Powder paint composition containing recycled material and method for manufacturing the same

Abstract

A powder coating composition containing recycled raw materials and a method for manufacturing the same are disclosed. A powder coating composition containing recycled raw materials according to one embodiment may comprise 50 to 70 weight% of a polyester resin made using recycled raw materials; 2 to 5 weight% of a curing agent; 0.01 to 10 weight% of an additive; 1 to 15 weight% of an inorganic filler; and 1 to 40 weight% of a pigment.

Description

Technology Field

[0001] The present disclosure relates to a powder coating composition comprising recycled raw materials and a method for manufacturing the composition. Background Technology

[0002] Recently, as part of the development of eco-friendly technologies, attempts are being made to recycle PET (Polyethylene Terephthalate) waste. In this regard, Korean Registered Patent Publication No. 10-2339830 presents a technology for producing high-grade PET chips from low-grade PET waste.

[0003] Previously, powder coatings were manufactured using polyester resins synthesized from petrochemical raw materials, rather than utilizing recycled raw materials. While producing polyester resin using PET flakes—obtained by crushing PET waste—offers advantages in terms of resource recycling, the inconsistent physical properties of the resulting resin have caused significant difficulties in their application. Furthermore, manufacturing powder coatings with such resins results in degraded coating film properties and reduced commercial value; therefore, the development of new technologies to address these conventional issues is required. The problem to be solved

[0004] The technical concept of the present disclosure is intended to solve the aforementioned problems and aims to provide a technology capable of producing an environmentally friendly powder coating with excellent physical properties.

[0005] The problems that the present invention aims to solve are not limited to the problems described above, and other technical problems not mentioned will be clearly understood by those skilled in the art to which the present invention belongs from the following description. means of solving the problem

[0006] In order to achieve this purpose, as an embodiment of the present invention, a powder coating composition comprising recycled raw materials may comprise 50 to 70 weight% of a polyester resin made using recycled raw materials; 2 to 5 weight% of a curing agent; 0.01 to 10 weight% of an additive; 1 to 15 weight% of an inorganic filler; and 1 to 40 weight% of a pigment.

[0007] In addition, the recycled raw material may be chemically extracted from waste polyester through at least one of the glycol addition decomposition method, the methanol addition decomposition method, and the hydrolysis method.

[0008] In addition, the recycled raw material may include at least one of bis-2-hydroxyethyl terephthalate, dimethyl terephthalate, monoethylene glycol, and terephthalic acid.

[0009] In addition, the additive may include at least one of a leveling agent, an anti-foaming agent, a heat resistance improver, a flexibility improver, and an antioxidant.

[0010] In addition, the curing agent may include at least one of a β-hydroxyalkylamide-based curing agent, a triglycidyl isocyanurate-based curing agent, and a glycidyl ester-based curing agent.

[0011] In addition, the glass transition temperature of the powder coating composition may be 55 to 90°C.

[0012] In addition, the content of the leveling agent may be 1 to 5 weight%, the content of the anti-foaming agent may be 0.1 to 0.5 weight%, the content of the heat resistance improving agent may be 0.3 to 0.7 weight%, the content of the flexibility improving agent may be 2 to 3 weight%, and the content of the antioxidant may be 0.5 to 1 weight%.

[0013] In addition, the recycled raw material may be included in the polyester resin in an amount of more than 0 to 50 weight percent or less based on the total weight of the polyester resin.

[0014] To achieve this objective, as another embodiment of the present invention, a method for manufacturing a powder coating composition comprising recycled raw materials comprises: a mixing step of mixing a polyester resin made using recycled raw materials; a curing agent; an additive; an inorganic filler; and a pigment to form a mixture; a melt dispersion step of melting and dispersing the mixture to form a dispersion; a cooling step of cooling the dispersion; and a grinding step of grinding the cooled dispersion; wherein the recycled raw materials may be chemically extracted from waste polyester.

[0015] The means for solving the problem described above are merely exemplary and should not be interpreted as intended to limit the invention. In addition to the exemplary embodiments described above, additional embodiments described in the drawings and the detailed description of the invention may exist. Effects of the invention

[0016] As described above, according to various embodiments of the present invention, a powder coating composition can be manufactured using a polyester resin made from recycled raw materials, making it environmentally friendly, and it has the advantage of having generally excellent physical properties of the coating film formed by the powder coating (e.g., impact resistance, adhesion, hot water resistance, pencil hardness, heat resistance, elongation, etc.).

[0017] The effects of the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art from the description in the claims. Brief explanation of the drawing

[0018] FIG. 1 is a flowchart schematically illustrating a method for manufacturing a powder coating composition according to one embodiment of the present invention. Specific details for implementing the invention

[0019] Preferred embodiments of the present invention will be described in more detail with reference to the attached drawings, provided that technical details that are already well known will be omitted or compressed for the sake of brevity.

[0020] It should be noted that references to "one" or "one" embodiment of the present invention in this specification do not necessarily refer to the same embodiment, but mean at least one.

[0021] In the following embodiments, terms such as first, second, etc. are used not in a limiting sense, but for the purpose of distinguishing one component from another component.

[0022] In the following examples, singular expressions include plural expressions unless the context clearly indicates a different meaning.

[0023] In the following examples, terms such as "include" or "have" mean that the features or components described in the specification are present, and do not preclude the possibility that one or more other features or components may be added.

[0024] In the following embodiments, when a part such as a film, region, or component is described as being on or above another part, it includes not only cases where it is directly on top of another part, but also cases where another film, region, or component is interposed in between.

[0025] Throughout this specification, the term "about" used before a number is used to mean at or near that number when inherent manufacturing and material tolerances are presented in the stated meaning, and is used to prevent unscrupulous infringers from unfairly exploiting the disclosure in which precise or absolute numbers are mentioned to aid in understanding this invention.

[0026] Where an embodiment can be implemented differently, a specific process sequence may be performed differently from the order described. For example, two processes described in succession may be performed substantially simultaneously or proceed in the reverse order of the order described. That is, each step of the method described herein may be appropriately performed in any order unless otherwise stated in the specification or clearly contradicted by the context.

[0027] A powder coating composition according to one embodiment may include a polyester resin, a curing agent, an additive, an inorganic filler, and a pigment. In one embodiment, the polyester resin is a polyester resin made using recycled raw materials. For example, the recycled raw materials may be a material chemically extracted from waste polyester through at least one of the glycol addition cracking method, the methanol addition cracking method, and the hydrolysis method.

[0028] According to one embodiment, the recycled raw material may include at least one of bis-2-hydroxyethyl terephthalate, dimethyl terephthalate, monoethylene glycol, and terephthalic acid. For example, bis-2-hydroxyethyl terephthalate (BHET), dimethyl terephthalate (DMT), monoethylene glycol (MEG), or terephthalic acid (TPA) may be chemically extracted from waste polyester, and a polyester resin may be made using the extracted raw material.

[0029] In one embodiment, bis-2-hydroxyethyl terephthalate, dimethyl terephthalate, monoethylene glycol, or terephthalic acid may be a depolymerized product obtained by depolymerizing waste polyester.

[0030] In one embodiment, recycled raw materials may be included in the polyester resin in an amount greater than 0 and less than or equal to 50 weight percent based on the total weight of the polyester resin. That is, the polyester resin can be synthesized using recycled raw materials in an amount greater than 0 and less than or equal to 50 weight percent. The lower the content of recycled raw materials in the polyester resin, the less desirable it is in terms of resource recycling, and if the content of recycled raw materials exceeds 50 weight percent, the film properties of the powder coating composition may deteriorate.

[0031] According to one embodiment, the recycled raw material may be about 5% by weight or more to about 25% by weight or less based on the total weight of the powder coating composition. If the content of the recycled raw material exceeds 25% by weight in the powder coating composition, the physical properties of the coating film may be generally degraded.

[0032] The polyester resin according to one embodiment may be manufactured directly or a commercially available product may be used. For example, a polyester resin can be manufactured using recycled raw materials (e.g., BHET, DMT, MEG, TPA, etc.), an acid (e.g., a dicarboxylic acid, etc.), and a diol (e.g., ethylene glycol, etc.). As a specific example, a polyester resin can be produced by esterifying the recycled raw materials, the dicarboxylic acid component, and the diol component, and then polycondensing the reaction mixture.

[0033] In one embodiment, the acid value of the polyester resin may be about 15 mgKOH / g or more to about 50 mgKOH / g or less. As a specific example, the acid values ​​of polyester resins are 15 mgKOH / g, 16 mgKOH / g, 17 mgKOH / g, 18 mgKOH / g, 19 mgKOH / g, 20 mgKOH / g, 21 mgKOH / g, 22 mgKOH / g, 23 mgKOH / g, 24 mgKOH / g, 25 mgKOH / g, 26 mgKOH / g, 27 mgKOH / g, 28 mgKOH / g, 29 mgKOH / g, 30 mgKOH / g, 31 mgKOH / g, 32 mgKOH / g, 33 mgKOH / g, 34 mgKOH / g, 35 mgKOH / g, 36 mgKOH / g, 37 mgKOH / g, 38 mgKOH / g, 39 mgKOH / g, 40 mgKOH / g, It may be 41 mg KOH / g, 42 mg KOH / g, 43 mg KOH / g, 44 mg KOH / g, 45 mg KOH / g, 46 mg KOH / g, 47 mg KOH / g, 48 mg KOH / g, 49 mg KOH / g, or 50 mg KOH / g. Additionally, the acid value of the polyester resin may be in a range of one or more of the above values ​​and one or less of the above values.

[0034] For example, the acid value range of the polyester resin may be 15 mg KOH / g to 50 mg KOH / g, 20 mg KOH / g to 50 mg KOH / g, 25 mg KOH / g to 50 mg KOH / g, 30 mg KOH / g to 50 mg KOH / g, 35 mg KOH / g to 50 mg KOH / g, 40 mg KOH / g to 50 mg KOH / g, or 45 mg KOH / g to 50 mg KOH / g.

[0035] In one embodiment, the content of the polyester resin may be applied as about 50 wt% or more to about 70 wt% or less. As a specific example, the content of the polyester resin may be applied as 50 wt%, 51 wt%, 52 wt%, 53 wt%, 54 wt%, 55 wt%, 56 wt%, 57 wt%, 58 wt%, 59 wt%, 60 wt%, 61 wt%, 62 wt%, 63 wt%, 64 wt%, 65 wt%, 66 wt%, 67 wt%, 68 wt%, 69 wt%, or 70 wt%. Additionally, the content of the polyester resin may be in a range of one or more of the above figures and one or less of the above figures.

[0036] For example, the content range of the polyester resin may be set to 50% to 70% by weight, 50% to 69% by weight, 50% to 65% by weight, 50% to 60% by weight, 60% to 67% by weight, or 60% to 70% by weight. The polyester resin according to one embodiment can maintain excellent coating properties within the above ranges.

[0037] If the polyester resin content is less than 50 weight%, the gloss and adhesion of the coating film may be reduced, and there is a risk that the appearance of the coating film may be poor. If it exceeds 70 weight%, a phenomenon of dripping due to paint flow may occur at the corners of the coated surface, making it difficult to coat the corners of the coated surface, and chemical resistance may be reduced. Therefore, it is desirable to carry out the polyester resin content within the aforementioned range.

[0038] In one embodiment, the curing agent may include at least one of a β-hydroxyalkyl amide (HAA)-based curing agent, a triglycidyl isocyanurate (TGIC)-based curing agent, and a glycidyl ester-based curing agent.

[0039] In one embodiment, the content of the curing agent may be applied as about 2 wt% or more to about 5 wt% or less. As a specific example, the content of the curing agent may be applied as 2 wt%, 2.1 wt%, 2.2 wt%, 2.3 wt%, 2.4 wt%, 2.5 wt%, 2.6 wt%, 2.7 wt%, 2.8 wt%, 2.9 wt%, 3 wt%, 3.1 wt%, 3.2 wt%, 3.3 wt%, 3.4 wt%, 3.5 wt%, 3.6 wt%, 3.7 wt%, 3.8 wt%, 3.9 wt%, 4 wt%, 4.1 wt%, 4.2 wt%, 4.3 wt%, 4.4 wt%, 4.5 wt%, 4.6 wt%, 4.7 wt%, 4.8 wt%, 4.9 wt%, or 5 wt%. In addition, the content of the curing agent may be in a range of one or more of the above values ​​and one or less of the above values.

[0040] For example, the content range of the curing agent may be provided in the range of 2 wt% to 5 wt%, 2 wt% to 4 wt%, 2 wt% to 3 wt%, 3 wt% to 5 wt%, 3 wt% to 4 wt%, or 4 wt% to 5 wt%. The curing agent according to one embodiment can maintain excellent film properties within the above ranges.

[0041] If the amount of curing agent is less than 2 weight%, the curability may be reduced and the physical properties of the coating film may generally deteriorate, and if it exceeds 5 weight%, the unreacted material may have a negative effect on the physical properties of the coating film.

[0042] According to one embodiment, in order to prevent deterioration of the appearance of the coating film, provide flowability in the drying oven after coating, increase productivity, and secure the physical properties of the coating film, a polyester resin and a curing agent may be mixed and used in a weight ratio of 80:20 to 97:3 when manufacturing a powder coating. For example, when mixing the polyester resin and the curing agent, a weight ratio of 95:5 to 93:7 or a weight ratio of 90:10 may be applied.

[0043] In one embodiment, the additive may include at least one of a leveling agent, an anti-foaming agent, a heat resistance improver, a flexibility improver, and an antioxidant. For example, the type of additive can be selected by considering the content of recycled raw materials present in the powder coating composition.

[0044] In one embodiment, the content of the leveling agent may be applied in an amount of about 1 weight% or more to about 5 weight% or less. As a specific example, the content of the leveling agent is 1 wt%, 1.1 wt%, 1.2 wt%, 1.3 wt%, 1.4 wt%, 1.5 wt%, 1.6 wt%, 1.7 wt%, 1.8 wt%, 1.9 wt%, 2 wt%, 2.1 wt%, 2.2 wt%, 2.3 wt%, 2.4 wt%, 2.5 wt%, 2.6 wt%, 2.7 wt%, 2.8 wt%, 2.9 wt%, 3 wt%, 3.1 wt%, 3.2 wt%, 3.3 wt%, 3.4 wt%, 3.5 wt%, 3.6 wt%, 3.7 wt%, 3.8 wt%, 3.9 wt%, 4 wt%, 4.1 wt%, 4.2 wt%, 4.3 wt%, 4.4 wt%, It may be applied in an amount of 4.5 wt%, 4.6 wt%, 4.7 wt%, 4.8 wt%, 4.9 wt%, or 5 wt%. Additionally, the content of the leveling agent may be in a range of one or more of the above values ​​and one or less of the above values.

[0045] For example, the content range of the leveling agent may be provided in the range of 1 wt% to 5 wt%, 2 wt% to 5 wt%, 2 wt% to 4 wt%, 2 wt% to 3 wt%, 3 wt% to 5 wt%, 3 wt% to 4 wt%, or 4 wt% to 5 wt%. The leveling agent according to one embodiment can maintain excellent film properties within the above ranges.

[0046] If the leveling agent is less than 1 weight%, the flowability of the paint is reduced, and craters or orange peel may occur on the surface of the film, and if it exceeds 5 weight%, the appearance of the film is poor and may have a negative effect on the physical properties of the film.

[0047] In one embodiment, the anti-foaming agent may include benzoin. According to one embodiment, the content of the anti-foaming agent may be applied in an amount of about 0.1 weight% or more to about 0.5 weight% or less. As a specific example, the content of the anti-foaming agent may be applied in an amount of 0.1 weight%, 0.2 weight%, 0.3 weight%, 0.4 weight%, or 0.5 weight%. Additionally, the content of the anti-foaming agent may be in a range of one or more of the above values ​​and one or less of the above values.

[0048] For example, the content range of the anti-foaming agent may be provided in the range of 0.1 wt% to 0.5 wt%, 0.2 wt% to 0.5 wt%, 0.2 wt% to 0.4 wt%, 0.2 wt% to 0.3 wt%, 0.3 wt% to 0.5 wt%, 0.3 wt% to 0.4 wt%, or 0.4 wt% to 0.5 wt%. The anti-foaming agent according to one embodiment can maintain excellent coating film properties within the above ranges.

[0049] If the amount of anti-foaming agent is less than 0.1 weight%, it may not suppress the generation of bubbles, which could lead to a decrease in the physical properties of the coating film, and if it exceeds 0.5 weight%, it may have a negative effect on the physical properties of the coating film due to excessive addition.

[0050] In one embodiment, a heat resistance improver is an additive added to improve the heat resistance of a powder coating composition. For example, the heat resistance improver can improve the heat resistance of a powder coating composition that may be reduced due to the addition of recycled raw materials. According to one embodiment, the heat resistance improver may include a fatty acid ester-based additive.

[0051] In one embodiment, the content of the heat resistance improver may be applied as about 0.3 wt% or more to about 0.7 wt% or less. As a specific example, the content of the heat resistance improver may be applied as 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, or 0.7 wt%. Additionally, the content of the heat resistance improver may be in a range of one or more of the above values ​​and one or less of the above values.

[0052] For example, the content range of the heat resistance improver may be provided in the range of 0.3 wt% to 0.7 wt%, 0.3 wt% to 0.6 wt%, 0.3 wt% to 0.5 wt%, 0.3 wt% to 0.4 wt%, 0.4 wt% to 0.7 wt%, 0.4 wt% to 0.6 wt%, or 0.4 wt% to 0.5 wt%. The heat resistance improver according to one embodiment can maintain excellent coating film properties within the above ranges.

[0053] If the heat resistance improver is less than 0.3 weight%, there is a risk that the heat resistance of the coating film will decrease, and if it exceeds 0.7 weight%, it may have a negative effect on the physical properties of the coating film due to excessive addition.

[0054] In one embodiment, a flexibility improver is an additive added to improve the mechanical properties and flexibility of a powder coating composition. For example, the flexibility improver can improve the mechanical properties of a powder coating composition that may be degraded due to the addition of recycled raw materials. According to one embodiment, the flexibility improver may include a copolyester-based additive.

[0055] In one embodiment, the content of the flexibility improver may be applied as about 2 wt% or more to about 3 wt% or less. As a specific example, the content of the flexibility improver may be applied as 2 wt%, 2.1 wt%, 2.2 wt%, 2.3 wt%, 2.4 wt%, 2.5 wt%, 2.6 wt%, 2.7 wt%, 2.8 wt%, 2.9 wt%, or 3 wt%. Additionally, the content of the flexibility improver may be in the range of one or more of the above figures and one or less of the above figures.

[0056] For example, the content range of the flexibility improver may be provided in the range of 2 wt% to 3 wt%, 2 wt% to 2.9 wt%, 2 wt% to 2.8 wt%, 2 wt% to 2.7 wt%, 2 wt% to 2.6 wt%, 2 wt% to 2.5 wt%, or 2 wt% to 2.4 wt%. The flexibility improver according to one embodiment can maintain excellent film properties within the above ranges.

[0057] If the flexibility improver is less than 2 weight percent, flexibility may decrease, and there is a risk that the mechanical properties of the coating film may deteriorate. If it exceeds 3 weight percent, excessive addition may have a negative effect on the properties of the coating film.

[0058] In one embodiment, the antioxidant may include bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite. In one embodiment, the antioxidant may improve the heat resistance of the coating film and suppress yellowing. In one embodiment, the content of the antioxidant may be applied in an amount of about 0.5 wt% or more to about 1 wt% or less. As a specific example, the content of the antioxidant may be applied as 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, or 1 wt%. Additionally, the content of the antioxidant may be in a range of one or more of the above values ​​and one or less of the above values.

[0059] For example, the content range of the antioxidant may be provided in the range of 0.5 wt% to 1 wt%, 0.6 wt% to 1 wt%, 0.7 wt% to 1 wt%, 0.8 wt% to 1 wt%, 0.9 wt% to 1 wt%, 0.2 wt% to 0.9 wt%, or 0.3 wt% to 0.8 wt%. The antioxidant according to one embodiment can maintain excellent film properties within the above ranges.

[0060] If the antioxidant is less than 0.5 weight%, it is difficult to expect the effect of the antioxidant, and if it exceeds 1 weight%, it may have a negative effect on the physical properties of the coating film due to excessive addition.

[0061] Depending on the implementation, various types of additives may be further used. For example, dispersants to enhance the dispersion effect of polyester resin and pigment, hydrophilic or hydrophobic fumed silica to prevent flow during melting of the paint and to improve the fluidity of the paint powder, polyethylene, polypropylene, polyamide wax, acrylic additives, castor oil, thermoplastic resin, etc. may be further used, and various known types of additives in addition to the types mentioned above may also be applied.

[0062] In one embodiment, the inorganic filler may include at least one selected from the group consisting of barium sulfate, calcium carbonate, silica, magnesium hydroxide, aluminum hydroxide, titanium dioxide, clay, alumina, talc, and mixtures thereof.

[0063] In one embodiment, the content of the inorganic filler may be applied as about 1 wt% or more to about 15 wt% or less. As a specific example, the content of the inorganic filler may be applied as 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, or 15 wt%. Additionally, the content of the inorganic filler may be in a range of one or more of the above figures and one or less of the above figures.

[0064] For example, the content range of the inorganic filler may be set to 1 wt% to 15 wt%, 1 wt% to 14 wt%, 1 wt% to 13 wt%, 1 wt% to 12 wt%, 1 wt% to 11 wt%, 1 wt% to 10 wt%, or 1 wt% to 9 wt%. The inorganic filler according to one embodiment can maintain excellent coating film properties within the above ranges.

[0065] If the inorganic filler is less than 1 weight%, sagging may occur in the coating film and the hiding power of the coating film may decrease, and if it exceeds 15 weight%, the melt viscosity of the powder coating increases, which lowers the appearance and gloss of the coating film, and as the content of the polyester resin decreases relatively, the physical properties of the coating film may decrease.

[0066] In one embodiment, the pigment may be used as a coloring pigment to impart various colors to the powder coating composition. According to one embodiment, the pigment may include at least one of titanium dioxide, bismuth vanadate, cyanine green, carbon black, red iron oxide, and yellow iron oxide.

[0067] In one embodiment, the pigment content may be applied in an amount of about 1 weight% or more to about 40 weight% or less. As a specific example, the pigment content may be applied as 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, 20 wt%, 21 wt%, 22 wt%, 23 wt%, 24 wt%, 25 wt%, 26 wt%, 27 wt%, 28 wt%, 29 wt%, 30 wt%, 31 wt%, 32 wt%, 33 wt%, 34 wt%, 35 wt%, 36 wt%, 37 wt%, 38 wt%, 39 wt%, or 40 wt%. In addition, the pigment content may be in the range of one or more of the above values ​​and one or less of the above values.

[0068] For example, the pigment content range may be set to 1 wt% to 40 wt%, 10 wt% to 40 wt%, 20 wt% to 40 wt%, 30 wt% to 40 wt%, 1 wt% to 10 wt%, 2 wt% to 9 wt%, or 3 wt% to 8 wt%. The pigment according to one embodiment can maintain excellent film properties within the above ranges.

[0069] If the pigment content is less than 1 weight%, the hiding power decreases, and if it exceeds 40 weight%, the oil absorption increases, which may cause an orange peel effect on the appearance of the coating film.

[0070] In one embodiment, the glass transition temperature of the powder coating composition may be about 55°C or higher to about 90°C or lower. As a specific example, the glass transition temperature of the powder coating composition may be applied as 55°C, 56°C, 57°C, 58°C, 59°C, 60°C, 61°C, 62°C, 63°C, 64°C, 65°C, 66°C, 67°C, 68°C, 69°C, 70°C, 71°C, 72°C, 73°C, 74°C, 75°C, 76°C, 77°C, 78°C, 79°C, 80°C, 81°C, 82°C, 83°C, 84°C, 85°C, 86°C, 87°C, 88°C, 89°C, or 90°C. In addition, the glass transition temperature of the powder coating composition may be in a range of one or more of the above values ​​and one or less of the above values.

[0071] For example, the glass transition temperature range of the powder coating composition may be set to a range of 55°C to 90°C, 60°C to 90°C, 65°C to 90°C, 70°C to 90°C, 75°C to 90°C, 80°C to 90°C, 85°C to 90°C, or 55°C to 80°C. The glass transition temperature of the powder coating composition according to one embodiment can maintain the physical properties of the coating at an excellent level within the above ranges.

[0072] If the glass transition temperature of the powder coating composition is less than 55°C, the storage stability of the coating may be reduced, and if it exceeds 90°C, the wetting ability of the coating may be reduced, and an orange peel phenomenon may occur on the coating film.

[0073] A method for manufacturing a powder coating composition according to one embodiment of the present invention will be described following the flowchart shown in FIG. 1, but for convenience, the description will be given in sequence.

[0074] 1. Mixing step <s101>< / s101>

[0075] In this step, a mixture can be prepared by mixing a polyester resin made using recycled raw materials, a curing agent, an additive, an inorganic filler, and a pigment. For example, the polyester resin, curing agent, additive, inorganic filler, and pigment, measured according to the input amount of each component, can be fed into a mixing device and mixed at 1000 to 2000 rpm for 5 to 7 minutes.

[0076] 2. Melt dispersion step <s102>< / s102>

[0077] In this step, the mixture mixed in step S101 can be melted and dispersed to create a dispersion. For example, the mixture can be fed into a melting and dispersion device and melted and dispersed at a temperature of 90 to 110°C for a certain period of time to create a dispersion.

[0078] 3. Cooling stage <s103>< / s103>

[0079] In this step, the dispersion can be solidified into a chip form by cooling it for a certain period of time.

[0080] 4. Grinding step <s104>< / s104>

[0081] In this step, the dispersion solidified in step S103 can be ground to a certain size. For example, in this step, the dispersion can be ground so that the average particle size is about 30 μm or more to about 50 μm or less.

[0082] 5. Filtering step <s105>< / s105>

[0083] In this step, the particles crushed in step S104 can be filtered to separate powder of a certain size. For example, in this step, the powder can be separated using a vibrating classifier having sieves of about 60 mesh or more to about 150 mesh or less.

[0084] The present invention will be explained in more detail below through specific embodiments and experimental examples. The following embodiments and experimental examples are merely illustrative examples to aid in understanding the present invention, and therefore the scope of the present invention is not limited thereto.

[0085] Preparation of powder coating composition

[0086] <Example 1 and Comparative Examples 1, 2, and 3>

[0087] Polyester resin, curing agent, leveling agent, anti-foaming agent, inorganic filler, and pigment, weighed according to the input amounts (units are weight%) of each component listed in Table 1 below, were fed into a mixing device and mixed at 1000 rpm for 5 minutes to create a mixture. Afterward, the mixture was fed into a melt dispersion device and melted and dispersed at a temperature of 100°C for 1 hour to create a dispersion. Subsequently, the dispersion was solidified by cooling for 1 hour, and the solidified dispersion was ground to have an average particle size of 30 to 50 μm. The ground particles were fed into a vibrating classifier, and the powder passing through a sieve of 60 to 150 mesh was selected to complete the manufacture of the powder coating.

[0088] division Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 1 57 57 57 57 2 3 3 3 3 3 1 1 1 1 4 0.3 0.3 0.3 0.3 5 30 30 30 30 6 8.7 8.7 8.7 8.7 1: Example 1 - Polyester resin containing 10 wt% BHET (Product of ENTIS), Comparative Example 1 - Polyester resin not containing BHET (Product of ENTIS), Comparative Example 2 - Polyester resin containing 20 wt% BHET (Product of ENTIS), Comparative Example 3 - Polyester resin containing 50 wt% BHET (Product of ENTIS) 2: Curing agent - HAA (EMS "XL 552") 3: Leveling agent (BYK "BYK 368P") 4: Anti-foaming agent - Benzoin (MIWON "Benzoin") 5: Coloring pigment (BASF "Yellow L 1130") 6: Inorganic filler (OMYA "Omyacarb 1")

[0089] <Examples 2, 3 and Comparative Examples 4, 5, 6, 7>

[0090] Polyester resin, curing agent, leveling agent, anti-foaming agent, heat resistance improver, flexibility improver, antioxidant, inorganic filler, and pigment were weighed according to the input amounts (units are weight%) of each component listed in Table 2 below, and a mixture was prepared by mixing at 1000 rpm for 5 minutes. Afterward, the mixture was introduced into a melt dispersion device and melted and dispersed at a temperature of 100°C for 1 hour to create a dispersion. Subsequently, the dispersion was solidified by cooling for 1 hour, and the solidified dispersion was ground to have an average particle size of 30 to 50 μm. The ground particles were introduced into a vibrating classifier, and the powder passing through a sieve of 60 to 150 mesh was selected to complete the manufacture of the powder coating.

[0091] division Comparative Example 4 Comparative Example 5 Example 2 Example 3 Comparative Example 6 Comparative Example 7 1 57 57 57 57 57 57 2 3 3 3 3 3 3 3 1 1 1 1 1 1 4 0.3 0.3 0.3 0.3 0.3 0.3 5 - 0.5 0.5 0.5 0.5 0.5 6 - - 2 2 5.3 2 7 - - - 0.5 - 3.3 8 30 30 30 30 30 30 9 8.7 8.2 6.2 5.7 2.9 2.9 1: Polyester resin containing 20 wt% BHET (Product of ENTIS) 2: Curing agent - HAA (EMS "XL 552") 3: Leveling agent (BYK "BYK 368P") 4: Anti-foaming agent - Benzoin (MIWON "Benzoin") 5: Heat resistance improver - Fatty acid ester additive (LITMUS "REACT GL-120") 6: Flexibility improver - Copolyester additive (EMS "Grilltex D 2132") 7: Antioxidant - Bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite (SHANDONG LINYI SUNNY WEALT H CHEMICALS "SONOX626") 8: Color pigment (BASF "Yellow L 1130") 9: Inorganic filler (OMYA "Omyacarb 1")

[0092] <Examples 4, 5 and Comparative Examples 8, 9>

[0093] Polyester resin, curing agent, leveling agent, anti-foaming agent, heat resistance improver, flexibility improver, antioxidant, inorganic filler, and pigment were weighed according to the input amounts (units are weight%) of each component listed in Table 3 below, and a mixture was prepared by mixing at 1000 rpm for 5 minutes. Afterward, the mixture was introduced into a melt dispersion device and melted and dispersed at a temperature of 100°C for 1 hour to create a dispersion. Subsequently, the dispersion was solidified by cooling for 1 hour, and the solidified dispersion was ground to have an average particle size of 30 to 50 μm. The ground particles were introduced into a vibrating classifier, and the powder passing through a sieve of 60 to 150 mesh was selected to complete the manufacture of the powder coating.

[0094] division Example 4 Example 5 Comparative Example 8 Comparative Example 9 1 57 57 57 57 2 3 3 3 3 3 1 1 1 1 4 0.2 0.2 0.2 0.2 5 0.5 0.5 0.5 0.5 6 2 3 0 5.3 7 - - - - 8 30 30 30 30 9 6.3 5.3 8.3 3 1: Polyester resin containing 20 wt% BHET (Product of ENTIS) 2: Curing agent - HAA (EMS "XL 552") 3: Leveling agent (BYK "BYK 368P") 4: Anti-foaming agent - Benzoin (MIWON "Benzoin") 5: Heat resistance improver - Fatty acid ester additive (LITMUS "REACT GL-120") 6: Flexibility improver - Copolyester additive (EMS "Grilltex D 2132") 7: Antioxidant - Bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite (SHANDONG LINYI SUNNY WEALT H CHEMICALS "SONOX626") 8: Color pigment (BASF "Yellow L 1130") 9: Inorganic filler (OMYA "Omyacarb 1")

[0095] <Examples 6, 7, 8 and Comparative Example 10>

[0096] Polyester resin, curing agent, leveling agent, anti-foaming agent, heat resistance improver, flexibility improver, antioxidant, inorganic filler, and pigment were weighed according to the input amounts (units are weight%) of each component listed in Table 4 below, and a mixture was prepared by mixing at 1000 rpm for 5 minutes. Afterward, the mixture was introduced into a melt dispersion device and melted and dispersed at a temperature of 100°C for 1 hour to create a dispersion. Subsequently, the dispersion was solidified by cooling for 1 hour, and the solidified dispersion was ground to have an average particle size of 30 to 50 μm. The ground particles were introduced into a vibrating classifier, and the powder passing through a sieve of 60 to 150 mesh was selected to complete the manufacture of the powder coating.

[0097] division Example 6 Example 7 Example 8 Comparative Example 10 1 57 57 57 57 2 3 3 3 3 3 1 1 1 1 4 0.2 0.2 0.2 0.2 5 0.5 0.5 0.5 0.5 6 2 2 2 2 7 0.5 1 0 3.3 8 30 30 30 30 9 5.8 5.3 6.3 3 1: Polyester resin containing 20 wt% BHET (Product of ENTIS) 2: Curing agent - HAA (EMS "XL 552") 3: Leveling agent (BYK "BYK 368P") 4: Anti-foaming agent - Benzoin (MIWON "Benzoin") 5: Heat resistance improver - Fatty acid ester additive (LITMUS "REACT GL-120") 6: Flexibility improver - Copolyester additive (EMS "Grilltex D 2132") 7: Antioxidant - Bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite (SHANDONG LINYI SUNNY WEALT H CHEMICALS "SONOX626") 8: Color pigment (BASF "Yellow L 1130") 9: Inorganic filler (OMYA "Omyacarb 1")

[0098] Preparation of specimens according to each example and comparative example

[0099] A 0.6 mm thick cold-rolled steel sheet treated with shot blasting and zinc phosphate phosphating coating was coated with paint according to each example and comparative example, with a dry film thickness of 60 to 80 μm, and the steel sheet was cured at 180°C for 10 minutes based on the steel sheet temperature to prepare a specimen.

[0100] Evaluation of coating properties

[0101] The impact resistance, adhesion, hot water resistance, pencil hardness, heat resistance, and elongation of the coating film formed on the specimen were evaluated according to the method described in Table 5 below, and the results are described in Tables 6 to 9 below.

[0102] Impact resistance A weight of a specific weight is dropped from a certain height to visually determine whether cracks have occurred in the coating film, and the weight of the weight used and the drop height at the time when no cracks occurred in the coating film are recorded. Adhesion When 11 horizontal and 11 vertical lines were crossed with a knife at 1mm intervals on the coating film, and cellophane tape was applied to and then removed, the number of coating fragments attached to the surface of the steel plate and the number of coating fragments detached from the steel plate were checked (number of fragments attached to the steel plate before the test / number of fragments remaining on the steel plate after the test). Hot water resistance After placing the specimen in 100℃ water and leaving it for 1 hour, remove it and visually inspect the appearance to check for any blistering on the film. Then, measure the gloss of the film before and after the test using a gloss meter and record the gloss retention rate. Gloss retention rate (%) = Film gloss after test / Initial film gloss × 100 Pencil hardness Record the density symbol of the hardest pencil that does not damage the surface of the coating when a load of 1 kg is applied to the pencil and the coating is scratched at a 45° angle. heat resistance ΔE was measured using a colorimeter after leaving the specimen at 230℃ for 30 minutes. Xinjiang When a steel ball with a diameter of 20 mm is pushed perpendicularly to the coating at a speed of approximately 0.2 mm / sec, the cracks in the coating resulting from the deformation of the specimen are observed through a magnifying glass, and the value at which cracks begin to form in the coating is recorded.

[0103] division Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Impact resistance 1kg×50cm 1kg×50cm 500g×30cm - Adhesion 100 / 100 100 / 100 100 / 100 - Hot water resistance No swelling / 85% No swelling / 84% No swelling / 81% - Pencil hardness H H H - heat resistance 2.93 2.98 3.65 - Xinjiang 5mm 3mm 3mm -

[0104] Referring to the results in Table 6, it was confirmed that when the content of recycled raw materials was small, the physical properties could be improved by adding an anti-foaming agent, and as the content of recycled raw materials increased, it had a negative effect on the impact resistance, heat resistance, and elongation of the paint. Furthermore, when the coating film of Comparative Example 3, in which the content of recycled raw materials exceeded a certain level, was visually inspected, it was confirmed that the film was unsuitable for commercialization due to defects in the film's appearance, such as uneven thickness and irregularities like craters, so no further evaluation of physical properties was performed.

[0105] division Comparative Example 4 Comparative Example 5 Example 2 Example 3 Comparative Example 6 Comparative Example 7 Impact resistance 500g×30cm 500g×30cm 1kg×90cm 1kg×90cm 1kg×50cm 1kg×50cm Adhesion 100 / 100 100 / 100 100 / 100 100 / 100 100 / 100 100 / 100 Hot water resistance No swelling / 81% No swelling / 83% No swelling / 84% No swelling / 84% No swelling / 83% No swelling / 74% Pencil hardness H H H H HB H heat resistance 3.65 3.09 2.99 2.53 2.98 2.60 Xinjiang 3mm 3mm 7mm 7mm 7mm 7mm

[0106] Referring to the results in Table 7, it was confirmed that the degradation of paint properties caused by recycled raw materials can be improved by adding flexibility improvers and antioxidants.

[0107] division Example 4 Example 5 Comparative Example 8 Comparative Example 9 Impact resistance 1kg×90cm 1kg×90cm 500g×30cm 1kg×50cm Adhesion 100 / 100 100 / 100 100 / 100 100 / 100 Hot water resistance No swelling / 84% No swelling / 84% No swelling / 83% No swelling / 83% Pencil hardness H H H HB heat resistance 2.99 2.99 3.09 2.98 Xinjiang 7mm 7mm 3mm 7mm

[0108] Referring to the results in Table 8, it was confirmed that the physical properties of Examples 4 and 5, which contain 2-3 weight% of a flexibility improver, are relatively superior to those of the comparative examples.

[0109] division Example 6 Example 7 Example 8 Comparative Example 10 Impact resistance 1kg×90cm 1kg×90cm 1kg×90cm 1kg×50cm Adhesion 100 / 100 100 / 100 100 / 100 100 / 100 Hot water resistance No swelling / 84% No swelling / 85% No swelling / 84% No swelling / 74% Pencil hardness H H H H heat resistance 2.53 2.48 2.99 2.60 Xinjiang 7mm 7mm 7mm 7mm

[0110] Referring to the results in Table 9, it was confirmed that the physical properties of Examples 6 and 7, which contain 0.5 to 1 weight percent of antioxidant, are relatively superior compared to paints that do not contain or contain an excess amount of antioxidant.

[0111] As described above, according to various embodiments of the present invention, a powder coating composition can be manufactured using a polyester resin made from recycled raw materials, making it environmentally friendly, and it has the advantage of having generally excellent physical properties of the coating film formed by the powder coating (e.g., impact resistance, adhesion, hot water resistance, pencil hardness, heat resistance, elongation, etc.).

[0112] Furthermore, according to various embodiments of the present invention, since powder coatings are manufactured using recycled raw materials, they offer effects such as carbon reduction and improved environmental pollution compared to conventional coatings, and exhibit excellent heat resistance and mechanical properties along with eco-friendly characteristics. The powder coating composition according to various embodiments of the present invention has strengths in terms of eco-friendliness and can replace conventionally used polyester resins, as mechanical and chemical properties can be realized that are similar to or superior to those of conventional coatings despite the use of recycled raw materials.

[0113] Furthermore, according to various embodiments of the present invention, by using recycled PET raw materials, it is possible to reduce marine or land environmental pollution caused by waste plastics and to reduce carbon emissions through the reuse of waste plastics.

[0114] In addition, conventional powder coatings using PET recycled in flake form are merely physical recycling methods, and since the possibility of recycling is determined based on the degree of contamination of the waste, recycling large quantities is limited. However, when polyester is recycled using a chemical extraction method, raw materials obtained through chemical reactions are used, allowing for freer use compared to physical recycling methods where the amount used is limited by the contamination status of the collected PET. Furthermore, among recycling methods, this method is economical and environmentally desirable. In various embodiments of the present invention, by applying a polyester resin containing recycled raw materials in an amount of more than 0% to 50% by weight compared to conventional powder coatings, a significant carbon reduction effect is achieved, and the material can be utilized as an eco-friendly powder coating.

[0115] As explained above, the specific description of the present invention has been provided through embodiments, but since the above-described embodiments are merely preferred examples of the present invention, the present invention should not be understood as being limited only to the above embodiments, and the scope of the rights of the present invention should be understood as the claims set forth below and their equivalents.

Claims

Claim 1 A powder coating composition comprising recycled raw materials, characterized by comprising 50-70 wt% of a polyester resin made using recycled raw materials; 2-5 wt% of a curing agent; 0.01-10 wt% of an additive; 1-15 wt% of an inorganic filler; and 1-40 wt% of a pigment; wherein the additive comprises 1-5 wt% of a leveling agent, 0.1-0.5 wt% of an anti-foaming agent, 0.3-0.7 wt% of a heat resistance improver, 2-3 wt% of a flexibility improver, and 0.5-1 wt% of an antioxidant, wherein the flexibility improver comprises a copolyester-based additive, and the antioxidant comprises bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite. Claim 2 A powder coating composition comprising a recycled raw material according to claim 1, characterized in that the recycled raw material is chemically extracted from waste polyester through at least one of the decomposition methods of glycol addition decomposition, methanol addition decomposition, and hydrolysis. Claim 3 A powder coating composition comprising a recycled raw material according to claim 1, characterized in that the recycled raw material comprises at least one of bis-2-hydroxyethyl terephthalate, dimethyl terephthalate, monoethylene glycol, and terephthalic acid. Claim 4 delete Claim 5 A powder coating composition comprising recycled raw materials, characterized in that, in claim 1, the curing agent comprises at least one of a β-hydroxyalkylamide-based curing agent, a triglycidyl isocyanurate-based curing agent, and a glycidyl ester-based curing agent. Claim 6 A powder paint composition comprising recycled raw materials, characterized in that, in claim 1, the glass transition temperature of the powder paint composition is 55 to 90°C. Claim 7 delete Claim 8 A powder coating composition comprising a recycled raw material according to claim 1, characterized in that the recycled raw material is included in the polyester resin in an amount of more than 0 to 50 weight percent or less based on the total weight of the polyester resin. Claim 9 A method for manufacturing a powder coating composition comprising recycled raw materials, comprising: a mixing step of mixing a polyester resin made using recycled raw materials; a curing agent; an additive; an inorganic filler; and a pigment to form a mixture; a melt dispersion step of melting and dispersing the mixture to form a dispersion; a cooling step of cooling the dispersion; and a grinding step of grinding the cooled dispersion; wherein the recycled raw materials are chemically extracted from waste polyester, and in the mixing step, the additives comprise 1 to 5 weight% of a leveling agent, 0.1 to 0.5 weight% of an anti-foaming agent, 0.3 to 0.7 weight% of a heat resistance improver, 2 to 3 weight% of a flexibility improver, and 0.5 to 1 weight% of an antioxidant, wherein the flexibility improver comprises a copolyester-based additive, and the antioxidant comprises bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite.

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