KR102548145B1 - High gloss and high leveling metallic powder coating composition - Google Patents

Abstract

The present invention relates to a high gloss, high leveling metallic powder coating.
It relates to a powder coating composition with high gloss, good leveling and excellent durability as a paint to which metallic pearls are added compared to conventional paints.
In more detail, a polyester resin with excellent chemical and mechanical properties, a curing agent TGIC, a curing accelerator, additives, sedimentary fillers, pigments, etc. are melted and dispersed, followed by cooling, grinding, and classification to add metallic pearls. After passing through, it relates to a polyester-TGIC type metallic powder coating composition.
The powder coating composition obtained by the present invention has excellent mechanical and chemical properties, and the metallic powder coating having excellent gloss and smoothness can be used for home appliances, communication equipment, and general steel materials that can be used outside.

Description

High gloss and high leveling metallic powder coating composition {High gloss and high leveling metallic powder coating composition}

The present invention relates to a metallic powder coating composition for forming high gloss and high leveling. More specifically, it relates to a new powder coating composition composed of two kinds of polyester resins having carboxyl groups at polymer terminals and a filler, which are formulated to enable high gloss, high leveling and beautiful appearance when the coating is electrostatically coated and cured.

Powder paints do not contain solvents such as organic solvents and water used in liquid paints, and use solid raw materials of 99% or more, mix appropriate pigments or hardeners as needed, and grind uniformly melted and mixed paints to a certain particle size. It means powdery paint composed only of the specified particle size.

Powder coating using powder coating has excellent coating film properties, does not require much worker skill compared to solvent-type coating, and has excellent impact resistance and chemical resistance, so it is widely used in various fields such as construction, home appliances, and automobile industries. Powder coating can be applied to the object to be coated by an electrostatic spray coating method, flow deposition method, electrostatic flow deposition method or the like.

A commonly used polyester resin containing a carboxyl group is cross-linked with a curing agent TGIC to obtain a durable coating film. That is, the polyester resin containing a carboxyl group is widely used as a composition for external powder coatings in Korea by using a curing agent TGIC. The amount of the curing agent is changed according to the acid value of the polyester resin, and high leveling can be obtained by using a resin having a low viscosity.

In order to obtain high gloss and high leveling, fillers such as barium sulfate, calcium carbonate, silica, magnesium hydroxide, alumina hydroxide, titanium dioxide, clay, alumina, mica, wollastonite, and talc are selected and used. can be obtained.

The metallic powder coating material may be prepared by using aluminum paste pearl and mica pearl after preparing the high gloss high leveling powder coating material. As the pearl content increases, the gloss and leveling of the paint may be lost.

In the case of such a conventional powder coating composition, it was possible to form an external appearance by curing the polyester resin, but the orange peel phenomenon and the gloss reduction phenomenon continuously occurred, and thus, a steady improvement request was received.

Therefore, the present invention is to improve the point that the beauty of the appearance was not pursued in the conventional powder coating composition to manufacture a higher quality (high gloss, high leveling) coating composition.

To this end, in using a polyester resin, the acid value, glass transition temperature, viscosity and equivalent weight are adjusted, the filler content is adjusted, and additives such as a wet dispersant are added in an appropriate ratio to produce a high-gloss, high-leveling powder coating. .

Through this, a new powder coating composition was devised using aluminum paste pearls to form a luxurious and beautiful appearance.

The powder coating composition according to the present invention for achieving the above object,

52 to 63% by weight of a polyester resin having a carboxyl group at the end group;

Curing agent TGIC (Triglycidylisocyanurate) 3.12 to 5% by weight,

Curing accelerator 1.2 ~ 1.5% by weight,

It is characterized in that it is composed of 25 to 35% by weight of the filler.

At this time, the polyester resin is a polyester resin (1) having an acid value of 32 to 38 mg KOH / g, a viscosity of 1400 to 3000 cP, and a glass transition temperature of 60 to 64 ° C. 30 to 35% by weight, an acid value of 30 to 36 mg KOH / g, and a viscosity of 2800 ~ 4200cP, a polyester resin having a glass transition temperature of 58 ~ 62 ℃ (2) characterized in that it is composed of 22 ~ 28% by weight.

In addition, the curing accelerator has an acid value of 30 to 40 mg KOH/g, a glass transition temperature of 50 to 70 °C, and a viscosity of 2,800 to 4,500 cP, and the curing agent Triglycidyllisocyanurate (TGIC) has an epoxy equivalent of 100 to 110 and a viscosity of 95 to 105 cP @120 °C. to be

In addition, the filler is characterized in that the precipitated barium sulfate. Barium sulfate fillers are divided into two types, which are natural type fillers, which are general barium sulfate, and precipitated barium sulfate, in which impurities are removed from natural type barium sulfate with a strong acidic solution. Precipitated barium sulfate is used in the present invention.

In addition, the pigment is selected from the group consisting of titanium dioxide, bismuth vanadate, cyanine green, carbon black, red iron oxide, iron oxide sulfur, navy blue, cyanine blue, ultramarine blue, manganese violet, aluminum paste pearl, mica pearl, etc. characterized by

In addition, the average particle size of the powder coating is 32 to 35 microns, and the thickness of the coating film when applied is 60 to 100 microns. In addition, it is characterized in that Long Wave ≤30, Short Wave ≤30 when measuring smoothness in a film thickness of 70 to 90 microns.

Known additives may be appropriately included in the powder coating composition of the present invention as described above according to the needs of those skilled in the art. For example, 52 to 63% by weight of a polyester resin having a carboxyl group at the terminal group, 3.12 to 5% by weight of triglycidylisocyanurate (TGIC) as a curing agent, 1.2 to 1.5% by weight of a curing accelerator, 0.1 to 1.0% by weight of a pinhole inhibitor as an additive, Wax 0.1 ~ 1.0% by weight, flowability improver 0.1 ~ 2.0% by weight, wetting dispersant 0.1 ~ 2.0% by weight, flow agent 0.1 ~ 1.0% by weight, filler 25 ~ 35% by weight, pigment 1.1 ~ 1.4% by weight, aluminum paste pearl 0.15 It can be composed by including ~0.2%.

A supplementary description of the configuration of the present invention is as follows.

The thermosetting powder coating composition according to the present invention is cured by crosslinking the carboxyl group of the polyester resin and the curing agent TGIC (Triglycidylisocyanurate). At this time, while the resin is bonded in an appropriate amount to the acid value, viscosity, and glass transition temperature of the polyester resin, the appearance of the high-gloss, high-leveling metallic powder paint is formed according to the weight parts of the additives, fillers, and aluminum paste pearls.

After melting and mixing the uniformly mixed composition at a high temperature of 90 to 120 ° C through a melt disperser, a powder coating composition having an average particle size of 32 to 35 microns and a particle distribution of 10 to 120 microns is prepared using a grinder. do. The prepared powder paint is prepared by adding aluminum paste pearl through a post-process and blending to produce a metallic powder paint. The prepared powder coating composition is applied by the electrostatic spray coating method, applied so that the coating film thickness is 60 to 100 microns, and then dried and cured at a temperature of 170 to 200 ° C. for 10 to 20 minutes to obtain a high gloss and high leveling coating film.

At this time, since the composition of the present invention is a high-gloss, high-leveling metallic powder coating composition, the particle size and coating thickness of the coating have a great influence on the appearance of the coating. Therefore, if you change the conventional average particle size from 38 to 42 microns to 32 to 35 microns and manage the thickness of the coating to at least 60 microns or more, you can obtain a high-gloss, high-leveling coating.

Conventional thermosetting powder coatings have been supplied according to the needs of consumers, but their appearance has not been beautiful, such as orange peel. A powder coating composition can be obtained.

According to the present invention, it is confirmed that the difference in crosslinking reaction and the glass transition temperature and viscosity of the polyester resin affect the appearance according to the content of the curing agent by the acid value of the polyester resin, and the acid value of the polyester resin is 32 ~ 38mg KOH / g , a glass transition temperature of 58 to 64°C, and a viscosity of 1,400 to 4,200 cP. Among polyester resins with an acid value of 30 to 40 mg KOH/g, polyester resins with low viscosity have excellent coating appearance, but the coating production efficiency, storage stability and mechanical properties are reduced. High viscosity polyester resins have excellent mechanical properties but poor coating appearance. It is lowered. Therefore, in the present invention, two of the polyester resins in the above range were mixed to obtain a powder coating composition having excellent mechanical properties and beautiful appearance.

If the two types of polyester resins matched to the acid value/glass transition temperature/viscosity values according to the present invention are not used, a problem of poor physical properties may occur even if the appearance is not beautiful or the appearance is beautiful.

In the case of the pinhole inhibitor, pinholes occur when the amount is less than 0.1% by weight, and yellowing occurs when the amount exceeds 1.0% by weight. Yellowing occurs mainly in powder coatings with light colors such as white, light gray, and ivory.

A curing catalyst (curing accelerator) is used that has an acid value of 30 to 40 mg KOH/g, a glass transition temperature of 50 to 70 °C, and a viscosity of 2,800 to 4,500 cP. If such a curing catalyst is used in excess, the appearance of the coating film is not beautiful due to the rapid progress of the curing reaction, and an orange peel phenomenon occurs. Conversely, if used in low amounts, the flowability of the powder coating is too good, so there is a concern that sagging may occur in the coating when applied with an overcoat.

In addition, if the content of the filler exceeds 35% by weight, the appearance is not beautiful, and if the content of the filler is less than 25% by weight, the appearance is beautiful, but the hardness of the coating film is weak, so scratches easily occur. may not be

As described above, the present invention relates to a composition as a high-gloss, high-leveling metallic powder coating, and more particularly, by converting a polyester resin having a carboxyl group at a polymer terminal into a powder coating and curing the hardener TGIC, the coating has high gloss and high leveling. A powder coating composition having a beautiful appearance and excellent in various physical properties can be obtained.

Hereinafter, the present invention will be described in detail based on examples. However, this is to aid understanding of the present invention, and the scope of the present invention is not limited thereby.

First, raw materials such as 1 to 12 in Table 1 are weighed and then uniformly mixed using a mixer.

The solid ingredients are well mixed and dispersed and mixed at a high temperature (90 ~ 120 ℃) using a melt disperser to prepare pellets, and the prepared pellets are prepared using a grinder to prepare a powder coating composition having an average particle size of 32 to 35 microns. A metallic powder composition is prepared by adding the additive (flow agent) of 13 and the aluminum paste pearl of 14 through a blending process.

The prepared powder coating composition is coated on an object (steel plate, aluminum plate, hot-dip galvanized steel sheet, electro-galvanized steel sheet) to be 60 to 100 microns based on the dry film thickness by electrostatic spray painting.

A high-gloss, high-leveling metallic powder coating composition can be prepared by maintaining the coated object at a temperature of 170 to 200° C. [material surface temperature] for 10 to 20 minutes in a hot air drying furnace where a constant temperature is maintained.

1. Polyester resin having a carboxyl group at the end (KHUA): acid value 32~38mg KOH/g, glass transition temperature 62℃, viscosity 1400~3000cP @ 200℃

2. Polyester resin having a carboxyl group at the end group (KHUA Company): acid value 30~36mg KOH/g, glass transition temperature 60℃, viscosity 2800~4200cP @ 200℃

3. Curing agent (HUA HUI): TGIC (epoxy equivalent 100~110, viscosity 95~105cP @120℃)

4. Curing catalyst (INOPOL), a polyester resin having a carboxyl group at the end group: acid value 30~36 mg KOH/g, glass transition temperature 60℃, viscosity 2,800~4,500 cP @200℃

5. Pinhole prevention agent: Benzoin (Miwon)

6. Surface Conditioner CEAR 960 (BYK Company)

7. Flow improver: BYK368P (BYK company)

8. Flow improver: BYK:3950 (BYK company)

9. Precipitated filler - Precipitated barium sulfate (KOCH)

10. Natural filler - general barium sulfate (KOCH)

11. Filler - OMYA#5 Calcium Carbonate (OMYA Company)

12. Pigment: HI BLACK (0RION)

13. Flow agent - SILICA#1 (HDK Company)

14. Aluminum paste SILVER1300 (SILVER LINE Co.)

Examples 1 to 3 of Table 1 are high-gloss, high-leveling powder coating compositions, with respect to 52-63% by weight of the two polyester resins, 3.12 to 5% by weight of the curing agent TGIC, 1.2 to 1.5% by weight of the curing accelerator, additives (pinhole inhibitor , surface conditioner, flow improver) 1.8 to 3.5% by weight, filler 25 to 35% by weight, pigment 1.8 to 3.0% by weight, and metallic pearl 1.8 to 2.0% by weight.

In Examples 1 to 3, polyester resin 1 has an acid value of 32 to 38 mg KOH/g, glass transition temperature of 60 to 64 ° C, viscosity of 1400 to 3000 cP @ 200 ° C, and polyester resin 2 has an acid value of 30 to 36 mg KOH / g, glass A transition temperature of 58 to 62 ℃ and a viscosity of 2800 to 4200 cP @ 200 ℃ were used, Resin 1 was fixed at 30 to 35% by weight and Resin 2 was fixed at 22 to 28% by weight, and then Filler Pigment 1 Precipitated barium sulfate was used. Therefore, high-gloss, high-leveling powder coating was designed by setting the formulation by content.

High leveling of the coating film can be obtained by using only a low-viscosity resin, but the pulverization production efficiency and mechanical properties of the coating material are reduced. In addition, the higher the acid value of the resin, the lower the molecular weight of the polyester resin, resulting in an excellent appearance of the coating film. Therefore, in the present invention, it is designed to satisfy the appearance and physical properties by mixing two kinds of polyester resins having the above physical properties.

In Examples 1 to 3, the additives were a mixture of a pinhole inhibitor, a flow improver, and a surface conditioner, and by using a product with a melting temperature of 90 to 120 ° C, the performance was exhibited even during curing, and two types of polyester resins 52 to 63 It was used by mixing 1.8 to 3.5% by weight based on weight%.

In Examples 1 to 3, precipitated barium sulfate was used as a filler. However, in Examples 1 to 3, physical property tests were conducted by content of the filler pigment to examine the effect on the appearance of the coating film. In addition, in the case of Comparative Examples 1 to 4, physical property tests were conducted using general barium sulfate or calcium carbonate fillers instead of precipitated barium sulfate and compared.

The results of the coating film properties of the high gloss, high leveling polyester powder coatings prepared in Examples 1 to 3 and Comparative Examples 1 to 4 in Table 1 are as follows.

As shown in Table 3, in the case of Examples 1 to 3 and Comparative Examples 1 to 4 under the curing condition of 180 ° C. X 10 minutes [M.T], the coating film property evaluation items were good. Examples 1 to 3 and Comparative Examples 1 to 3, excluding Comparative Example 4, satisfy the specification Long Wave ≤ 30 Short Wave ≤ 30 when measuring the average value after measuring the smoothness by thickness of the coating film at 70 to 90 microns. The smoothness comparison results are in the order of Example 1> Example 2> Example 3> Comparative Example 1> Comparative Example 2> Comparative Example 3.

In comparison of smoothness and gloss, Examples 1 and 2 were the best, and Example 3 and Comparative Examples 2 and 3 were inferior to Examples 1 and 2 in gloss evaluation, and Example 1 was the best as a high-gloss, high-leveling paint. .

As a result of the experiment, when the glossiness and smoothness are comprehensively considered, Examples 1 to 3 can be said to be excellent.

Claims (6)

52 to 63% by weight of a polyester resin having a carboxyl group at the end group;
Curing agent TGIC (Triglycidylisocyanurate) 3.12 to 5% by weight,
1.2 to 1.5% by weight of a curing accelerator and
It is composed of 25 to 35% by weight of the filler,
At this time, the polyester resin is a polyester resin (1) having an acid value of 32 to 38 mg KOH / g, a viscosity of 1400 to 3000 cP, and a glass transition temperature of 60 to 64 ° C. 30 to 35% by weight, an acid value of 30 to 36 mg KOH / g, and a viscosity of 2800 ~ 4200cP, a polyester resin having a glass transition temperature of 58 ~ 62 ℃ (2) composed of 22 ~ 28% by weight,
The curing accelerator has an acid value of 30 to 40 mg KOH / g, a glass transition temperature of 50 to 70 ° C, and a viscosity of 2,800 to 4,500 cP,
The curing agent Triglycidylisocyanurate (TGIC) has an epoxy equivalent of 100 to 110 and a viscosity of 95 to 105 cP @ 120 ° C.
The filler is precipitated barium sulfate,
The powder coating composition, characterized in that the average particle size of the powder coating is 32 to 35 microns and the thickness of the coating film when applied is 60 to 100 microns. delete delete delete According to claim 1,
The pigment is selected from the group consisting of titanium dioxide, bismuth vanadate, cyanine green, carbon black, red iron oxide, iron oxide sulfur, navy blue, cyanine blue, ultramarine blue, manganese violet, aluminum paste pearl, and mica pearl. Powder coating composition. delete