JPH10338823A - Powder coating material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a powder coating material made capable of curing at low temperature and of maintaining sufficient storage stability by imparting such thermosetting properties that it by itself is not cured at a specified low temperature and it in combination with another powder coating material can be cured by heating. SOLUTION: There is provided a coating material which by itself is not cured at 160 deg.C or below but can be cured at 160 deg.C or below when used in combination with another powder coating material. Although the type of the resin used is not particularly limited, the melting temperature of the resin needs to be adjusted to 160 deg.C or below. Practically, there are an embodiment where the resins contained in the powder coating material are melt-mixed to give a resin which cures at 160 deg.C or below (e.g. a combination of a carboxyl- containing resin with an epoxy-containing resin) and an embodiment where the resin of each powder coating is mixed with a curing agent for the resin of the other resin, and the individual resin by itself can not cure at 160 deg.C or below, and the both are mixed and the mixture is applied and cured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a powder coating, a powder coating composition and a coating method using the same, which are used in a coating method for mixing and coating two or more powder coatings.

[0002]

2. Description of the Related Art Conventionally, a powder coating material is mixed with a resin, a curing agent, an additive, and the like, melted and kneaded, and then cooled, pulverized,
Although it is manufactured by classification, it is necessary to melt and knead by applying heat of about 60 to 160 ° C. in order to uniformly disperse such additives.

However, if a curing agent capable of curing at a low temperature in the above temperature range is used, curing of the resin starts during melt-kneading, so that a powder coating cannot be prepared. In addition, when a curing agent having a high curing temperature is used to suppress the curing of the resin during kneading, the baking temperature becomes high, and new equipment investment is required, and the running cost is disadvantageously increased.

On the other hand, when a kneading temperature is lowered and a curing agent having a low curing temperature is used, it is necessary to lower the melting temperature of the resin contained in the powder coating so that the kneading can be sufficiently performed even at a low temperature. However, a resin having a low melting temperature has a low glass transition temperature and poor storage stability, and thus poses a problem in quality assurance of a powder coating. Also known is a method of mixing a curing agent into a powder coating by dry blending, but there is a disadvantage that curing unevenness is apt to occur, and the properties of the coating film are deteriorated. (Japanese Unexamined Patent Application Publication No. 57-3
1966, JP-A-59-24762, etc.).

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a powder coating composition and a powder coating composition which can be cured at a low temperature and maintain sufficient storage stability and are used for mixing and coating. And Still another object of the present invention is to provide a coating method using the powder coating and the powder coating composition.

[0006]

The gist of the present invention is to provide (1)
A powder coating used in a coating method in which two or more powder coatings are mixed and applied. The powder coating alone does not thermoset at a temperature of 160 ° C. or lower.
A powder coating having a property of being thermoset at a temperature of 60 ° C. or lower, (2)
A powder coating composition containing two or more powder coatings, each of which alone does not thermally cure at 160 ° C. or lower,
A powder coating composition comprising two or more powder coatings having a property of forming a coating film by heat curing at 160 ° C. or lower by mixing and coating two or more of these powder coating compositions;
(3) (a) Two or more kinds of powder coatings according to (1) are mixed to form a mixture, (b) the mixture is applied to an object to be coated, and (c) the applied mixture is heated to 160 ° C. (4) (a) applying the powder coating composition as described in (2) above to an object to be coated, and (b) applying the powder coating composition; A coating method, wherein the powder coating composition is heated at a temperature of 160 ° C. or lower and thermally cured.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The powder coating of the present invention is a powder coating used in a coating method in which two or more powder coatings are mixed and applied. It has the property of being thermally cured at 160 ° C. or lower by being mixed and applied with another type of powder coating.

As the resin used in the powder coating of the present invention, various types of conventionally known resins can be used without limitation, but the melting temperature of the resin is 160.
It is necessary to adjust the temperature so as to be lower than or equal to 90 ° C., preferably 90 to 140 ° C., and lower than or equal to the curing temperature of the mixed powder coating. In the present invention, the melting temperature is a softening point, that is, a temperature at which the resin liquefies. The melting temperature of the resin can be adjusted by changing the chemical structure of the resin, changing the molecular weight distribution, or the like.

The glass transition point of the resin used in the present invention is preferably 40 ° C. or higher, and more preferably 50 ° C. or higher, in consideration of storage stability, and in consideration of the melting temperature of the powder coating. It is desirable that the temperature be 90 ° C or lower, preferably 80 ° C or lower.

In the present invention, as described above, 160
When two or more kinds of powder coatings are mixed and applied by appropriately selecting a combination of resins to be used for each of two or more kinds of powder coatings that do not thermoset at a temperature of not more than ℃ and performing preparations according to each aspect. Are melt-mixed with each other and thermoset at 160 ° C. or lower to form a coating film. In addition, "does not thermoset" means a differential scanning calorimeter (manufactured by Seiko Instruments Inc.,
This means that when measured at a heating rate of 10 ° C./min using DSC 210), an exothermic peak corresponding to thermosetting cannot be detected. The term “resin” as used herein refers to a high-molecular substance having a number average molecular weight of 500 or more, preferably 1,000 or more.
A material capable of forming a film by heating and melting.

In the present invention, the resin contained in the powder coating is melt-mixed to use a resin which causes a curing reaction at 160 ° C. or less. It does not cause a curing reaction, but is melt-mixed by using a curing agent together.
There is a mode in which a curing reaction occurs at 60 ° C. or lower. Hereinafter, each embodiment will be described.

(1) When Resin Causes a Curing Reaction When the powder coatings used in this embodiment are indicated as powder coating A and powder coating B, respectively, the resin used for powder coating A and the powder coating are used. The resin used for B is 16
It is necessary to select a resin which cannot cause a reaction (curing reaction) at 0 ° C or lower, but can cause a curing reaction at 160 ° C or lower by being melt-mixed. As a combination of functional groups capable of causing a curing reaction, for example, a group selected from a carboxyl group, an acid anhydride group, an amino group and a phenolic hydroxyl group and a glycidyl group, an epoxy group, an isocyanate group and a group having an unsaturated bond. There is a combination with one selected.

Accordingly, as a combination of the resin used for the powder coating A and the resin used for the powder coating B, for example,
A resin having a carboxyl group, a resin having an amino group,
There is a combination of a resin selected from the group consisting of a resin having a phenolic hydroxyl group and an acid anhydride resin and a resin selected from the group consisting of a resin having an epoxy group, a resin having a glycidyl group and a resin having an unsaturated bond. In addition,
Examples of the resin having a carboxyl group include polyester resins, polyester polyamide resins, and (meth) acrylic acrylic resins. Examples of the resin having an amino group include polyamide resins and polyester polyamide resins, and examples of the resin having a phenolic hydroxyl group. Is a novolak resin or the like;
Maleic anhydride copolymers and the like, epoxy resins and the like having an epoxy group, glycidyl group-containing resins include glycidyl methacrylate-based acrylic resins, and resins having an unsaturated bond include non-saturated bonds. And a saturated polyester resin. In this case, the polyester resin, polyester polyamide resin, polyamide resin and acid anhydride resin more preferably have an amino group, a carboxyl group or an acid anhydride group at the terminal. The method for producing the resin is not particularly limited, and the resin can be produced by an ordinary method.

In this embodiment, when a resin of the above combination is used, a curing agent is not particularly required, but a curing agent may be used if necessary. In this case, conventionally known various curing agents can be used without particular limitation, but the combination of the resin and the curing agent is appropriately selected so that a single powder coating does not thermally cure at 160 ° C. or lower. There is a need to. That is, powder coating A,
The resins in B are denoted as resin a and resin b, respectively,
When a curing agent that reacts with but does not react with the resin b is indicated as a curing agent a ′, and a curing agent that reacts with the resin b but does not react with the resin a is indicated as a curing agent b ′, the curing agent with the resin in the powder coating is cured. As for the combination of agents, it is necessary to select a resin and a curing agent such that powder coating A = resin a + curing agent b ′ powder coating B = resin b + curing agent a ′. That is, a curing agent suitable for each resin used in each powder coating is added to the other powder coating.
A powder coating that does not thermoset at 60 ° C. or lower can be prepared. Further, as another embodiment when using a curing agent,
An embodiment in which a curing agent is used only in one of the following powder coatings may be used. Powder coating A = Resin a Powder coating B = Resin b + Curing agent a ′ In this embodiment, resin A and resin b, and resin a and curing agent a ′
This is an embodiment in which the curing reaction proceeds by each of the above reactions. As the curing agent, a known blocked isocyanate-based curing agent, an epoxy-based curing agent, an alkoxysilane-based curing agent, a polyaziridine-based curing agent, an oxazoline-based curing agent, and the like may be appropriately selected in accordance with the functional group of the corresponding resin. Good.

The combination of the resin used in the present invention and a curing agent that reacts with the resin (eg, resin a <curing agent a ′> or resin b <curing agent b ′>) includes, for example,
Organopolysiloxane <aminoxysilane compound>,
Organopolysiloxane <alkoxysilane compound>,
Silicone polymer <tin compound>, polysulfide polymer <lead dioxide>, urethane resin <acrylic oligomer>, urethane resin <polyol compound>, urethane prepolymer <polyol compound>, polyester resin <polyepoxy compound>, polyester resin <polyanhydride Compound>, polyester resin <polyamine compound>,
Polyester resin <modified melamine compound>, polyester resin having a hydroxyl group at the terminal <alkoxy compound>, polyester resin having a carboxyl group <triglycidyl isocyanurate (hereinafter abbreviated as TGIC)>, polyester resin having an amino group at the terminal <TGIC>,
Polyester resin having a terminal amino group <Modified melamine compound>, Polyester resin having a phenolic hydroxyl group <TGIC>, Unsaturated polyester resin having a non-phenolic hydroxyl group at the terminal <Melamine compound>, Non-phenolic hydroxyl group at the terminal Having an unsaturated polyester resin <2,4,6-triaminopyridine>, an epoxy resin <polyamine compound>, an epoxy resin <polyanhydride compound>, an epoxy resin <aromatic diamine compound>,
Epoxy resin <adipic dihydrad>, epoxy resin <2,4,6-triaminopyridine>, epoxy resin <polycarboxylic acid compound>, epoxy resin and acrylic resin having glycidyl group <2,4,6-triaminopyridine > Acrylic resin having amino group <TGI
C>, a polyamide resin <polycarboxylic acid compound>, a polyamide resin having a terminal amino group <TGIC>, a polyester polyamide resin <polycarboxylic acid compound>, a polyester polyamide resin <TGIC>, a novolak resin <polycarboxylic acid compound>, Alkoxy resin <polyol compound> and the like.

Preferable specific examples of the combination of the resin and the curing agent in the powder coatings A and B are described in Table 1 below.
The following combinations can be mentioned.

[0017]

[Table 1]

The mixing ratio (weight ratio) of the resins a and b used in the present embodiment depends on the amount of the functional group present in the resin, but is 10/90 to 90/10, preferably 25/7.
The ratio is preferably 5 to 75/25, and the functional group ratio is preferably 0.8 to 1.2. The amount of the curing agent may be an amount necessary for a normal thermosetting reaction, and the resin reacts together with the amount of the same kind of functional group contained in the resin contained in the same powder coating. It is preferable to adjust the equivalent of the functional group equivalent to 0.8 to 1.2 times.

(2) An embodiment in which the resin and the resin alone do not cause a curing reaction at 160 ° C. or lower When the powder coatings used in this embodiment are indicated as powder coating C and powder coating D, respectively, As the resin to be used and the resin to be used for the powder coating material D, it is necessary to select a resin that does not cause a curing reaction at 160 ° C. or lower even when these are melt-mixed.

That is, in this embodiment, the resins in the powder coatings C and D are referred to as a resin c and a resin d, respectively (however, the resin c and the resin d do not undergo a curing reaction at 160 ° C. or lower even if melted and mixed. And a curing agent that reacts with the resin c but does not react with the resin d is indicated as a curing agent c ′, and a curing agent that reacts with the resin d but does not react with the resin c is indicated as a curing agent d ′. The combination of the resin and the curing agent in the powder coating should be selected such that the powder coating C = the resin c + the curing agent d 'and the powder coating D = the resin d + the curing agent c'. There is. That is, a curing agent suitable for each resin used in each powder coating is added to the other powder coating, and a powder coating that does not thermoset alone can be prepared.

The combination of the resin and the curing agent that react with each other in the powder coatings C and D is not particularly limited as long as it has the above-described relationship.

Therefore, preferred examples of the combination of the resin and the curing agent in the powder coatings C and D include, for example, the combinations shown in Table 2.

[0023]

[Table 2]

The mixing ratio (weight ratio) of the resins c and d is 10 /
It is preferably 90 to 90/10, and the amount of the curing agent is preferably adjusted to 0.8 to 1.2 times the equivalent of the functional group of the resin to be reacted.

In the powder coating of the present invention, a coloring agent, various additives and the like can be further used, if necessary.

As the colorant, a conventionally known colorant can be used without any particular limitation, and is appropriately selected according to the color tone of the powder coating. For example, titanium oxide, carmine 6B, carbon black, copper phthalocyanine, acetoacetic acid arylamide-based monoazo yellow pigment, disazo yellow, pigment red and the like can be mentioned. The amount used is preferably about 5 to 60 parts by weight based on 100 parts by weight of the resin. When no colorant is used for preparing the powder coating, the obtained powder coating has a transparent color.

As the various additives, those conventionally known as those used in coating compositions can be used without any particular limitation. Examples thereof include a spreading agent such as an acrylate polymer, a crosslinking accelerator such as various catalysts and organic tin compounds, and a pinhole inhibitor such as benzoin.
Each of these additives is preferably used in an amount of about 0.1 to 5 parts by weight based on 100 parts by weight of the resin.

To prepare the powder coating of the present invention, first,
The above various components are melt-kneaded with a kneader or the like. And after cooling, for example, physical pulverization is performed using a pulverizer such as a hammer mill and a jet impact mill, and then an air classifier,
Classification is performed using a classifier such as a Micron classifier to obtain a powder having a desired average particle size. Further, a fluidity modifier such as silica, alumina, titania, or zirconia may be added to the powder surface.

The average particle size of the powder coating of the present invention thus obtained is at least 1 μm, preferably at least 5 μm, more preferably at least 5 μm, in order to prevent agglomeration and to uniformly mix two or more powder coatings. The thickness is desirably 10 μm or more, and is desirably 50 μm or less, preferably 30 μm or less in order to prevent the film thickness of the obtained coating film from becoming too large.

The curing temperature at the time of mixing and applying the powder coating of the present invention is desirably 50 ° C. or higher, preferably 60 ° C. or higher, from the viewpoint of the storage stability of the powder coating. And from the viewpoint of capital investment, 16
It is preferably 0 ° C or lower, more preferably 90 to 150 ° C. Here, the curing temperature is calculated from the temperature of the exothermic peak top measured when the temperature is raised at 10 ° C./min using a differential scanning calorimeter.

The powder coating material of the present invention does not thermoset at 160 ° C. or less by itself, but heat cures at 160 ° C. or less by mixing and coating two or more types. That is, at the time of baking hardening, each powder coating material is thermally hardened after being melted and mixed.

A conventionally known powder coating contains a curing agent which can be cured at a low temperature.
During the kneading, thermal curing itself occurs at 160 ° C. or lower, so that it was necessary to pay close attention to temperature control when preparing individual powder coatings. There is also a method in which a curing agent is blended immediately before coating. However, the reaction locally proceeds, curing unevenness is likely to occur, and the physical properties of the coating film are poor.

On the other hand, in the embodiment of the present invention in which no curing agent is used, the resin used for each powder coating is not thermoset at 160 ° C. or less by itself, but two or more powder coatings are mixed. Only when the resin and resin used in each powder coating melt and mix at the time of baking, one resin will act as a curing agent for the other resin and the curing reaction will take place. Occurs. Therefore, it is necessary to select a combination of a resin and a resin so that one resin has a functional group having a function that can serve as a curing agent for the other resin. As the combination of the resins, the combination described above is applied.

On the other hand, in the embodiment of the present invention in which a curing agent is used, unlike the prior art in which a mutually reactive resin and a curing agent are blended in the same powder coating, they are blended in the same powder coating. A resin and a curing agent that do not react with each other are selected. Therefore, the powder coating alone does not cure at 160 ° C. or lower, and two or more powder coatings are melted and mixed at the time of baking, whereby a curing reaction occurs due to the action of a curing agent in the powder coating on the other side. .

In the present invention, "mixed coating" means that two or more powder coatings are mixed and applied. As a result of the mixed application, two or more kinds of powder coatings are mutually melted by heat and, as a result, can be thermally cured to give a coating film. Here, as a method of mixing the powder coatings, a conventionally known method such as a method of dry-mixing each powder coating with a high-speed stirrer such as a Henschel mixer or a super mixer can be used. The term “coating” as used herein refers to a series of processes for forming a coating film through a baking process at 160 ° C. or lower after coating the object by various methods as described below. The same applies to "application" of the powder coating composition in the present invention.

The present invention provides a powder coating composition in which two or more powder coatings are mixed in advance. That is,
A powder coating composition containing two or more powder coatings, each of which alone does not thermally cure at 160 ° C. or lower,
A powder coating composition containing two or more powder coatings having a property of forming a coating film by being thermally cured at 160 ° C. or lower by mixing and coating two or more of these. Therefore, the powder coating composition of the present invention contains two or more powder coatings having the above-mentioned properties, so that the powder coating composition is melted and mixed during baking and curing. Thermoset.

The powder coating composition of the present invention contains at least one resin selected from the group consisting of a resin having a carboxyl group, a resin having an amino group, a resin having a phenolic hydroxyl group, and an acid anhydride resin. It is preferable to include a powder paint and a powder paint containing at least one resin selected from the group consisting of a resin having an epoxy group, a resin having a glycidyl group, and a resin having an unsaturated bond.
In this case, the polyester resin, polyester polyamide resin, polyamide resin and acid anhydride resin more preferably have an amino group, a carboxyl group or an acid anhydride group at the terminal. In addition, when using a curing agent together with a resin, the above-described combinations are similarly applied.

As a method of preparing a powder coating composition by mixing two or more kinds of powder coatings, a method of dry-mixing each powder coating with a high-speed stirrer such as a Henschel mixer, a super mixer or the like has been used. Known methods can be used.

Here, the combination of the powder coating of the present invention,
Alternatively, as an embodiment of the powder coating composition, for example,
Examples of the following (1) to (3) are given,
In the case of (2), the present invention can be pursued more effectively, which is preferable. (1) Of two or more powder coatings, one powder coating is transparent and the other powder coating is mixed with a colored powder coating. (2) Two or more powder coatings of the same color are mixed. (3) Two or more powder coatings having different colors are mixed.

The powder coating of the present invention is obtained by mixing two or more powder coatings to form a mixture, and applying the mixture to an object to be coated.
A coating method in which the applied mixture is heated at 160 ° C. or lower and thermally cured, or the powder coating composition of the present invention is applied to an object to be coated, and the applied powder coating composition is heated at 160 ° C. or lower. Then, it is used for a coating method of thermosetting. In addition,
When two or more powder coatings are mixed and applied, a mixture of two or more powder coatings in advance may be used, and two or more powder coatings are mixed at the time of application using an electron gun or the like. You may paint while doing. Examples of the coating means include a coating method using an electrostatic spray, a fluid immersion method, and a plastic spraying method. Using the powder coating of the present invention, or the coating film and the coated product obtained by using the powder coating composition of the present invention, after the respective powder coatings are melt-mixed, and then heat-cured. It becomes a more uniform coating film and is excellent in coating film strength, gloss and weather resistance.

In addition, the powder coating composition and the powder coating composition of the present invention can increase the glass transition temperature of each powder coating and maintain sufficient storage stability.

[0042]

EXAMPLES The softening point, glass transition temperature, amine value, oxirane value, and curing temperature shown in the examples were measured according to the following methods.

[Softening point] The softening point is measured according to a method according to ASTM E28-67. [Glass transition temperature] Measured with a differential scanning calorimeter (DSC210, manufactured by Seiko Denshi Kogyo Co., Ltd.) at a heating rate of 10 ° C./min. From the extension of the base line below the glass transition temperature and the rising portion of the peak. The temperature at the point of intersection with the tangent showing the maximum slope up to the peak apex is defined as the glass transition temperature. [Amine value and oxirane value] ASTM D2073-
It is measured according to the method according to No. 66. [Curing temperature] Differential scanning calorimeter (DSC210, manufactured by Seiko Instruments Inc.) using 3 mg of powder coating material as a sample
Is calculated from the temperature of the exothermic peak top measured when the temperature is raised at a rate of 10 ° C./min. [Average particle diameter] It is measured using a Coulter Multisizer (manufactured by Coulter Co., Ltd.).

Resin Production Example 1 630 g (6.0 mol) of neopentyl glycol, 750 g (4.5 mol) of terephthalic acid and 660 adipic acid
g (4.5 mol) was placed in a 3 liter four-necked flask equipped with a thermometer, a stainless steel stirring rod, a flow-down condenser, and a nitrogen inlet tube, and heated to 230 ° C. to react. Then, 409 g of m-xylylenediamine (3.0
Mol), and the reaction was terminated when the softening point reached 100 ° C. to obtain a polyester polyamide resin.

The obtained resin is referred to as resin A. Resin A has an amine value of 57.8 mg KOH / g and a glass transition temperature of 5
The curing temperature was 4 ° C and 160 ° C or higher.

Resin Preparation Example 2 700 g of propylene oxide adduct of bisphenol A
(2.0 mol) and 440 g (3.0 mol) of adipic acid
In the same manner as in Resin Production Example 1 by using 270 g (2.0 mol) of m-xylylenediamine, and the reaction was terminated when the softening point reached 110 ° C. Obtained.

The obtained resin is referred to as a resin B. Resin B has an amine value of 62.6 mgKOH / g and a glass transition temperature of 5
The curing temperature was 9 ° C. and the curing temperature was 160 ° C. or higher.

Resin Production Example 3 3 liters of toluene were placed in a 10-liter four-necked flask prepared in the same manner as in Resin Production Example 1, and the temperature was raised to 100 ° C. Thereafter, 142 g of glycidyl acrylate
(1.0 mol), 900 g of methyl methacrylate (9.0
Mol) and 20 g (0.2 mol) of dicumyl peroxide were placed in a dropping funnel, and the resulting mixture was dropped into the flask over a period of 2 hours to cause a reaction. After performing the reaction at 100 ° C. for 3 hours after the completion of the dropwise addition, the temperature was raised to 160 ° C., the pressure was further reduced under a reduced pressure of 100 Torr, and the remaining toluene was distilled off to obtain an acrylic resin having a glycidyl group.

The obtained resin is referred to as resin C. Resin C has an oxirane value of 65 mg KOH / g and a glass transition temperature of 6
0 ° C. and the curing temperature was 160 ° C. or higher.

Resin Production Example 4 3 liters of toluene and 180.3 g of acrylic acid (2.5
Mol), 1302.5 g of methyl methacrylate (12.5
Mol), 320.5 g (2.5 mol) of butyl acrylate
And a resin having a carboxyl group was obtained in the same manner as in Resin Production Example 3 using 20 g (0.2 mol) of dicumyl peroxide.

The obtained resin is referred to as “resin D”. Resin D has an acid value of 65.0 mgKOH / g and a glass transition temperature of 48.
℃, the curing temperature was 160 ℃ or more.

Resin Production Example 5 150 g of ethylene glycol, 64 g of neopentyl glycol, 174 g of fumaric acid, 114 g of terephthalic acid, 2 g of dibutyltin oxide and 1.5 g of hydroquinone
The mixture was placed in a glass two-liter four-necked flask prepared in the same manner as in Resin Production Example 1 and reacted while stirring at 200 ° C. under a nitrogen stream. When the softening point reached 105 ° C., the reaction was terminated. Thus, a resin having an unsaturated bond was obtained.

The obtained resin is referred to as “resin E”. Resin E has an acid value of 50.0 mgKOH / g and a glass transition temperature of 60.
℃, the curing temperature was 160 ℃ or more.

Production Examples 1 to 13 of Powder Coatings The compositions shown in Tables 3 and 4 were dry-blended with a Henschel mixer and kneaded at 80 to 130 ° C. with a bush kneader. After cooling, the mixture was pulverized with a PJM pulverizer (manufactured by Nippon Pneumatic) to obtain a powder having an average particle diameter of 25 μm. To 100 parts by weight of this powder, 0.3 part by weight of hydrophobic silica (R-972, manufactured by Nippon Aerosil Co., Ltd.) was uniformly mixed with a Henschel mixer to obtain powder coatings 1 to 13.
I got

[0055]

[Table 3]

[0056]

[Table 4]

Examples 1 to 11 In the combinations shown in Table 5, 50 parts by weight of each powder coating was used and mixed with a Henschel mixer. Next, the obtained powder coating material was applied to a degreased steel plate by electrostatic spraying, and baked at 140 ° C. for 10 minutes to obtain a coating film.

The physical properties of the obtained powder coating and the obtained coating film were measured by the following methods. Table 5 shows the results.

(1) Pencil hardness of coating film Tested according to the method specified in ASTM 3363-74,
Shows the hardest pencil strength with no cuts in the coating. In the evaluation criterion, the softest is 6B, and hereinafter, 5B, 4B, 3B, 2B, B, F, H, 2
Following H, 3H, 4H, and 5H, 6H is the hardest one.

(2) Impact resistance of coating film A test is performed according to the method specified in JIS K 5460 6.13, and the minimum height at which the coating film does not crack or peel off is measured.

(3) Erichsen test of coating film A test was conducted in accordance with the method specified in JIS B 7777. A coating film which did not crack or peel at a pushing distance of 7 mm was evaluated as "O", and a coating film within a pushing distance of 7 mm was applied. Those that cause cracking and peeling are denoted by "x".

(4) Accelerated weathering resistance of coating film A steel plate coated with a powder coating according to the method specified in JIS K5400 9.8 is exposed in a weather tester having a 313 nm fluorescent tube to change the glossiness. If there is no mark, it is described as "○".

(5) Glossiness of coating film Measured using a gloss meter (GM-60, manufactured by Minolta Co., Ltd.) according to the method specified in ASTM 3363-74.

[0064]

[Table 5]

Comparative Example 100 parts by weight of powder coating 7 and 10 parts by weight of TGIC
(Araldide PT810, manufactured by Ciba-Gaiky) was mixed using a Henschel mixer. The obtained mixture was applied in the same manner as in the example to form a coating film. The physical properties of the obtained powder coating and the obtained coating film were measured in the same manner as in Examples 1 to 11. The curing temperature of the obtained powder coating is 140
° C, the pencil height of the obtained coating film was HB, the impact resistance was 40 cm, and the evaluation of the Erichsen test was “×” (5 mm).
, The coating film cracked), and the glossiness was 35%.

As can be seen from the above results, the curing temperatures of the powder coatings obtained in the examples were 110-130.
C. and low temperature, and the obtained coating film has excellent coating film strength, glossiness and weather resistance.

[0067]

According to the present invention, there are provided a powder coating material, a powder coating composition and a coating method using the same, which can be cured at a low temperature and maintain sufficient storage stability and are used for mixed application. It became possible to do.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI C09D 201/06 C09D 201/06 // C09D 135/00 135/00 (72) Inventor Hisakazu Tajima 1334 Minato, Wakayama-shi Kao Stock Inside the Company Research Institute (72) Inventor Takehiko Tojo 2606 Akabane, Kaigamachi, Haga-gun, Tochigi Prefecture Inside Kao Co., Ltd. Shingo 1-4-1 Noribori, Nishi-ku, Osaka Kao Corporation Osaka Office

Claims (6)

[Claims] 1. A powder coating used in a coating method in which two or more powder coatings are mixed and applied.
A powder coating which does not thermoset in the following but has the property of being thermoset at 160 ° C. or lower when mixed and applied with another type of powder coating. 2. The powder coating is mixed with (1) a powder coating containing at least one resin selected from the group consisting of a resin having an epoxy group, a resin having a glycidyl group and a resin having an unsaturated bond. A powder coating to be applied,
A resin having a carboxyl group, a resin having an amino group,
A powder coating containing at least one resin selected from the group consisting of a resin having a phenolic hydroxyl group and an acid anhydride resin, or (2) a resin having a carboxyl group, a resin having an amino group, and having a phenolic hydroxyl group. A powder paint mixed and applied with a powder paint containing at least one resin selected from the group consisting of a resin and an acid-based resin, comprising a resin having an epoxy group, a resin having a glycidyl group, and an unsaturated bond. The powder coating according to claim 1, which is a powder coating containing at least one resin selected from the group consisting of resins having the following formula: 3. A powder coating composition containing two or more powder coatings, each of which does not thermoset at 160 ° C. or less by itself, but is heated to 160 ° C. or lower by mixing and coating two or more of these. A powder coating composition comprising two or more powder coatings having a property of forming a coating film by heat curing in the above. 4. A powder coating containing at least one resin selected from the group consisting of a resin having a carboxyl group, a resin having an amino group, a resin having a phenolic hydroxyl group and an acid anhydride resin, and an epoxy group. 4. The powder coating composition according to claim 3, comprising a powder coating containing at least one resin selected from the group consisting of a resin having a glycidyl group and a resin having an unsaturated bond. 5. A mixture obtained by mixing (a) two or more kinds of powder coatings according to claim 1 or 2; (b) applying the mixture to an object to be coated; and (c) applying the mixture. 160
A coating method, wherein the coating is heated at a temperature of not more than ℃ and thermally cured. 6. A powder coating composition according to claim 3 or 4, which is applied to an object to be coated, and (b) the applied powder coating composition is heated at 160 ° C. or lower, Curing, a coating method.