other piping materials and other anticorrosive linings; chemical / medical instruments, wafer baskets, coil bobbin tower packing, chemicals And other anticorrosive materials such as valves and pump impellers.

The base material may be subjected to cleaning, roughening, or the like as pretreatment as necessary. The pretreatment includes, for example, removal of oil from the base material by solvent, cleaning agent, baking off, etc .; chemical etching using hydrochloric acid, sulfuric acid, alkali, etc .; blasting treatment using silica sand, alumina powder, etc. For example, the removal of oxides on the surface of the substrate by means of the above, the provision of irregularities for increasing the surface area, and the like. Moreover, after blasting, it is also possible to coat a material such as ceramic by spraying and to coat it.

The coated article can be produced by applying the powder coating described above on the substrate, drying as necessary, and then firing to form the coating film.

The method for applying the above-mentioned powder coating is not particularly limited, and examples thereof include spraying, electrostatic spraying, electrostatic spray coating, fluidized immersion coating, electrostatic fluidized immersion coating, and a rotational training method.

The calcination is not particularly limited as long as the temperature is higher than the melting point, softening point or glass transition point of the polymer and does not cause decomposition of the polymer. Run for 60 minutes. When the above-mentioned powder coating is applied by rotrining, the coating film is formed and baked at the same time.

The coating film preferably has a film thickness after firing of 100 to 10,000 μm. When the thickness is less than 100 μm, the excellent properties of the polymer may not be sufficiently exhibited. When the thickness exceeds 10,000 μm, cracks or the like may occur. A more preferred upper limit is 5000 μm.

The powder coating material of the present invention can be used in rice cookers, pots, hot plates, irons, frying pans, home bakery, etc. for home appliances / kitchen relations, and for industrial use, rolls for OA equipment, belts for OA equipment, It is widely applied to mold release applications such as paper rolls, calender rolls for film production, injection molds, etc .; and corrosion resistance applications such as stirring blades, tank inner surfaces, vessels, towers, and centrifuges.

The use of the coated article of the present invention is not particularly limited, for example, coating materials for various electric wires such as heat-resistant enamel wires; information equipment parts (paper separation claw, printer guide, gear, bearing), connector, vernier socket, IC sockets, oil field electrical components, relays, electromagnetic shielding, relay cases, switches, covers, terminal board buses and other electrical / electronic industry related applications; valve seats, hydraulic seals, backup rings, piston rings, wear bands, vanes, Ball bearing retainer, roller, cam, gear, bearing, labyrinth seal, pump part, mechanical linkage, bushing, fastener, spline liner, bracket, hydraulic piston, chemical pump casing, valve, valve, tower packing, coil bobbin, packing, Connector, gas Machine industry related applications such as valve seals, thrust washers, seal rings, gears, bearings, tappets, engine parts (pistons, piston rings, valve steers), transmission parts (spool valves, ball check valves, sealing), Applications related to the vehicle industry such as rocker arms; jet engine parts (bushings, washers, spacers, nuts), power control clutches, bearings for door hinges, connectors, tube clamps, brackets, hydraulic parts, antennas, radomes, frames, fuel system parts, Compressor parts, rocket engine parts, wearstrips, connector shelves, space structures and other aviation and space industry related applications. In addition, there are applications such as iron making machine pin covers, plating equipment parts, nuclear power related parts, ultrasonic transducers, potentiometer shafts, faucet parts and the like.

Examples of the use of the coated article of the present invention include stirring blades, tank inner surfaces, vessels, towers, centrifuges, pumps, valves, piping, ventilation holes, ducts, heat exchangers, plating jigs, tank lorry inner surfaces, screw conveyors, etc. Corrosion-resistant applications; semiconductor-related applications such as semiconductor factory ducts; industrial mold release applications such as OA rolls, OA belts, papermaking rolls, film production calendar rolls, injection molds; rice cookers, pots, hot plates, irons, frying pans , Home bakery, pan tray, gas table top plate, pan top plate, pan, pot, and other household appliances and kitchen-related applications; precision mechanism sliding members including various gears, papermaking rolls, calendar rolls, mold release parts, casings, valves , Valves, packing, coil bobbins, oil seals, joints, antenna caps, connectors, gaskets , Valve seals, buried bolts, industrial parts related applications such as built-in nut and the like.

Next, the present invention will be described with reference to examples, but the present invention is not limited to such examples.

Examples 1, 2, 4 and 5
Polymer powders having the compositions shown in Table 1 were reacted by contacting with ammonia water (amidation treatment). By changing the concentration of ammonia water, the reaction temperature, and the reaction time, the reaction was carried out so that the number of —CONH ₂ groups became the number shown in Table 1. The following evaluation was performed about the powder coating material containing the obtained polymer. The results are shown in Table 1.

Example 3
Polymer powder having the composition shown in Table 1 was allowed to react with an aqueous sodium hydroxide solution. The following evaluation was performed about the powder coating material containing the obtained polymer. The results are shown in Table 1.

In each comparative example, a powder coating material was prepared from a known polymer. The following evaluation was performed about the powder coating material containing the obtained polymer. The results are shown in Table 1.

Polymer composition The polymer before contact with aqueous ammonia or aqueous sodium hydroxide was subjected to ¹⁹ F-NMR using a nuclear magnetic resonance apparatus AC300 (manufactured by Bruker-Biospin) at a measurement temperature of (polymer melting point + 20) ° C. Measurement was performed, and an integral value of each peak and an elemental analysis were appropriately combined depending on the type of monomer.

Using a melting point differential scanning calorimeter RDC220 (manufactured by Seiko Instruments), heat measurement was performed at a heating rate of 10 ° C./min in accordance with ASTM D-4591, and the melting point was obtained from the peak of the obtained endothermic curve. .

Melt flow rate [MFR]
MFR conforms to ASTM D3307-01, and uses a melt indexer (manufactured by Toyo Seiki Co., Ltd.) under the following conditions, the mass of the polymer flowing out from a nozzle having an inner diameter of 2 mm and a length of 8 mm per 10 minutes (g / 10 Min) was defined as MFR.
Polymer having a melting point of 200 ° C. or higher: 265 ° C., 5 kg load Polymer having a melting point of 140 ° C. or higher and lower than 200 ° C .: 230 ° C., 2.16 kg load

A piece of each powder (or pellet) of -CONH _2- group polymer was compression-molded at room temperature to prepare a film having a thickness of 200 μm (± 5 μm). Infrared spectral analysis of these films was performed. The obtained IR spectrum was analyzed by scanning 128 times using Perkin-Elmer Spectrum Ver3.0, and the absorbance of the peak was measured.
The film thickness was measured with a micrometer.
In the obtained infrared absorption spectrum, the absorbance of the peak appearing at 2900 to 3100 cm ⁻¹ due to the CH ₂ group of the main chain was normalized to 1.0.
The absorbance of the peak due to the NH bond of the —CONH ₂ group appearing in the vicinity of 3400 to 3470 cm ^{−1 of the} spectrum is determined. The baseline is automatically determined, and the peak height A is obtained as the peak absorbance. Using the absorbance A of a peak derived from -CONH ₂ group, the following equation to determine the number of -CONH ₂ groups having 10 per ⁶ carbon atoms (number).
Number of —CONH ₂ groups per 10 ⁶ carbon atoms = K × A
A: Absorbance of peak derived from -CONH ₂ group K: Coefficient 4258

A piece of each powder (or pellet) of the —COOH group number polymer was compression molded at room temperature to prepare a film having a thickness of 200 μm (± 5 μm). Infrared spectral analysis of these films was performed. The obtained IR spectrum was analyzed by scanning 128 times using Perkin-Elmer Spectrum Ver3.0, and the absorbance of the peak was measured.
The film thickness was measured with a micrometer.
In the obtained infrared absorption spectrum, the absorbance of the peak appearing at 2900 to 3100 cm ⁻¹ due to the CH ₂ group of the main chain was normalized to 1.0.
The absorbance of the peak due to the C═O bond of the —COOH group appearing in the vicinity of 1700 to 1780 cm ^{−1 of the} spectrum is determined. The baseline is automatically determined, and the peak height A is obtained as the peak absorbance. Using the absorbance A of the peak derived from —COOH group, the number (number) of —COOH groups per 10 ⁶ carbon atoms is obtained by the following formula.
Number of —COOH groups per 10 ⁶ carbon atoms = K × A
A: Absorbance of peak derived from —COOH group K: Coefficient 4057

A piece of each powder (or pellet) of a number polymer of —OCOOR groups was compression-molded at room temperature to prepare a film having a thickness of 200 μm (± 5 μm). Infrared spectral analysis of these films was performed. The obtained IR spectrum was analyzed by scanning 128 times using Perkin-Elmer Spectrum Ver3.0, and the absorbance of the peak was measured.
The film thickness was measured with a micrometer.
In the obtained infrared absorption spectrum, the absorbance of the peak appearing at 2900 to 3100 cm ⁻¹ due to the CH ₂ group of the main chain was normalized to 1.0.
The absorbance of the peak due to the C═O bond of the —OCOOR group appearing in the vicinity of 1780 to 1830 cm ^{−1 of the} spectrum is determined. The baseline is automatically determined, and the peak height A is obtained as the peak absorbance. Using the absorbance A of a peak derived from -OCOOR group, the following equation to determine the number of -OCOOR group having 10 per ⁶ carbon atoms (number).
Number of —OCOOR groups per 10 ⁶ carbon atoms = K × A
A: Absorbance of peak derived from —OCOOR group K: coefficient 1265

Confirmation of film bubbles (visual)
A predetermined amount of powder coating material is placed on a SUS304 substrate (width 5 × height 10 × thickness 0.1 cm) (the weight is set so that the thickness after firing is 1 mm), and the firing conditions described in Table 1 The foaming state of the coating film obtained by baking with was confirmed.
○: Air bubbles ×: No air bubbles

90 degree peel test (adhesion)
A 1 cm wide cut was made in the coating film, and the 90-degree peel strength was measured with Tensilon (manufactured by Orientec).

Explanation of abbreviations listed in Table 1 TFE: Tetrafluoroethylene VDF: Vinylidene fluoride HFP: Hexafluoropropylene (CF ₂ = CFCF ₃ )
Unsaturated monomer: CH ₂ ═CH—C ₆ F ₁₃
* 1: Almost all of the ends of the main chain are —CONH ₂ groups. * 2: Almost all of the ends of the main chain are —CF ₂ H groups—: Not measured

Claims (5)

A powder coating material comprising a polymer containing a vinylidene fluoride unit and having at least one terminal group selected from the group consisting of a -CONH ₂ group and a -COOH group at a main chain terminal. The powder coating material according to claim 1, wherein the polymer has 50 or more terminal groups per 10 ⁶ main chain carbon atoms of the polymer. The polymer includes a vinylidene fluoride unit and a tetrafluoroethylene unit, and the vinylidene fluoride unit is 10.0 to 98.0 mol% of the total monomer units constituting the polymer, and the tetrafluoroethylene unit is the above-mentioned The powder paint according to claim 1 or 2, wherein the content is 2.0 to 90.0 mol% of all monomer units constituting the polymer. A coating film formed from the powder coating material according to claim 1, 2 or 3. A coated article comprising: a base material; and a coating film of the powder coating material according to claim 1, 2 or 3 provided on the base material.