WO2024111926A1 - Powder coating composition - Google Patents

Abstract

The present invention relates to a powder coating composition which provides excellent pliability and high-temperature corrosion resistance without a reduction in the glass transition temperature of a cured product.

Description

powder coating composition

The present invention relates to a powder coating composition that provides excellent flexibility and high-temperature corrosion resistance without reducing the glass transition temperature of the cured product.

Pipelines for oil mining and transportation buried underground or under the sea are coated with paint to prevent corrosion and improve durability. In order to prevent corrosion of pipes due to harsh conditions such as microcurrents and moisture in buried environments such as above ground, underground, and underwater, coating materials are applied to the inside and outside of pipes, and the long-term property management standards for coating materials required by the industry are established. It is gradually being strengthened. In particular, as mining in harsh environments becomes more frequent due to the depletion of underground resources, mining depths deepen and burial environments become harsher. In order to protect pipes from corrosion under high-temperature conditions, paints for pipe coatings are also subject to thermal, chemical, and mechanical changes. Improvements in properties are continuously required, and research on paints that satisfy these properties continues. For example, U.S. Patent No. 5,407,978 discloses a powder coating for pipes containing an aliphatic polyol-modified epoxy resin and a phenol curing agent.

Additionally, in addition to corrosion resistance and heat resistance, the pipe interior and exterior coating materials require flexibility to protect the material from impacts, scratches, etc. In order to provide flexibility to powder coatings, technologies using auxiliary resins such as rubber-modified resin type, core-shell resin type, and block copolymer type have been proposed. However, since the glass transition temperature of conventional auxiliary resins is much lower than that of epoxy resins, there is a problem of lowering the overall glass transition temperature of the coating composition containing them. Accordingly, there is a need for the development of powder coatings containing auxiliary resins that provide excellent flexibility without lowering the glass transition temperature of the coating composition.

The present invention provides a powder coating composition that has excellent flexibility and high-temperature corrosion resistance without reducing the glass transition temperature of the cured product.

The powder coating composition of the present invention includes an isocyanate-modified epoxy resin, a silicone-modified resin, a curing agent, and a filler.

The powder coating composition of the present invention maintains the excellent adhesion, thermal stability, and mechanical properties of epoxy-based paints, while improving brittleness, which is a disadvantage, and provides excellent flexibility and high-temperature corrosion resistance without reducing the glass transition temperature of the final cured product. . The powder coating composition according to the present invention can form a coating film with excellent heat resistance, adhesion, flexibility, and corrosion resistance even in a high temperature/high pressure environment. Therefore, the powder coating composition of the present invention can be used as a powder coating for pipe coating required to transport high-temperature fluids.

Hereinafter, the present invention will be described in more detail. However, it is not limited to the following content, and each component may be variously modified or selectively mixed as needed. Accordingly, it should be understood to include all changes, equivalents, and substitutes included in the spirit and technical scope of the present invention.

“Viscosity” as used herein is measured by a common method known in the art, and can be measured, for example, using a CONE & PLATE viscometer at the temperature described. “Weight average molecular weight” is measured by a common method known in the art, and can be measured, for example, by GPC (gel permeation chromatography) method.

The powder coating composition of the present invention includes an isocyanate-modified epoxy resin, a silicone-modified resin, a curing agent, and a filler. The powder coating composition of the present invention may further include additives commonly used in the relevant technical field, such as curing aids, pigments, pinhole preventers, and leveling agents, as necessary, to the extent that they do not impair the inherent physical properties and characteristics.

Isocyanate modified epoxy resin

The powder coating composition of the present invention includes an isocyanate-modified epoxy resin. By including an isocyanate-modified epoxy resin, a powder coating composition having a high glass transition temperature (eg, 140° C. or higher) can be provided.

Isocyanate-modified epoxy resin is a polymer obtained by modifying an epoxy resin with an isocyanate compound, and contains an oxazolidone ring in the main chain of the epoxy resin and a glycidyl group at the terminal. This isocyanate-modified epoxy resin can be produced by reacting an epoxy resin and an isocyanate compound in the presence of a catalyst.

As the epoxy resin, multifunctional epoxy resins such as bisphenol A-type epoxy resin, bisphenol F-type epoxy resin, polyol-modified epoxy resin, novolac-modified epoxy resin, and cresol novolac epoxy resin can be used. These can be used individually or in combination of two or more types.

Monoisocyanate or diisocyanate can be used as the isocyanate compound. Non-limiting examples of the monoisocyanate include p-toluenesulfonyl isocyanate, 4-phenoxyphenyl isocyanate, and 4-cyanophenyl isocyanate. Non-limiting examples of the diisocyanate include methane diisocyanate, butane-1,1-diisocyanate, ethane-1,2-diisocyanate, butane-1,2-diisocyanate, transvinyline diisocyanate, and heptane-1. ,7-diisocyanate, 2,2-dimethyl-pentane-1,5-diisocyanate, hexane-1,6-diisocyanate, octane-1,8-diisocyanate, nonane-1,9-diisocyanate, dimethylsilane Diisocyanate, diphenylsilane diisocyanate, cyclohexane-1,4-diisocyanate, dicyclohexylmethane-4,4-diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,6-toluene diisocyanate, These include 2,4-toluene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, trans-1,4-cyclohexane diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate. These can be used individually or in combination of two or more types.

The catalyst may include bases, amines, hydrogen compounds, imidazoles, phosphonium salts and derivatives thereof, but is not limited to these. These can be used individually or in combination of two or more types.

The epoxy equivalent weight of the isocyanate-modified epoxy resin may be 200 to 700 g/eq, for example, 300 to 500 g/eq. When the epoxy equivalent weight satisfies the above-mentioned range, flexibility, corrosion resistance, and manufacturing workability can be secured. If the epoxy equivalent weight is less than the above-mentioned range, cross-linking may not occur properly and flexibility may be reduced, and if it exceeds the above-mentioned range, excessive cross-linking may occur and adhesion may be reduced.

The viscosity (200°C) of the isocyanate-modified epoxy resin may be 5 to 15 poise, for example, 7 to 12 poise. When the viscosity satisfies the above-mentioned range, the appearance characteristics and corrosion resistance of the coating film can be improved. If the viscosity is less than the above-mentioned range, the viscosity may be too low and sagging properties may be reduced, and if it exceeds the above-mentioned range, the viscosity may be high and the wetting property may be reduced because it does not spread well.

The isocyanate modification rate of the isocyanate-modified epoxy resin may be 15 to 35% by weight, for example, 20 to 30% by weight. If the isocyanate modification rate is less than the above-mentioned range, the molecular weight of the epoxy resin may decrease due to the small content of the isocyanate resin, which may reduce corrosion resistance and weather resistance, and if it exceeds the above-mentioned range, the molecular weight of the epoxy resin may decrease due to the increase in the isocyanate resin content. As it increases, flexibility may decrease.

The glass transition temperature of the isocyanate-modified epoxy resin may be 120 to 200 °C, for example, 140 to 185 °C. If the glass transition temperature is less than the above-mentioned range, boiling water resistance and cathode peeling resistance may be reduced, and if it exceeds the above-mentioned range, flexibility and bendability may be reduced.

The powder coating composition of the present invention may include 45 to 75% by weight, for example, 55 to 75% by weight, of the isocyanate-modified epoxy resin based on the total weight of the composition. If the content of the isocyanate-modified epoxy resin is less than the above-mentioned range, flexibility may be reduced, and if it exceeds the above-mentioned range, boiling water resistance and corrosion resistance may be reduced due to unreacted residual epoxy resin.

silicone modified resin

The powder coating composition of the present invention includes silicone-modified resin as an auxiliary resin. The silicone-modified resin is a polymer synthesized by polymerizing silicone to a polymer, and is a compound that simultaneously has a silicone group, a lipophilic group, and a hydrophilic group.

In general, epoxy resins have a high crosslinking density due to their structural characteristics, but due to this high crosslinking density, they have the disadvantage of being brittle and weak against momentary impacts. Therefore, when a brittle epoxy resin is applied to a paint coated on a pipe with a curved surface, etc., the coating film may be easily broken by external stimuli. In the present invention, in order to provide flexibility to the epoxy resin, the brittleness of the epoxy resin can be improved by mixing and curing a silicone-modified resin as an auxiliary resin.

The silicone-modified resin is a polymer, for example, an alkylene oxide polymer modified with polydimethylsiloxane in a pendant type, and through the modification, the resin has the characteristics of silicone, including heat resistance, water repellency, and weather resistance.

Alkylene oxide polymer is a compound that has both lipophilic and hydrophilic groups. Its structure allows the rotation of the molecules, giving it excellent flexibility. However, due to the inclusion of organic substances, the bonding energy with the material is relatively low, which reduces physical properties such as chemical resistance and corrosion resistance. It can be. On the other hand, siloxane has silicone properties with excellent heat resistance, water repellency, and weather resistance, but when used alone, it may be difficult to manufacture paints due to lack of compatibility with the main resin, epoxy resin. In the present invention, a silicone-modified resin synthesized by polymerizing an alkylene oxide polymer and silicone is used, and the silicone-modified resin has the flexibility and dispersibility of the alkylene oxide polymer polymer, and heat resistance, water repellency, weather resistance, and appearance due to silicone modification. It has characteristics such as: As a result, appearance, corrosion resistance, and flexibility can be improved without reducing the deformation or glass transition temperature of the final cured product when forming a coating film.

Examples of the alkylene oxide include ethylene oxide, propylene oxide, butylene oxide, pentylene oxide, hexylene oxide, and octylene oxide. These may be used alone or in combination of two or more types. For example, the alkylene oxide may be an alkylene oxide having 1 to 4 carbon atoms. In this case, the silicone-modified resin has excellent compatibility with the epoxy resin, so dispersibility can be further improved.

The silicone content of the silicone-modified resin may be 5 to 15% by weight based on the total amount of the silicone-modified resin. If the amount of silicone modification is less than the above-mentioned range, the corrosion resistance may be reduced due to the high content of alkylene oxide with low binding energy, and if the amount of silicone modification is more than the above-mentioned range, the compatibility with the epoxy resin is poor due to the high silicone content. Acidity may decrease.

The silicone modified resin may further include an epoxy group. Silicone-modified resin contains silicon, so its compatibility with organic substances may be reduced. However, by containing an epoxy group, compatibility with the main resin, epoxy resin, is improved and dispersibility can be improved.

The epoxy equivalent weight of the silicone modified resin may be 800 to 1,200 g/eq, and the viscosity (175°C) may be 20 to 30 poise. If the epoxy equivalent weight is less than the above-mentioned range, cross-linking may not occur sufficiently and flexibility may be reduced, and if it exceeds the above-mentioned range, excessive cross-linking may occur and adhesion may be reduced. If the viscosity is less than the above-mentioned range, the sagging property may be reduced, and if it exceeds the above-mentioned range, the viscosity may not spread well and the wetting property may be reduced.

The weight average molecular weight of the silicone modified resin may be 5,000 to 20,000 g/mol, for example, 6,000 to 10,000 g/mol. When the weight average molecular weight of the silicone modified resin is within the above-mentioned range, the flexibility, corrosion resistance, and appearance of the coating film can be improved. If the weight average molecular weight of the silicone modified resin is less than the above-mentioned range, corrosion resistance may be reduced, and if it exceeds the above-mentioned range, the appearance may be inferior due to a decrease in compatibility.

The powder coating composition of the present invention may include 1 to 30% by weight, for example, 2 to 10% by weight, of the silicone modified resin based on the total weight of the composition. If the content of the silicone modified resin is less than the above-mentioned range, the effect of improving flexibility may not be sufficient, and if it exceeds the above-mentioned range, the appearance and adhesion may be deteriorated.

hardener

The powder coating composition of the present invention includes a curing agent. The curing agent includes an amine-based curing agent, a phenol-based curing agent, a dicyandiamide-based curing agent, a hydrazide-based curing agent, phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenone tetracarboxylic anhydride, and mixtures thereof. One or more types selected from can be used. For example, an amine-based curing agent can be used.

The amine-based curing agent may be an aliphatic amine-based curing agent, an alicyclic amine-based curing agent, or an aromatic amine-based curing agent. These may be used alone or in combination of two or more types. Non-limiting examples of amine-based curing agents that can be used include 4,4'-diaminodiphenylsulfone, 4,4'-diaminodiphenylmethane, and dicyandiamide.

The active hydrogen equivalent of the amine-based curing agent may be 10 to 50 g/eq, for example, 15 to 30 g/eq. If the active hydrogen equivalent is less than the above-mentioned range, flexibility may be reduced, and if it exceeds the above-mentioned range, corrosion resistance may be reduced.

The molecular weight of the amine-based curing agent may be 60 to 100 g/mol, for example, 70 to 90 g/mol. If the molecular weight of the amine-based curing agent is less than the above-mentioned range, flexibility may be reduced, and if it exceeds the above-mentioned range, corrosion resistance may be reduced.

The powder coating composition of the present invention may include 0.1 to 3.5% by weight, for example, 1 to 3% by weight of the curing agent, based on the total weight of the composition. If the content of the hardener is outside the above-mentioned range, the mechanical properties of the coating film may deteriorate. If the content of the hardener is less than the above-mentioned range, the strength of the coating film may decrease due to a decrease in crosslinking density, and if it exceeds the above-mentioned range, the crosslinking density of the coating film may rapidly increase and processability may be reduced.

filler

The powder coating composition of the present invention includes a filler. The filler may include an inorganic filler, a metal filler, or a mixture thereof.

Non-limiting examples of the inorganic fillers include feldspar, barium sulfate, silica, alumina hydroxide, titanium dioxide, calcium carbonate, magnesium carbonate, alumina, mica, olastonite, and talc. These can be used alone or in combination of two or more types.

The powder coating composition of the present invention may include 1 to 30% by weight of the inorganic filler based on the total weight of the composition. If the content of the inorganic filler is outside the above-mentioned range, the mechanical properties of the coating film may deteriorate. If the content of the inorganic filler is less than the above-mentioned range, mechanical properties may become poor, and if it exceeds the above-mentioned range, physical properties such as bending resistance may be deteriorated.

Non-limiting examples of the metal fillers include potassium, calcium, sodium, magnesium, aluminum, zinc, and their oxides. These can be used alone or in combination of two or more types.

The powder coating composition of the present invention may include 1 to 30% by weight of the metal filler based on the total weight of the composition. If the content of the metal filler is outside the above-mentioned range, the corrosion resistance and mechanical properties of the coating film may be reduced. If the content of the metal filler is less than the above-mentioned range, corrosion resistance may be poor, and if it exceeds the above-mentioned range, the specific gravity of the paint may increase and workability may be poor.

cure accelerator

The powder coating composition of the present invention may further include a curing accelerator. A curing accelerator can shorten the curing time by improving the reaction rate between the epoxy resin and the curing agent.

Non-limiting examples of curing accelerators that can be used in the present invention include phenylphosphine, phenylphosphonium salts, imidazoles, imidazole-modified epoxy resins, DiBiu, DiBiu salts, and metal chelates. These can be used individually or in combination of two or more types. For example, triphenylphosphine, benzyltriphenylphosphonium chloride, butyltriphenylphosphonium chloride, tetraphenylphosphonium chloride, 1-methylimidazole, 2-methylimidazole, 1,2-dimethylimidazole , 1,5-dimethylimidazole, 2-butyl-5-chloro-1H-imidazole-4-carbaldehyde, vinylimidazole, climbazole, 1,1-carbonyldiimidazole, tert-butyl Selected from the group consisting of dimethylsilyl chloride, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-ethylimidazole, 1-benzyl-2-methylimidazole and 2-butylimidazole One or more types can be used.

The powder coating composition of the present invention may include 0.01 to 2% by weight of the curing accelerator based on the total weight of the composition. When the content of the curing accelerator is within the above-mentioned range, excellent workability and mechanical properties of the coating film can be secured.

pigment

The powder coating composition of the present invention may further include pigments commonly used in the powder coating field, within the range that does not impair the inherent properties of the composition.

Pigments can be used to give powder coatings a desired color or to increase the strength or gloss of the coating film. Organic pigments, inorganic pigments, metallic pigments, aluminum-paste, pearl, etc. can be used as the pigments, and these can be used alone or in combination of two or more types. Non-limiting examples of pigments that can be used include azo-based, phthalocyanine-based, iron oxide-based, cobalt-based, carbonate-based, sulfate-based, silicate-based, and chromate-based pigments, such as titanium dioxide, zinc oxide, and bismuth vanadate. , cyanine green, carbon black, iron oxide red, iron oxide sulfur, navy blue, cyanine blue, and mixtures of two or more thereof. In one example, the pigment may be titanium dioxide.

The composition of the present invention may contain 1 to 20% by weight of the pigment based on the total weight of the powder coating composition. When the pigment content is within the above-mentioned range, the color expression of the coating film is excellent, and the hiding properties and mechanical properties of the coating film can be improved.

additive

The powder coating composition of the present invention may further include additives commonly used in the powder coating field within the range that do not impair the inherent properties of the composition.

Non-limiting examples of additives that can be used in the present invention include pinhole preventers, leveling agents, waxes, stress reducing agents, dispersants, flow improvers, anti-cratering agents, coupling agents, gloss control agents, adhesion improvers, flame retardants, There are matting agents, light absorbers, etc. These may be used alone or in combination of two or more types.

The flow improver is used to prevent cratering and lower the surface tension of the coating film to achieve a flexible appearance, and common agents known in the art can be used. For example, an acrylic or silicone-based flow improver may be used. The content of the flow improver is not particularly limited and may be 0.1 to 5% by weight based on the total weight of the powder coating composition. If the content of the flow improver is outside the above-mentioned range, flowability may be reduced.

Wax facilitates dispersion when manufacturing powder coatings and serves as a surface conditioner for the paint film. As the wax, amide-based, polypropylene-based, olefin-based, Teflon-based wax, etc. can be used.

The powder coating composition according to the present invention can be manufactured by methods known in the art. In one example, the ingredients of the powder coating composition described above are mixed and uniformly mixed using a container mixer, and the mixed composition is melted using a kneader or extruder at 80 to 120 ° C. After mixing, powder coating can be manufactured using a grinder.

The average particle size of the powder coating material is not particularly limited, but may be, for example, 20 to 80 ㎛. When the average particle size of the powder coating is within the above range, excellent painting workability and appearance characteristics can be achieved.

A coating film using the powder coating composition according to the present invention can be formed by methods known in the art. For example, while preheating a steel pipe base with a pre-blasted undercoat to 180 to 250°C, the powder coating composition of the present invention is applied to a thickness of 200 to 500 ㎛ using an electrostatic spray paint machine, and then the steel pipe base is heated to 180 to 250°C. After heating for about 5 minutes, a coating film can be formed, and then immediately immersed in cold water to form the final coating film.

The powder coating composition of the present invention can form a coating film with excellent heat resistance, adhesion, flexibility, and corrosion resistance even in a high temperature/high pressure environment. Therefore, the powder coating composition of the present invention can be used as a powder coating for pipe coating required to transport high-temperature fluids.

Hereinafter, the present invention will be described in more detail through experimental examples. However, the following experimental examples are only intended to aid understanding of the present invention, and the scope of the present invention is not limited to the experimental examples in any way.

[Experimental Examples 1 to 13]

According to Tables 1 to 2 below, each ingredient was mixed using a container mixer and mixed uniformly. The mixed composition was melt-mixed at 100°C using a kneader, and then a powder coating composition of each example with an average particle size of 50 ㎛ was prepared using a grinder.

Epoxy resin 1: Isocyanate modified epoxy resin (epoxy equivalent weight 330 g/eq, viscosity (200°C) 7 poise, modification rate 22.5% by weight, glass transition temperature 142°C)

Epoxy resin 2: Isocyanate modified epoxy resin (epoxy equivalent weight 420 g/eq, viscosity (200°C) 10 poise, modification rate 24.6% by weight, glass transition temperature 160°C)

Epoxy resin 3: Isocyanate modified epoxy resin (epoxy equivalent weight 497 g/eq, viscosity (200°C) 12 poise, modification rate 29.8% by weight, glass transition temperature 181°C)

Epoxy resin 4: Isocyanate modified epoxy resin (epoxy equivalent weight 180 g/eq, viscosity (200°C) 20 poise, modification rate 23.1% by weight, glass transition temperature 105°C)

Epoxy Resin 5: Novolac modified epoxy resin (ALNOVOL® PN 320, allnex)

Auxiliary resin 1: Silicone-modified resin (silicon-modified ethylene oxide polymer polymer, silicone content 5.3% by weight, epoxy equivalent weight 830 g/eq, viscosity (175°C) 21 poise, weight average molecular weight 6,310 g/mol)

Auxiliary resin 2: Silicone-modified resin (silicon-modified propylene oxide polymer polymer, silicone content 9.1% by weight, epoxy equivalent weight 1,010 g/eq, viscosity (175°C) 25 poise, weight average molecular weight 8,320 g/mol)

Auxiliary resin 3: Silicone-modified resin (silicon-modified ethylene oxide polymer polymer, silicone content 14.6% by weight, epoxy equivalent weight 1,165 g/eq, viscosity (175°C) 29 poise, weight average molecular weight 9,350 g/mol)

Auxiliary resin 4: Silicone-modified resin (silicon-modified ethylene oxide polymer polymer, silicone content 21% by weight, epoxy equivalent weight 1,310 g/eq, viscosity (175°C) 28 poise, weight average molecular weight 11,200 g/mol)

Auxiliary Resin 5: Silicone Resin (Silres604, Waker)

Hardener: dicyandiamide (active hydrogen equivalent weight 21 g/eq, molecular weight 84.1 g/mol)

Catalyst: 2-Methyl Imidazole

Additive: Leveling agent (2-Propenoic acid butyl ester homopolymer)

Pigment: Diiron trioxide (colored pigment)

Inorganic filler: barium sulfate

[Physical property evaluation]

The physical properties of the powder coating composition prepared in each experimental example were measured by the following method, and the results are shown in Tables 3 and 4 below.

Appearance (leveling)

Steel of 100 mm (width) Х 100 mm (length) Х 6 mm (thickness) was prepared, and the surface was treated with grit blasting. After electrostatic spray painting of each powder coating composition, the appearance condition was confirmed using PCI GRADE.

[Evaluation standard]

GRADE 1: Bad ↔ GRADE 10: Good

Adhesion

An adhesion test was conducted using the same specimen used in the above appearance test. In accordance with the ASTM D4541 standard, the dolly was attached to the specimen and pressure was applied to measure the pressure when the paint film fell off.

flexibility

After preparing a short specimen (size: 200 mm Х 25 mm Х 6 mm), the specimen was preheated at a temperature of 230 ° C. for more than 40 minutes, and then each powder coating composition was painted on the preheated specimen using a painting gun. Afterwards, the temperature of the specimen was set to -30°C, and the bending properties (2.0˚ Bending) were measured using a bending tester.

Aqueous resistance

Prepare steel of 100 mm (width) Х 100 mm (length) Х 6 mm (thickness), subject to grit blasting surface treatment, preheat to 230°C, and then apply each powder coating composition as described above. A specimen was produced by coating the steel surface with an electrostatic spray method to a film thickness of 350 ㎛. Afterwards, the specimen was immersed in a water bath at 75°C and taken out after 48 hours to evaluate adhesion. The adhesion strength was measured by cooling the removed specimen to room temperature for 1 hour, scraping a rectangular shape measuring 15 mm wide and 30 mm long with a knife until the base material was exposed, and then pushing the knife between the coating film and the base material centered on the exposed area of the base material using a lever. After measuring adhesion according to the principle, a rating was obtained according to the peeling area, etc.

[Evaluation standard]

Rating 1: No film peeling at all

Rating 2: Less than 50% film peeling

Rating 3: More than 50% peeling of paint film

Rating 4: The film peels off easily into large pieces.

Rating 5: The film peels off easily in one piece.

Cathodic peelability

The same specimen as used in the above appearance test was used. After drilling a hole with a diameter of 3 mm in the center of the specimen, salt water with a concentration of 3% was applied to the surface of the coating film to make contact with it. After preventing evaporation using a container, a 1.5 V voltage was applied to the material at 150 ° C. for 28 days. The peeling distance from the hole was measured. It can be interpreted that the larger the peeling distance, the lower the adhesion of the powder coating composition to the substrate. The specimen production and physical property evaluation were performed according to CSA Z245.20, the Canadian standard for pipes.

As shown in Tables 3 and 4, the powder coatings of Experimental Examples 1 to 11 according to the present invention showed excellent physical properties in all measurement items. On the other hand, the powder coating of Experimental Example 12 containing a phenol novolac epoxy resin instead of an isocyanate-modified epoxy resin showed poor flexibility and cathodic peeling properties, and a silicone resin containing no alkylene oxide group and epoxy group was used instead of the silicone-modified resin. It was impossible to manufacture the powder coating of Experimental Example 13 containing the paint due to insufficient paint compatibility.

The powder coating composition of the present invention maintains the excellent adhesion, thermal stability, and mechanical properties of epoxy-based paints, while improving brittleness, which is a disadvantage, and provides excellent flexibility and high-temperature corrosion resistance without reducing the glass transition temperature of the final cured product. . The powder coating composition according to the present invention can form a coating film with excellent heat resistance, adhesion, flexibility, and corrosion resistance even in a high temperature/high pressure environment. Therefore, the powder coating composition of the present invention can be used as a powder coating for pipe coating required to transport high-temperature fluids.

Claims (6)

1. A powder coating composition comprising an isocyanate-modified epoxy resin, a silicone-modified resin, a curing agent, and a filler.
2. The method of claim 1, wherein the isocyanate-modified epoxy resin has an epoxy equivalent weight of 200 to 700 g/eq, a viscosity (200° C.) of 5 to 15 poise, an isocyanate modification ratio of 15 to 35% by weight, and a glass transition temperature of A powder coating composition having a temperature of 120 to 200°C.
3. The powder coating composition according to claim 1, wherein the silicone content of the silicone-modified resin is 5 to 15% by weight based on the total amount of the silicone-modified resin.
4. The powder coating composition according to claim 1, wherein the silicone modified resin has an epoxy equivalent weight of 800 to 1,200 g/eq, a viscosity (175° C.) of 20 to 30 poise, and a weight average molecular weight of 5,000 to 20,000 g/mol.
5. The powder coating composition according to claim 1, wherein the curing agent is an amine-based curing agent, has an active hydrogen equivalent of 10 to 50 g/eq, and has a molecular weight of 60 to 100 g/mol.
6. The method of claim 1, wherein, based on the total weight of the composition, 45 to 75% by weight of the isocyanate modified epoxy resin, 1 to 30% by weight of the silicone modified resin, 0.1 to 3.5% by weight of the curing agent, and 2 to 60% by weight of the filler. A powder coating composition comprising: