JP3521054B2 - Composition for powder coating - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a fluororesin-based powder coating composition.

[0002]

2. Description of the Related Art Conventionally, fluororesin paints utilizing the excellent weather resistance of fluorocopolymers have been industrialized. In particular, solvent-soluble fluorine-based copolymers having a curing site have been synthesized (for example, JP-A-57-34107 and JP-A-6-36107).
1-57609), and is widely applied as a weather-resistant paint in the fields of construction, automobiles, chemical industry and the like. The main component of these coating resins is a fluorine-based raw material such as chlorotrifluoroethylene, tetrafluoroethylene or vinylidene fluoride, and further a hydrocarbon-based monomer such as carboxylic acid vinyl ester or vinyl ether is copolymerized as a copolymerization component. Therefore, the solubility of the resin is increased.

On the other hand, water-based paints and powder paints using these fluororesins have been developed from the viewpoint of environmental friendliness. A particularly important issue in designing powder coatings is to raise the glass transition point so that blocking of powder particles does not occur during storage of the coating powder.
However, the conventional type fluororesin for paints, that is, the fluorine-based linear molecular chain, has a maximum temperature of about 55 ° C even if the glass transition point is devised to be increased by the monomer composition, and the glass transition point is further increased. It was difficult.

On the other hand, in the field of fluororesins for paints, research and development for carrying out a graft reaction on fluororesins from the viewpoints of their industrial economic efficiency, adhesion to a substrate, coating film hardness, etc. (see, for example, JP-A-59-59). 41315, JP-A-61-24
No. 7717, JP-A No. 62-295914), but when a fluorocarbon resin has a reactive double bond and the reactive double bond is used to copolymerize with a graft monomer. However, there have been problems to be solved such as gelation during polymerization, generation of many low-molecular weight substances not graft-bonded, multi-step reaction and insufficient economic merit. Also, examples of grafts of fluorine-containing acrylic resin (JP-A-61-43667 and JP-A-02-58513) have been reported, but they have drawbacks that the raw materials are expensive and the weather resistance is not sufficient. It was
Further, JP-A-58-206615 reports an example of graft polymerization in which a peroxy group is contained in a fluororesin, but a fluorine-containing compound is also used as a graft monomer, which is economically problematic. Was left.

Further, Japanese Patent Laid-Open No. 6-25595 discloses that
Graft resin obtained by graft-copolymerizing methyl methacrylate, ethyl acrylate and hydroxyethyl methacrylate to a vinylidene fluoride polymer having a peroxy group obtained by copolymerizing vinylidene fluoride and t-butylperoxyallyl carbonate Discloses a coating composition containing polyvinylidene fluoride, an acrylic resin and a solvent.

[0006]

DISCLOSURE OF THE INVENTION The present invention is directed to stain resistance, while maintaining the characteristics of a fluororesin coating having excellent weather resistance.
Provided are a fluorine-based graft resin and a powder coating composition which can form a coating film having high gloss and can prepare a coating material having excellent storage stability.

[0007]

Means for Solving the Problems The present inventors have studied a method for producing a fluororesin by copolymerizing various monomers with a fluoroolefin, and found that a peroxy group was previously formed in the fluorocopolymer. Introduced various functional groups to the introduced fluororesin by further graft-copolymerizing a polymerizable monomer with the peroxy group as a starting point,
The glass transition point can be easily increased, and the powder coating prepared by mixing the obtained graft copolymer with a curing agent has excellent storage stability and maintains the weather resistance which is a characteristic of fluororesin. The inventors have found that a stain resistant, high gloss coating film can be prepared, and completed the present invention.

That is, according to the present invention, 100 parts by weight of a fluorocopolymer [A] obtained by copolymerizing a fluoroolefin and a monomer having a peroxy group and 1 to 1 of the polymerizable monomer [B].
It has at least one functional group of a hydroxy group, a carboxyl group, a glycidyl group, an amino group or an alkoxysilyl group obtained by graft-polymerizing 300 parts by weight of the fluorine-based copolymer [A] using a peroxy group as a starting point. , Glass transition temperature of 56 ° C or higher and number average molecular weight of 15,000
It is a composition for powder coating, which is obtained by blending a curing agent [C] with the following fluorine-based graft resin and which contains substantially no organic solvent.

The invention will be described in detail below. In the fluoroolefin-based structural unit of the fluorine-based copolymer [A] according to the present invention, at least one hydrogen atom of ethylene is substituted with a fluorine atom, and optionally one to three other hydrogen atoms are halogen (fluorine). , Chlorine, bromine), fluoromethyl groups, difluoromethyl groups, trifluoromethyl groups, etc., and the fluoroolefins include, for example, chlorotrifluoroethylene, tetrafluoroethylene, vinylidene fluoride, fluorinated Vinyl, trifluoroethylene, hexafluoropropene, hexafluoroisobutene and the like can be mentioned, and chlorotrifluoroethylene and tetrafluoroethylene are particularly preferable. These may be used in combination of two or more. The copolymerization ratio of the fluoroolefin in the fluorocopolymer [A] is not necessarily limited,
Since the deterioration of weather resistance is not preferable, it is 20 mol% or more, preferably 40 mol% or more of the total amount of the monomers, and 70 mol% or less for ensuring surface fluidity during baking as a powder coating. It is preferably 60 mol% or less.

Examples of the peroxy group-containing monomer used in the fluorine-based copolymer [A] include various unsaturated peroxyesters or peroxycarbonates. Specifically, t-butylperoxymethacrylate, Di (t-butylperoxy) fumarate, t-
Butyl peroxy crotonate, t-butyl peroxy allyl carbonate, t-hexyl peroxy allyl carbonate, 1,1,3,3-tetramethylbutyl peroxy allyl carbonate, t-butyl peroxy methallyl carbonate, 1,1,3,3- Tetramethylbutyl peroxy methallyl carbonate, p-menthane peroxy allyl carbonate, p-menthane peroxy methallyl carbonate etc. are illustrated. The copolymerization ratio of these peroxy group-containing monomers in the fluorocopolymer [A] is not particularly limited, but it is preferably used in the range of 0.01 to 15 mol% of all the monomers. 0.01 mol%
If the amount is less than the above, the amount of the starting point of the graft is insufficient, and not only the graft reactivity is low, but also the thermal fluidity at the time of baking becomes poor due to the increase in the molecular weight. Again 15
If it exceeds mol%, the amount of starting points for grafting is too large.
It is not preferable because it may impair the weather resistance.

The other polymerizable monomer used in the fluorocopolymer [A] according to the present invention is not particularly limited, and vinyl carboxylate, vinyl ether, olefin, allyl ether and the like are preferably adopted. But,
Carboxylic acid vinyl ester is particularly preferred for maintaining compatibility with the graft portion. The carboxylic acid vinyl ester is specifically a vinyl ester of an alicyclic or aromatic carboxylic acid which may have a branched chain having 2 to 22 carbon atoms or which may have a substituent, such as acetic acid. Vinyl, vinyl propionate, vinyl butyrate, vinyl pivalate, vinyl caproate, vinyl caprylate, vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate, vinyl versatate 9 acid, vinyl versatate 10 acid, vinyl cyclohexanoate. , Vinyl benzoate, vinyl t-butyl benzoate and the like.

Examples of the vinyl ether include methyl vinyl ether, ethyl vinyl ether, butyl vinyl ether, cyclohexyl vinyl ether and the like, but any vinyl ether may be used as long as it has a reactive vinyl group in the molecule. Examples of the allyl ether include ethyl allyl ether, butyl allyl ether, benzyl allyl ether and cyclohexyl allyl ether, but the allyl ether is not limited to these and can be used.

The amount of these polymerizable monomers is preferably 10 to 70 mol% and more preferably 20 to 60 mol% based on the total amount of monomers which polymerize the fluorocopolymer [A]. preferable. If it is less than 20 mol%, the coating film forming ability when used as a powder coating, that is, the heat fluidity at the time of baking is inferior, and it is difficult to obtain gloss, and if it exceeds 70 mol%, a fluorine-based copolymer [ The weather resistance of the coating film of the powder coating material prepared from A] is unfavorable.

A monomer having a hydroxy group, a carboxyl group, a glycidyl group, an amino group, an alkoxysilyl group or another functional group as a comonomer for introducing a functional group into the fluorocopolymer [A]. You can use your body. The purpose of introducing these functional groups includes, for example, introducing a crosslinking site and changing the polarity to improve the compatibility with the curing agent.

The hydroxy group-containing monomer copolymerized in the fluorine-based copolymer [A] has 2 to 2 carbon atoms such as allyl alcohol, ethylene glycol monoallyl ether, propylene glycol monoallyl ether and hydroxybutyl allyl ether. Alkylene glycol monoallyl ethers having a C4-40 alkylene glycol group such as hydroxyalkyl allyl ethers having a hydroxyalkyl group of 8, diethylene glycol monoallyl ether, polyethylene glycol monoallyl ether, hydroxymethyl vinyl ether, hydroxyethyl vinyl ether , Hydroxybutyl vinyl ether, hydroxypentyl vinyl ether, hydroxyhexyl vinyl ether and other hydroxyalkyl vinyl ethers Polyethylene glycol monovinyl ether such as diethylene glycol monomethyl ether, and the like crotonic acid-modified compound such as crotonic acid hydroxyethyl. Of these, the above-mentioned hydroxyalkyl allyl ethers and alkylene glycol monoallyl ethers are particularly preferable. These hydroxy group-containing monomers are not essential as monomers for polymerizing the fluorine-based copolymer [A], but 30 mol% of all monomers for polymerizing the fluorine-based copolymer [A].
It is preferably used in the following amount, and more preferably 20 mol% or less. If it exceeds 30 mol%, the water resistance and weather resistance of the coating film prepared from the fluorocopolymer [A] will be low, which is not preferable. Further, when the hydroxy group-containing monomer is used, if it is less than 1 mol%, the effect of intentionally using cannot be obtained.

As the carboxyl group-containing monomer, an unsaturated aliphatic carboxylic acid having 2 to 12 carbon atoms, for example, an unsaturated carboxylic acid such as vinyl acetic acid, undecylenic acid, crotonic acid, acrylic acid or methacrylic acid is used. it can. The amount of these unsaturated carboxylic acids is preferably 20 mol% or less, more preferably 10 mol% or less, based on the total amount of the monomers that polymerize the fluorocopolymer [A]. If it exceeds 20 mol%, the weather resistance of the coating film prepared from the fluorine-based copolymer [A] becomes low, which is not preferable. When a carboxyl group-containing monomer is used, if it is less than 0.1 mol%, the effect of intentionally using it cannot be obtained.

As the glycidyl group-containing monomer,
It is not particularly limited as long as it is a polymerizable compound having an epoxy ring, but allyl glycidyl ether, vinyl glycidyl ether, glycidyl methacrylate, glycidyl acrylate and the like are preferably used. Further, a polymerizable compound having an alicyclic epoxy group can also be used. The amount of these epoxy group-containing monomers is preferably 30 mol% or less of all the monomers that polymerize the fluorocopolymer [A]. If it exceeds 30 mol%, a large amount of a curing agent is required and the weather resistance is impaired.

The amino group-containing monomer is not particularly limited as long as it is a polymerizable compound having an amino ring, but allylamine, acrylamide, methacrylamide, dimethylaminoethylmethacrylate, N-methylolacrylamide, methylenebisacrylamide. Are preferably adopted. The amount of these amino group-containing monomers is preferably 30 mol% or less of all the monomers that polymerize the fluorocopolymer [A]. When it exceeds 30 mol%, the yellowing of the coating film becomes remarkable, which is not preferable.

Further, a monomer having an alkoxysilyl group can be used in the fluorine-based copolymer [A], and specific examples thereof include vinyltrimethoxysilane, vinyltriethoxysilane and vinyltriisopropoxysilane. Examples thereof include vinylalkoxysilane, vinylmono (or di) alkoxysilane, and alkoxysilane-containing (meth) acrylic acid ester. The amount of these alkoxysilyl group-containing monomers is preferably 20 mol% or less of all the monomers that polymerize the fluorine-based copolymer [A]. Two
If it exceeds 0 mol%, the coating film may become too hard and may be easily cracked.

In the fluorine-based graft resin according to the present invention, the above-mentioned hydroxy group, carboxyl group, glycidyl group, amino group or alkoxysilyl group is contained in the fluorine-based copolymer [A] or the polymerizable monomer [B]. However, in order to improve weather resistance and develop flexibility, it is contained in both the fluorocopolymer [A] and the polymerizable monomer [B]. Is preferred.

Further, in the present invention, at least a part of the fluorocopolymer [A] and the polymerizable monomer [B] are modified with ε-caprolactone for the purpose of improving the compatibility with the graft part and the cross-linking property of the coating film. Vinyl ether, allyl ether, acrylic acid ester, methacrylic acid ester, β
Vinyl compounds having a ketoester group, allyl compounds,
Acrylic acid ester and methacrylic acid ester are preferably used. Specifically, -C (= O) (CH obtained by ring-opening addition of ε-caprolactone to a hydroxyalkyl group.
₂ ) Examples include ε-caprolactone-modified vinyl ether, allyl ether, and methacrylic acid ester having a ₅ O-group, and commercially available products include PLACEL manufactured by Daicel Chemical Industries. In this case, a compound containing a hydroxy group at the end can also be used.

As the vinyl compound or allyl compound having a β-ketoester group, allyl acetoacetate having a acetoacetoxy group [-OC (= O) CH ₂ C (= O) CH ₃ ] as a side chain, diacetone acrylamide, etc. Is preferably used. By introducing these polar monomers, the fluorine-based copolymer [A] has improved compatibility with the graft portion, and a coating film having high gloss and weather resistance can be obtained even if the fluorine content is high. Further, the use of a monomer containing a β-ketoester group makes it possible to use a metal alkoxide, a chelate-based curing agent, or a hydrazine-based compound as a curing agent.

Further, glycerin monoallyl ether, which has two hydroxy groups in the molecule and part of which is a secondary hydroxy group, can be used in a small amount and can introduce a high OH value. The group is preferably used because it has low reactivity at the time of curing and remains as a hydroxy group in the coating film, and it is effective in improving the stain resistance by making the surface of the coating film hydrophilic.

Solution polymerization, bulk polymerization, suspension polymerization, or emulsion polymerization can be used as the method for producing the fluorine-based copolymer [A] copolymerized with these monomers. Solvent solubilization is desirable for the reaction, and solution polymerization is preferred. Therefore, as the solvent at the time of polymerization, water, alcohol compounds such as methanol and isopropanol, and n-hexane,
Saturated hydrocarbon type such as n-heptane, aromatic hydrocarbon type such as toluene and xylene, fluorine type such as trichlorotrifluoroethane and dichlorotetrafluoroethane,
Acetone, methyl ethyl ketone, methyl isobutyl ketone, and other ketones, ethyl acetate, butyl acetate, and other ester systems, and petroleum-based solvents such as Mineral Spirit,
A terpene solvent can be used. Further, these may be used alone or in combination.

Examples of the radical initiator which can be used here include diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate and di-
Dicarbonates such as 2-ethylhexyl peroxydicarbonate, n-heptafluorobutyric peroxide, lauroyl peroxypivalate, t-
Diacyl peroxides such as butyloxy neodecanoate, alkyl peroxides such as di-t-butyl peroxide, t-butyl cumyl peroxide, t-butyl peroxypivalate, t-butyl peroxy neodecanoate Specific examples thereof include peroxyesters, etc., but it is necessary to select a radical initiator that decomposes at a temperature lower than that of the peroxy group copolymerized in the fluorocopolymer [A]. Furthermore, an azo initiator can be used without particular limitation.

On the other hand, in the graft reaction according to the present invention, the polymerizable monomer [B] is initiated with the radical as a starting point by decomposition of the peroxy group copolymerized in the fluorocopolymer [A].
Although the reaction form is not particularly limited, solution polymerization in the presence of a solvent-solubilized copolymer (fluorine-based copolymer [A]) and monomer [B] preferable. Therefore, for example, when the fluorine-based copolymer [A] is produced by solution polymerization, the polymerizable monomer [B] can be introduced into the reactor immediately after the polymerization and grafted, which simplifies the production. Great economic benefits of manufacturing. Further, it is a major feature that the graft polymerization proceeds even when a new polymerization initiator does not coexist.

The polymerizable monomer [B] according to the present invention is not particularly limited as long as it is a (meth) acrylic acid ester which is usually used in the production of acrylic resins, but has 1 to 22 carbon atoms.
An alkyl group which may have a branch, a cycloalkyl group which may have a substituent or an aromatic group and (meth)
Specific examples of suitable (meth) acrylic acid esters composed of an acryloyl group include methyl acrylate, ethyl acrylate, butyl acrylate, isobutyl acrylate, -tert-butyl acrylate, cyclohexyl acrylate, ethylhexyl acrylate. , Acrylic acid-n
-Octyl, isooctyl acrylate, nonyl acrylate, tridecyl acrylate, lauryl acrylate, benzyl acrylate (meth) acrylate, isobornyl, methyl methacrylate, ethyl methacrylate, butyl methacrylate, isobutyl methacrylate, methacrylic acid-te
Examples thereof include rt-butyl, cyclohexyl methacrylate, ethylhexyl methacrylate, -n-octyl methacrylate, isooctyl methacrylate, nonyl methacrylate, tridecyl methacrylate, lauryl methacrylate, benzyl methacrylate and isobornyl methacrylate.

Further, an ester of (meth) acrylic acid with a fluorine-containing alcohol represented by the general formula R _f --CH ₂ --OH (R _f represents a perfluoroalkyl group having 1 to 30 carbon atoms), for example, _{n-C 8 F 17 CH 2} -O-C (= O) CH
_{= CH 2, n-C 8} F 17 CH 2 -O-C (= O) C (-C
_{H 3) = CH 2, i} -C 3 F 6 CH-O-C (= O) CH =
_{CH 2, i-C 3 F} 6 CH-O-C (= O) C (-CH 3)
= Or CH _2, the general formula _{(CH 3) 3 Si- (O} -Si (C
Esters of H _{2) 2)} alcohol and (meth) acrylic acid represented by the n-OH (n is an integer), for example, (C
_{H 3) 3 Si- (O-} Si (CH 3) 2) n -, (CH 3) 3
_{Si- (O-Si (CH 3} ) 2) n- with having in the molecule (meth) may also be used acrylic acid ester, formed from these powder coating composition obtained to use The coating film has a feature of excellent water repellency.

Further, the polymerizable monomer [B] according to the present invention
The (meth) acrylic acid ester that can be used in the above may be a hydroxy group-containing (meth) acrylic acid ester, and may have a hydroxyalkyl group which may have a branched chain having 1 to 22 carbon atoms, a hydroxy group, and other substituents. A cycloalkyl group or aromatic group which may have and a (meth) acryloyl group, specifically, hydroxymethyl
Examples thereof include (meth) acrylate, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate and hydroxybutyl (meth) acrylate.

Further, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, methacryloxymethyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, methacrylic acid. Those having an alkoxysilyl group such as roxymethyltriethoxysilane and those having an epoxy group such as glycidyl (meth) acrylate can also be used.

Further, a compound having an ultraviolet absorbing group or a photostable group and an unsaturated bond in the molecule is used as a copolymerization component in either the fluorocopolymer [A] or the polymerizable monomer [B]. be able to. This is particularly used for the purpose of suppressing photodegradation of the graft chain and maintaining high weather resistance even when the fluorine content decreases. Specifically, a (meth) acrylic acid ester having a benzotriazole group as an ultraviolet absorbing group, for example, RUVA-93 manufactured by Otsuka Chemical, that is, 2- (2'-hydroxy-5'-methacryloxyethylphenyl) -2H-benzo. Triazole or the like can be used, but the chemical structure of the ultraviolet absorbing group is not particularly limited.
Further, as the compound having a photostable group, 2, 2, 6,
A (meth) acrylic acid ester having a hindered amine type substituent having a 6-tetramethylpiperidine skeleton is suitable, and examples thereof include HALS hybrid type monomers ADK STAB LA-82 and LA-87 manufactured by Asahi Denka Kogyo. .

As other copolymerizable monomers, acrylonitrile, styrene as an aromatic vinyl compound, ethylene, propylene and butene as an olefin can be used. In addition, monomers such as carboxylic acid vinyl ester and vinyl ether exemplified as the monomer usable in the fluorine-based copolymer [A] can also be used.

The other copolymerizable monomer may be a hydroxy group- or carboxyl group-containing monomer, and the hydroxy group exemplified as the polymerizable monomer usable in the fluorine-based copolymer [A]. Allyl ether and vinyl ether contained can also be used.

The polymerizable monomer [B] includes (meth) acrylic acid ester, hydroxy group-containing (meth) acrylic acid ester, carboxyl group-containing (meth) acrylic acid ester, glycidyl group-containing (meth) acrylic acid ester. Alternatively, it is preferable to use an alkoxysilyl group-containing (meth) acrylic acid ester in an amount of 50 mol% or more, and a copolymerizable monomer other than the (meth) acrylic acid ester may be used in combination therewith.

The amount of the polymerizable monomer [B] grafted is 1 to 3 parts by weight with respect to 100 parts by weight of the fluorocopolymer [A].
It is 00 parts by weight. If it is less than 1 part by weight, the glass transition point is 5
It is difficult to control the temperature to 6 ° C or higher, and it is difficult to obtain the effect of the graft such as economical efficiency, coating film hardness, and adhesion. If it exceeds 300 parts by weight, the graft reaction rate is lowered and the weather resistance and The coating strength decreases.

In the powder coating composition of the present invention, the polymerizable monomer [B] is added to a polymerization vessel preliminarily loaded with the fluorocopolymer [A] to prepare the fluorocopolymer [A]. The reaction proceeds only by raising the temperature required for the decomposition of the peroxy group contained in, but at this time, the polymerization solvent such as water or an organic solvent exemplified in the case of producing the fluorine-based copolymer [A] is used. You can add more. Further, a mercaptan-based compound may be appropriately added as a molecular weight modifier.

When the fluorine-based graft resin produced in this manner has a hydroxyl group, it has a hydroxy value of 10 to 180 mgKOH /
It is g. If it is less than 10 mgKOH / g, the number of cross-linking sites is small and the weather resistance of the coating film is insufficient. If it exceeds 180 mgKOH / g, the required curing agent is too much, and the weather resistance is not sufficient. In the case of a carboxyl group, the acid value is preferably in the range of 0.1 to 80 mgKOH / g. 0.1
If it is less than mgKOH / g, the pigment dispersibility and the crosslinkability are low and 80
If it exceeds mgKOH / g, the water resistance will decrease. When the fluorine-based graft resin contains an amino group, a glycidyl group or an alkoxysilyl group, the ratio of structural units based on these functional group-containing monomers is 1 to 1 of all structural units.
It is in the range of 45 mol%. At least one of these hydroxy group, carboxyl group, amino group, glycidyl group, and alkoxysilyl group is contained in at least one of the fluorine-based copolymer [A] and the polymerizable monomer [B] in the above-mentioned proportion. It may be included in both.

The glass transition point of the fluorine-based graft resin according to the present invention must be 56 ° C. or higher, preferably 60 ° C. or higher. The glass transition point of the present invention is measured by a differential scanning calorimeter which is a static condition, and corresponds to the most general and original meaning glass transition point. If the temperature is lower than 56 ° C., the thermal stability of the powder coating material is low and it cannot be stored for a long time. Generally, it is difficult to raise the glass transition point with a fluororesin for a coating having a linear molecular form, that is, a copolymer obtained by polymerizing a fluoroolefin and a polymerizable monomer in one step. Even if a component having a cyclo ring is used, it is difficult to exceed about 55 ° C. One of the purposes of preparing the fluorine-based graft resin according to the present invention is to make the glass transition point of the entire resin 56 ° C. or higher by utilizing the graft chain having a high glass transition point.

The molecular weight of the fluorine-based graft resin according to the present invention is 1,000 to 15,000 (number average molecular weight; styrene conversion). When it is less than 1,000, the weather resistance and flexibility of the coating film are deteriorated, and when it exceeds 15,000, the heat fluidity of the powder coating material is deteriorated and the surface property is deteriorated, which is not preferable. An even more preferable molecular weight range is 3,000.
~ 10,000. In order to achieve this molecular weight, it is preferable to polymerize the fluorine-based graft resin in an organic solvent. In that case, a method of evaporating the organic solvent used after the polymerization or separating and drying the solid matter by adding the reaction solution to the poor solvent, followed by drying is preferably used. Is not necessarily limited.

The fluororesin of the present invention is a blocked isocyanate, an acid anhydride, a melamine resin, a hydrazine compound,
Compounds that are solid at room temperature, such as amino resins, carboxyl group-containing compounds, and glycidyl compounds, are particularly preferable.

The blocked isocyanate is not particularly limited, but ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), dodecamethylene diisocyanate, 1,
6,11-undecane triisocyanate, 2,2,4
-Trimethylhexane diisocyanate, 2,6-diisocyanate methyl caproate (LDI), bis (2
-Isocyanate ethyl) fumarate, bis (2-isocyanate ethyl) carbonate, 2-isocyanate ethyl-2,6-diisocyanate hexanoate, isophorone diisocyanate (IPDI), 4,4'-diphenylmethane diisocyanate (MDI), dicyclohexylmethane diisocyanate ( Hydrogenated MDI), cyclohexylene diisocyanate, methyl cyclohexylene diisocyanate (hydrogenated TDI), bis (2-isocyanatoethyl) -4-cyclohexene-1,2-dicarboxylate, xylylene diisocyanate (XD)
1), polyisocyanates such as diethylbenzene diisocyanate and toluene diisocyanate (TDI), and isocyanate groups such as dimers, trimers and polyhydric alcohol modified polyisocyanates of ε-caprolactam, phenol, benzyl alcohol, methyl ethyl ketoxime, etc. The compound blocked with the blocking agent is mentioned.

Further, aliphatic dibasic acids such as fumaric acid, succinic acid, adipic acid, azelaic acid, sebacic acid and dodecanedioic acid, acid anhydrides such as phthalic anhydride, trimellitic anhydride and pyromellitic anhydride, Polyester resin or acrylic resin having multiple carboxyl groups in the molecule,
Examples thereof include dicyandiamide and its derivative, imidazole and its derivative, dibasic acid dihydrazide, diaminophenylmethane, and amine compounds such as cyclic amidine compounds.

Further, as the melamine resin, melamine,
Condensates obtained by reacting an amino group-containing compound such as urea, acetoguanamine, benzoguanamine, steroguanamine or spiroguanamine with aldehydes such as formaldehyde, paraformaldehyde, acetaldehyde or glyoxazole by a conventional method or a condensate thereof is an alcohol. Examples thereof include those in which at least a part of them is etherified.

Further, glycidyl compounds such as terephthalic acid diglycidyl ester, paraoxybenzoic acid diglycidyl ester, triglycidyl isocyanurate, spiroglycol diglycidyl ether, hydantoin compound, and alicyclic epoxy resin, 1.4-bis (2'- (Hydroxyethoxy) benzene, bishydroxyethyl terephthalate, and other hydroxy-containing resins.

Further, an acrylic resin having a carboxyl group, a glycidyl group or the like in the molecule, a fluororesin or the like can also be used as a curing agent. The powder coating composition of the present invention contains a curing agent in the range of 1 to 200 parts by weight with respect to 100 parts by weight of the fluorine-based graft resin. If it is less than 1 part by weight, the effect of curing due to crosslinking is not exerted and the strength of the coating film is lowered.

The powder coating composition of the present invention or the powder coating composition containing the composition can be produced by a known thermosetting powder coating method. For example, the fluorine-based graft resin solution obtained in the present invention is distilled under reduced pressure to remove an organic solvent or water, and a miller type, a vibration mill type, an impact hammer mill, a rotary cutter type, a cage type, or any other crusher. After crushing with, hardener, pigment, leveling agent, reaction catalyst, UV absorber,
A heat deterioration inhibitor, foaming and other additives are blended, temporarily mixed with a Henschel mixer, etc., and then the mixed powder is kneaded with an extrusion molding machine to form pellets, and again by pulverizing with the above method. A powder coating composition or powder coating can be prepared.

The coating composition prepared by adding a curing agent to a powder to prepare a coating composition is uniformly coated by a conventional powder coating machine such as electrostatic powder coating or fluidized dipping method, and then baked by heat treatment. A coating film can be formed. This gives a crosslinked coating film that is tough and has excellent weather resistance.

The powder coating composition of the present invention can be made into a paint like ordinary powder resins, and pigments and dyes can be added as appropriate. Agents, rust preventives, dispersants, anti-sagging agents, fungicides, leveling agents, heat deterioration inhibitors, foam inhibitors, metal powders and the like can also be added.

In the case of coating, other resins such as fluorine-based polyols, other fluorine-containing resins having alkoxysilane, acrylic silicone, acrylic-based polyols,
Polyvinyl ester, silicone compound, polyalkylene glycol, alkyd resin, wax, polytetrafluoroethylene resin and the like can be added as appropriate.

The present invention will be specifically described below with reference to examples, but the embodiments of the present invention are not limited to these. In the examples, "parts" means "parts by weight" unless otherwise noted.

[0051]

【Example】

Production Example 1 500 g of toluene and 19 vinyl pivalate were placed in an autoclave made of SUS and equipped with a magnetic stirrer and having an internal capacity of 3.5 liters.
3 g (25 mol% of the fluorinated copolymer [A] component), 88 g of versatic vinyl acetate 9 (fluorinated copolymer [A]
8 mol% of the component), ethylene glycol monoallyl ether 92 g (15 mol% of the fluorine-based copolymer [A] component), t-butylperoxyallyl carbonate 10 g
(1 mol% of the fluorinated copolymer [A] component), 11 g of undecylenic acid (1 mol% of the fluorinated copolymer [A] component), 5 g of t-butylperoxypivalate, 4 g of sodium carbonate, After degassing with nitrogen gas was repeated 3 times to degas, 350 g of chlorotrifluoroethylene
(50 mol% of the fluorinated copolymer [A] component) was charged, the unreacted monomer was degassed under reduced pressure after polymerizing at 60 ° C. for 10 hours, and about 600 g of the fluorinated copolymer as a resin solid content was obtained. [A] was obtained.

Next, the autoclave containing the toluene solution of the fluorine-based copolymer [A] after polymerization was heated to 105 ° C., 350 g of methyl methacrylate, 150 g of cyclohexyl methacrylate, 50 g of n-butyl methacrylate, and methacrylic acid. Hydroxyethyl 45g, methacrylic acid 3
g, toluene 600 g, and t-dodecyl mercaptan 0.1 g were added over about 2 hours, and the reaction was continued for another 4 hours, and then the contents were taken out and filtered to give a transparent fluorine-based solid having a solid content of about 50%. A graft resin varnish was obtained. The fluorine-based graft resin varnish was evaporated under reduced pressure with an evaporator at 80 ° C. and concentrated to 80%, followed by vacuum distillation at room temperature for 2 hours and further vacuum distillation at 60 ° C. for 10 hours to obtain a product. The solid matter was roughly crushed with a cutter mill. Further, the coarse powder was subjected to vibration fluidization drying under reduced pressure at 50 ° C. to obtain a fluorine-based graft resin powder substantially free of volatile components. The hydroxy value and acid value, glass transition point, and number average molecular weight of the obtained resin are shown in Table 1.

Production Examples 2 to 5 and Comparative Production Example In the same manner as in Production Example 1, polymerization was carried out with the monomer composition shown in Table 1. In each case, after the polymerization was completed, the contents were taken out and filtered to obtain a transparent fluorine-based graft resin varnish having a solid content of about 50%. Then, in the same manner as in Production Example 1, a fluorine-based graft resin powder was obtained. The hydroxy value and acid value, glass transition point, and number average molecular weight of the obtained resin are shown in Table 1.

[0054]

[Table 1]

CTFE Chlorotrifluoroethylene TFE Tetrafluoroethylene VPv Vinyl pivalate V9 Versatic vinyl 9-pentate CHVE Cyclohexyl vinyl ether EGMAE Ethylene glycol monoallyl ether HBVE Hydroxybutyl vinyl ether UA Undecylenic acid AGE Allyl glycidyl ether PAC t-Butyl peroxyallyl carbonate MMA Methacryl Methyl acid CHMA Cyclohexyl methacrylate nBMA n-Butyl methacrylate HEMA Hydroxyethyl methacrylate MA GMA glycidyl methacrylate AK-5 Toa Gosei Chemical Co., Ltd. Silicone group-containing methacrylic acid ester FMA 2- (perfluorooctyl) ethyl methacrylate MPTMS γ-methacryloxypropyltrimethoxysilane Nippon Unicar A174 LA82 Metastabilizer containing light stable groups (HALS) manufactured by Asahi Denka Co., Ltd. Phosphoric acid ester Tg Glass transition point ° C OH value mgKOH / resin solid content 1 g Acid value mgKOH / resin solid content 1 g Epoxy equivalent g / equiv Examples 1 to 6, Comparative Examples 1 and 2, Manufacturing Examples 1 to 6 and Comparative Manufacturing Examples The fluorine-based graft resin, the pigment, and the curing agent obtained in Nos. 1 and 2 were mixed in the types and composition ratios (parts) shown in Table 2, and uniformly mixed for about 3 minutes using a Henschel mixer, and then Toyo Seiki Seisakusho Lab. The mixture was extruded and kneaded at about 100 ° C. using a plastomill. 180 after cooling using hammer type impact crusher and cutter mill
The powder was pulverized into a powder or less to obtain a powder coating.

Next, the obtained powder coating material was applied using an electrostatic coating machine and baked at 180 ° C. for 20 minutes. The film thickness of the obtained coating film was about 45 microns in each case. An iron plate was used as the base material after being subjected to chromate treatment and zinc phosphate treatment. The coating film after baking was subjected to 60-degree gloss measurement, rubbing test, accelerated weather resistance test, and stain resistance test. The results are shown in Table 2. Further, the powder coating material was placed in a stainless steel vat and allowed to stand still at 55 ° C. for 1 month, and the solidification state of the powder was observed. The coatings of each example showed good results in each test. In each of the comparative examples, the storage stability, 60-degree gloss and stain resistance were poor.

[0057]

[Table 2]

TiO2 Teika JR805 VPLS2122 Sumitomo Bayer Urethane Block Isocyanate VB1065 Hurus Block Isocyanate Vestag
on B1065 Dodecanedioic acid Wako Pure Chemical Industries PL1175 Cyanamid amino resin Powderlink11
75 ADH Otsuka Chemical's adipic acid dihydrazide <55 ° C storage stability> The powder coating was placed in a stainless steel vat and allowed to stand at 55 ° C for 1 month, after which the powder was observed for solidification. ○ No abnormality, × Caking between particles.

<60 degree gloss measurement> The 60 degree specular gloss of the baked coating film is measured. <Rubbing test> A xylene rubbing test of a baked coating film. The surface was wiped off with absorbent cotton soaked with xylene. Observe the surface condition after 50 round trips at the same location. ○ indicates no abnormality.

<Weather resistance test> An acceleration test was carried out for 5000 hours using a sunshine weatherometer.
The gloss retention rate is displayed in%.

<Staining resistance test> Kerosene in which carbon is dispersed is dropped, and after 24 hours, a wiping test is carried out. ○ Carbon fell. × Carbon remains.

[0062]

The fluorine-based graft resin according to the present invention has a high glass transition point because the (meth) acrylic resin is efficiently grafted onto the trunk made of the fluorine resin.
Powder coating composition of the present invention prepared therefrom and /
Further, since the powder coating material has excellent storage stability, it can be stored for a long period of time, and when a coating film is formed, a coating film having good smoothness and high gloss can be obtained.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kentaro Tsutsumi 2805 Imafuku Nakadai, Kawagoe-shi, Saitama Central Chemical Co., Ltd. (56) Reference JP-A-6-25595 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C09D 151/00-151/06 C08L 51/00-51/06

Claims (12)

(57) [Claims] 1. A fluorine-based copolymer [A] 10 obtained by copolymerizing a fluoroolefin and a monomer having a peroxy group.
Hydroxy group, carboxyl group, glycidyl group, amino obtained by graft polymerization of 0 part by weight and 1 to 300 parts by weight of the polymerizable monomer [B] with the peroxy group of the fluorocopolymer [A] as a starting point. Group or a fluorosilyl group having at least one functional group selected from alkoxysilyl groups, having a glass transition point of 56 ° C. or higher and a number average molecular weight of 15,000 or lower, and a curing agent [C]. A composition for powder coating which is substantially free of an organic solvent. 2. A fluorocopolymer [A] is a copolymer obtained by copolymerizing a fluoroolefin, a peroxy group-containing allyl compound and a vinyl carboxylate, wherein the fluoroolefin is 20 to 70 mol%. The powder coating composition according to claim 1, wherein the peroxy group-containing allyl compound is 0.01 to 15 mol% and the carboxylic acid vinyl ester is 10 to 70 mol%. 3. A fluorocopolymer [A] is a copolymer obtained by copolymerizing a fluoroolefin, a peroxy group-containing allyl compound, a carboxylic acid vinyl ester, a hydroxy group-containing allyl compound and an unsaturated carboxylic acid. Therefore, fluoroolefin 20 to 70 mol%, peroxy group-containing allyl compound 0.01 to 15 mol%, carboxylic acid vinyl ester 10 to 70 mol%, hydroxy group containing allyl compound 1 to 30 mol%, unsaturated carboxylic acid 0 The composition for powder coating according to claim 1, wherein the composition is 1 to 20 mol%. 4. A fluorocopolymer [A] is a copolymer obtained by copolymerizing a fluoroolefin, a peroxy group-containing allyl compound, a carboxylic acid vinyl ester, and a glycidyl group-containing allyl compound, wherein the fluoroolefin is a fluoroolefin. Two
0-70 mol%, peroxy group-containing allyl compound 0.0
1 to 15 mol%, carboxylic acid vinyl ester 10 to 70
Mol%, glycidyl group-containing allyl compound 1 to 30 mol%
The composition for powder coating according to claim 1, wherein 5. The polymerizable monomer [B] is a (meth) acrylic acid ester, a hydroxy group-containing (meth) acrylic acid ester, a carboxyl group-containing (meth) acrylic acid ester,
Consists of one or more monomers selected from glycidyl group-containing (meth) acrylic acid ester and alkoxysilyl group-containing (meth) acrylic acid ester and optionally 0 to 50 mol% of other copolymerizable monomer The composition for powder coating according to any one of claims 1 to 4, wherein 6. The powder coating composition according to claim 1, wherein either the fluorocopolymer [A] or the polymerizable monomer [B] has a β-ketoester group. 7. A fluorine-based copolymer [A] or a polymerizable monomer [B] is a dimethylsiloxane group,-(Si.
(CH _{3) 2} -O) - claim 1, characterized in that it comprises a
The composition for powder coating according to 5 above. 8. A fluorine-based copolymer [A] or a polymerizable monomer [B] derived from ε-caprolactone-C.
(= O) (CH ₂₎ powder coating composition of claims 1 to 5, wherein the having ₅ O-group. 9. The composition for powder coating according to claim 1, wherein either the fluorocopolymer [A] or the polymerizable monomer [B] has a trifluoromethyl group. . 10. The powder according to claim 1, wherein either the fluorocopolymer [A] or the polymerizable monomer [B] has an ultraviolet absorbing group or a photostable group. Paint composition. 11. The powder according to claim 1, wherein the curing agent [C] is a blocked isocyanate, an acid anhydride, an amine compound, a melamine resin, a hydrazine compound, a glycidyl compound, or a carboxylic acid-containing compound which is solid at room temperature. Composition for body paint. 12. The powder coating composition according to claim 1, wherein 1 to 200 parts by weight of the curing agent [C] is mixed with 100 parts by weight of the fluorine-based graft resin.