JPH0987552A - Resin composition for powder coating material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a resin compsn. for a blocking-resistant powder coating material which gives a coating film excellent in appearance, curability, weatherability, and mechanical properties by compounding a specific vinyl copolymer, a specific compd., and an aliph. dibasic acid as the essential ingredients. SOLUTION: This compsn. contains as the essential ingredients a vinyl copolymer having epoxy and hydroxyl groups in the molecule and obtd. by copolymerizing an epoxidized polymerizable monomer and a hydroxylated polymerizable monomer as the essential comonomers (e.g. a copolymer obtd. from methyl methacrylate, n-butyl methacrylate, glycidyl methacrylate, and 2-hydroxyethyl methacrylate), an aliph. dibasic acid, and a compd. having at least one org. group represented by formula I (wherein R1 is CH2 or CH2 CH2 ; and R2 is H or a 1-12C alkyl) or formula II in the molecule.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a new and useful resin composition for powder coatings. More specifically, the present invention provides a cured coating film which is excellent not only in the mechanical properties of the coating film, but also in the appearance, curability and weather resistance of the coating film. The present invention relates to a resin composition for powder coating, which has extremely high practicality.

[0002]

2. Description of the Related Art As one form of paint containing no organic solvent, powder paint can be mentioned. In recent years, however, such as air pollution,
From the viewpoint of so-called environmental problems, its pollution-free property has been attracting attention and its usage has been increasing year by year.

Various kinds of polymer compounds are used depending on the kind of binder resin used in the powder coating material. Among them, only representative ones are exemplified, and in an acrylic copolymer having a glycidyl group in the molecule, a composition in the form obtained by mixing an aliphatic dibasic acid, etc. But

Such a type of composition is a resin composition for powder coatings other than a resin composition for powder coatings, for example, a block polyisocyanate-curable polyester resin is used as a binder composition. In comparison, although the coating films obtained there are particularly excellent in transparency, hardness and weather resistance, mechanical properties and flexibility, among others, are mechanical properties. Has the disadvantage of being inferior.

[0005]

As described above, as long as the conventional technique as described above is followed, not only the mechanical properties of the coating film, but also the appearance and curing of the coating film are of course notable. It was extremely difficult to obtain a resin composition having a very high practicality, in particular, a resin composition for powder coating, which gives a cured coating film excellent in properties and weather resistance.

[0006] The present inventors, however, intend to mitigate, solve and eliminate various drawbacks or problems in the conventional techniques as described above, and in particular, the appearance, curability and weather resistance of the coating film. In order to provide a resin composition having an extremely high practicality, that is, a resin composition for powder coatings, which gives an excellent cured coating film to the above, the inventors have earnestly started research.

[0007] Therefore, the problem to be solved by the present invention is, in part, to be excellent not only in the anti-blocking property of the paint, but also in the mechanical properties of the paint film, among others. Another object of the present invention is to provide a resin composition for a powder coating, which has an extremely high practicality and can provide a cured coating film that is excellent in the appearance, curability and weather resistance of the coating film.

[0008]

[Means for Solving the Problems]

[0009] Therefore, the inventors of the present invention mitigate various drawbacks or problems in the above-mentioned conventional techniques.
In order to solve and eliminate, in addition, especially the appearance of the coating film,
To provide a cured coating film having excellent curability and weather resistance, which is extremely practical, to provide a resin composition, in particular, a resin composition for powder coating, as a result of earnest studies, A composition obtained by blending an aliphatic dibasic acid and a compound having a specific organic group into a specific copolymer having both an epoxy group and a hydroxyl group is, of course, mechanical properties of the coating film. In particular, the present invention has been completed by finding a resin composition having extremely high practicability that is particularly excellent in the appearance, curability and weather resistance of the coating film.

That is, in the present invention, basically, a polymerizable monomer having an epoxy group in the molecule and a polymerizable monomer having a hydroxyl group in the molecule are copolymerized as an essential raw material component. A vinyl-based copolymer (A) having both an epoxy group and a hydroxyl group in one molecule, obtained by
An aliphatic dibasic acid (B) and at least one of the following general formula [I-1] or [I-2] in one molecule, respectively.

[0011]

[Chemical 6]

(Wherein R ₁ represents a group of —CH ₂ — or —CH ₂ CH ₂ —, and R ₂ represents a hydrogen atom or an alkyl group of 1 to 12 carbon atoms. And)

[0013]

[Chemical 7]

(Wherein R _{1 s} may be the same or different, --CH ₂ -or --C
R ₂ represents H ₂ CH ₂ — and R ₂ represents a hydrogen atom or an alkyl group having 1 to 12 carbon atoms, which may be the same or different. )

It is an object of the present invention to provide a resin composition for powder coating, which comprises a specific form of compound (C) having an organic group represented by the formula (C) as an essential film-forming component.

Specifically, the above-mentioned vinyl copolymer (A) having both an epoxy group and a hydroxyl group in one molecule,

The following general formula [II]

[0018]

Embedded image

(Provided that R ₃ and R ₄ in the formula are the same or different and each represents a hydrogen atom or a methyl group.)

There is provided a specific resin composition for powder coating, which is obtained by using a specific polymerizable monomer as an essential raw material component and copolymerizing the same, as shown in Is what you are trying to

A number average molecular weight in the range of about 1,000 to about 15,000, and about 80
To provide a specific resin composition for powder coating having a softening point by the ring and ball method within the range of about 150 ° C.

A specific polymerizable monomer as represented by the above-mentioned general formula [II] is used as an indispensable raw material component and is obtained by copolymerizing it, and particularly, about 1,000 to Having a number average molecular weight within the range of about 15,000 and having a number average molecular weight of about 80 to about 1
The present invention is intended to provide a specific resin composition for powder coating, which has a softening point by the ring and ball method within a range of 50 ° C.

Furthermore, the above-mentioned compound (C) having at least one specific organic group in one molecule, represented by the above-mentioned general formula [I-1] or [I-2], respectively. ) Is especially an aminoplast,
It is intended to provide a specific resin composition for powder coating.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION As described above, in one aspect, the present invention comprises a polymerizable monomer having an epoxy group in the molecule and a polymerizable monomer having a hydroxyl group in the molecule as essential raw materials. A vinyl-based copolymer (A) having both an epoxy group and a hydroxyl group in one molecule obtained by copolymerizing as a component, an aliphatic dibasic acid (B), and at least one in one molecule, The following general formula [I-1] or [I-2]

[0025]

Embedded image

(Wherein R ₁ represents a group of —CH ₂ — or —CH ₂ CH ₂ —, and R ₂ represents a hydrogen atom or an alkyl group of 1 to 12 carbon atoms. And)

[0027]

Embedded image

(Provided that R _{1 s} in the formula may be the same or different, --CH ₂ -or --C
R ₂ represents H ₂ CH ₂ — and R ₂ represents a hydrogen atom or an alkyl group having 1 to 12 carbon atoms, which may be the same or different. )

The present invention intends to claim a resin composition for powder coating which comprises a compound (C) in a specific form having an organic group represented by the formula (1) as an essential film-forming component. ,

Secondly, such vinyl copolymer (A) having both an epoxy group and a hydroxyl group in one molecule.
Is particularly represented by the above-mentioned general formula [II],
Using a specific polymerizable monomer as one essential raw material component, and copolymerizing the polymerizable monomer with another polymerizable monomer that can be copolymerized with the monomer. It is intended to claim a specific resin composition for powder coating, which is obtained by

Third, such a vinyl-based copolymer (A) having both an epoxy group and a hydroxyl group in one molecule.
Is particularly represented by the above-mentioned general formula [II],
Using a specific polymerizable monomer as one essential raw material component, and copolymerizing the polymerizable monomer with another polymerizable monomer that can be copolymerized with the monomer. And a softening point by the ring and ball method having a number average molecular weight in the range of about 1,000 to about 15,000 and in the range of about 80 to about 150 ° C. It is also intended to claim a resin composition for a specific powder coating, which has

Fourthly, at least one of the above-mentioned general formulas [I-1] or [I-2] in one molecule.
A compound (C) having a specific organic group as shown in
However, the present invention also intends to claim a specific resin composition for powder coating, which is an aminoplast.

The resin composition for powder coating material according to the present invention, in particular, the composition of the resin composition for powder coating material, will be described below.
It will be described in more detail.

That is, first, the above-mentioned vinyl copolymer (A) having both an epoxy group and a hydroxyl group, which is one of the essential constituents of the resin composition for powder coating material according to the present invention, is, for example, the molecule thereof. Is a specific vinyl-based copolymer, which has both an epoxy group and a hydroxyl group at the terminal or side chain thereof.

Thus, at the terminal or side chain of the molecule,
In preparing the specific vinyl-based copolymer (A) each having both an epoxy group and a hydroxyl group, the epoxy group-free copolymer previously synthesized, in particular, the epoxy group If only to exemplify a typical method as a method of introducing

A desired vinyl-based monomer having an epoxy group may be copolymerized with the vinyl-based monomer and other vinyl-based monomers copolymerizable with the monomer. Method, or synthesized in advance,
For example, the epoxy group-free vinyl copolymer may be modified to introduce the desired epoxy group.

Of these, only typical ones will be exemplified as the above method.
A vinyl-based copolymer having an isocyanate group in the molecule has been synthesized, and then the vinyl-based copolymer thus obtained is further reacted with glycidol,

For example, a vinyl-based copolymer obtained by copolymerizing a vinyl-based monomer having a glyceryl carbonate group in the molecule is converted to a copolymer having an epoxy group through a decarboxylation reaction. In particular, it is particularly recommended because the above method is convenient.

In the case where the above-mentioned method is followed, a particularly representative among polymerizable monomers having an epoxy group in the molecule (hereinafter, also referred to as epoxy group-containing polymerizable monomer). To give just examples, various glycidyl esters of (meth) acrylic acid, such as glycidyl (meth) acrylate or β-methylglycidyl (meth) acrylate,

Various allyl glycidyl ethers such as allyl glycidyl ether or allyl methyl glycidyl ether, and various alicyclic epoxy group-containing vinyl systems such as 3,4-epoxycyclohexyl acrylate or 3,4-epoxycyclohexyl methacrylate. Such as monomers.

On the other hand, in the previously synthesized copolymer,
If only typical examples of the method of introducing a hydroxyl group are exemplified, a vinyl-based monomer having a desired hydroxyl group in the molecule can be copolymerized with the monomer. It is a method such as copolymerizing with other vinyl monomers,

Alternatively, a method in which the desired hydroxyl group is introduced into the vinyl copolymer by modifying the previously synthesized hydroxyl group-free vinyl copolymer. However, in the present invention, it can be prepared by various methods such as the above, or each of the above.

Among them, in the case where the above method is followed, for example, a method in which the epoxy group-containing vinyl copolymer obtained as described above is subjected to an addition reaction with a monobasic acid, etc. However, above all, it is particularly recommended because the above method is convenient.

Further, of the hydroxyl group-containing polymerizable monomers used in the case where the above method is followed, only representative ones will be exemplified.

2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3
-Hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate or 4-hydroxybutyl (meth) acrylate,

Alternatively, various hydroxyl group-containing (meth) acrylates such as polyethylene glycol mono (meth) acrylate or polypropylene glycol mono (meth) acrylate,

These are the main components of the addition reaction of various (meth) acrylates listed above with ε-caprolactone.

Of the other polymerizable monomers copolymerizable with these epoxy group-containing vinyl monomers and hydroxyl group-containing vinyl monomers, only typical ones will be illustrated. In other words, various acrylic acid esters such as methyl acrylate, ethyl acrylate, butyl acrylate or cyclohexyl acrylate;

Various methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate or benzyl methacrylate;

Various carboxyl group-containing monomers such as (meth) acrylic acid, crotonic acid, itaconic acid, maleic acid or fumaric acid, or various polyvalent carboxyl groups such as itaconic acid, maleic acid or fumaric acid Mono- or diesters of the contained monomer and monoalkyl alcohols having 1 to 18 carbon atoms;

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 monomer;

Various dialkylaminoalkyl (meth) acrylates such as dimethylaminoethyl (meth) acrylate or diethylaminoethyl (meth) acrylate;

Tert-Butylaminoethyl (meth) acrylate, tert-butylaminopropyl (meth)
Various amino group-containing monomers such as acrylate, aziridinylethyl (meth) acrylate, pyrrolidinylethyl (meth) acrylate or piperidinylethyl (meth) acrylate;

Ethylene, propylene or butene-1
, Various kinds of α-olefins; various kinds of halogenated olefins such as vinyl chloride or vinylidene chloride, excluding fluoroolefins; various kinds of aromatic vinyl compounds such as styrene, α-methylstyrene or vinyltoluene;

Monomers containing various hydrolyzable silyl groups such as γ- (meth) acryloyloxypropyltrimethoxysilane, γ- (meth) acryloyloxypropyltriethoxysilane or γ- (meth) acryloyloxypropylmethyldimethoxysilane. Quantity;

Various fluorine-containing α-olefins such as vinyl fluoride, vinylidene fluoride, trifluoroethylene, tetrafluoroethylene, chlorotrifluoroethylene, bromotrifluoroethylene, pentafluoropropylene or hexafluoropropylene;

Or various perfluoroalkyl perfluorovinyl ethers or (per) fluoroalkyl vinyl ethers, such as trifluoromethyl trifluorovinyl ether, pentafluoroethyl trifluorovinyl ether or heptafluoropropyl trifluorovinyl ether, provided that As the alkyl group, those having a carbon number of 1 to 18 are suitable.), And various fluorine-containing vinyl monomers;

Vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl caproate, vinyl caprylate, vinyl caprate, vinyl laurate, C ₉ branched (branched) aliphatic vinyl carboxylate, C ₁₀ branched (branched) aliphatic vinyl carboxylates, C ₁₁ branched (branched) aliphatic vinyl carboxylates or aliphatic vinyl carboxylates such as vinyl stearate;

Vinyl esters of various carboxylic acids having a cyclic structure such as vinyl cyclohexanecarboxylate, vinyl methylcyclohexanecarboxylate, vinyl benzoate or vinyl p-tert-butylbenzoate.

An epoxy group-containing vinyl monomer as exemplified above and another polymerizable monomer copolymerizable therewith, especially a vinyl monomer, are used. make use of,
In preparing the epoxy group- and hydroxyl group-containing vinyl copolymer (A), the amount of the epoxy group-containing vinyl monomer used is all polymerizable monomers used, and particularly all vinyl. A range of about 5 to about 80% by weight, preferably a range of 10 to 50% by weight based on the total amount of the system monomers is suitable.

When the amount of the epoxy group-containing vinyl monomer used is less than about 5%, the coating film obtained, in particular, mechanical properties are liable to deteriorate. On the other hand, in the case where the amount exceeds about 80% by weight and becomes too large, the effect of the present invention is inevitably exerted especially on the blocking resistance of the coating, and further on the mechanical properties of the coating film. Since it will not be possible to exhibit physical properties, appearance, curability and weather resistance,
Either case is not preferable.

In preparing the vinyl group-containing copolymer (A) having both an epoxy group and a hydroxyl group, the amount of the hydroxyl group-containing vinyl monomer used is all the polymerizable monomers used. Medium, about 2 to the total amount of all vinyl monomers
A range of about 50% by weight, preferably 5 to 30% by weight is suitable.

When the amount of the epoxy group-containing vinyl monomer used is less than about 2% each, on the other hand, when the amount is more than about 50% by weight and too much. Also, by all means, the effects of the present invention, in particular, including the blocking resistance of the coating, further, it becomes impossible to exert the mechanical physical properties of the coating film, appearance, curability and weather resistance, etc. Is also not preferable.

Separately, the number average molecular weight of the copolymer (A) is appropriately within the range of about 1,000 to about 15,000, and preferably within the range of 1,500 to 7,000. . When the number average molecular weight is less than about 1,000, the mechanical properties of the coating film tend to be inferior, and on the other hand, about 1
In the case where it exceeds 5,000 and becomes too large, the appearance of the coating film, especially the smoothness of the coating film, and the like are liable to be deteriorated.

Further, the softening point of the copolymer (A) by the ring and ball method is appropriately in the range of about 80 to about 150 ° C. When the softening point is lower than about 80 ° C., the blocking resistance as a powder coating tends to be deteriorated, and on the other hand, about 150
If the temperature is too high above 0 ° C., the appearance of the coating film is inevitably deteriorated, especially, the smoothness of the coating film is deteriorated.

In order to obtain the vinyl copolymer (A) from various polymerizable monomers such as those exemplified above, especially various vinyl monomers, there are known Although various conventional methods can be used and applied, among them,
Since it is easy to use the solution radical polymerization method,
Recommended.

Next, the above-mentioned aliphatic dibasic acid (B), which is another essential constituent component of the resin composition for powder coating material according to the present invention, is represented by, for example, the general formula [II
I] means a compound represented by the formula [I].

[0068]

[Image Omitted] HOOC-R-COOH [III]

[However, R in the formula has 1 to 20 carbon atoms.
Which represents a straight-chain or branched (branched) alkylene group. ]

Of these compounds, only typical ones will be exemplified. Succinic acid, adipic acid,
Pimelic acid, suberic acid, azelaic acid, sebacic acid,
Decanedicarboxylic acid, brassylic acid and the like.

Among these various compounds, in view of the appearance of the coating film and the like, "R" in the above general formula has a carbon number of 8 or more and is linear or branched. (Branched) alkylene groups are suitable and it is therefore desirable to use these particular ones.

Another essential constituent component of the resin composition for powder coating material according to the present invention is the above-mentioned at least one compound represented by the following general formula [I-1] or [I-2]. And a compound (C) having a specific organic group represented by the following general formula [I-1] or [I-
2], which is a compound having a specific organic group, and the compound (C) may be a low molecular compound or a high molecular compound. Of course, it is okay.

[0073]

[Chemical 12]

(In the formula, R ₁ represents a group of —CH ₂ — or —CH ₂ CH ₂ —, and R ₂ represents a hydrogen atom or an alkyl group of 1 to 12 carbon atoms. And)

[0075]

Embedded image

(Provided that R _{1 s} in the formula may be the same or different, --CH ₂ -or --C
R ₂ represents H ₂ CH ₂ — and R ₂ represents a hydrogen atom or an alkyl group having 1 to 12 carbon atoms, which may be the same or different. )

Of the compounds (C), only representative ones will be exemplified. Melamine, urea, acetoguanamine, benzoguanamine,
Condensates obtained by reacting various amino group-containing compounds such as steroganamin or spiroguanamine with aldehyde compound components such as formaldehyde, paraformaldehyde, acetaldehyde or glyoxal by various known and conventional methods;

Further, there are so-called aminoplasts and the like obtained by etherifying each of these condensates with alcohols. Only specific representative examples of such aminoplasts are shown. Speaking only as an example, hexamethyletherified methylolmelamine, hexabutyletherified methylolmelamine, methylbutyl mixed etherified methylolmelamine,
Examples thereof include methyl etherified methylol melamine, butyl etherified methylol melamine, isobutyl etherified methylol melamine, and condensation products thereof.

In addition to the above, a so-called bicyclic compound such as hexamethoxyglycouril or hexabutoxyglycouril, and the above-mentioned aliphatic dibasic acid represented by adipic acid and diethanolamine are used. Such as so-called acid amides obtained by a condensation reaction with such an alkanolamine, and further, a polymerizable monomer such as a butyl ether compound of N-methylol acrylamide alone or A so-called polymer compound obtained by copolymerizing a polymerizable monomer and other polymerizable monomers copolymerizable with the monomer by a conventional method is also exemplified.

The above has been mentioned and described,
As the usage ratio of the component (A) and the component (B), which are the essential film forming components of the resin composition for powder coating according to the present invention, respectively, the epoxy equivalent number of the vinyl copolymer as the former component (A) is used. Is represented by “a” and the equivalent number of the aliphatic dibasic acid as the latter component (B) is represented by “b”, it is appropriate that the equivalent ratio of “a / b” is in the range of about 0.5 to about 2. is there.

Further, as the amount of the other essential film forming component (C) used in the resin composition for powder coating according to the present invention, the total amount of the components (A) and (B) is 10
A suitable range is about 0.1 to about 40 parts by weight with respect to 0 parts by weight. In the case where the amount of the component (C) used is less than about 0.1 part by weight, the effects of the present invention are inevitably exerted, in particular, on the blocking resistance of the coating, and further on the coating film. Mechanical properties, appearance, curability, weather resistance, etc. are difficult to be exhibited. On the other hand, when the amount is more than about 40 parts by weight and the amount is too large, the storage stability of the paint is particularly important. In any case, it is not preferable because it becomes inferior.

As a method for producing a powder coating material which is a resin composition for powder coating material according to the present invention from each of these essential constituents, various known and conventional methods can be utilized and applied.

As a method for preparing such a powder coating material, only representative ones will be exemplified. First, each of these essential constituents is mixed, and if necessary, further, a pigment or After also mixing the leveling agent and the like, further melt-kneading the mixed mixture thus obtained, then, respectively, through the fine pulverization step and classification step, to make the target powder coating, A so-called mechanical crushing method is used.

The resin composition for powder coating according to the present invention includes
Furthermore, such as organic or inorganic pigments, flow regulators, ultraviolet absorbers or antioxidants,
Various known and conventional additives; various fibrin derivatives such as nitrocellulose or cellulose acetate butyrate; or various resins such as chlorinated polyethylene, chlorinated polypropylene, petroleum resin, epoxy resin or chlorinated rubber Can also be added.

The thus obtained resin composition for powder coating according to the present invention is applied to various base materials by a conventional method, and then baked and dried according to a conventional method. It is extremely practical because it can provide a coating film excellent in appearance, curability, weather resistance and mechanical properties.

As the above-mentioned base materials, only representative ones are exemplified, and 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, and more specifically, such as automobile bodies or automobile (for) parts, two-wheelers or two-wheelers (for) parts, household appliances, and various gates or fences. Materials for interior and exterior construction; or various non-ferrous metal materials or products such as aluminum foil.

The resin composition for powder coating according to the present invention thus obtained is particularly suitable for automotive top coating, solid color, clearing of metallic coat, and clear form in combination with an aqueous metallic base. It can be widely used and applied as a coating for automobile intermediate coating, automobile parts, building materials, various metal products, etc.

[0088]

EXAMPLES Next, the present invention will be explained more specifically with reference to Reference Examples, Examples and Comparative Examples, but the present invention is never limited to these Examples. is not. In the following, all parts and percentages are by weight unless otherwise specified.

Reference Example 1 [Preparation Example of Vinyl Copolymer (A)] In a reaction vessel equipped with a stirrer, a thermometer, a condenser and a nitrogen gas inlet, 500 parts of xylene was charged and placed under a nitrogen atmosphere. The temperature was raised to 130 ° C.

Here, methyl methacrylate of 150
Parts, 100 parts of n-butyl methacrylate, 150 parts of glycidyl methacrylate and 100 parts of 2-hydroxyethyl methacrylate, 3 parts of azobisisobutyronitrile and tert-butyl peroxyoctoate (hereinafter abbreviated as TBPO). Of 30 parts) was added dropwise over 4 hours, and the temperature was maintained at the same temperature for 10 hours after the completion of the addition.

After the completion of the polymerization reaction, the solution of the objective vinyl-based copolymer thus obtained is kept under reduced pressure of about 30 Torr, and xylene is distilled off to obtain a nonvolatile content of 99.6%.
Thus, a solid product of a vinyl-based copolymer (A) having a softening point by the ring and ball method of 110 ° C., an epoxy equivalent of 495, and a number average molecular weight of 3,100 was obtained. Hereinafter, this is abbreviated as polymer (A-1).

Reference Example 2 (same as above) As a dropping mixture to be used, 150 parts of methyl methacrylate, 100 parts of n-butyl methacrylate, β
-With the exception that a mixture of 50 parts methyl glycidyl methacrylate, 100 parts glycidyl methacrylate and 100 parts 2-hydroxyethyl methacrylate, 3 parts azobisisobutyronitrile and 30 parts TBPO is used. Is a vinyl-based copolymer having a nonvolatile content of 99.5%, a softening point by the ring and ball method of 106 ° C., an epoxy equivalent of 516, and a number average molecular weight of 2,900 in the same manner as in Reference Example 1. A solid product of (A) was obtained. Hereinafter, this is abbreviated as a polymer (A-2).

Reference Example 3 [Preparation Example of Compound (C) Having Specific Organic Group in Molecule] As polymerizable monomers to be used, 50 parts of styrene,
The nonvolatile content was 9% in the same manner as in Reference Example 1 except that a mixture of 250 parts of methyl methacrylate, 50 parts of n-butyl acrylate and 150 parts of N-methylol acrylamide butyl ether was used.
9.6%, the softening point by the ring and ball method is 113 ° C., and
A solid copolymer having a number average molecular weight of 4,700, which was the target compound (C), was obtained. Hereinafter, the compound (C-
Abbreviated as 1).

In the examples of the present invention, the following various compounds are used in addition to the compound (C-1). The contents of such compounds and their abbreviations are shown.

Compound (C-2) ... "Super Beckamine L-164" [trade name of high nonvolatile content type n-butyl etherified melamine formaldehyde resin manufactured by Dainippon Ink and Chemicals, Inc.]

Compound (C-3) ... "Cymel 30
0 ”[trade name of hexamethoxymethylated melamine formaldehyde resin manufactured by Mitsui Cyanamide Co., Ltd.]

Compound (C-4) ... "POWDERL
INK 1174 "(commercial name of American Cyanamid Co., Ltd., aminoplast containing tetramethoxymethylglycoluril as a main component in a form represented by the following structural formula)

[0098]

Embedded image

Compound (C-5) ... "PRIMID
XL-552 "(trade name, manufactured by Rohm and Haas Company, USA, acid amide compound in the form represented by the following structural formula)

[0100]

[Chemical 15]

Reference Example 4 [Preparation Example of Control Vinyl Copolymer] As a dropping mixture to be used, 250 parts of methyl methacrylate, 100 parts of n-butyl methacrylate and 150 parts of glycidyl methacrylate, and azobisisoiso As in Reference Example 1, except that the mixture consisting of 3 parts of butyronitrile and 30 parts of TBPO was used, the nonvolatile content was 99.7%, and the softening point by the ring and ball method was 109 ° C. A solid of the control copolymer having an epoxy equivalent of 514 and a number average molecular weight of 2,800 was obtained. Hereinafter, this is abbreviated as a polymer (A'-1).

Reference Example 5 (Same as above) Using the same apparatus as in Reference Example 1, 500 parts of butyl acetate was charged and heated to 120 ° C. under a nitrogen atmosphere. A mixture of 150 parts of butyl methacrylate and 100 parts of 2-hydroxyethyl methacrylate, 3 parts of azobisisobutyronitrile and 30 parts of TBPO was added to 4 parts of the mixture.
After the dropping, the temperature was maintained at the same temperature for 10 hours even after the dropping.

After the completion of the polymerization reaction, the thus-obtained solution of the vinyl copolymer for control was kept under a reduced pressure of about 30 Torr, and butyl acetate was distilled off to obtain a nonvolatile content of 99.5%. , Softening point by ring and ball method is 111 ℃
And has a hydroxyl value of 83 and a number average molecular weight of 2,70.
A control copolymer solid of 0 was obtained. Less than,
This is abbreviated as a polymer (A'-2).

Reference Examples 6 to 15 (Preparation Examples of Powder Coating for Top Coat and Powder Coating for Control Top Coat)

The respective components were mixed in the mixing ratios shown in Tables 1 and 2, and each mixture was mixed with "Cokneader" (trade name of uniaxial kneader manufactured by Buss, Switzerland). And of these, "PR-46 type" was used) and kneaded by heating.

Next, each kneaded product was coarsely pulverized and then further finely pulverized to prepare various powder coatings having an average particle diameter of 30 to 40 μm (μm).

[0107]

[Table 1]

<< Footnote in Table 1 >> 1) Abbreviation of decanedicarboxylic acid

2) "Taipec CR-93" [trade name of Ishihara Sangyo Co., Ltd.] is used.

3) Trade name of the leveling agent manufactured by Monsanto

[0111]

[Table 2]

[0112]

[Table 3]

Each of the powder coatings obtained in Examples 1 to 7 and Comparative Examples 1 to 3 and Reference Examples 6 to 15 was
On "Bondelite # 3030" [mild steel sheet treated with zinc phosphate-based treatment agent manufactured by Nippon Parkerizing Co., Ltd.], a dry film thickness of 60 µm was obtained by electrostatic powder coating.
And was baked at 150 ° C. for 20 minutes.

After that, each cured coating film thus obtained was evaluated for various properties. The results are summarized in Table 2.

[0115]

[Table 4]

<< Footnote in Table 2 >> Smoothness: The surface condition of the coating film is visually evaluated.

Evaluation criteria for this "smoothness":

Yu Shu ... No abnormalities are observed. Good… Slightly unevenness is observed. Slightly good ... considerable unevenness is observed.

Bad: The smoothness is completely lost.

Mitsuzawa ............ Evaluation is judged by the specular reflectance (%) at an incident angle of 60 degrees.

Adhesion ………………………………………………………………………………………………………………………………………………
Conveniently put 100 cross cuts of the following size and peel off the cross cuts with cellophane tape, and the number of stitches remaining without peeling (X)
Was evaluated by "X / 100" and this value was displayed.

Pencil hardness ......... Displayed with "Mitsubishi Uni" [trade name of pencil manufactured by Mitsubishi Pencil Co., Ltd.] with the maximum pencil hardness display so that the painted surface is not scratched. did.

Erichsen value ... The evaluation judgment was made by the coating film destruction test by the Erichsen tester, and the evaluation judgment was made by the entry distance (mm) at the time when abnormalities appeared on the coated surface, and this value was displayed.

Impact resistance: Using a DuPont type impact tester, with 1/2 inch notch, and 500 g
When the load was dropped, a convex test was conducted, and when the irregularity was observed on the coated surface, the drop height (cm) was used for evaluation and judgment, and this value was displayed.

Weather resistance ……………… 2 in the suburbs of Miyazaki City
After annual outdoor exposure to natural light, the gloss retention rate (%) as described above, that is, the specular reflectance retention rate (%) at an incident angle of 60 degrees, was used for evaluation and judgment. The value of was displayed.

[0126]

[Table 5]

[0127]

[Table 6]

[0128]

As is clear from the above detailed description, the resin composition for powder coating according to the present invention has the following properties in the coating itself, especially in blocking resistance, etc .: The excellent mechanical properties of the coating film mean that
Of course, it is intended to provide a cured coating film excellent in appearance, curability and weather resistance, among others.

Claims (4)

[Claims] 1. Obtained by copolymerizing a polymerizable monomer having an epoxy group in the molecule and a polymerizable monomer having a hydroxyl group in the molecule as an essential raw material component.
A vinyl-based copolymer (A) having both an epoxy group and a hydroxyl group in one molecule, an aliphatic dibasic acid (B), and at least one in each molecule, represented by the following general formula [I-
1] or a compound (C) having an organic group represented by [I-2] as an essential component, a resin composition for powder coatings. Embedded image (However, R ₁ in the formula is —CH ₂ — or —CH ₂ CH ₂
And R ₂ represents a hydrogen atom or an alkyl group having 1 to 12 carbon atoms. ) (However, R ₁ in the formula represents —CH ₂ — or —CH ₂ CH ₂ —, which may be the same or different, and R ₂ is the same. May be different or different, and the number of hydrogen atoms or carbon atoms is 1 to
12 represents an alkyl group. ) 2. The above-mentioned vinyl-based copolymer (A) having both an epoxy group and a hydroxyl group in one molecule uses a polymerizable monomer represented by the following general formula [II] as an essential raw material component. The composition according to claim 1, which is obtained by copolymerization using the composition. Embedded image (However, R ₃ and R ₄ in the formula each represent a hydrogen atom or a methyl group, which may be the same or different.) 3. The number average molecular weight of the epoxy group- and hydroxyl group-containing vinyl copolymer (A) having both an epoxy group and a hydroxyl group in one molecule in the range of about 1,000 to about 15,000. And has
The composition according to claim 1 or 2, which has a softening point by the ring and ball method in the range of about 80 to about 150 ° C. 4. At least one of the above-mentioned general formulas [I-1] and [I-2], respectively, in one molecule.
The composition according to any one of claims 1 to 3, wherein the compound (C) having an organic group represented by is an aminoplast. Embedded image (However, R ₁ in the formula is —CH ₂ — or —CH ₂ CH ₂
And R ₂ represents a hydrogen atom or an alkyl group having 1 to 12 carbon atoms. ) [Chemical 5] (However, R ₁ in the formula represents —CH ₂ — or —CH ₂ CH ₂ —, which may be the same or different, and R ₂ is the same. May be different or different, and the number of hydrogen atoms or carbon atoms is 1 to
12 represents an alkyl group. )