JP2849353B2 - Powder paint - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a powder coating which has excellent transportability and forms a coating film having a high appearance.

[0002]

2. Description of the Related Art Powder coatings generally comprise a resin for forming a coating film, and have a volume average particle size of about 30 to 40 μm.
It is applied to the object to be coated by a method such as electrostatic spray coating or fluidized bed immersion coating and baked to form a coating film. However, such a powder coating has a drawback that a glossy and smooth coating film cannot be formed and the appearance of the coating film is poor.

As a technique for improving such a defect and obtaining a coating film having a high appearance, for example, Japanese Patent Application No. Hei 3-26402 is disclosed.
No. 5 discloses a powder coating material having an average particle size smaller than that of the conventional one, and further having an upper limit for the ratio of the small particle size, and an average particle size of 5 to 20 μm and a ratio of particles of 5 μm or less. Is 25% by weight or less. This powder coating is capable of forming a glossy, dense and smooth coating film, but has a smaller average particle size than conventional powder coatings, so it is transported through a pipe by airflow or the like. Troubles such as clogging of pipes on the way
There was a problem in transportability.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a powder coating which can form a high-appearance coating film and has excellent transportability in view of the above situation.

[0005]

SUMMARY OF THE INVENTION The gist of the present invention is that a powder coating is formed of a resin for forming a coating film and has a volume average particle diameter of 20 to 20%.
50 μm, and the standard deviation of the particle size distribution is set to 20 μm or less. Hereinafter, the present invention will be described in detail.

The volume average particle size of the powder coating of the present invention is 20
５０50 μm. When the volume average particle size is less than 20 μm, the pipe tends to be clogged when transported by an air stream, causing a problem in transportability. When the volume average particle size is more than 50 μm, a high-appearance coating film cannot be obtained, so the content is limited to the above range. You. Preferably it is 20 to 40 μm. The volume average particle size is
It can be measured by a particle size measuring device such as Microtrac-II manufactured by And Northrop Co., Ltd. by electromagnetic wave scattering.

The standard deviation of the particle size distribution of the powder coating of the present invention is:
20 μm or less. If the standard deviation of the particle size distribution is more than 20 μm, a coating film having a high appearance cannot be obtained, so that the range is limited. The particle size distribution standard deviation of the powder coating material of the present invention is preferably 16 μm or less, more preferably 13 μm.
It is as follows. When the thickness is 16 μm or less, the appearance of the coating film is further improved, and when it is 13 μm or less, the appearance of the coating film is further improved.

[0008] The standard deviation of the particle size distribution of the powder coating can be determined by the following equation using data obtained by a particle size measuring device. σ = [{(DX) ² F} / ΔF] ^1/2 where σ represents the standard deviation of the particle size distribution. D represents the particle size of each particle. X represents a volume average particle diameter, and X = Σ
(DF) / ΔF. Where F is the frequency of the particles.

In the powder coating of the present invention, the largest one of the particles has a particle size of 90 μm or less. 90μm particle size
If the particles exceed the above, a coating film having a high appearance cannot be obtained.
Preferably, the largest one of the particles has a particle size of 80 μm
It is as follows. In the powder coating of the present invention, it is preferable that the largest one of the particles has a particle size of 90 μm or less, and the smallest one of the particles has a particle size of 1 μm or more. When particles having a particle size of less than 1 μm are present, the transportability is reduced.

The powder coating of the present invention comprises a resin for forming a coating film as a binder component. The resin for forming a coating film is not particularly limited, and those usually used in the field of powder coating can be used. Examples of such a resin include a thermoplastic resin and a thermosetting resin. Can be mentioned. The thermoplastic resin is not particularly limited, and among them, a vinyl resin such as a polyvinyl chloride resin, a polyethylene resin, a polyamide resin and the like can be suitably used. The thermosetting resin is not particularly limited, among them, epoxy resin, thermosetting acrylic resin,
A thermosetting polyester resin or the like can be suitably used. When the thermosetting resin is used as the resin for forming a coating film, the powder coating composition of the present invention preferably contains a curing agent and a curing accelerator.

[0011] The content of the curing agent is 5 to 100 parts by weight of the thermosetting resin used as the resin for forming a coating film.
80 parts by weight are preferred. If the amount is less than 5 parts by weight, the curing will be insufficient, and if it exceeds 80 parts by weight, the curing will proceed too much, and the physical properties of the coating film will decrease. The content of the curing accelerator is preferably from 0.1 to 5 parts by weight per 100 parts by weight of the thermosetting resin used as the resin for forming a coating film. If the amount is less than 0.1 part by weight, the curing is insufficient. If the amount exceeds 5 parts by weight, the curing proceeds excessively, and the physical properties of the coating film are deteriorated.

In the present invention, when an epoxy resin is used as the resin for forming a coating film, if necessary, for example, a curing agent such as phthalic anhydride, an amine compound, an imidazole compound, and dicyandiamide, a curing accelerator; Other resins such as resins can be used in combination. In the present invention, when a thermosetting acrylic resin is used as the resin for forming a coating film, if necessary, for example, another resin such as an epoxy resin or a melamine resin; a polyvalent carboxylic acid;
A curing agent such as a blocked isocyanate compound can be used.

In the present invention, when a thermosetting polyester resin is used as the resin for forming a coating film, if necessary, other resins such as melamine resin and epoxy resin; polybasic acid, blocked isocyanate compound And a curing agent such as triglycidyl isocyanurate.

The powder coating of the present invention may optionally contain a pigment,
Other additives may be included. As the other additives, other resins, curing agents, curing accelerators or curing catalysts, surface conditioners, plasticizers, ultraviolet absorbers, antioxidants,
Examples include an anti-armpit agent and a pigment dispersant. The pigment is not particularly limited, and among them, titanium dioxide, red iron oxide, yellow iron oxide, carbon black, phthalocyanine blue, phthalocyanine green, and quinacridone red pigment can be preferably used.

The content of the pigment is preferably 1 to 80 parts by weight based on 100 parts by weight of the powder coating. If the content is less than 1 part by weight, the effect of the pigment such as coloring cannot be obtained,
If the amount exceeds 0 parts by weight, a coating film having a high appearance cannot be obtained. The pigment and other additives may be contained in the particles of the powder coating together with the resin for forming a coating film, or may be added as particles separate from the resin for forming a coating film.

The powder coating material of the present invention may be a clear coating material which can form a transparent coating film without containing any amount or kind of pigment which does not impair the transparency, or without any pigment.

The powder coating composition according to the present invention is a powder coating composition wherein the powder coating particles are obtained by combining second particles on the surface of first particles containing a part of a resin for forming a coating film. May contain the remainder of the resin for forming a coating film and have a glass transition point of 50 to 150 ° C. The composited powder coating particles have a second particle on the surface of the first particle.
May be attached, or the second particles may be slightly embedded in the surface of the first particles. The powder coating of the present invention may include both of these two states of powder coating particles.

As described above, by forming the second particles on the surface of the first particles to form the composite particles, the first particles constituting the composite powder coating particles come into direct contact with each other. As a result, blocking during storage is less likely to occur, and the fluidity during transportation is also improved. Further, by forming the composite particles as described above, a resin having a low glass transition point (hereinafter also referred to as “Tg”) as a resin for forming a coating film, for example, a resin having a Tg of about 40 ° C. is used as the first particles. It is possible to do.

In the composite powder coating particles, the second particles are melted together with the resin for forming the coating film of the first particles during baking of the powder coating to form a coating film. In the coating film, poor appearance such as surface roughness due to the second particles hardly occurs.

The second particles are preferably made of the same resin as the resin for forming a coating film. However, from the viewpoint of production or practical use, vinyl resin, acrylic resin, epoxy resin, polyester resin, melamine resin, etc. Is usually used. Of these, vinyl resins are preferred from the viewpoints of ease of production and design flexibility.

The resin constituting the second particles has a Tg of 50 to 150 ° C. When Tg is lower than 50 ° C., the effect of combining the second particles on the surface of the first particles cannot be expected, and when Tg exceeds 150 ° C., further increase in the effect cannot be expected. Preferably 70-120 ° C
It is.

The volume average particle diameter of the second particles is preferably set smaller than the volume average particle diameter of the powder coating. The volume average particle diameter of the second particles is 0.001 to 1
0 μm is preferable, and 0.01 to 5 μm is more preferable.
The addition amount of the second particles is preferably 0.05 to 35 parts by weight based on 100 parts by weight of the powder coating. If the amount is less than 0.05 parts by weight, the effect of the second particles cannot be expected and 3
If it exceeds 5 parts by weight, the appearance of the coating film is impaired.

The second particles can be directly produced by, for example, emulsion polymerization, suspension polymerization or the like. Alternatively, it can be obtained by producing a resin by solution polymerization, bulk polymerization or the like, pulverizing and classifying the resin.

The method for producing the powder coating of the present invention is not particularly limited, and it can be carried out by a method generally used in the field of powder coating production. For example, the above-mentioned resin for forming a coating film, and a pigment used as necessary, and other additives may be added to a Henschel mixer, a super mixer,
The mixture is uniformly mixed by a mixer such as a ball mill and a Banbury mixer, and then the obtained mixture is melt-kneaded by a kneader such as an extruder or a hot roll, and the components other than the resin are contained in the molten resin for forming a coating film. Is uniformly dispersed, and the resulting mixture is formed into pellets. After the obtained pellets are pulverized by an impact type pulverizer such as a hammer mill or an air current pulverizer such as a jet mill, and then classified, the powder coating of the present invention is obtained.

By the above classification, the above-mentioned particle size distribution can be achieved, and the amount of particles larger than the above-mentioned particle size range and the amount of particles smaller than the above-mentioned particle size range are reduced. The above classification is
A 170 mesh, preferably 200 mesh Tyler standard sieve, a fluid separator such as a dispersion separator for separating and removing particles larger than 90 μm, preferably 80 μm, a micron separator, and 1 μm.
The separation can be performed using a fluid classifier such as a cyclone, a dispersion separator, or a micron separator that separates and removes particles smaller than m.

As a method for producing the powder coating of the present invention, in addition to the above-mentioned methods, for example, the raw materials are mixed in a solvent, and the resulting mixture is dried and finely pulverized, or the powder is dried by a spray drying method. Can be adopted. The obtained powder can be subjected to the above-mentioned pulverization and classification as needed.

When the powder coating material of the present invention is obtained as the composite powder coating particles, the second particles are added to the first particles classified as described above. Mix. In the mixing, by appropriately selecting a mixer and mixing conditions, the composite state of the first particles and the second particles can be set to a desired state. For example, when a hybridizer is used as a mixer, Thus, a powder coating in a composite state in which the second particles are embedded in the particle surfaces of the classified material is obtained. In the above mixing, for example,
General mixers such as a super mixer, a Henschel mixer, a hybridizer, and a ball mill can be appropriately used. By compounding as described above,
Alternatively, by classifying the composite particles as required after the composite, the powder coating of the present invention can be obtained as being composed of the composite powder coating particles.

In the production of the powder coating material of the present invention, the raw materials used are the following:
The particles preferably contain 40 to 100% by weight, more preferably 60 to 100% by weight, of particles having a particle size of less than m. When such a powder coating material is used, a pellet in which a pigment and various additives are uniformly dispersed in a resin component is obtained.
Various raw material components are almost uniformly contained in each particle. For this reason, in the coating film forming step, for example, the curing reaction of the resin is likely to occur uniformly, so that a coating film having better appearance such as smoothness can be formed.

The application target of the powder coating of the present invention is not particularly limited. For example, it is used for automobiles, home electric appliances, building materials,
Steel plates for miscellaneous goods, zinc phosphate treated steel plates, aluminum or aluminum alloy materials, and the like can be given. As a coating method of the powder coating of the present invention, for example, a well-known method such as an electrostatic spraying method and a fluid immersion method is used to deposit the pulverized coating of the present invention on a surface of an object to be coated in a desired thickness, and then bake. Can be performed. When a thermosetting resin is used as the resin component, a cured coating film is formed.

[0030]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Example 1 Glycidyl group-containing solid acrylic resin (Tg = 50 ° C., number average molecular weight 3,000, epoxy equivalent 350) 48 parts by weight, 1,10-decanedicarboxylic acid 12 parts by weight, bisphenol A type epoxy resin 2.2 parts by weight (YD-012, manufactured by Toto Kasei Co., Ltd.), 0.1 parts by weight of a polysiloxane surface modifier, and 0.3 parts by weight of benzoin were stirred and mixed with a super mixer (manufactured by Nippon Spindle Mfg. Co., Ltd.). (Manufactured by Bus), and the mixture was cooled and solidified. The cooled solid was coarsely pulverized to obtain a pellet for powder coating.

The obtained pellets for powder coating were pulverized with an impact type pulverizer (Atomizer, manufactured by Fuji Paudal Co.), and the pulverized material was passed through a screen mesh at 0.7 mm intervals.
325 mesh Tyler standard sieve (44 μm pore size)
To remove particles larger than 44 μm, and classify and remove all particles smaller than 2 μm by an airflow classifier (DS-2, manufactured by Nippon Pneumatic Industries, Ltd.) to obtain a powder coating.

Example 2 The target value of the classification was set to the value shown in Table 1, and instead of the 325-mesh Tyler standard sieve, a 250-mesh Tyler standard sieve (pore diameter 61 μm) was used. A powder coating was obtained in the same manner as in Example 1, except that particles smaller than the particle size were classified and removed.

Example 3 The target value of classification was set to the value shown in Table 1, and particles smaller than the particle size shown in Table 1 were removed by classification using a 325-mesh Tyler standard sieve (pore size: 44 μm) using an airflow classifier. A powder coating was obtained in the same manner as in Example 1 except that the coating was performed.

Example 4 The target value for classification was set to the value shown in Table 1, and a 250-mesh Tyler standard sieve (pore diameter 61 μm) was used instead of the 325-mesh Tyler standard sieve, and classification was not performed by an airflow classifier. Except for this, a powder coating was obtained in the same manner as in Example 1.

Example 5 The target value of the classification was set to the value shown in Table 1, and a 170-mesh Tyler standard sieve (pore size: 88 μm) was used instead of the 325-mesh Tyler standard sieve, and the air-flow classifier shown in Table 1. A powder coating was obtained in the same manner as in Example 1, except that particles smaller than the particle size were classified and removed.

Example 6 The acrylic powder coating obtained in Example 4 had a particle size of 0.03.
Acrylic resin (87 parts by weight of methyl methacrylate, 10 parts by weight of styrene, 3 parts by weight of methacrylic acid) having a fine powder of .about.0.05 .mu.m and Tg = 100.degree. I got The mixing ratio of the fine powder was set to 1.0% by weight of the powder coating.

The volume average particle diameter of the obtained composite powder coating,
The particle size distribution standard deviation and appearance hardly changed from before mixing the acrylic resin fine powder. However, transportability was significantly improved. Further, the powder coating was stored at 30 ° C. for 6 months, and the state of aggregation of the powder was visually evaluated. As a result, no aggregation of the powder was observed and the blocking property during storage was excellent. On the other hand, when the blocking property of the powder coating material of Example 4 was evaluated in the same manner, there was almost no aggregation of the powder.

Example 7 A commercially available polyester powder paint (P-100, manufactured by Nippon Paint Co., Ltd.) was set to the target value shown in Table 1,
A powder coating was obtained in the same manner as in Example 1 except that particles smaller than the particle size shown in Table 1 were classified and removed by an airflow classifier using a 0-mesh (pore size: 74 μm) Tyler standard sieve.

This polyester powder paint contains 17 parts by weight of a blocked isocyanate as a curing agent with respect to 100 parts by weight of a thermosetting polyester resin which is a resin for forming a coating film, and the pigment content is based on the total weight of the powder paint. On the other hand, it was 40% by weight.

Example 8 A commercially available hybrid powder coating material (H-100, manufactured by Nippon Paint Co., Ltd.) was set to the target value shown in Table 1,
A powder coating was obtained in the same manner as in Example 1 except that particles smaller than the particle size shown in Table 1 were classified and removed by an airflow classifier using a 0-mesh (pore size: 74 μm) Tyler standard sieve.

This hybrid powder coating composition contained 50 parts by weight of a polyester resin and 50 parts by weight of an epoxy resin as a resin for forming a coating film, and had a pigment content of 40% by weight based on the total weight of the powder coating composition.

Example 9 The composition used in Example 1 was further added with titanium oxide (CR-5).
0, manufactured by Ishihara Sangyo Co., Ltd.)
And the content of components having a particle size of less than 700 μm is 40% by weight.
The raw material particles for powder coating having a particle size of less than 1 were stirred and mixed with a super mixer, melt-kneaded with a co-kneader, and the cooled and solidified product was roughly pulverized to obtain a powder coating pellet of Example 9. The obtained pellets were pulverized in the same manner as in Example 1, the target value of classification was set to the value shown in Table 1, and 250 mesh (pore size: 61
Using a Tyler standard sieve (μm), particles smaller than the particle size shown in Table 1 were classified and removed by an airflow classifier to obtain a powder coating.

Example 10 A powder coating was obtained in the same manner as in Example 9, except that a raw material particle group for powder coating having a content of a component having a particle diameter of less than 700 μm was 40% by weight or more.

Comparative Example 1 A powder coating was obtained in the same manner as in Example 1 except that particles having a particle size larger than those shown in Table 1 and particles having a smaller particle size were removed by an airflow classifier.

Comparative Examples 2 and 3 The target values of the classification were set to the values shown in Table 1, and a 150-mesh Tyler standard sieve (pore size: 104 μm) was used instead of the 325-mesh Tyler standard sieve. A powder coating material was obtained in the same manner as in Example 1 except that particles smaller than the particle size shown in Table 1 were classified and removed.

Comparative Example 4 The target value of the classification was set to the value shown in Table 1, and a 170-mesh Tyler standard sieve (pore size: 88 μm) was used instead of the 325-mesh Tyler standard sieve. A powder coating was obtained in the same manner as in Example 1, except that particles smaller than the particle size were classified and removed.

Comparative Example 5 A commercially available polyester powder coating material (P-100, manufactured by Nippon Paint Co., Ltd.) was set to a classification target value shown in Table 1,
A powder coating was obtained in the same manner as in Example 1 except that a particle smaller than the particle size shown in Table 1 was classified and removed by an airflow classifier using a 0-mesh (pore size: 104 μm) Tyler standard sieve.

The polyester powder coating composition contains 17 parts by weight of a blocked isocyanate as a curing agent with respect to 100 parts by weight of a thermosetting polyester resin as a resin for forming a coating film, and the pigment content is based on the total weight of the powder coating composition. On the other hand, it was 40% by weight.

Comparative Example 6 A commercially available hybrid powder coating material (H-100, manufactured by Nippon Paint Co., Ltd.) was set to a classification target value shown in Table 1, and 17
A powder coating was obtained in the same manner as in Example 1 except that particles smaller than the particle size shown in Table 1 were classified and removed by an airflow classifier using a 0-mesh (pore size: 88 μm) Tyler standard sieve.

This hybrid powder coating composition contained 50 parts by weight of a polyester resin and 50 parts by weight of an epoxy resin as a resin for forming a coating film, and had a pigment content of 40% by weight based on the total weight of the powder coating composition.

Comparative Example 7 The composition used in Example 1 was further added with titanium oxide (CR-5).
0, manufactured by Ishihara Sangyo Co., Ltd.)
And the content of components having a particle size of less than 700 μm is 40% by weight.
The raw material particles for powder coating having a particle size of less than 1 were stirred and mixed by a super mixer, melted and kneaded with a co-kneader, and the cooled and solidified product was roughly pulverized to obtain pellets for powder coating. The obtained pellets were pulverized in the same manner as in Example 1, the target value of the classification was set to the value shown in Table 1, and a 150-mesh (pore size: 104 μm) Tyler standard sieve was used, and the results were shown in Table 1 by an airflow classifier. Particles smaller than the particle size were classified and removed to obtain a powder coating.

Evaluation Each of the obtained powder coating materials was evaluated for the following items.
The results are shown in Table 1. 1. Measurement of Particle Size and Particle Size Distribution The particle size was measured using a particle size measuring device (Microtrac-II, manufactured by Reed & Northrop Co.). From the obtained particle size / frequency results, the volume average particle size and the particle size distribution standard deviation were determined by the following formula. σ = [{(DX) ² F} / ΔF] ^1/2 (where σ is the standard deviation of the particle size distribution, D is the particle size of each particle, and X is the volume average particle size. X = Σ (DF) / Σ
F, F is the frequency of the particles. )

2. Appearance evaluation Each powder coating material of the example and the comparative example was uniformly applied to an iron plate by an electrostatic coating method and baked at 140 ° C. for 20 minutes to form a coating film. The appearance of the obtained coating film was evaluated by NSIC value (%) measured by a mapping clarity measuring device (manufactured by Suga Test Instruments Co., Ltd.). The NSIC value was obtained by Fourier spectrum analysis of an image of a rectangular wave pattern formed through reflection on the coating film surface using the optical system shown in FIG.

Referring to FIG. 1, light emitted from a light source 1 includes a condenser lens 2, a pattern 3, and a projection lens 4.
Then, the light was reflected by the coating surface of the coating object 5 and formed on the light receiving surface of the photodiode array 6 to obtain an imaging waveform.
The light source 1 and the light receiving surface of the photodiode array 6 were arranged at an angle θ with respect to the painted surface of the painted object 5.

The NSIC value is the fundamental frequency ν of the imaging waveform obtained by subtracting the baseline intensity b to emphasize shape information.
The sum {P (ν ₀ ) ^1/2 + P (3ν ₀ ) ^1/2 } of ₀ and three times its square root of the power of the frequency 3ν ₀ is replaced by a similar value ｛P (ν ₀ ) ¹ for the black glass plate. ^{/ 2} + P (3ν ₀ ) ^1/2 _{BG BG} normalized: NSIC = [{P (ν ₀ ) ^1/2 + P (3ν ₀ ) ^1/2 } /
{P (ν ₀ ) ^1/2 + P (3ν ₀ ) ^1/2 ｝ _BG ] × 100, which mainly represents the tinge of the image (distortion of shape from a rectangular mesh).

3. Evaluation of transportability In a coating system for powder coating, usually, a powder feeder (fluidized bed) is connected to a coating gun by a hose via an injector. After the powder coating was continuously transported for one hour by the above-mentioned coating system, the state of accumulation of the powder coating in the injector and the hose was visually observed to evaluate the transportability. The evaluation criteria were as follows. A: No powder was deposited at all. ：: Almost no powder was deposited. X: Powder was deposited and almost clogged the injector or hose.

[0058]

[Table 1]

The following was found from the results shown in Table 1. The powder coatings of Comparative Example 2 and Comparative Example 3 had a volume average particle diameter of 26.5 μm and 30.5 μm, respectively, and corresponded to a conventional clear powder coating, and had a particle diameter distribution standard deviation of 20 μm.
m, a coating film having poor appearance was formed. In Comparative Example 4, since the volume average particle diameter exceeded 50 μm, a coating film with poor appearance was formed even when the particle diameter distribution standard deviation was 20 μm or less. Comparative Example 1 had a volume average particle size of 9.5 μm and a particle size distribution standard deviation of 7.2 μm, which corresponds to the powder coating proposed in the above publication, and has an average particle size of less than 20 μm. Was inferior.

The powder coatings of Examples 1 to 6 had a volume average particle size of 20 to 50 μm and a standard deviation of particle size distribution of 20 μm or less, had excellent transportability, and had excellent appearance with an NSIC value of 60% or more. Formed. In Example 1 having a particle size distribution standard deviation of 16 μm or less, a high appearance coating film having an NSIC value of 65% or more was formed. The powder coating of Example 6 had the same level of appearance as the powder coating of Example 4, but had significantly improved transportability and also had excellent blocking properties during storage.

The powder coatings of Comparative Examples 5 and 6 had a particle size distribution standard deviation of more than 20 μm, and thus formed coating films having the same appearance as powder coatings containing conventional pigments. Since the powder coating of Example 7 had a particle size distribution standard deviation of 20 μm or less, a coating film having an excellent appearance was formed as compared with that of Comparative Example 5. Since the powder coating material of Example 8 had a particle size distribution standard deviation of 20 μm or less, a coating film having an excellent appearance was formed as compared with that of Comparative Example 6. Example 7 and Example 8
The powder coatings of Examples 1 to 6 are different from those of Examples 1 to 6 in that the resin for forming a coating film is different from that of Examples 1 to 6, but the standard deviation of the particle size distribution is 20 μm or less, thereby improving the appearance without impairing the transportability. A film was formed.

Since the powder coating of Comparative Example 7 had a particle size distribution standard deviation of more than 20 μm, a coating film having the same appearance as an acrylic powder coating containing a conventional pigment was formed. The powder coatings of Example 9 and Example 10 had a volume average particle size of 20 to
It was within the range of 50 μm, the standard deviation of the particle size distribution was 20 μm or less, and a coating film excellent in appearance was formed as compared with Comparative Example 7. Further, Example 10 was composed of a raw material particle group for a powder coating material in which the content of the component having a particle diameter of less than 700 μm was 40% by weight or more, and the appearance was further improved as compared with Example 9.

[0063]

Since the powder coating of the present invention has the above-mentioned constitution, it is possible to form a coating film having excellent transportability and high appearance.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an optical system of an apparatus used for evaluating the appearance of a coating film.

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ Identification code FI C09D 167/00 C09D 167/00 175/04 175/04 177/00 177/00 (72) Inventor Shannon Ribuki Ikeda, Neyagawa-shi, Osaka Nakamachi 19-17 Nippon Paint Co., Ltd. (56) References JP-A-49-108136 (JP, A) JP-A-59-226065 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , (DB name) C09D 5/03

Claims (14)

(57) [Claims] 1. A resin for forming a coating film having a volume average particle diameter of 20 to 50 μm and a standard deviation of particle diameter distribution of 20 μm.
A powder coating characterized by the following. 2. A film-forming resin having a volume average particle size of 20 to 50 μm and a particle size distribution standard deviation of 16 μm.
A powder coating characterized by the following. 3. A film-forming resin having a volume average particle diameter of 20 to 50 μm and a particle diameter distribution standard deviation of 13 μm.
A powder coating characterized by the following. 4. The powder coating according to claim 1, wherein the maximum particle size of the powder coating particles is 90 μm or less. 5. The powder coating according to claim 4, wherein the smallest one of the powder coating particles has a particle size of 1 μm or more. 6. The powder coating according to claim 1, wherein the coating film forming resin is at least one selected from the group consisting of vinyl resins, polyethylene resins and polyamide resins. 7. The resin for forming a coating film is at least one selected from the group consisting of an epoxy resin, a thermosetting acrylic resin, and a thermosetting polyester resin, and at least one of a curing agent and a curing accelerator. The powder coating according to claim 1, comprising: 8. A curing agent is contained in an amount of 5 to 80 parts by weight based on 100 parts by weight of the resin for forming a film, and a curing accelerator is used in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of the resin for forming a film. The powder coating composition according to claim 7, wherein the powder coating composition contains at least one part. 9. Titanium dioxide, red iron oxide, yellow iron oxide,
The powder coating according to claim 1, 2 or 3, comprising at least one pigment selected from the group consisting of carbon black, phthalocyanine blue, phthalocyanine green and quinacridone red pigment. 10. The powder coating according to claim 9, wherein the pigment is contained in an amount of 1 to 80 parts by weight based on 100 parts by weight of the powder coating. 11. A powder coating material comprising a first particle containing a part of a resin for forming a coating film and a second particle compounded on a surface of the first particle. Including the remainder of the film-forming resin and having a glass transition point of 50 to 150
The powder coating according to claim 1, 2 or 3, which has a temperature of ℃. 12. The method according to claim 12, wherein the second particles have a volume average particle size of 0.00.
The powder coating according to claim 11, which is 1 to 10 µm. 13. The powder coating composition according to claim 1, wherein the content of the second particles is 10%.
The amount is 0.05 to 35 parts by weight per 0 parts by weight.
The powder coating according to 1. 14. The powder coating according to claim 11, wherein the second particles are made of at least one selected from the group consisting of vinyl resins, acrylic resins, epoxy resins, polyester resins, and melamine resins.