JPH09302274A - Thermosetting resin composition for powder coating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a thermosetting composition for powder coating excellent in various properties, especially yellowing resistance, of coating films, storage stability and in especially weathering resistance by adding a transesterification catalyst to fluoro copolymers each having specified groups. SOLUTION: This composition comprises a fluoro copolymer (A) having carboxylic ester groups and having a softening point of about 70 to about 150 deg.C and a fluorine content of 7wt.% or above, a fluoro copolymer (B) having hydroxyl groups and having a fluorine content of 7wt.% or above and a transesterification catalyst (C) and having a total fluorine content of copolymers A and B of 12% or above. An example of copolymer A is a copolymer consisting essentially of a fluorovinyl monomer, a dialkyl unsaturated dicarboxylate and vinyl ether and/or a vinyl carboxylate. Component C is particularly desirably a sulfonic compound.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a new and useful thermosetting powder coating resin composition. More specifically, the present invention comprises a carboxylic acid alkyl ester group-containing fluorine-containing copolymer, a hydroxyl group-containing fluorine-containing copolymer, and an ester exchange catalyst. Crosslinking of the resin composition for a thermosetting powder coating for the purpose of a so-called transesterification reaction between an ester bond in an alkyl ester group and a piece or a hydroxyl group in a hydroxyl group-containing fluorocopolymer. The present invention relates to a resin composition for a thermosetting powder coating, which has a very high practicality and is used for curing, and particularly excellent in heat yellowing, storage stability and particularly weather resistance.

[0002]

2. Description of the Related Art Thermosetting powder coatings have been widely used in the industrial coating field due to the recent increase in pollution regulations and excellent coating performance, but anyway,
In the field of polyester-based powder coatings, the safety of block isocyanate compounds and epoxy compounds used as curing agents for powder coatings has been widely questioned.

In addition to these, such hardeners, in particular,
In the case of a blocked isocyanate compound, there is also a problem that the coating film tends to yellow when it is obtained when the powder coating material is cured at a high temperature in an actual baking oven.

In addition, in the acrylic powder coatings, a curing method using a glycidyl group-containing acrylic resin as a base resin and a polycarboxylic acid as a curing agent is mainly adopted. But these,
On the other hand, the reactivity between the base resin component and the curing agent component is high, but on the storage stability side, there is a problem.

Further, in recent years, there has been an increasing demand for improving the weather resistance of coating films in powder coating materials.
A method in which a fluororesin is used as a main component
However, even in the case of this method, since various known and commonly used curing agents are used as the curing agent to be used in combination with the main component, the above-mentioned baking Problems such as yellowing of coating film and storage stability are inevitable.

[0006] In addition, in order to obtain a coating film having sufficiently excellent weather resistance, it is necessary to increase the fluorine content of the main component fluororesin, but as the fluorine content increases, curing From problems such as compatibility with the agent, during kneading, mixing of the main agent and the curing agent is likely to be insufficient, and eventually, including the weather resistance of the obtained coating film,
That is, there is a possibility that the physical properties of the coating film may be deteriorated.

Therefore, the powder coating material or the resin composition for powder coating material itself is safe, and is resistant to yellowing during the crosslinking reaction, and in addition, it has excellent weather resistance.
The reality is that the development of new powder coatings is awaited.

Among these problems, the inventors of the present invention have already addressed the problems of yellowing of the coating film during baking and storage stability, and the present inventors have already proposed a specific solid resin containing a carboxylic acid alkyl ester group. And a specific hydroxyl group-containing compound, further,
By using a novel curing method of adding a transesterification catalyst, various physical properties of the coating film, among others, can be obtained without using a compound of a class which has been questioned for safety.
It has been found that a resin composition for a thermosetting powder coating having an extremely high practicality, which is excellent in coating film appearance, heat-resistant yellowing and storage stability, can be obtained.

However, even when the thermosetting resin composition for powder coating according to the present invention is used, the resulting coating film, especially the weather resistance, has a conventional acrylic resin composition for powder coating. Although it is not inferior to the products, it does not seem to be able to sufficiently meet the demand for higher weather resistance in the market, and further improvement in weather resistance, It is still required.

[0010]

However, the inventors of the present invention grapple, solve and solve various problems and drawbacks in the conventional techniques as described above, thereby improving safety in handling. There are no problems, the physical properties of the coating film,
Above all, the resin composition for thermosetting powder coatings has extremely high practicality, which is excellent in coating film appearance, heat yellowing resistance, and coating stability, and in particular, the coating film also has excellent weather resistance. In order to obtain the things, I started my research.

Therefore, the problem to be solved by the present invention is that there is no problem in safety in handling, and in addition to the physical properties of the coating film, especially the appearance of the coating film and heat yellowing, and the stability of the coating material. In addition to excellent properties, in particular, the coating film is very excellent in weather resistance, which is extremely practical,
It is to provide a thermosetting powder coating material, that is, a resin composition for powder coating material.

[0012]

Means for Solving the Problems Accordingly, the present inventors have:
As mentioned above, by solving and solving various drawbacks or problems in various conventional thermosetting powder coating materials,
In order to obtain a greatly improved powder coating material,
As a result of repeated studies, it was found that a desired and highly practical thermosetting powder coating can be provided.
Here, the present invention has been completed.

That is, according to the present invention, basically, a carboxylic acid alkyl ester group-containing fluorine-containing copolymer and a hydroxyl group-containing fluorine-containing copolymer are further coated with an ester exchange catalyst to form a coating solution. Membrane properties, especially
An attempt is made to provide a novel resin composition for thermosetting powder coatings, that is, a resin composition for thermosetting powder coatings, which is excellent in weather resistance, heat yellowing resistance, and storage stability. It is a thing.

Specifically, the softening point is about 70 to about 150 ° C.
Within a range of a specific carboxylic acid alkyl ester group-containing fluorocopolymer (A), a specific hydroxyl group-containing fluorocopolymer (B) and an ester exchange catalyst (C), and It is an object of the present invention to provide a resin composition for a thermosetting powder coating, which is extremely highly practical, in which the total fluorine content of the polymer (A) and the fluorine copolymer (B) is 12% by weight or more. To do.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION As described above, the present invention provides a carboxylic acid alkyl ester group-containing fluorocopolymer (A having a softening point of about 70 to about 150 ° C. and a fluorine content of 7% by weight or more). ), A fluorine-containing copolymer (B) having a fluorine content of 7% by weight or more, and an ester exchange catalyst (C), in addition, the above-mentioned fluorine-containing copolymer having a carboxylic acid alkyl ester group. Claimed is a resin composition for thermosetting powder coating, which comprises a total fluorine content of 12% by weight or more of (A) and the above-mentioned hydroxyl group-containing fluorocopolymer (B). Is something

As the above-mentioned fluorine-containing copolymer (A) containing a carboxylic acid alkyl ester group, in particular, a fluorine-containing vinyl monomer (a-1), an unsaturated dicarboxylic acid dialkyl ester (a-2) and a vinyl ether. (A-3) and / or carboxylic acid vinyl ester (a-4),
As an essential raw material component, a resin composition for thermosetting powder coating material in the form of using a material obtained by copolymerization is also claimed.

As the above-mentioned fluorine-containing copolymer (A) containing a carboxylic acid alkyl ester group, in particular, the above-mentioned unsaturated dicarboxylic acid dialkyl ester (a-2) is fumaric acid dialkyl ester, maleic acid dialkyl ester and itaconic acid. It is said that a resin composition for a thermosetting powder coating material is also claimed, in the form of being obtained by using at least one compound selected from the group consisting of dialkyl esters,

Then, the above-mentioned transesterification catalyst (C)
In particular, it also claims a thermosetting powder coating resin composition in the form of using a compound having a sulfonic acid group.

The structure of the present invention will be described in detail below.

First, of the various essential components constituting the resin composition for a thermosetting powder coating material according to the present invention, the above-mentioned carboxylic acid alkyl ester group-containing fluorocopolymer (A) component will be described. I will decide.

For preparing the carboxylic acid alkyl ester group-containing fluorine-containing copolymer (A), of course, various known and conventional methods can be applied. Among them, fluorine-containing vinyl monomers (a- 1) and an unsaturated carboxylic acid alkyl ester, and further, if necessary, other vinyl monomers, and each of these monomers is subjected to radical copolymerization in an organic solvent. The method of polymerizing and then removing the solvent is recommended because it is the simplest method.

First, the fluorine-containing vinyl monomers (a-1) used in this case have a fluorine atom in the molecule and have a polymerizable unsaturated double bond (hereinafter referred to as unsaturated unsaturated bond). (Also referred to as a double bond), and preferably in the case where the fluorine-containing vinyl monomers are polymerized, the following general formula (I)

[0023]

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[However, W, X, Y and Z in the formula are
Respectively represent a hydrogen atom or a halogen atom, an alkyl group or a halogenated alkyl group, which may be the same or different, and at least one of W, X, Y or Z is It shall be a fluorine atom. ]

The fluoroolefin structural unit represented by is referred to as a compound having such a form that it can be introduced into the main chain.

Of these, only typical ones are exemplified by vinyl fluoride, vinylidene fluoride, trifluoroethylene, tetrafluoroethylene,
Various fluorine-containing-α-olefins such as chlorotrifluoroethylene, bromotrifluoroethylene, pentafluoropropylene or hexafluoropropylene;

Alternatively, various perfluoroalkyl-perfluorovinyl ethers such as trifluoromethyl trifluorovinyl ether, pentafluoroethyl trifluorovinyl ether or heptafluoropropyl trifluorovinyl ether, and the like,

Further, there are various (per) fluoroalkyl vinyl ethers (provided that the number of carbon atoms of the alkyl group is within the range of 1 to 18) and the like, and these fluorine-containing vinyls are used. Monomers (a-
1) may be used singly or in combination of two or more, but in view of weather resistance and the like, the fluoroolefin structural unit represented by the general formula (I) is the carboxylic acid alkyl ester. Since it is introduced into the molecule of the group-containing fluorocopolymer (A) through a copolymerization reaction, vinyl fluoride, vinylidene fluoride, trifluoroethylene,
It is desirable to use at least one fluorine-containing vinyl monomer selected from the group consisting of tetrafluoroethylene and chlorotrifluoroethylene.

Next, the unsaturated carboxylic acid alkyl ester used for introducing the carboxylic acid alkyl ester group into the carboxylic acid alkyl ester group-containing fluorocopolymer (A) will be described.

As the unsaturated carboxylic acid alkyl ester used in the present invention, various known conventional ones such as unsaturated monocarboxylic acid alkyl ester, unsaturated dicarboxylic acid monoalkyl ester, unsaturated dicarboxylic acid dialkyl ester and the like can be used. Unsaturated carboxylic acid alkyl ester can be used, but, in particular, in view of reactivity with a hydroxyl group during curing reaction, the use of unsaturated dicarboxylic acid dialkyl ester (a-2) is particularly desirable. Is.

The unsaturated dicarboxylic acid dialkyl ester (a-2) will be described in more detail. The alkyl group has 1 to 8 carbon atoms, and is linear or branched (branched). It is desirable to use a dialkyl ester of an unsaturated dicarboxylic acid such as that of the above-mentioned), and to exemplify only those particularly representative of such a form,

Dimethyl fumarate, diethyl fumarate, dibutyl fumarate, diisobutyl fumarate, dit fumarate
ert-butyl, dihexyl fumarate, dioctyl fumarate, di2-ethylhexyl fumarate, dimethyl maleate, diethyl maleate, dibutyl maleate, diisobutyl maleate, ditert-butyl maleate,
Dihexyl maleate, dioctyl maleate, di-2-ethylhexyl maleate,

Various unsaturated dicarboxylic acid dialkyl esters such as dimethyl itaconic acid, diethyl itaconic acid, dibutyl itaconic acid, diisobutyl itaconic acid, dihexyl itaconic acid, dioctyl itaconic acid or di-2-ethylhexyl itaconic acid, etc., Of course, these may be used alone or in combination of two or more.

In addition to the above, methyl methacrylate, ethyl methacrylate, butyl methacrylate,
Various methacrylic acid esters such as isobutyl methacrylate, tert-butyl methacrylate, lauryl methacrylate, cyclohexyl methacrylate or benzyl methacrylate;

Methyl acrylate, ethyl acrylate, butyl acrylate, isobutyl acrylate, 2
Various acrylic esters such as ethylhexyl acrylate or cyclohexyl acrylate; or various α, β such as maleic acid or fumaric acid
Monoesters of unsaturated dicarboxylic acids and monohydric alcohols having 1 to 18 carbon atoms can also be used.

Further, in addition to the above-mentioned fluorine-containing vinyl monomer (a-1) and unsaturated dicarboxylic acid dialkyl ester (a-2), vinyl ether (a-3) and / or carboxylic acid vinyl ester (a- It is desirable to also use 4).

These vinyl ethers (a-3) and / or carboxylic acid vinyl esters (a-4) are used in combination with a fluorine-containing vinyl monomer (a-1) and an unsaturated carboxylic acid vinyl ester (a-2). It is excellent in copolymerizability and can efficiently introduce a fluorine atom and a carboxylic acid alkyl ester group into the carboxylic acid alkyl ester group-containing fluorocopolymer (A).

If only typical examples of the vinyl ether (a-3) and the carboxylic acid vinyl ester (a-4) are exemplified, firstly, the former vinyl ether (a-3) is as follows:

Methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, tert-butyl vinyl ether, n-
Including pentyl vinyl ether, n-hexyl vinyl ether or n-octyl vinyl ether,

Various (substituted) alkyl vinyl ethers or aralkyl vinyl ethers such as 2-ethylhexyl vinyl ether, chloromethyl vinyl ether, chloroethyl vinyl ether, benzyl vinyl ether or phenethyl ethyl vinyl ether;

Or various cycloalkyl vinyl ethers such as cyclopentyl vinyl ether, cyclohexyl vinyl ether or methylcyclohexyl vinyl ether, and the like,

On the other hand, if only typical examples of the latter vinyl carboxylic acid ester (a-4) are to be exemplified, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl caproate, capryl. Vinyl acetate, vinyl caprate, vinyl laurate, vinyl stearate, etc.,

Further, a branched (branched) aliphatic vinyl carboxylate having 9 carbon atoms, a branched (branched) aliphatic vinyl carboxylate having 10 carbon atoms, or 1 carbon atom
A variety of aliphatic carboxylic acid vinyl esters, such as branched (branched) aliphatic vinyl carboxylic acid 1.

Or vinyl cyclohexanecarboxylate,
Examples thereof include various vinyl carboxylates having a cyclic structure such as vinyl methylcyclohexanecarboxylate, vinyl benzoate or vinyl p-tert-butylbenzoate.

In addition to the various compounds listed above,
If necessary, other copolymerizable monomers (a-5)
It can also be used. As the other copolymerizable unsaturated monomers, only typical ones are listed, and various α-olefins such as ethylene, propylene or butene-1;

Various halogenated olefins other than fluoroolefins such as vinyl chloride or vinylidene chloride; various aromatic vinyl compounds such as styrene, α-methylstyrene or vinyltoluene;

Various amino group-containing amides such as N-dimethylaminoethyl (meth) acrylamide, N-diethylaminoethyl (meth) acrylamide, N-dimethylaminopropyl (meth) acrylamide or N-diethylaminopropyl (meth) acrylamide Unsaturated monomers;

Various dialkylaminoalkyl (meth) acrylates such as dimethylaminoethyl (meth) acrylate or diethylaminoethyl (meth) acrylate; or tert-butylaminoethyl (meth) acrylate, tert-bitylaminopropyl (meth) ) Various amino group-containing monomers such as acrylate, aziridinylethyl (meth) acrylate, pyrrolidinylethyl (meth) acrylate or piperidinylethyl (meth) acrylate;

Various carboxyl group-containing monomers such as (meth) acrylic acid, crotonic acid, itaconic acid, maleic acid or fumaric acid; diethyl-2- (meth) acryloyloxyethyl phosphate, dibutyl-2-
Various phosphoric acid ester group-containing monomers such as (meth) acryloyloxybutyl phosphate, dioctyl-2- (meth) acryloyloxyethyl phosphate or diphenyl-2- (meth) acryloyloxyethyl phosphate;

Glycidyl (meth) acrylate, β-methylglycidyl (meth) acrylate or (meth)
Various epoxy group-containing monomers such as allyl glycidyl ether; vinyltrimethoxysilane, vinyltriethoxysilane, vinyltripropoxysilane, vinylmethyldiethoxysilane, vinyltris (β-methoxyethoxy) silane or allyltrimethoxysilane. ,

Trimethoxysilylethyl vinyl ether, triethoxysilylethyl vinyl ether, methyldimethoxysilylethyl vinyl ether, trimethoxysilylpropyl vinyl ether, triethoxysilylpropyl vinyl ether or methyldiethoxysilylpropyl vinyl ether,

Or having a hydrolyzable silyl group, such as γ- (meth) acryloyloxypropyltrimethoxysilane, γ- (meth) acryloyloxypropyltriethoxysilane or γ- (meth) acryloyloxypropylmethyldimethoxysilane, It is various monomers.

The fluorine content of the carboxylic acid alkyl ester group-containing fluorocopolymer (A) thus obtained is preferably 7% by weight or more.
It is preferably 10% by weight or more. When the fluorine content is less than 7% by weight, it has sufficient weather resistance even when used in combination with the above-mentioned hydroxyl group-containing fluorocopolymer (B) used in the present invention. It is not preferable because a coating film having high property cannot be obtained.

On the other hand, the content of the carboxylic acid alkyl ester group of the carboxylic acid alkyl ester group-containing fluorocopolymer (A) is about 0.05, especially from the viewpoint of mechanical properties of the coating film. A range of from about 0.5 (mol / 100 g of copolymer) is suitable.

When the content of the carboxylic acid alkyl ester group is less than about 0.05 (mol / copolymer 100 g), the mechanical properties of the resulting coating film tend to be inevitably deteriorated. Not preferable.

The softening point of the carboxylic acid alkyl ester group-containing fluorocopolymer (A) is about 70.
A temperature within the range of about 150 ° C is suitable. Softening point is about 70
When the temperature is lower than ℃, the storage stability of the powder coating is apt to be deteriorated, and when the temperature is higher than about 150 ° C and is too high, the appearance of the coating film is deteriorated. In any case, it is not preferable because it is easy to do.

The number average molecular weight of the carboxylic acid alkyl ester group-containing fluorocopolymer (A) is about 50.
Within the range of 0 to about 50,000, preferably 1,0
The range of 00 to 10,000 is suitable. If the number average molecular weight is less than about 500,
Inevitably, especially, the mechanical properties of the coating film tend to be inferior, and on the other hand, when it exceeds about 50,000 and becomes too large, the smoothness of the coating film tends to be deteriorated. In any case, it is not preferable.

Next, the hydroxyl group-containing fluorine-containing copolymer (B), which is another essential constituent component of the resin composition for thermosetting powder coating material according to the present invention, will be described in more detail. To do.

In order to prepare the hydroxyl group-containing fluorine-containing copolymer (B), of course, various known and conventional methods can be applied. Among them, fluorine-containing vinyl monomers (a-
1) and a hydroxyl group-containing monomer, and further, if necessary, other vinyl monomers, and each of these monomers is radical-copolymerized in an organic solvent. The method in which the solvent is removed and then the solvent is removed is recommended because it is the simplest method.

As the above-mentioned fluorine-containing vinyl monomers (a-1) used in that case, the carboxylic acid alkyl ester group-containing fluorine-containing copolymer (A) as described above is used.
Various fluorine-containing vinyl monomers, such as those listed as those which can be used in the preparation of, can be used as they are.

Next, only the typical examples of the above-mentioned hydroxyl group-containing vinyl monomers will be exemplified.
Various hydroxyl group-containing vinyl ethers such as 2-hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether or 4-hydroxybutyl vinyl ether; or addition reaction products of various vinyl ethers such as those listed above with ε-caprolactone;

Various hydroxyl group-containing allyl ethers such as 2-hydroxyethyl (meth) allyl ether, 3-hydroxypropyl (meth) allyl ether or 4-hydroxybutyl (meth) allyl ether; or various as listed above. Addition reaction product of allyl ethers of ε-caprolactone;

Alternatively, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate,
2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, polyethylene glycol mono (meth) acrylate or polypropylene glycol mono (meth) ) Various hydroxyl group-containing (meth) acrylates such as acrylate; or addition reaction products of various (meth) acrylates with ε-caprolactone as described above.

Further, if necessary, other copolymerizable monomers such as those listed as those which can be used in the preparation of the carboxylic acid alkyl ester group-containing fluorine-containing copolymer (A). The class (a-5) can also be used.

The hydroxyl group-containing fluorocopolymer (B) thus obtained is preferably solid at room temperature.

The hydroxyl value of the hydroxyl group-containing fluorocopolymer (B) is about 20 to about 200 (mgKOH
/ G solid content; the same applies hereinafter) is preferred.

If the hydroxyl value is less than about 20, it means that the mechanical properties of the coating film are inferior, and on the other hand, if it exceeds about 200 and is too large. In any case, the water resistance of the coating film tends to decrease, which is not preferable.

Further, the fluorine content of the hydroxyl group-containing fluorocopolymer (B) is 7% by weight or more,
It is preferably 10% by weight or more. When the fluorine content is less than 7% by weight, a coating film having sufficient weather resistance can be obtained even when used in combination with the carboxylic acid alkyl ester group-containing fluorine-containing copolymer (A). Absent.

Furthermore, the total fluorine content of the carboxylic acid alkyl ester group-containing fluorocopolymer (A) and the hydroxyl group-containing fluorocopolymer (B) is 12 respectively.
It is desirable that the content be not less than% by weight. If the total fluorine content is less than 12% by weight, it will no longer be possible to impart sufficient weather resistance to the resulting coating film, which is not preferable.

In the resin composition for a thermosetting powder coating material according to the present invention, a carboxylic acid alkyl ester group-containing fluorocopolymer (A) and a hydroxyl group-containing fluorocopolymer (B), respectively, are prepared. The ratio of use is the ratio of the number of moles of carboxylic acid alkyl ester groups in the former copolymer (A) to the number of moles of hydroxyl groups in the latter copolymer (B), that is, A / B
It is preferable that the ratio is in the range of about 4/1 to about 1/4.

If this A / B ratio is too much greater than about 4/1, then by all means,
The mechanical properties of the coating film become inferior, and on the other hand, when the A / B ratio is much smaller than about 1/4, the water resistance of the coating film is inevitable. In any case, it is not preferable because the above-mentioned tendency is likely to decrease.

The above-mentioned transesterification catalyst (C), which is a further essential constituent component of the resin composition for thermosetting powder coating composition according to the present invention, is the fluorine-containing carboxylic acid ester group-containing fluorinated copolymer as described above. This refers to a compound in the form of accelerating the transesterification reaction between the carboxylic acid alkyl ester group in the polymer (A) and the hydroxyl group in the hydroxyl group-containing fluorocopolymer (B) as described above. That is, generally, an acidic or basic compound is used.

As the transesterification catalyst (C), only typical ones will be exemplified. Hydrochloric acid, sulfuric acid,
Various acidic compounds such as nitric acid, acetic acid, phosphoric acid or sulfonic acid; various basic compounds such as LiOH, KOH or NaOH, and further,
Various metal compounds such as PbO, zinc acetate, lead acetate, antimony trioxide, tetraisopropyl titanate, dibutyltin dilaurate, dibutyltin dioctate or monobutylstannic acid.

In particular, a compound having a sulfonic acid group in the molecule or a group consisting of an alkali metal salt or an amine salt of sulfonic acid, that is, an alkali metal base or an amine base is one that can sufficiently exert the effects of the present invention. It is particularly desirable to use a compound having

Here, the above-mentioned compound having a sulfonic acid group means, for example, a sulfonic acid group in the molecule;

[0076]

Embedded image

A compound having the formula

On the other hand, the above-mentioned compound having an alkali metal base or amine base of sulfonic acid means, for example, a salt of sulfonic acid group;

[0079]

Embedded image

[Wherein M represents an alkali metal atom or -NR ₃ (wherein, each R may be the same or different, and represents a hydrogen atom or an alkyl group). Shall be represented). ]

The compound having a group represented by is referred to.

Of the various compounds, only typical ones will be exemplified. Benzene sulfonic acid, paratoluene sulfonic acid, dodecyl benzene sulfonic acid, sodium salts thereof and the like,
Furthermore, these ammonium salts or amine salts are also included.

The transesterification catalyst (C) is usually
Within a range of about 0.01 to about 10 parts by weight based on 100 parts by weight of the total solid content of the carboxylic acid alkyl ester group-containing fluorine-containing copolymer (A) and the hydroxyl group-containing fluorine-containing copolymer (B). Therefore, it is preferable that the addition is made within a range of 0.1 to 5 parts by weight.

When the amount added is less than about 0.01 parts by weight, the curability of the coating film tends to be inferior, and the amount added exceeds 10 parts by weight. In that case, especially, since the storage stability of the paint tends to deteriorate,
Either case is not preferred.

It is needless to say that these transesterification catalysts may be used alone or in combination of two or more kinds.

As a method for preparing a powder coating material from the resin composition for thermosetting powder coating material according to the present invention, which is obtained by using the essential constituent components as described above in detail,
Of course, any known method can be adopted.

As a particularly typical method among them, first, the essential constituents as described in detail above, and if necessary, known compounds such as pigments and leveling agents are used. A step of mixing with various commonly used additives; a step of melt-kneading the mixture (or a compound) thus obtained; then, a fine grinding step (fine grinding step), and classification There is a so-called mechanical pulverization method in which a desired powder coating material is obtained by passing through a step (classifying step).

The resin composition of the present invention may further contain various known and commonly used pigments such as organic or inorganic pigments, flow regulators, ultraviolet absorbers, antioxidants and the like. Additives; various fibrin derivatives such as nitrocellulose or cellulose acetate butyrate; or various known and conventional resins such as chlorinated polyethylene, chlorinated polypropylene, petroleum resin, epoxy resin or chlorinated rubber It can be said that a kind is added.

The resin composition for a thermosetting powder coating material according to the present invention thus obtained is applied to various base materials by a conventional method, and then baked and dried by a conventional method. Above all, the coating film appearance, curability,
It is possible to provide a coating film excellent in weather resistance and mechanical properties.

The resin composition for thermosetting powder coating composition according to the present invention thus obtained is mainly used for top coating of automobiles, intermediate coating of automobiles, automobile parts, building materials, and further, As a paint for various metal products, it can be widely used and applied.

Therefore, only typical examples of so-called base materials to be coated, which are used when the resin composition for thermosetting powder coating material of the present invention is used as a powder coating material and applied, are given below. In other words, various metal materials or metal products such as aluminum, stainless steel, chrome plating, galvanized iron plate or tin plate; or roof tiles; glass; or various inorganic building materials,

Specifically, it includes an automobile body or automobile (for) parts, a motorcycle or a motorcycle (for) parts, and various building materials such as gates or fences; aluminum sashes. , Various building interior and exterior materials; or various materials or products of various ferrous or non-ferrous metals such as aluminum foil.

[0093]

EXAMPLES Next, the present invention will be explained more specifically by reference examples, examples and comparative examples, but the present invention is by no means limited to these illustrative examples. Absent. In the following, unless otherwise specified, the parts are
All are parts by weight.

Reference Examples 1 to 6 [Preparation Examples of Fluorine-Containing Copolymer (A) Containing Carboxylic Acid Alkyl Ester Group]

1000 parts of xylene was charged into a stainless steel autoclave having an inner volume of 3,000 milliliters, and nitrogen gas was blown thereinto to replace the air in the autoclave.

Next, the inside of the autoclave was heated to 75 ° C., the monomers and the polymerization initiator in the amounts shown in Table 1 were added over 8 hours, and then 1 hour. While maintaining the temperature for 5 minutes, 5 parts of tert-butyl peroxypivalate was added, and the reaction was further continued for 8 hours to complete the polymerization reaction.

By removing the solvent from the solution of the copolymer thus obtained, the objective fluorinated copolymer (A) containing a carboxylic acid alkyl ester group is obtained.
I got The various characteristic values of each fluorinated copolymer containing a carboxylic acid alkyl ester group are shown together in the same table.

[0098]

[Table 1]

[0099]

[Table 2]

[0100]

[Table 3]

[0101]

[Table 4]

<< Footnote of Table 1 >>"CTFE" ……………… Abbreviation of chlorotrifluoroethylene “HFP” ………………… Abbreviation of hexafluoropropylene “TFE” …………… Abbreviation for tetrafluoroethylene

"EVE": Abbreviation of ethyl vinyl ether "IBVE": Abbreviation of isobutyl vinyl ether "tBVE": Abbreviation of tert-butyl vinyl ether

“VAc” …………………… Abbreviation of vinyl acetate “VCH” ………………… Abbreviation of vinyl cyclohexanecarboxylate “VV-9” ……………… “Veova-9” An abbreviation, trade name of vinyl ester of branched aliphatic acid having 9 carbon atoms, manufactured by Shell Co., Netherlands

“VTB” …………………… p-tert-
Abbreviation of vinyl butyl benzoate “TBPV” ……………… Abbreviation of tert-butyl peroxypivalate “AIBN” ……………… Abbreviation of azobisisobutyronitrile

“Fluorine content”: The fluorine content in the copolymer measured by the alizarin complexon method, and the unit is% by weight.

"Carboxylic Acid Alkyl Ester Group Content"
It is a value showing the content of the carboxylic acid alkyl ester group of the copolymer, and the unit is mol / 100 g-copolymer.

Reference Examples 7 to 10 [Preparation Example of Fluorine-Containing Fluorine-Containing Copolymer (B)] In a stainless steel autoclave having an internal volume of 3,000 milliliters, 1,000 parts of xylene and bis (1, 10 parts of 2,2,6,6-pentamethylpiperidinyl) sebacate was charged and nitrogen gas was blown thereinto to replace the air in the autoclave.

Next, the temperature inside the autoclave was raised to 75 ° C., the monomers and the polymerization initiator in the amounts shown in Table 2 were added over 8 hours, and then the mixture was heated for 1 hour. While maintaining the temperature for 5 minutes, 5 parts of tert-butyl peroxypivalate was added, and the reaction was further continued for 8 hours to complete the polymerization reaction.

From the solution of the copolymer thus obtained,
By removing the solvent, the target fluorinated copolymer (B) having a hydroxyl group was obtained. The various characteristic values of the respective fluorine-containing copolymers having hydroxyl groups are shown together in the same table.

[0111]

[Table 5]

Reference Example 11 [Preparation Example of Acrylic Copolymer (D-1) Containing Carboxylic Acid Alkyl Ester Group]

667 parts of xylene was charged into a reaction vessel equipped with a thermometer, a stirrer, a reflux, a condenser and a nitrogen inlet, the air in the reaction vessel was replaced with nitrogen, and the mixture was heated to reflux. It was

Thereto, a mixture of monomers and a polymerization initiator consisting of 750 parts of styrene and 250 parts of dibutyl fumarate and 40 parts of azobisisobutyronitrile was added over 4 hours. Approximately 10 after cooling after adding
At a temperature of 0 ° C., 5 parts of azobisisobutyronitrile were added to complete the polymerization reaction.

The solvent was removed from the thus obtained solution of the acrylic copolymer to obtain the desired carboxylic acid alkyl ester group-containing acrylic copolymer (D-1). The content of the carboxylic acid alkyl ester group in the obtained carboxylic acid alkyl ester group-containing acrylic copolymer was 0.11 (mol / 100 g of copolymer).

Reference Example 12 [Preparation Example of Epoxy Group-Containing Fluorine-Containing Copolymer (D-2)] 1,000 parts of xylene was charged into a stainless steel autoclave having an internal volume of 3,000 milliliters, and nitrogen was added. A gas was blown in to replace the air in the autoclave.

Next, the temperature inside the autoclave was raised to 75 ° C., and from 500 parts of chlorotrifluoroethylene, 300 parts of cyclohexyl vinyl ether and 200 parts of glycidyl vinyl ether, and 80 parts of azobisisobutyronitrile. After adding the monomers and the polymerization initiator over 8 hours, the temperature was maintained for 1 hour, and tert-butylperoxypivalate
Parts were added and the reaction was allowed to continue for a further 8 hours to complete the polymerization reaction.

From the solution of the copolymer thus obtained,
By removing the solvent, the target epoxy group-containing fluorocopolymer (D-2) was obtained. Epoxy group-containing fluorine-containing copolymer obtained here (D-2)
Has a fluorine content of 24.1 (wt%), and
The epoxy equivalent was 500 (g / eq).

Reference Example 13 [Preparation example of acid group-containing fluorocopolymer (D-3)] The hydroxyl group-containing fluorocopolymer (B- By dissolving 100 parts of 3) in xylene, then adding 5.6 parts of succinic anhydride and continuing stirring at 100 ° C. for 4 hours, the solvent was removed. The desired fluorine-containing copolymer containing an acid group (D-3) was obtained.

The acid group-containing fluorocopolymer (D-3) thus obtained had a fluorine content of 15.7 (% by weight) and an acid value of 30 (mgKOH / g copolymer). Met.

Examples 1 to 8 and Comparative Examples 1 to 8

(1) Preparation example of powder coating

As shown in Table 3, the carboxylic acid alkyl ester group-containing fluorine-containing copolymers (A) obtained in Reference Examples 1 to 6 and the hydroxyl group-containing fluorine-containing copolymers obtained in Reference Examples 7 to 10 were obtained. The polymer (B), the transesterification catalyst (C), and various resins, curing agents, additives and pigments used in the thermosetting powder coating material,

Further, as comparative controls, Reference Examples 11 to 11 were used.
Carboxylic acid alkyl ester group-containing acrylic copolymer (D-1) obtained in No. 13, epoxy group-containing fluorine-containing copolymer (D-2), and acid group-containing fluorine-containing copolymer (D-
3) and various resins, curing agents, additives and pigments used in the thermosetting powder coating,

At 110.degree. C., "Conyder PR-
Type 46 "(trade name of Buss, Switzerland) was melt-kneaded, cooled, and crushed. Next, various powder coating materials were obtained by collecting the powders that passed through each pulverized product using a 150 mesh screen.

(2) Evaluation of powder coating

Powder coatings prepared with the composition ratios shown in Table 3 were applied to a zinc phosphate treated 0.8 mm thick satin finished steel sheet by an electrostatic spray coating machine. , 50 ± 5 micrometer (μm), and baked at 180 ° C. for 20 minutes to obtain various test plates (that is, coated plates having a cured coating film).

Then, for each coated plate, the fourth
The coating film was evaluated for various test items as shown in the table. The results are shown together in the same table.

[0129]

[Table 6]

<< Footnote in Table 3 >>"A-224S" ............ "Findick A
-224S ", a trade name of a glycidyl group-containing acrylic resin manufactured by Dainippon Ink and Chemicals, Inc .;
Epoxy equivalent = 525

“M-8020”: an abbreviation for “Findick M-8020”, which is a trade name of a hydroxyl group-containing polyester resin manufactured by the same company; hydroxyl value =
30

"B-1530" ............ "IPDI
-addition B-1530 ", a trade name of a block isocyanate compound manufactured by Hüls, Germany

"PTSA": Abbreviation of paratoluene sulfonic acid "DBSA": Abbreviation of dodecylbenzene sulfonic acid

"Taipec CR-90" ... Trade name of rutile titanium oxide manufactured by Ishihara Sangyo Co., Ltd.

"Acronar 4F" ...... Germany B
Product name of flow control agent manufactured by ASF

[0136]

[Table 7]

[0137]

[Table 8]

<< Footnote of Table 3 >>"D-1" ... Abbreviation of carboxylic acid alkyl ester group-containing acrylic copolymer (D-1) "D-2" ... carboxylic acid alkyl ester group-containing acrylic Abbreviation for copolymer (D-2)

"B-1" ... Abbreviation of hydroxyl group-containing fluorocopolymer (B-2)

"DBTDR": Abbreviation of dibutyltin dilaurate "CR-90": Abbreviation of "Typepek CR-90"

[0141]

[Table 9]

<< Footnote of Table 3 >>"A-5" ... Abbreviation of fluorinated copolymer (A-5) containing carboxylic acid alkyl ester group

"D-3" ... Abbreviation of acid group-containing fluorocopolymer (D-3)

"B-3" ... Abbreviation of hydroxyl group-containing fluorocopolymer (B-3) "B-4" ... Hydroxyl group-containing fluorocopolymer (B-
Abbreviation of 4)

[0145]

[Table 10]

<< Footnotes in Table 4 >> Yellowing resistance: The degree of yellowing of the coating film when baked was evaluated by visual inspection.

Erichsen: This was a squeeze test using an Erichsen tester, and the value was indicated by the limit value (mm number) at which no crack was formed on the coated surface. The larger this value is, the more excellent the flexibility of the coating film is.

Impact resistance: The test was carried out using a DuPont impact tester in accordance with JIS K-5981, a load of 500 g and a notch of 1/2 inch.

Gel fraction: The coating film after baking was isolated, and the residual weight when immersed in acetone at room temperature for 24 hours was divided by the initial weight to obtain a percentage. Was displayed.

The larger this value is, the higher the curability is.

Accelerated weather resistance: The evaluation was judged by the gloss retention rate (%) of the test piece (cured coating film) after 2000 hours using a Sunshine Weatherometer manufactured by Suga Test Instruments Co., Ltd.

Storage stability: The powder coating material was stored in a constant temperature bath at 40 ° C. for one month, and then evaluated by the coating workability when the powder coating material was applied.

[0153]

[Table 11]

[0154]

[Table 12]

[0155]

[Table 13]

As described above, the resin composition for thermosetting powder coating material according to the present invention is not only excellent in storage stability of the coating material but also particularly in the appearance of the coating film, various physical properties of the coating film, and particularly weather resistance. It is also excellent and extremely practical,
Let's know without difficulty.

[0157]

As described above in detail, the thermosetting powder coating resin composition according to the present invention purposely uses a compound whose safety is questioned. In addition, it does not easily turn yellow, and the coating film has excellent appearance and various physical properties of the coating film, and further has excellent storage stability. In particular, it is excellent in weather resistance and is extremely practical.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C09D 201/04 PDP C09D 201/04 PDP // (C08F 214/18 222: 10 216: 12 220: Ten)

Claims (4)

[Claims] 1. A fluorinated alkyl ester group-containing fluorocopolymer (A) having a softening point of about 70 to about 150 ° C. and a fluorine content of 7% by weight or more, and a fluorine content of 7% by weight. It comprises the above-mentioned fluorine-containing copolymer (B) having a hydroxyl group and an ester exchange catalyst (C), and in addition, the above-mentioned fluorine-containing copolymer (A) having a carboxylic acid alkyl ester group and the above fluorine-containing hydroxyl group A resin composition for a thermosetting powder coating material, which has a total fluorine content of 12% by weight or more with the copolymer (B). 2. The carboxylic acid alkyl ester group-containing fluorine-containing copolymer (A) is a fluorine-containing vinyl monomer (a-1), an unsaturated dicarboxylic acid dialkyl ester (a-2) and a vinyl ether (a). The composition according to claim 1, which is obtained by copolymerizing a-3) and / or carboxylic acid vinyl ester (a-4) as an essential raw material component. 3. A carboxylic acid alkyl ester group-containing fluorine-containing copolymer (A) is obtained as the unsaturated dicarboxylic acid dialkyl ester (a-2) from fumaric acid dialkyl ester, maleic acid dialkyl ester and itaconic acid dialkyl ester. The composition according to claim 1 or 2, which is obtained by using at least one compound selected from the group consisting of: 4. The composition according to claim 1, wherein the transesterification catalyst (C) is a compound having a sulfonic acid group.