JPH0987551A - Resin composition for powder coating material and method for forming multilayered coating film using the same - 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, scratch resistance, weatherability, and mechanical properties by compounding a specific vinyl polymer. a specific compd., and an aliph. dibasic acid as the essential ingredients. SOLUTION: This compsn. contains as the essential ingredients an epoxidized vinyl polymer obtd. by polymerizing an epoxidized vinyl monomer as the essential monomer (e.g. a polymer obtd. from methyl methacrylate, n-butyl methacrylate, and glycidyl methacrylate), an aliph. dibasic acid (e.g. decanedicarboxylic 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 (e.g. a compd. obtd. from styrene, methyl methacrylate, and N-methylolacrylamide butyl ether).

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a new and useful resin composition for powder coatings, and a method for forming a multilayer coating film by applying the resin composition.

More specifically, the present invention relates to an epoxy group-containing vinyl polymer (A) obtained by polymerizing a polymerizable monomer having an epoxy group in the molecule as an essential raw material component, and an aliphatic group. The anti-blocking property of the coating material itself, which comprises a dibasic acid (B) and a compound (C) having a specific organic group, as essential film-forming components is not only the A resin composition for a powder coating which gives a coating film excellent in appearance, weather resistance and scratch resistance,

This resin composition for powder coating is
By using it as a top coat, it is possible to obtain a very practical multi-layer coating film especially when it is formed on an automobile body. The present invention relates to a film forming method.

[0004]

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

Such a composition is another conventional resin composition for powder coatings, such as a resin composition for powder coatings, for example, a block polyisocyanate-curable polyester resin is used as a binder composition. The resin composition for powder coatings, particularly for transparent (clear) coatings used outdoors because the resulting coating has excellent transparency, hardness, weather resistance, etc. It can be said that it is really suitable as such.

On the other hand, however, the flexibility and mechanical properties of the coating film, in particular, are compared with those of the coating film obtained by using the powder coating material composed of the blocked polyisocyanate-curable polyester resin composition. That is, it has the disadvantage of being inferior.

Further, it is obtained by using a composition in a form obtained by blending the above-mentioned glycidyl group-containing acrylic copolymer with an aliphatic dibasic acid,
The scratch resistance of the coating film is considerably inferior to that of a conventional, so-called organic solvent-based baked coating film, and therefore, this glycidyl group-containing acrylic copolymer-fat In terms of performance, the group-dibasic acid-blended composition was not sufficient for use as a top coat for automobiles.

Further, from the viewpoint of the method of coating automobile bodies, the conventional technique will be examined. At present, a base coat resin composition containing an organic solvent is coated on an intermediate coating film. Similarly, a so-called two-coat one-bake system in which an organic solvent-based transparent topcoat resin composition is applied and both layers are simultaneously baked and dried is widely adopted.

In that case, it is inevitable that volatilization of the organic solvent is unavoidable, and particularly from the viewpoint of environmental protection, that the generation of such volatile matter is suppressed as a problem to be solved. It becomes a place to do.

As a powerful means for that purpose, for example, it is possible to use a resin composition for powder coating which does not contain volatile matter, but it is said to contain the above-mentioned base coating coating, particularly metallic powder. Even if you try to apply the resin composition for powder coating to the shape, it is possible to obtain a product with a good coating appearance.
It can be said that it is extremely difficult.

Therefore, at present, the most excellent form of environmental hygiene is a coating system in which a so-called water-based base coat resin composition containing water as a diluent is applied, and a resin for powder coating is further applied. It can be said that the system is in the form of powder coating of the composition.

However, a resin composition for a powder coating, which is highly practical and is desired to be applied to a coating film for an automobile body, in particular, to provide a coating film excellent in scratch resistance, has not been obtained yet. It is the actual situation.

[0014]

Thus, as long as the above-mentioned conventional techniques are followed, the blocking resistance of the paint itself is inevitable, especially, the appearance and the curability of the coating film, respectively. It is also possible to provide a resin composition for a powder coating having extremely high practicality, that is, to provide a coating film having excellent mechanical properties, scratch resistance, weather resistance, and the like. It can also be said that providing a high method of forming a coating film, especially a method of forming a multilayer coating film is very difficult.

However, the inventors of the present invention provide a coating film that cannot be achieved by any means as long as the conventional technique is followed, and in particular, it has excellent appearance, mechanical properties, scratch resistance and weather resistance. , Respectively, to provide an extremely highly practical resin composition for powder coating, and for the purpose of providing an extremely highly practical coating film forming method, and in particular, a multilayer coating film forming method, The research was earnestly started.

[0016] Therefore, the problem to be solved by the present invention lies once and for all, in addition to the blocking resistance of the paint itself, especially the appearance, curability and mechanical properties of the coating film, respectively. To give a coating film with excellent physical properties, scratch resistance, weather resistance, etc.
It is also to provide an extremely highly practical resin composition for powder coatings, and in addition, to provide an extremely highly practical coating film forming method, and in particular, a multilayer coating film forming method. .

[0017]

Means for Solving the Problems Accordingly, the present inventors have:
In order to solve the problems without the drawbacks of the conventional techniques as described above, and focusing on the problems to be solved by the invention as described above, as a result of earnest and repeated studies,
A composition comprising a compound consisting of a specific component and an aliphatic dibasic acid and a compound having a specific organic group is the object to be achieved by the present inventors, such as the blocking resistance of the coating itself. Furthermore, it was found that a coating film having excellent appearance, curability, weather resistance, mechanical properties, scratch resistance and the like can be provided, and the present invention has been completed.

Furthermore, the present inventors have found that when an aqueous basecoat resin composition is applied and then the above-mentioned resin composition for powder coating is powder-coated and baked and dried, an extremely excellent coating is obtained. The present invention has been completed by finding that the appearance of the film can be realized and, of course, that the excellent scratch resistance of the coating film can be realized. It was

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION
One of them is an epoxy group-containing vinyl polymer (A) obtained by polymerizing a polymerizable monomer having an epoxy group in the molecule as an essential raw material component,
An aliphatic dibasic acid (B) and at least one of the following general formulas per molecule:

[0020]

Embedded image

(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. )

Or

[0023]

Embedded image

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

The present invention intends to provide a resin composition for powder coatings, which is extremely highly practical, and which comprises the compound (C) having an organic group represented by as an essential component.

In addition, secondly, after coating an aqueous base coat resin composition containing an aqueous resin (D) as an essential component on an object to be coated, such a resin composition for a specific powder coating as described above. It is also an object of the present invention to provide a method for forming a multilayer coating film, which comprises coating an object, baking it, and drying it.

Specifically, each of the above epoxy group-containing vinyl polymers (A) is

[0028]

[Chemical 6]

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

A specific resin composition for powder coating, or a novel method for forming a multilayer coating film, is obtained by polymerizing the polymerizable monomer represented by the formula (1) as an essential raw material component. Is also intended to be provided,

The above-mentioned epoxy group-containing vinyl polymer (A) has a number average molecular weight within the range of about 1,000 to about 10,000, and about 80 to about 150 ° C.
Within the range, having a softening point according to the ring and ball method, it is also intended to provide a specific powder coating resin composition, or a novel multilayer coating film forming method,

Further, the present invention is intended to provide a specific resin composition for powder coating, wherein the compound (C) is aminoplast, or a novel method for forming a multilayer coating film.

The constitution of the resin composition for powder coating according to the present invention will be described in detail below.

The present invention is, first of all, as described above.
Obtained by polymerizing each of the polymerizable monomers having an epoxy group in the molecule (hereinafter, also referred to as an epoxy group-containing polymerizable monomer) as an essential raw material component. Epoxy group-containing vinyl polymer (A), aliphatic dibasic acid (B), and at least one of the following general formula [I-1] in one molecule:

[0035]

[Chemical 7]

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

Or the following general formula [I-2]

[0038]

Embedded image

(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. )

Disclosed and provided is a novel and extremely highly practical resin composition for powder coatings, which comprises a compound (C) having an organic group represented by as an essential component. Is to do.

Here, the aforementioned epoxy group-containing vinyl-based copolymer (A), which is one of the essential constituents of the resin composition for powder coating according to the present invention, is attached to the terminal or side chain of the molecule. A vinyl-based copolymer having an epoxy group is referred to, and the copolymer (A) is, for example,
Respectively,

The epoxy group-containing vinyl monomer is polymerized by itself, or the epoxy group-containing vinyl monomer and another vinyl monomer which can be copolymerized with the epoxy group-containing vinyl monomer. It is a method of copolymerizing with the body, or a method of introducing an epoxy group into the molecule of the copolymer by modifying a so-called vinyl-based copolymer prepared in advance, etc. Can be prepared by various methods such as.

Among the above methods, for example, a method of synthesizing a vinyl copolymer having an isocyanate group in the molecule and further reacting the copolymer with glycidol, or a method of glyceryl in the molecule. There is a method such as converting a vinyl-based copolymer obtained by copolymerizing a vinyl-based monomer having a carbonate group into a copolymer having an epoxy group in the molecule through a decarboxylation reaction. However, it is particularly recommended because the above method is simple and convenient.

If only the representative epoxy group-containing polymerizable monomers used for obtaining the epoxy group-containing vinyl polymer by the above method are given as examples, Various glycidyl esters of (meth) acrylic acid, such as glycidyl (meth) acrylate or β-methylglycidyl (meth) acrylate;

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

Furthermore, it goes without saying that other vinyl-based monomers copolymerizable with the above-mentioned epoxy group-containing monomers can also be used.

Of these, only representative ones are exemplified by various acrylic acid esters such as methyl acrylate, ethyl acrylate, butyl acrylate or cyclohexyl acrylate;
Or methyl methacrylate, ethyl methacrylate,
Various methacrylic acid esters such as butyl methacrylate, cyclohexyl methacrylate or benzyl methacrylate;

Various kinds of carboxyl group-containing monomers such as (meth) acrylic acid, crotonic acid, itaconic acid, maleic acid or fumaric acid, as well as various polyacetic acid such as itaconic acid, maleic acid or fumaric acid. Various mono- or diesters of valent carboxyl group-containing monomers and monoalkyl alcohols having 1 to 18 carbon atoms;

Various amino group-containing amide systems 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; 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;

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;

Various hydrolyzable silyl group-containing monovalent compounds such as γ- (meth) acryloyloxypropyltrimethoxysilane, γ- (meth) acryloyloxypropyltriethoxysilane or γ- (meth) acryloyloxypropylmethyldimethoxysilane. Quantities;

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

Alternatively, various perfluoroalkyl perfluorovinyl ethers such as trifluoromethyltrifluorovinyl ether, pentafluoroethyl trifluorovinyl ether or heptafluoropropyl trifluorovinyl ether, or (per) fluoroalkyl vinyl ethers (wherein alkyl is used). The number of carbon atoms in the group is within the range of 1 to 18) and other 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 _A variety of aliphatic vinyl carboxylates such as C ₁₀ branched (branched) aliphatic vinyl carboxylate, C ₁₁ branched (branched) aliphatic vinyl carboxylate or vinyl stearate,

Further, various vinyl esters of carboxylic acid having a cyclic structure such as vinyl cyclohexanecarboxylate, vinyl methylcyclohexanecarboxylate, vinyl benzoate or vinyl p-tert-butylbenzoate can be used.

The amount of the above-mentioned epoxy group-containing vinyl-based monomer used is such that all monomers used as raw material components for preparing the epoxy group-containing vinyl-based polymer (A), Especially, it is suitable to be in the range of about 5 to 100% by weight, preferably 10 to 60% by weight, based on the total amount of all vinyl-based monomers.

If the amount of the epoxy group-containing vinyl-based monomer used is less than 5% by weight, the mechanical properties of the coating film obtained, especially the mechanical properties of the coating film, tend to deteriorate. Therefore, various effects that the present invention should achieve cannot be exhibited.

The number average molecular weight of the vinyl (co) polymer (A) is about 1,000 to about 10,000.
It is suitable within the range, and preferably 1,500 to
A range of 7,000 is suitable.

When the number average molecular weight is less than about 1,000, the mechanical properties of the coating film tend to be inferior, and when it is more than about 10,000, the coating film becomes smooth. Sex decreases.

Further, the vinyl-based (co) polymer (A)
The softening point by the ring and ball method is about 80 to about 150 ° C.
If the range is suitable and is lower than about 80 ° C., then it is inevitable that the powder coating itself, especially
Blocking resistance tends to be inferior, on the other hand, about 15
If the temperature is too high than 0 ° C., the smoothness of the coating film is apt to be deteriorated.
Either case is not preferable.

By using various monomers, especially various vinyl monomers as exemplified above, it is possible to obtain the epoxy group-containing vinyl copolymer. Although various known and commonly used methods can be used and applied, among them, the solution radical polymerization method is particularly preferable because it is simple and convenient.

Next, the above-mentioned aliphatic dibasic acid (B), which is another essential constituent of the resin composition for powder coating material according to the present invention, has the following general formula:

[0064]

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

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

It refers to a compound represented by

Of these compounds, only representative 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, from the viewpoint of the appearance of the coating film, in particular, “R” in the above general formula
It is desirable to use a compound having 8 or more carbon atoms.

Further, the above-mentioned compound (C) which is another essential constituent of the resin composition for powder coating according to the present invention, that is, at least one compound represented by the following general formula:

[0070]

Embedded image

(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 having 1 to 12 carbon atoms. )

Or the following general formula

[0073]

Embedded image

(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. )

The compound (C) represented by the formula (C) having a specific organic group is represented by the general formula [I-1] or [I-2]
The compound (C) may be a low molecular weight compound, or a compound having a specific organic group in the molecule. Further, it may be a polymer compound,
Of course.

Of these compounds, only representative ones are exemplified, and various amino group-containing compounds such as melamine, urea, acetoguanamine, benzoguanamine, steroganamin or spiroguanamine, and formaldehyde, Various condensates in the form of being obtained by reacting various aldehyde compounds such as paraformaldehyde, acetaldehyde or glyoxal with various known and commonly used methods, or each condensate thereof with alcohols. Thus, the so-called aminoplasts obtained by etherification,

Specific examples of such aminoplasts include:
Hexamethyletherified methylolmelamine, hexabutyletherified methylolmelamine, methylbutyl mixed etherified methylolmelamine, methyletherified methylolmelamine, butyletherified methylolmelamine or isobutyletherified methylolmelamine, and further various condensates thereof. And so on.

In addition to the above, various bicyclic compounds such as hexamethoxyglycoluril or hexabutoxyglycoluril, and aliphatic dibasic acids,
Examples include acid amides obtained by condensation reaction with various alkanolamines such as diethanolamine.

Further, various polymerizable monomers such as butyl ethers of N-methylol acrylamide can be polymerized alone or with the polymerizable monomer.
Also included are polymeric compounds in the form of being obtained by copolymerizing them with other monomers capable of copolymerization.

As the ratio of use of both essential components of the component (A) and the component (B) as exemplified above,
The former (A) component is an epoxy group-containing vinyl (co) polymer, and the epoxy equivalent number is "a", while the latter (B) is
When the equivalent number of the component aliphatic dibasic acid is “b”, the ratio a / b is appropriately within the range of about 0.5 to about 2.

The amount of the compound (C), which is another essential component, used is as follows: the component (A) and the component (B).
About 0.1 to about 100 parts by weight of the total amount of the ingredients used
A range of about 50 parts by weight is suitable.

When the amount of the compound (C) used is less than about 0.1 part by weight, the effect of the present invention tends to be difficult to exert, and on the other hand, it is too much than about 50 parts by weight. If the amount is too large, the storage stability of the coating tends to be deteriorated, which is not preferable.

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 used and applied. Of course.

If only representative methods for preparing such powder coatings are given as examples, first of all, as described above, the respective essential constituents are mixed, and if necessary, the pigment is added. Alternately, a so-called mechanical crushing, in which a leveling agent, etc. is also mixed, and then it is further melt-kneaded, and then subjected to a fine pulverization step and a classification step to form an intended powder coating Method etc.

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 of the present invention is applied to various base materials by a conventional method, and then baked and dried according to a conventional method to prevent the coating itself from blocking. It is extremely highly practical in that it can provide a coating film having excellent properties such as appearance, curability, scratch resistance, 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. Building materials; various building interior and exterior materials such as aluminum sashes; and various ferrous or non-ferrous metal materials or products such as aluminum foil.

The thus obtained resin composition for powder coating according to the present invention is particularly suitable for top coating of automobiles, middle coating of automobiles, automobile parts, building materials and home appliances, or for various metal products. It can be used and applied in a wide range as paints.

Next, the structure of the multilayer coating film forming method according to the present invention will be described in detail.

The method for forming a multi-layer coating film is, for example, after coating a material to be coated with a so-called water-based base coat resin composition containing a so-called water-based resin as an essential film-forming component. The novel coating film forming method, which consists of applying the resin composition for powder coating material according to the present invention as described in detail above, baking and drying, is named, among others, an innovative method. The method for forming a layer coating film is referred to.

Here, the above-mentioned aqueous base coat resin composition means, for example, a so-called water dilutable resin composition in the form of containing water as an essential solvent. Naturally, various types of known and commonly used types can be used.

Of these, only typical ones are exemplified by a water-soluble resin as a binder, or a dispersion type (water dispersion) type resin. The binder may be in the form of a binder, or may be an emulsion polymer in the form of a binder.

To exemplify only particularly representative ones belonging to the above-mentioned type, those obtained by water-solubilizing an acrylic resin having an acid group in the molecule by amine neutralization And so on
To exemplify only typical ones belonging to the above type, water-dispersible polyurethane resin having an anion-forming group in the molecule as disclosed in Japanese Patent Publication No. 3-45755. In addition, if only representative ones belonging to the above-mentioned type are exemplified, JP-A-56-157 will be used.
For example, an emulsion polymer aqueous solution containing fine particles of a crosslinkable polymer as disclosed in Japanese Patent No. 358.

[0094]

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 examples. It is not something that In the following, parts and%
All are by weight unless otherwise specified.

Reference Example 1 [Epoxy Group-Containing Vinyl (Co)]
Preparation Example of Polymer (A)] 500 parts of xylene was charged into a reaction vessel equipped with a stirrer, a thermometer, a condenser and a nitrogen gas inlet, and heated to 130 ° C. under a nitrogen atmosphere.

Next, 250 parts of methyl methacrylate, 100 parts of n-butyl methacrylate and 150 parts of glycidyl methacrylate, 3 parts of azobisisobutyronitrile and tert-butyl peroxyoctoate (hereinafter referred to as TBPO) were added. 20) of
The mixture consisting of 1 part and 4 parts was added dropwise over 4 hours, and after the completion of the addition, the same temperature was maintained for 10 hours.

After the completion of the polymerization reaction, the resin solution thus obtained was kept under a reduced pressure of about 30 Torr, and xylene was distilled off to obtain a nonvolatile content of 99.5%.
The softening point by ring and ball method is 115 ° C, and the epoxy equivalent is 49
A solid product of the copolymer (A) having a number average molecular weight of 4,500 and a number average molecular weight of 4,500 was obtained. Hereinafter, the polymer (A-
Abbreviated as 1).

Reference Example 2 (Same as above) As a mixture of monomers to be used, styrene of 150
Parts, 150 parts of methyl methacrylate, 50 parts of dibutyl fumarate, 50 parts of β-methylglycidyl methacrylate and 100 parts of glycidyl methacrylate, and the amount of TBPO used is 30 parts.
In the same manner as in Reference Example 1, except that the content was changed to 9 parts, the nonvolatile content was 99.7%, the softening point by the ring and ball method was 103 ° C., the epoxy equivalent was 515, and the number average molecular weight was 2,30.
A solid product of copolymer (A) of 0 was obtained. Hereinafter, this is abbreviated as a polymer (A-2).

Reference Example 3 [Preparation example of aqueous resin (D) used in the method for forming a multilayer coating film according to the present invention]

Apparatus similar to that of Reference Example 1, that is, Reference Example 1
Using the same reaction container as above, it was prepared by the following method.

That is, 250 parts of styrene, 157 parts of methyl methacrylate, 63 parts of 2-hydroxyethyl methacrylate and 30 parts of methacrylic acid, and T
A mixture with 8 parts of BPO is obtained, then 7 parts of this mixture
Charge 5 parts and 500 parts of methyl ethyl ketone (MEK) to a reaction vessel, and stir under a nitrogen blanket while stirring to 75
After being kept at 0 ° C. for 30 minutes, the remaining mixed solution was added dropwise over 2 hours.

Even after the dropping, the reaction is carried out at the same temperature for 12 hours, so that the nonvolatile content is 50%.
And the solution acid value is 20, the solution hydroxyl value is 25, and
A resin solution having a Gardner viscosity of Z at 25 ° C. was obtained. To 1,000 parts of the acrylic resin solution thus obtained, 31 parts of dimethylaminoethanol was added, and then water was added to obtain a 55% concentration water-soluble acrylic resin solution. Hereinafter, this is abbreviated as water-soluble resin (D-1).

Reference Example 4 (same as above) In the same reaction vessel as in Reference Example 1, 680 parts of deionized water,
2 parts of ammonium persulfate and "Triton x-
15 parts of "200" were added and heated to 95 ° C.

Then, an aqueous emulsion of an acrylic monomer component as described below was added dropwise to the reaction system at 95 ° C. over 4 hours, and the temperature was maintained at the same temperature for 3 hours after the completion of the addition. did.

After that, the reaction solution was cooled, and 5 parts of dimethylethanolamine and 40 parts of deionized water were added. Thus, a stable milky white dispersion liquid of a water-dispersible acrylic resin having a solid content (nonvolatile content) of 45% was obtained. Hereinafter, this is abbreviated as an aqueous resin (D-2).

Styrene 150 parts Methyl methacrylate 300 parts Ethyl acrylate 380 parts 2-Hydroxyethyl methacrylate 150 parts Acrylic acid 20 parts

N-octyl mercaptan 5 parts ammonium persulfate 4 parts

"Triton X-200" 15 parts "Emulgen 840s" 10 parts

530 parts of deionized water

The above-mentioned "Triton X-200"
Is Rohm & Haas, USA
s) is a trade name of an anionic surfactant.

The above-mentioned "Emulgen 840s" is a trade name of a nonionic surfactant manufactured by Kao Atlas Co., Ltd.

Reference Example 5 (same as above) In the same manner as in Reference Example 4, except that the acrylic monomer component to be used was changed as follows, the solid content was 45%, and the solvent was used as a solvent. A milky-white, stable dispersion of a water-dispersible acrylic resin containing insoluble crosslinkable fine particles was obtained. Hereinafter, this is abbreviated as an aqueous resin (D-3).

Styrene 450 parts Ethyl acrylate 350 parts 2-Hydroxyethyl methacrylate 150 parts Acrylic acid 20 parts Ethylene glycol dimethacrylate 30 parts

N-octyl mercaptan 5 parts ammonium persulfate 4 parts

"Triton X-200" 15 parts "Emulgen 840s" 10 parts

530 parts of deionized water

Reference Example 6 [Preparation Example of Compound (C) Having Specific Organic Group] As a mixture of polymerizable monomers to be used, styrene of 5
The nonvolatile content was 99.% in the same manner as in Reference Example 1 except that a mixture of 0 parts, 250 parts of methyl methacrylate, 50 parts of n-butyl acrylate and 150 parts of N-methylol acrylamide butyl ether was used. A solid product of a copolymer, which was 6% and had a softening point by the ring and ball method of 113 ° C. and a number average molecular weight of 4,700, was obtained as a target compound. Hereinafter, this is referred to as a compound (C
-1) is abbreviated.

In the embodiment of the present invention, the above (C
In addition to -1), since the following compounds are used, the contents and abbreviations of these compounds will be shown.

Compound (C-2) ... "Super Beckamine L-164" [trade name of a highly nonvolatile 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 "(trade name of aminoplast manufactured by American Cyanamid Co., Ltd., which has tetramethoxymethylglycoluril as a main component and is represented by the following structural formula).

[0122]

[Chemical 12]

Compound (C-5) ... "PRIMID
XL-552 "(a product name of an acid amide compound manufactured by Rohm and Haas Company, which is a compound represented by the following structural formula).

[0124]

Embedded image

Reference Example 7 (Preparation Example of Thickener) 64 of "Acrisol ASE-60" (trade name of thickener manufactured by Rohm and Haas Co .; solid content = 28%)
By adding 6 parts of dimethylethanolamine and 530 parts of deionized water to 3 parts, the solid content is reduced to 3 parts.
% Target product was obtained. Hereinafter, this is abbreviated as a thickener (P).

Reference Example 8 (Preparation Example of Metallic Paint for Aqueous Base Coat) To 100 parts of the aqueous resin (D-1) obtained in Reference Example 3, the thickener (P) obtained in Reference Example 7 was added. 10 parts, 6 parts of "Cymel 300", 1 part of paratoluene sulfonic acid, and 3 parts of "aluminum paste dispersion liquid # 4919" (trade name of aluminum paste manufactured by Toyo Aluminum Co., Ltd.).
Part, 1.5 parts of "aluminum paste dispersion liquid # 55-519" (product of the same company) was mixed,

Further, 12 parts of isopropanol was also mixed, and then deionized water was added at 20 ° C.
The Ford Cup No. 4 viscosity was adjusted to 16 seconds. Hereinafter, this is abbreviated as an aqueous base coat metallic coating (X-1).

Reference Example 9 (same as above) To 100 parts of the aqueous resin (D-2) obtained in Reference Example 4,
10 parts of the thickener (P) obtained in Reference Example 7, 5 parts of "Cymel 300", 1 part of paratoluenesulfonic acid,
Mix 3 parts of "Aluminum paste dispersion liquid # 4919" and 1.5 parts of "Aluminum paste dispersion liquid # 55-519",

Further, 12 parts of isopropanol was also mixed, and then deionized water was added at 20 ° C.
The Ford Cup No. 4 viscosity was adjusted to 16 seconds. Hereinafter, this is abbreviated as an aqueous base coat metallic coating (X-2).

Reference Example 10 (same as above) To 100 parts of the aqueous resin (D-3) obtained in Reference Example 5,
10 parts of the thickener (P) obtained in Reference Example 7, 5 parts of "Cymel 300", 1 part of paratoluenesulfonic acid,
Mix 3 parts of "Aluminum paste dispersion # 4919" and 1.5 parts of "Aluminum paste dispersion # 55-519",

Further, 12 parts of isopropanol was also mixed, and then deionized water at 20 ° C. was added.
The Ford Cup No. 4 viscosity was adjusted to 16 seconds. Hereinafter, this is abbreviated as an aqueous base coat metallic coating (X-3).

Reference Examples 11 to 20 (Preparation Examples of Clear Powder Paint for Top Coat and Powder Paint for Control)

The respective components were mixed at the blending ratios shown in Table 1, and the mixture thus obtained was blended.
The kneaders were individually kneaded by heating with a "co-kneader" (the product name of the uniaxial kneading machine manufactured by Buss, Switzerland, of which "PR-46 type" was used).

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

[0135]

[Table 1]

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

2) Trade name of extender manufactured by Monsanto, USA

[0138]

[Table 2]

[0139]

[Table 3]

Examples 1 to 10 and Comparative Examples 11 to 13 Various coating films as shown in Table 2 were prepared according to the method for forming a multilayer coating film described below, and various coating films were prepared. A performance evaluation judgment test was performed. The results are shown together in the same table.

Various multilayer coating films in each of Examples and Comparative Examples were prepared by the following method.

That is, the metallic coating for aqueous base coat prepared in Reference Examples 8 to 10 and the clear powder coating for top coat obtained in Reference Examples 11 to 20 were processed by the following method to obtain so-called 2 A coat 1 bake was applied. The substrate to be coated at that time was used after the following pretreatment.

That is, "Bondelight # 3030"
[Product name of mild steel plate treated with zinc phosphate-based treatment agent manufactured by Nippon Parkerizing Co., Ltd.] is electrodeposited with an epoxy resin-based cationic electrodeposition coating, and then,
An amino-polyester resin-based intermediate coating composition was used.

Then, the specific coating method of the two coats and one bake described above is as follows.

First, a water-based base coat metallic paint (X-1) or the like was applied so that the dry film thickness was 20 μm in a coating atmosphere having a temperature of 25 ° C. and a relative humidity of 65 to 70%. , Each of which was painted twice.

A setting for 2 minutes was performed between these two coatings. The air pressure of the spray gun at the time of the first coating was 5 kg / cm ² , and the coating flow rate was 400 m.
/ Min, and the flow rate of the paint was 20 during the second coating.
The distance between the coated object and the spray gun is 40 m / min.
cm.

The coated surface on the coated object is always
The article to be coated was held so as to be perpendicular to the discharge direction of the spray gun.

After such two coatings, this coated object was
It was air dried at a temperature of 30 ° C. for 5 minutes. Further, after cooling to room temperature, a clear powder coating for top coat (powder coating for top clear) T1 etc. is applied by electrostatic powder coating so that the dry film thickness becomes 60 μm, Baking was performed at 150 ° C. for 20 minutes.

Each cured coating film thus obtained was tested for evaluation and judgment of various properties. The results are summarized in Table 2.

The evaluation judgment procedure was as follows.

Smoothness: Visual evaluation judgment.

◎ ………… For a very smooth and smooth coated surface ○ ………… For a large round × ………… For fine dust skin

20 ° gloss ... Evaluation judgment by 20 ° specular reflectance (%).

Metallic feeling ………… [ALCOPE L
MR-00 "[trade name of metallic feeling measuring device manufactured by Kansai Paint Co., Ltd.] was used for evaluation and determination according to the IV value obtained.

Excellent: When it exceeds 250 Good: When it is 200 or more and less than 250 Bad: When it is less than 200

DuPont impact: The highest evaluation of physical properties (that is, mechanical properties), that is, evaluation by a DuPont impact tester (1/2 inch), 50
The height (cm) that does not cause defects such as cracks in the coating film when a load of 0 g is dropped is shown. The larger this value, the better the impact resistance. ing.

Erichsen: Similarly, this is the highest evaluation judgment of physical properties, and this is the evaluation judgment by the Erichsen tester. The larger this value, the more flexible the coating film. It means good.

Scratch resistance: When a rubbing flannel containing a 5% cleanser aqueous solution is used and a rubbing tester is used to apply a load of 1.5 kg to perform rubbing 20 times. The gloss retention rate (%) with respect to the initial gloss is indicated, and the higher this value, the better the scratch resistance.

Interphase Adhesion: The test plate was immersed in warm water of 40 ° C. for 10 days, and after 30 minutes of pulling up, a cross cut was put in, and a peeling test using an adhesive tape was conducted.

○: No peeling was observed at all Δ: When peeling was observed between the base coat and top coat ×: When significant delamination was observed

Water resistance …………………………………………………………………………………………………………………………………………………………………………………… of of the test plate.

∘: When the gloss retention rate exceeds 80% ○: When the gloss retention rate is 60% or more and less than 80% x: When the gloss retention rate is less than 60%

Weather resistance …………………… It was displayed by the gloss retention rate (%) after 1,000 hours using the Sunshine Weather Meter [trade name of Suga Test Instruments Co., Ltd.]. The higher the value, the better the weather resistance.

[0164]

[Table 4]

[0165]

[Table 5]

[0166]

[Table 6]

[0167]

[Table 7]

[0168]

As described above in detail, according to the present invention,
Respectively, the resin composition for powder coating and the method for forming a multilayer coating film, the anti-blocking property of the coating itself is, of course, in particular, the coating film, respectively, appearance, mechanical properties, flexibility, It will be easy to know that it gives a cured coating film having excellent scratch resistance and weather resistance.

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location C09D 163/00 PJK C09D 163/00 PJK // B05D 7/14 B05D 7/14 Z

Claims (5)

[Claims] 1. An epoxy group-containing vinyl polymer (A) obtained by polymerizing a polymerizable monomer having an epoxy group in a molecule as an essential raw material component, and an aliphatic dibasic acid (B). , At least one in one molecule, having the general formula: (However, R ₁ in the formula is —CH ₂ — or —CH ₂ CH ₂
And R ₂ is a hydrogen atom or has 1 to 10 carbon atoms.
12 represents an alkyl group. ) Or (However, R ₁ in the formula is —CH ₂ — or —CH ₂ CH ₂
And R ₂ is a hydrogen atom or has 1 to 10 carbon atoms.
12 represents an alkyl group. The compound (C) which has the organic group shown by these is included as an essential component, The resin composition for powder coatings characterized by the above-mentioned. 2. The epoxy group-containing vinyl polymer (A) is represented by the following general formula: (In the formula, R ₃ and R ₄ may be the same or different and each represents a hydrogen atom or a methyl group.) The composition according to claim 1, which is obtained by polymerization as a raw material component. 3. The epoxy group-containing vinyl polymer (A) has a number average molecular weight within the range of about 1,000 to about 10,000, and within the range of about 80 to about 150 ° C. The composition according to claim 1 or 2, which has a softening point according to the ring and ball method. 4. The composition according to claim 1, wherein the compound (C) is aminoplast. 5. The resin composition for powder coatings according to claim 1, which is obtained by applying an aqueous basecoat resin composition containing the aqueous resin (D) as an essential component onto an object to be coated. A method for forming a multilayer coating film, which comprises coating an object, baking it, and drying it.