Polyester resin composition, method for preparing the same, and molded article manufactured using the same

Abstract

The present invention relates to a polyester resin composition and a molded article manufactured using the same. According to the present invention, the polyester resin composition can provide similar mechanical properties, particularly injection properties, to inexpensive PBT materials, and satisfy eco-friendliness and heat resistance. Due to these advantages, the polyester resin composition can be applied to a motor insulator part for a refrigerator used inside, which requires excellent dimensional stability, heat resistance, and injection properties.

Description

Technical Field

[0001] [Cross-reference to related applications]

[0002] This application claims priority to Korean Patent Application No. 10-2022-0063834, filed with the Korean Intellectual Property Office on May 25, 2022, the disclosure of which is incorporated herein by reference.

[0003] This invention relates to a polyester resin composition, a method for preparing the same, and molded articles made using the same. More specifically, this invention relates to a polyester resin composition and a molded article comprising the polyester resin composition, which, even when the polyester resin composition contains inexpensive PBT material, exhibits excellent mechanical properties, particularly excellent injection molding performance, and meets the requirements of eco-friendliness and heat resistance. Due to these characteristics, the polyester resin composition and the molded article are suitable for internal motor insulation components. Background Technology

[0004] Polybutylene terephthalate resin (hereinafter referred to as "PBT") has excellent mechanical and electrical properties as well as excellent physical and chemical properties, and is used in many fields such as automobiles, electronic and electrical devices and office equipment.

[0005] PBT is suitable for various injection molding processes due to its low cost and easily controllable physical properties. To improve the physical properties of PBT, reinforced resin compositions prepared by adding inorganic fillers such as glass fiber, carbon fiber, talc, or clay are widely used. However, when using reinforcing materials composed of inorganic fillers, low filler content may not improve mechanical properties or heat resistance, or the increased mass of the prepared resin composition due to its high specific gravity may cause problems.

[0006] Various plastic products made from polyethylene terephthalate resin (hereinafter referred to as "PBT") are discarded after use. Recently, methods for utilizing this waste plastic have attracted attention.

[0007] Like PBT, PET is classified as a polyester resin. However, due to its higher crystallization temperature than PBT, PET exhibits poor moldability and relatively unstable mechanical properties, such as dimensional instability.

[0008] Therefore, when PET is added, the physical properties are more difficult to control compared to reinforced resin compositions prepared by adding inorganic fillers such as glass fibers to conventional PBT. Thus, there is a need to develop technologies that can address these issues.

[0009] On the other hand, technologies for producing polyester resin from recycled mineral water bottles are being researched. Currently, approximately 2.5 billion PET bottles (100,000 tons) are used and discarded. However, there are only a few ways to recycle waste PET bottles. For example, recycling waste PET bottles includes reusing PET bottles as beverage bottles, and reusing PET bottles as fiber or packaging materials.

[0010] Therefore, when using waste mineral water bottles to prepare compositions with excellent mechanical properties, such as heat resistance, injection performance and dimensional stability, environmental pollution can be prevented.

[0011] [Related Technical Documents]

[0012] [Patent Literature]

[0013] KR 2019-027115 A. Summary of the Invention

[0014] Technical issues

[0015] Therefore, the present invention addresses the aforementioned problems, and one object of the present invention is to provide a polyester resin composition that, even when comprising inexpensive PBT material, possesses excellent mechanical properties, particularly excellent injection molding performance, and also satisfies eco-friendliness and heat resistance. Due to these characteristics, the polyester resin composition is suitable for internal motor insulation components.

[0016] Another object of the present invention is to provide a method for preparing the polyester resin composition.

[0017] Another object of the present invention is to provide a molded article manufactured using the said polyester resin composition.

[0018] The above and other objectives can be achieved by the invention described below.

[0019] Technical solution

[0020] According to one aspect of the present invention, a polyester resin composition is provided, comprising:

[0021] 26.7% to 54% by weight of polybutylene terephthalate resin;

[0022] 10% to 37.5% by weight of polyethylene terephthalate resin; and 10% to 43% by weight of glass fiber.

[0023] The glass fiber contains 35.6% to 60% by weight or 13% to 24% by weight of calcium oxide.

[0024] The weight ratio of polybutylene terephthalate (PBT) to polyethylene terephthalate (PET) (PBT:PET) can be from 1:0.7 to 1:3.

[0025] Polyethylene terephthalate resin can be a resin obtained by processing mineral water bottles.

[0026] Resin obtained from processing mineral water bottles can be obtained by flake processing and chip molding of waste mineral water bottle granules.

[0027] The resin obtained by processing waste mineral water bottles can be recycled into resin through sheet processing.

[0028] The intrinsic viscosity of polyethylene terephthalate resin, as measured according to ASTM D2857, is 0.5 to 1.0.

[0029] The intrinsic viscosity of polybutylene terephthalate resin, as measured according to ASTM D2857, is 0.6 to 1.8.

[0030] Based on the total weight of 100% by weight of the components constituting the composition, glass fibers containing 35.6% to 60% by weight of calcium oxide may be included in an amount of 10% to 31% by weight.

[0031] Based on the total weight of 100% by weight of the components constituting the composition, glass fibers containing 13% to 24% by weight of calcium oxide may be included in an amount of 15% to 35% by weight.

[0032] Based on the total weight of 100% by weight of the components constituting the composition, the polyester resin composition may contain 0.1% to 10% by weight of one or more additives selected from lubricants, transesterification inhibitors, antioxidants, heat stabilizers, flame retardants, flame retardant additives, colorants, release agents, pigments, dyes, antistatic agents, antibacterial agents, processing aids, metal passivators, smoke inhibitors, fluorinated anti-drip agents, anti-friction agents, anti-wear agents, and coupling agents.

[0033] The polyester resin composition can be a polyester resin composition for use in motor insulation.

[0034] The polyester resin composition, measured according to ASTM D790 using 1 / 8-inch molded article specimens at a span of 50 mm and a speed of 1.3 mm / min, exhibits a flexural strength of 1,700 kgf / cm. 2 The flexural modulus can be 70,000 kgf / cm. 2 above.

[0035] The polyester resin composition has a cantilever beam impact strength of ≥7.0 kgf·cm / cm measured using a notched specimen at 23°C according to ASTM D256, and a heat distortion temperature of ≥200°C measured under a load of 18.6 kg according to ASTM D648.

[0036] According to another aspect of the present invention, a polyester resin composition is provided, comprising:

[0037] 26.7% to 54% by weight of polybutylene terephthalate resin;

[0038] 10% to 37.5% by weight of recycled resin; and 10% to 43% by weight of glass fiber,

[0039] The glass fiber contains 35.6% to 60% by weight or 13% to 24% by weight of calcium oxide.

[0040] Regenerated resin can be obtained by slicing and molding waste polyester mineral water bottle granules with an intrinsic viscosity of 0.5 dl / g to 1.0 dl / g.

[0041] According to another aspect of the present invention, a method for preparing a polyester resin composition is provided, comprising:

[0042] Melting-kneading and extrusion of 26.7% to 54% by weight of polybutylene terephthalate resin, 10% to 37.5% by weight of polyethylene terephthalate resin, and 10% to 43% by weight of glass fiber.

[0043] The glass fiber contains 35.6% to 60% by weight or 13% to 24% by weight of calcium oxide.

[0044] Based on the total weight of 100% by weight of the components constituting the composition, glass fibers containing 35.6% to 60% by weight of calcium oxide may be included in an amount of 10% to 31% by weight.

[0045] Based on the total weight of 100% by weight of the components constituting the composition, glass fibers containing 13% to 24% by weight of calcium oxide may be included in an amount of 15% to 35% by weight.

[0046] According to another aspect of the present invention, a method for preparing a polyester resin composition is provided, comprising:

[0047] Waste polyester mineral water bottles with an intrinsic viscosity of 0.5 dl / g to 1.0 dl / g are sheeted to obtain waste mineral water bottle granules, and recycled molded products are manufactured by slicing the obtained waste mineral water bottle granules.

[0048] The product consists of 10% to 37.5% by weight of recycled molded articles, 26.7% to 54% by weight of polybutylene terephthalate resin, and 10% to 43% by weight of glass fiber, obtained by melt-kneading and extrusion.

[0049] The glass fiber contains 35.6% to 60% by weight or 13% to 24% by weight of calcium oxide.

[0050] Based on the total weight of 100% by weight of the components constituting the composition, glass fibers containing 35.6% to 60% by weight of calcium oxide may be included in an amount of 10% to 31% by weight.

[0051] Based on the total weight of 100% by weight of the components constituting the composition, glass fibers containing 13% to 24% by weight of calcium oxide may be included in an amount of 15% to 35% by weight.

[0052] Recycled products can be produced by sorting waste mineral water bottles made of polyethylene terephthalate with an intrinsic viscosity (IV) of 0.5 dl / g to 1.0 dl / g into colored and transparent bottles, washing the bottles, crushing the bottles, washing and drying the crushed bottles, processing them into sheets, and then extruding them.

[0053] According to another aspect of the present invention, a molded article manufactured by molding the above-described polyester resin composition is provided.

[0054] This molded product can be an insulator component for internal use in motors.

[0055] Beneficial effects

[0056] Although the polyester resin composition according to one embodiment of the present invention comprises a thermoplastic resin composition reinforced with polybutylene terephthalate resin; and a polyethylene terephthalate resin having a higher crystallization temperature than polybutylene terephthalate resin and relatively stable mechanical properties such as dimensional stability, the polyester resin composition can provide mechanical properties similar to those of conventional materials, particularly injection molding properties, and can improve eco-friendliness and heat resistance.

[0057] Therefore, the polyester resin composition and molded article according to the present invention can be applied to various internal components. As a preferred example, the polyester resin composition and molded article can be applied to motor insulation components used inside refrigerators that require excellent heat resistance and moldability.

[0058] Figure Labels

[0059] Figure 1This is a process flow diagram illustrating the manufacturing process of recycled molded articles made from waste mineral water bottles used in the embodiments described below.

[0060] Figure 2 Image including PET resin (left) and according to Figure 1 The image shown is of the resin obtained by processing waste mineral water bottles (right). Here, PET resin refers to virgin resin prepared by the DMT method.

[0061] Here, the DMT method refers to the transesterification reaction of dimethyl terephthalate (DMT) with ethylene glycol (EG), which is known in the art. Detailed Implementation Plan

[0062] The invention will be described in more detail below to aid in understanding it.

[0063] The terms and words used in this specification and the appended claims should not be construed as limited to their ordinary or dictionary meanings, but should be understood as having meanings and concepts that match the technical concept of the invention in order to best describe the invention.

[0064] In this invention, it should be understood that, unless otherwise stated, when a part “comprises” any element, that part may include other elements without excluding other elements.

[0065] As used herein, unless otherwise specified, the term “content” may mean “weight %”.

[0066] The inventors conducted research on developing a material for an insulator component of a motor inside a refrigerator. As a result of this research, the inventors confirmed that when preparing a material reinforced with polyethylene terephthalate (PET) resin, when PET resin with a relatively high crystallization temperature and unstable mechanical properties such as dimensional stability is included in a predetermined amount, and the composition of the reinforcing material is also adjusted, similar mechanical properties to conventional materials can be provided, particularly injection molding properties, while improving both eco-friendliness and heat resistance. Based on these results, the inventors conducted further research to complete this invention.

[0067] According to one embodiment of the present invention, a polyester resin composition comprising polybutylene terephthalate resin, polyethylene terephthalate resin and glass fiber can be provided.

[0068] By adjusting the weight ratio of polybutylene terephthalate resin to polyethylene terephthalate resin, the polyester resin composition according to one embodiment of the present invention can provide mechanical properties, particularly injection performance, similar to conventional materials, while satisfying both eco-friendliness and heat resistance.

[0069] The polyester resin composition may also contain a nucleating agent.

[0070] The components constituting the polyester resin composition of the present invention are described in detail below.

[0071] Polybutylene terephthalate resin

[0072] According to one embodiment of the invention, the polyester resin composition comprises polybutylene terephthalate resin. As described above, by including polybutylene terephthalate resin in the polyester resin composition, the physical properties required for internal motor insulation components can be achieved.

[0073] In one embodiment of the present invention, as a polybutylene terephthalate resin, a polybutylene terephthalate resin obtained by direct esterification or transesterification polycondensation of 1,4-butanediol and terephthalic acid or dimethyl terephthalate can be used.

[0074] Polybutylene terephthalate (PBT) resin can have repeating units represented by the following chemical formula 1.

[0075] [Chemical Formula 1]

[0076]

[0077] In chemical formula 1, n represents an average degree of polymerization of 50 to 200.

[0078] In one embodiment of the present invention, in order to increase the impact strength of the polyester resin composition, a copolymer obtained by copolymerizing polybutylene terephthalate resin with impact-improving compounds such as polytetramethylene glycol, polyethylene glycol, polypropylene glycol, aliphatic polyester or aliphatic polyamide, or a modified polybutylene terephthalate resin obtained by mixing polybutylene terephthalate resin with impact-improving compounds can be used.

[0079] In one embodiment of the invention, for example, the intrinsic viscosity (η) of the polybutylene terephthalate resin, measured according to ASTM D2857, can be from 0.6 dl / g to 1.8 dl / g, from 0.7 dl / g to 1.3 dl / g, or from 0.9 dl / g to 1.3 dl / g. When the intrinsic viscosity of the polybutylene terephthalate resin meets this range, a polyester resin composition with an excellent balance of physical properties between mechanical and processability properties can be obtained.

[0080] The intrinsic viscosity (η) can be measured using an Ubbelohde viscometer by dissolving the sample in dichloromethane and obtaining the filtrate at 20°C.

[0081] For example, the weight-average molecular weight of polybutylene terephthalate resin can be from 10,000 g / mol to 80,000 g / mol, 20,000 g / mol to 100,000 g / mol, 30,000 g / mol to 90,000 g / mol, 40,000 g / mol to 80,000 g / mol, or 50,000 g / mol to 70,000 g / mol. Within this range, mechanical properties can be improved.

[0082] When measuring the weight-average molecular weight, a 1% by weight sample was prepared by placing tetrahydrofuran (THF) and the compound in a 1 ml glass vial. After filtering the standard sample (polystyrene) and the sample through a filter (pore size: 0.45 μm), the filtered sample was injected into a GPC injector. The molecular weight and molecular weight distribution of the compound were then obtained by comparing the elution time of the sample with the calibration curve of the standard sample. An Infinity II 1260 (Agilient Co.) was used as the measuring instrument, with a flow rate set to 1.00 mL / min and a column temperature set to 40.0 °C.

[0083] In one embodiment of the invention, for example, the content of polybutylene terephthalate resin may be 26.7% to 54% by weight, 27% to 50% by weight, 27% to 30% by weight, 30% to 54% by weight, or 30% to 49% by weight, based on the total weight of 100% by weight of the components constituting the composition. When polybutylene terephthalate resin is contained in amounts less than these ranges, problems such as increased cycle time may occur due to a decrease in the solidification rate during injection molding. When polybutylene terephthalate resin is contained in amounts exceeding these ranges, injection performance may be poor.

[0084] As a method for preparing polybutylene terephthalate resin, polymerization methods commonly used in the technical field to which this invention pertains can be used without particular limitation. When a commercially available polybutylene terephthalate resin meets the definition of polybutylene terephthalate resin according to this invention, the commercially available polybutylene terephthalate resin can be used in this invention.

[0085] polyethylene terephthalate resin

[0086] According to one embodiment of the invention, the polyester resin composition comprises polyethylene terephthalate resin. As described above, by including polyethylene terephthalate resin in the polyester resin composition, the physical properties required for motor insulation components used internally can be achieved.

[0087] According to one embodiment of the present invention, conventional polyethylene terephthalate resin can be used as polyethylene terephthalate resin without particular limitation.

[0088] Polyethylene terephthalate resins can have repeating units represented by the following chemical formula 2 as their basic structure.

[0089] [Chemical Formula 2]

[0090]

[0091] In the chemical formula, n′ represents an average degree of polymerization of 40 to 160.

[0092] In one embodiment of the invention, to increase the impact strength of the polyester resin composition, a copolymer obtained by copolymerizing polyethylene terephthalate resin with an impact-improving compound, such as polytetramethylene glycol, polyethylene glycol, polypropylene glycol, aliphatic polyester, or aliphatic polyamide, a modified polyethylene terephthalate resin obtained by mixing polyethylene terephthalate resin with an impact-improving compound, or a copolymer-polyethylene terephthalate resin polymer containing an impact-improving compound or an eco-friendly compound as a comonomer can be used. For example, the comonomer can be 1,4-cyclohexanediol or isophthalic acid.

[0093] In one embodiment of the invention, taking into account the processing and mechanical properties of polyethylene terephthalate (PET) resin, the PET resin can have an intrinsic viscosity (IV, η) of 0.5 dl / g to 1 dl / g, preferably 0.6 dl / g to 1.0 dl / g, as measured according to ASTM D2857. When the intrinsic viscosity of the PET resin is within this range, a polyester resin composition with improved injection molding properties can be obtained.

[0094] For example, the weight-average molecular weight of polyethylene terephthalate resin can be from 5,000 g / mol to 80,000 g / mol or from 10,000 g / mol to 60,000 g / mol. Within this range, hydrolysis resistance and injection deviation can be improved.

[0095] In one embodiment of the invention, the content of polyethylene terephthalate resin can be 10% to 37.5% by weight, 10% to 35% by weight, 15% to 37.5% by weight, or 15% to 25% by weight, based on the total weight of the polyester resin composition. Within this range, the mechanical properties of the polyester composition can be improved, and its injection performance can be excellent.

[0096] As a method for preparing polyethylene terephthalate resin, polymerization methods commonly used in the technical field to which this invention pertains can be used without particular limitation. When a commercially available polyethylene terephthalate resin meets the definition of polyethylene terephthalate resin of this invention, the present invention may use a commercially available polyethylene terephthalate resin.

[0097] As a specific example, as a polyethylene terephthalate resin, a resin obtained by processing waste mineral water bottles can be used.

[0098] The resin obtained by processing waste mineral water bottles is a resin containing polyethylene terephthalate, and it can be polyethylene terephthalate prepared by condensation polymerization of terephthalic acid and ethylene glycol, but the present invention is not limited thereto.

[0099] For example, in one embodiment of the invention, the recycled resin can be as described below. Figure 1 The process flow diagram shows the white or green slices obtained by processing PET bottles into thin sheets.

[0100] under Figure 1 This is a process flow diagram illustrating the process of preparing the recycled resin or polyethylene terephthalate resin used in the embodiments described below.

[0101] See below Figure 1 A sorting process is performed to classify waste mineral water bottles into colored and transparent bottles. In this case, sorting can be done visually, with green being the primary color.

[0102] Next, the bottles are pulverized using a cutting machine. Specifically, first, the bottles, weighing approximately 200 kg, are cleaned. Then, taking into account washing, drying, and flake processing, the bottles are preferably pulverized to a size of 3 mm to 5 mm, but the invention is not limited to this. Within this range, by increasing the surface area of ​​the pulverized PET flakes, the drying efficiency in the subsequent drying process can be improved, and a uniform reaction between the thickener and the pulverized flakes can be ensured.

[0103] Next, the pulverized flakes are further cleaned, then dried and sheeted.

[0104] Drying can be carried out after a pre-drying step, which involves removing moisture from the pulverized tablets and mixing the pulverized tablets with a thickener to obtain the PET reaction mixture.

[0105] In the pre-drying step, drying is carried out at 120°C to 140°C, so that the moisture content of the pulverized PET sheets is about 1,000 ppm, and the thickener and pulverized PET sheets are uniformly mixed to achieve a uniform reaction.

[0106] For example, in the pre-drying step, the sorted and pulverized PET flakes and thickener are placed in a friction dryer. The pulverized PET flakes are dried for about 2 hours at a dryer temperature of 140°C and a stirrer speed of 50 rpm, while high-temperature air at 120°C to 140°C is continuously passed through the dryer to make the moisture content of the pulverized PET flakes 1,000 ppm.

[0107] As a thickener, compounds that induce a thickening reaction without melting at dryer temperatures of approximately 140°C and 165°C (described later) can be used without restriction. As a specific example, carbodiimide thickeners can be used.

[0108] Carbodiimide thickeners are well-known compounds; examples include carbodiimides and polycarbodiimides. The amount of thickener is appropriately adjusted according to the intrinsic viscosity suitable for the desired product. For example, based on the total weight of PET, the thickener can be added in amounts from 0.25% to 0.75% by weight.

[0109] The dehumidification process is performed to prevent the hydrolysis of PET in the reaction mixture. Specifically, the dehumidification process involves drying and dehumidifying the PET reaction mixture to reduce the moisture content to less than 50 ppm, thereby obtaining dry PET.

[0110] According to the dehumidification process, the PET reaction mixture is placed in a drying hopper. Dehumidified hot air from a dehumidifier is injected into the hopper under conditions of a dryer temperature of 165°C, a dew point of -60°C to -40°C, and a residence time of approximately 5 hours for drying and dehumidification. This process is continued until the moisture content of the PET reaction mixture is below 50 ppm.

[0111] Thin sheets are processed at a thickness of approximately 5 mm using an optical thin sheet sorting machine.

[0112] Then, extrusion is performed in a temperature range of 200°C to 270°C to obtain granular slices.

[0113] Specifically, the extrusion is a process in which dry and dehumidified PET sheets with a water content of less than 50 ppm are mixed with a thickener, melt extruded at a melting temperature, and foreign matter is physically removed from the melt product to obtain a PET melt product.

[0114] Since the melting temperature of the additional thickener is lower than that of the aforementioned thickener, this thickener cannot be used because it melts at a dryer temperature of 140°C and a dryer temperature of 165°C in the process described below.

[0115] For reference, when additional thickeners and the aforementioned thickeners are added simultaneously, the thickeners melt in the dryer, thus eliminating the need for pre-drying and dehumidification processes. Therefore, the thickeners are added during the extrusion process where the PET reaction mixture is melted.

[0116] As an additional thickener, compounds known as oxazoline thickeners can be used. For example, oxazoline, 1,3-phenylenebisoxazoline, etc., can be used. For example, the thickener can be added in an amount of 0.1% to 0.75% by weight, based on the total weight of the PET melt product.

[0117] In addition, by appropriately adjusting the mixing ratio of the thickener in the extrusion process during the pre-drying step, recycled PET chips with a characteristic viscosity suitable for manufacturing the desired product can be obtained.

[0118] For example, according to the extrusion process, dry and dehumidified PET material with a moisture content of less than 50 ppm is introduced into the extruder along with the aforementioned additional thickener. Melt extrusion is carried out at a melting temperature of 275°C to 280°C and a maximum melting pressure of 110 bar. The molten extrudate is then passed through a 20-micron SUS filter under a vacuum of 10 mbar to remove foreign matter, thereby obtaining a high-purity PET melt product.

[0119] The PET melt product obtained through the extrusion process is cut while cooling to obtain specific types of PET chips.

[0120] According to the molding process, at a mold plate temperature of 320°C and a blade rotation speed of 3,200 rpm, the PET melt discharged from the filter is cut into spherical PET chips with a diameter of 2.8 mm by a granulator in circulating water at 90°C.

[0121] For reference, in the manufacturing process of recycled PET chips, the residual heat from the molding process is used to crystallize the surface of the PET chips, resulting in recycled PET chips with the desired intrinsic viscosity and high purity. Therefore, since the PET chips produced in the molding process must have residual heat above 140°C for surface crystallization, the molding temperature conditions must be appropriately controlled for crystallization.

[0122] In the recycled PET chip manufacturing process, the PET chips, formed into sheet shapes, become crystallizable as they pass through an in-line crystallizer equipped with a vibrating conveyor after a dwell time of approximately 15 minutes.

[0123] The reason for surface crystallization in recycled PET chips is to provide energy savings by eliminating the surface crystallization essential during the PET drying process when the PET chips are ultimately used as raw materials. When raw materials with uncrystallized surfaces are dried directly, they entangle and clump together, making them impossible to transfer or feed into the system.

[0124] If necessary, the obtained recycled PET chips are mixed with talc, coupling agent or glass fiber to obtain recycled resin.

[0125] Based on the total weight of the polyester resin composition, the resin content obtained by processing waste mineral water bottles can be from 10% to 37.5% by weight, 10% to 35% by weight, 15% to 37.5% by weight, or 15% to 25% by weight. Within this range, by controlling the content of recycled resin, the mechanical properties of the polyester composition can be improved, and a polyester resin composition with an excellent balance with injection molding properties can be obtained.

[0126] Fiberglass

[0127] In one embodiment of the invention, the physical properties of molded articles manufactured using the polyester resin composition can be improved by including glass fibers in the composition. Specifically, the tensile strength and flexural strength of the molded articles can be improved.

[0128] According to one embodiment of the invention, glass fiber can be used in combination with other inorganic fibers. For example, inorganic fibers may include one or more selected from carbon fiber; basalt fiber; and natural fibers such as kenaf or hemp.

[0129] In one embodiment of the present invention, the cross-section of the glass fiber can be circular, rectangular, elliptical, dumbbell-shaped, or rhomboid, and the average diameter of the glass fiber can be 7 μm to 20 μm or 7 μm to 15 μm, and the average length can be 2 mm to 6 mm or 3 mm to 6 mm. When the average diameter and average length meet the above ranges, an excellent balance between injection molding performance and physical properties can be achieved.

[0130] The average diameter and average length of glass fibers can be measured using methods commonly used in the art. For example, 30 strands of glass fibers can be observed using a scanning electron microscope (SEM), and the average value can be calculated based on the observation results.

[0131] Glass fibers can be treated with sizing agents during fiber manufacturing or post-processing. Examples of sizing agents include lubricants, coupling agents, and surfactants.

[0132] The lubricant is primarily used to form good strands, and the coupling agent serves to achieve good adhesion between the glass fiber and the polybutylene terephthalate (PET) or polyethylene terephthalate (PET) resin. When the types of PET, PET, and glass fiber are appropriately selected and used, the polyester resin composition can be endowed with excellent physical properties.

[0133] Coupling agents can be applied directly to glass fibers or added to polybutylene terephthalate (PET) or polyethylene terephthalate (PET) resins. To fully utilize the performance of the coupling agent, its content can be appropriately selected. For example, based on 100% by weight of the total weight of glass fibers (glass fiber + coupling agent), the coupling agent can be included in amounts from 0.1% to 10% by weight, 0.1% to 5% by weight, or 0.1% to 3% by weight.

[0134] Examples of coupling agents include amine coupling agents; acrylic coupling agents; and silane coupling agents, such as γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)γ-aminopropyltriethoxysilane, γ-methacryloyloxypropyltriethoxysilane, γ-glycidyl etheroxypropyltrimethoxysilane, and β(3,4-epoxyethyl)γ-aminopropyltrimethoxysilane.

[0135] In particular, in order to obtain rigidity and mechanical properties, the glass fiber of the present invention preferably contains a predetermined amount of calcium oxide.

[0136] For example, calcium oxide can be included in glass fibers at a high content of 35.6% to 60% by weight, or at a low content of 13% to 24% by weight.

[0137] For reference, as shown in Comparative Examples 1 to 3, which will be described below, when calcium oxide is contained in an amount greater than 24% by weight and less than 35.6% by weight, for example, in an amount of 25% to 35% by weight, the mechanical properties include poor cantilever beam impact strength.

[0138] As a specific example, when the glass fiber contains a high content of calcium oxide, the calcium oxide can be included in an amount of 35.6% to 58% by weight, preferably 35.6% to 55% by weight. Within this range, by adjusting the content of glass fiber, the impact resistance and mechanical properties of the polyester composition can be improved. When the calcium oxide content is less than this range, the effect of adding glass fiber on heat resistance and mechanical properties may be negligible. When the calcium oxide content exceeds this range, the surface gloss may be significantly reduced.

[0139] As a specific example, when the glass fiber contains a low amount of calcium oxide, the calcium oxide can be included in an amount of 13% to 22% by weight, preferably 13% to 20% by weight. Within this range, by adjusting the content of glass fiber, the impact resistance and mechanical properties of the polyester composition can be improved. When the calcium oxide content is less than this range, the effect of adding glass fiber on heat resistance and mechanical properties may be negligible. When the calcium oxide content exceeds this range, the surface gloss may be significantly reduced.

[0140] Alternatively, for example, alumina may be included in the glass fibers in amounts from 1% to 40% by weight or from 5% to 30% by weight.

[0141] Alternatively, for example, silica may be included in the glass fibers in amounts of 20% to 60% by weight, 30% to 50% by weight, or 30% to 50% by weight.

[0142] In addition, one or more selected from iron oxide, magnesium oxide, sodium oxide, iron and boron oxide may be included in the glass fiber in an amount of less than 5% by weight or from 0.001% by weight to 5% by weight.

[0143] In one embodiment of the invention, the glass fiber content can be 10% to 43% by weight, 10% to 40% by weight, 15% to 40% by weight, 25% to 45% by weight, 10% to 40% by weight, or 10% to 35% by weight, based on the total weight of the components constituting the composition. Within this range, the mechanical properties of molded articles made using the polyester resin composition, such as dimensional stability and heat resistance, can be improved.

[0144] When using glass fibers containing a high content of calcium oxide, the glass fiber content is preferably 10% to 43% by weight, 10% to 40% by weight, 15% to 40% by weight, 25% to 45% by weight, 10% to 40% by weight, 10% to 35% by weight, 10% to 31% by weight, or 25% to 35% by weight, based on the total weight of the components constituting the composition. Conversely, when using glass fibers containing a low content of calcium oxide, the glass fiber content is preferably 10% to 35% by weight, 15% to 35% by weight, 20% to 35% by weight, 25% to 35% by weight, or 30% to 35% by weight, based on the total weight of the components constituting the composition.

[0145] When the glass fiber content is adjusted to the above range according to the calcium content, the mechanical properties of molded articles made using the polyester resin composition, such as dimensional stability and heat resistance, can be improved.

[0146] Polyester resin composition

[0147] The polyester resin composition according to the present invention may comprise polybutylene terephthalate resin and polyethylene terephthalate resin in a weight ratio (PBT:PET) of 1:0.7 to 1:3. Within this range, hydrolysis resistance and injection deviation can be improved.

[0148] For example, the weight ratio of polybutylene terephthalate (PBT) to polyethylene terephthalate (PET) can be from 1:0.7 to 1:3, preferably from 1:0.75 to 1:2. Within this range, hydrolysis resistance and deviation of injection molding samples can be improved. When PBT and PET are contained in a weight ratio less than this range, injection performance may be poor. When PBT and PET are contained in a weight ratio exceeding this range, injection molding may be poor due to the high crystallization temperature.

[0149] When polyethylene terephthalate resin is obtained by processing mineral water bottles, its eco-friendliness can be improved.

[0150] Resin obtained from processing mineral water bottles can be obtained by processing waste mineral water bottle granules into thin sheets and slices.

[0151] The resin obtained by processing waste mineral water bottles can be recycled into resin through sheet processing.

[0152] The polyester resin composition according to the present invention may contain one or more additives selected from lubricants, transesterification inhibitors, antioxidants, heat stabilizers, flame retardants, flame retardant additives, colorants, release agents, pigments, dyes, antistatic agents, antibacterial agents, processing aids, metal passivators, smoke inhibitors, fluorinated anti-drip agents, anti-friction agents, anti-wear agents, and coupling agents.

[0153] In one embodiment of the invention, the additive may be included in the composition in an amount of 0.1% to 10% by weight, preferably 0.1% to 5% by weight. Within this range, the properties of the additive can be effectively exhibited without affecting the physical properties of the resin composition.

[0154] The lubricant can be an olefin wax and is used to help the polyester resin composition maintain excellent release properties and injection performance.

[0155] Olefin waxes can be polymers with low melt viscosity and can be oily solids with sliding and plastic properties. For example, olefin waxes can include at least one selected from polyethylene waxes and polypropylene waxes, and commercially available olefin waxes can be used.

[0156] In one embodiment of the invention, for example, the lubricant may be included in the composition in an amount of 0.001% to 3% by weight, preferably 0.01% to 2% by weight. Within this range, excellent mold release and injection properties can be achieved.

[0157] In one embodiment of the invention, various known hydrolysis inhibitors can be used as hydrolysis inhibitors within a range that does not adversely affect the polyester resin composition of the invention. Representative commercially available hydrolysis inhibitors include phosphate compounds, such as sodium dihydrogen phosphate represented by the chemical formula NaH2PO4.

[0158] In one embodiment of the invention, for example, the hydrolysis inhibitor may be included in the composition in an amount of 0.001 wt% to 3 wt%, preferably 0.01 wt% to 2 wt%. Within this range, excellent hydrolysis resistance and stability can be achieved.

[0159] Antioxidants may include phenolic antioxidants. As described above, by using phenolic antioxidants, the polymer contained in the polyester composition can be further stabilized. Specifically, when molding the polyester composition, phenolic antioxidants can protect the composition by removing free radicals from the polymer contained in the polyester composition. In this invention, hindered phenolic antioxidant 1010 can be used as a phenolic antioxidant.

[0160] The antioxidant may be included in the composition in an amount of 0.001% by weight to 1% by weight. More specifically, based on the total weight of 100% by weight of the components constituting the composition, the antioxidant may be included in an amount of 0.002% by weight to 0.7% by weight, or in an amount of 0.002% by weight to 0.5% by weight.

[0161] When the content of antioxidants contained in the polyester composition is adjusted within the above-mentioned range, discoloration of the polyester composition can be prevented. Furthermore, by adjusting the content of antioxidants within the above-mentioned range, the molecular chains of the polymers contained in the polyester composition can be prevented from being cleaved or cross-linked due to oxidation, thereby effectively suppressing the deterioration of physical properties.

[0162] Phenolic heat stabilizers can be used as heat stabilizers. Specifically, a phenolic heat stabilizer can be pentaerythritol tetra(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate).

[0163] Specifically, the heat stabilizer can be included in the composition in an amount of 0.001 wt% to 3 wt%, or 0.002 wt% to 2.5 wt%. Within this range, by adjusting the content of the heat stabilizer, the impact strength can be excellent, the heat distortion temperature can be increased, while keeping the deviation of the heat distortion temperature from the outside value below 3°C. Therefore, the heat resistance can be excellent, and the melt flow index can be reduced.

[0164] Polyester resin compositions may contain plasticizers, such as glycerol, to control crystallization by increasing the number of nucleation sites.

[0165] Specifically, the plasticizer may be included in the composition in an amount of 0.001% to 3% by weight, or 0.002% to 2.5% by weight. Within this range, by adjusting the content of the plasticizer, chain folding can be promoted during crystal formation.

[0166] The polyester resin composition may be a polyester resin composition for motor insulation components inside a refrigerator.

[0167] For example, a polyester resin composition can have a strength of 1,700 kgf / cm³. 2 The above bending strength and 70,000 kgf / cm 2 The flexural modulus above, as a specific example, is 1,800 kgf / cm², measured according to ASTM D790 using a 1 / 8-inch molded specimen at a span of 50 mm and a speed of 1.3 mm / min. 2 Up to 2,020 kgf / cm 2 Flexural strength and 73,000 kgf / cm 2 Up to 110,000 kgf / cm 2 Optimal 75,000 kgf / cm 2 Up to 105,000 kgf / cm 2 The flexural modulus. Within this range, excellent injection performance and mechanical properties, such as cantilever beam impact strength, can be achieved.

[0168] For example, when the cantilever beam impact strength is measured at 23°C using a notched specimen according to ASTM D256 and the heat deflection temperature is measured under a load of 18.6 kg according to ASTM D648, the polyester resin composition can have a cantilever beam impact strength of 7.0 kgf·cm / cm or higher and a heat deflection temperature of 200°C or higher. Specific examples include a cantilever beam impact strength of 7.1 kgf·cm / cm to 7.9 kgf·cm / cm and a heat deflection temperature of 201°C to 210°C, preferably 7.1 kgf·cm / cm to 7.7 kgf·cm / cm and a heat deflection temperature of 201°C to 209°C. Within this range, excellent injection molding properties and mechanical properties, such as the cantilever beam impact strength, can be achieved.

[0169] Method for preparing polyester resin compositions

[0170] The polyester resin composition according to the invention can be prepared by methods known in the art. For example, the polyester resin composition can be prepared in granule form by melt extruding a mixture of components and additives in an extruder, and the granules can be used to manufacture injection-molded articles and extruded articles.

[0171] In one embodiment of the invention, the pellets are extruded at a temperature of 240°C to 300°C or 250°C to 290°C. Here, the temperature refers to the temperature set in the cylinder.

[0172] There are no particular limitations on the use of extrusion kneaders commonly used in the field to which this invention pertains, and a twin-screw extrusion kneader is preferred.

[0173] Additionally, when injecting granules, the mold temperature is preferably between 40°C and 120°C. When the mold temperature is below 40°C, the appearance may deteriorate. When the mold temperature is above 120°C, the granules may stick to the mold, reducing release properties and increasing the cooling rate. Specifically, the mold temperature can be between 60°C and 88°C, 70°C and 80°C, or 72°C and 78°C. Within this range, even if the mold temperature is controlled during injection molding of the melt product containing the polyester composition, injection deviations at all points of the molded article can be minimized, thereby improving injection performance and hydrolysis resistance.

[0174] For example, an injection molding machine with a hopper temperature or nozzle temperature set to 230°C to 260°C can be used for the injection process.

[0175] According to one embodiment of the present invention, when an injection-molded article is manufactured by injection molding, the injection speed of the melt product containing the polyester resin composition can be from 30 mm / s to 100 mm / s. Specifically, when an injection-molded article is manufactured by injection molding, the injection speed of the melt product containing the polyester resin composition can be from 35 mm / s to 95 mm / s, 50 mm / s to 80 mm / s, or 60 mm / s to 70 mm / s. Within this range, when an injection-molded article is manufactured by injection molding, even when adjusting the temperature of the mold for injecting the melt product containing the polyester composition, the injection deviation at all points of the molded article can be minimized, thereby improving injection performance and hydrolysis resistance.

[0176] For example, a method for preparing a polyester resin composition according to the present invention includes the steps of kneading and extruding a polyester resin composition comprising polybutylene terephthalate resin, polyethylene terephthalate resin, glass fiber, and additives. The polyethylene terephthalate resin is a resin obtained by processing mineral water bottles. In this case, the balance of physical properties between rigidity, processability, and specific gravity can be excellent.

[0177] The resin obtained by processing mineral water bottles can be obtained by sheeting and slicing waste mineral water bottle granules with an intrinsic viscosity of 0.5 dl / g to 1.0 dl / g.

[0178] According to one embodiment of the present invention, a method for preparing a polyester resin composition may include: processing waste polyester mineral water bottles with an intrinsic viscosity of 0.5 dl / g to 1.0 dl / g into sheets to obtain waste mineral water bottle granules, and manufacturing recycled molded articles by slicing the obtained waste mineral water bottle granules; and melting-kneading and extruding 10% to 37.5% by weight of the recycled molded articles, 26.7% to 54% by weight of polybutylene terephthalate resin, and 10% to 43% by weight of glass fiber.

[0179] As a specific example, a method for preparing a polyester resin composition may include: processing waste polyester mineral water bottles into sheets to obtain waste mineral water bottle granules, and manufacturing recycled molded articles by slicing the obtained waste mineral water bottle granules; and melting-kneading and extruding 10% to 37.5% by weight of the recycled molded articles, 26.7% to 54% by weight of polybutylene terephthalate resin with an intrinsic viscosity of 0.6 dl / g to 1.5 dl / g.

[0180] Molded products

[0181] The thermoplastic resin composition of the present invention can be used as a material for molded articles requiring excellent mechanical properties, such as dimensional stability, heat resistance and injection performance.

[0182] The thermoplastic resin composition of the present invention can be applied to various products that require heat resistance and injection performance.

[0183] According to another embodiment of the present invention, a molded article manufactured using the above-described thermoplastic resin composition is provided.

[0184] For example, the molded article can be a household appliance component with high heat resistance and excellent injection performance.

[0185] As another example, the molded product can be an insulator for a refrigerator motor.

[0186] For example, the flexural strength of this molded article, measured according to ASTM D790 using 1 / 8-inch specimens at a span of 50 mm and a speed of 1.3 mm / min, is 1,700 kgf / cm². 2 The preferred value is 1,800 kgf / cm³. 2 Up to 2,020 kgf / cm 2 .

[0187] Furthermore, the flexural modulus of this molded article, measured according to ASTM D790 using 1 / 8-inch specimens at a span of 50 mm and a speed of 1.3 mm / min, is 70,000 kgf / cm². 2 The above, as a specific example, is 73,000 kgf / cm². 2 Up to 110,000 kgf / cm 2 The preferred value is 75,000 kgf / cm³. 2 Up to 105,000 kgf / cm 2 .

[0188] Additionally, for example, the cantilever beam impact strength of the molded article, measured using a notched specimen at 23°C according to ASTM D256, can be above 7.0 kgf·cm / cm, and as a specific example, from 7.1 kgf·cm / cm to 7.9 kgf·cm / cm, preferably from 7.1 kgf·cm / cm to 7.7 kgf·cm / cm.

[0189] In addition, the heat distortion temperature of the molded article, measured according to ASTM D648 under a load of 18.6 kg, can be above 200°C, and as a specific example, 201°C to 210°C, preferably 201°C to 209°C.

[0190] Therefore, the thermoplastic resin composition of the present invention can be used as a material for molded articles requiring excellent formability, heat resistance and dimensional stability.

[0191] Furthermore, in describing the polyester resin composition according to the present invention, its preparation method, and molded articles comprising the present invention, it should be noted that other conditions or equipment not explicitly described in this specification may be appropriately selected within the scope of what is commonly practiced in this art, without particular limitation.

[0192] Hereinafter, embodiments of the invention will be described in detail to enable those skilled in the art to readily implement the invention. However, the invention can be implemented in various different forms and is not limited to these embodiments.

[0193] Example

[0194] The polybutylene terephthalate, polyethylene terephthalate, regenerated resin, lubricant, hydrolysis inhibitor, and antioxidant used in the embodiments and comparative examples of the present invention are as follows. Here, "%" refers to "% by weight".

[0195] (A) Polybutylene terephthalate resin (PBT: 0.8 dl / g)

[0196] (B) Polyethylene terephthalate resin (PET: homopolymer, 0.8 dl / g)

[0197] (B1) Native PET

[0198] (B2) Reclaimed resin: According to Figure 1 The flowchart shown depicts white slices obtained by processing waste mineral water bottles. Figure 2 (The image on the right).

[0199] (G) Glass fiber (average diameter: 7 μm to 15 μm, average length: 3 mm to 6 mm)

[0200] (C1) Glass fiber 1 (Silica: 48 wt%, Alumina: 12 wt%, Calcium oxide: 35 wt%, and other components: 6 wt%)

[0201] (C2) Glass fiber 2 (Silica: 44 wt%, Alumina: 14 wt%, Calcium oxide: 36 wt%, and other components: 6 wt%)

[0202] (C3) Glass fiber 3 (silicon dioxide: 52 wt%, aluminum oxide: 18 wt%, calcium oxide: 16 wt%, and other components: 14 wt%)

[0203] (D) Lubricant (Polyethylene Wax) LDPE Wax

[0204] (E) Hydrolysis inhibitor (ester exchange inhibitor): Sodium dihydrogen phosphate represented by the chemical formula NaH2PO4

[0205] (F) Phenolic antioxidants (Product name: Pentaerythritol (3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate)

[0206] Examples 1 to 4 and Comparative Examples 1 to 5

[0207] The components were added according to the amounts shown in Table 1, and the mixture was melt-kneaded using a twin-screw extruder with L / D = 42 and Φ = 40 mm at a temperature range of 250°C to 290°C to obtain a resin composition in granular form. For reference, 0.4 wt% of an antioxidant, 0.3 wt% of a lubricant, and 0.1 wt% of a hydrolysis inhibitor were added.

[0208] After drying the prepared granules at 100°C for more than 4 hours, the dried granules were injected into an 80-ton injection molding machine (Victory 80, Engel Co.) at an injection temperature of 260°C to 290°C, a mold temperature of 60°C, and an injection speed of 30 mm / s to prepare specimens for mechanical property evaluation. The physical properties of the prepared specimens with a thickness of 3.2 mm, a width of 12.7 mm, and a marked line segment of 115 mm (elongation measurement) were measured as follows, and the results are shown in Table 2 below.

[0209] *Melt Flow Index (unit: g / 10min): The melt flow index is measured according to ASTM D1238 at 260°C and a load of 2.16 kg.

[0210] *Tensive strength (unit: kgf / cm²) 2 Tensile strength and elongation (in %): Tensile strength and elongation were measured at a speed of 5 mm / min according to ASTM D638.

[0211] * Bending strength (unit: kgf / cm) 2 ) and flexural modulus (unit: kgf / cm) 2 According to ASTM D790, flexural strength and flexural modulus are measured at a span of 50 mm and a speed of 1.3 mm / min. A 1 / 8-inch specimen is used in this test.

[0212] *Cantilever beam impact strength (unit: kgf·cm / cm): Cantilever beam impact strength (notched, room temperature 23°C) was measured according to ASTM D256.

[0213] *Heat distortion temperature (unit: °C): Measured under a high load of 18.6 kg according to ASTM D648.

[0214] [Table 1]

[0215]

[0216] [Table 2]

[0217]

[0218] As shown in Tables 1 and 2, according to the present invention, Examples 1 to 4, which contain polybutylene terephthalate, recycled resin obtained by sheet processing of waste mineral water bottles, and glass fiber as necessary components in predetermined content ratios, exhibit melt flow indices of 17.1 g / 10 min to 26.7 g / 10 min and 1,290 kgf / cm², respectively. 2 Up to 1,465 kgf / cm 2 Tensile strength, elongation of 2.3% to 2.8%, 1,925 kgf / cm² 2 Up to 2,110 kgf / cm 2 Flexural strength, 77,650 kgf / cm 2 Up to 102,000 kgf / cm 2 The flexural modulus, cantilever beam impact strength of 7.1 kgf·cm / cm to 7.7 kgf·cm / cm, and heat distortion temperature of 202°C to 207°C were also observed. Based on these results, it can be confirmed in Examples 1 to 4 that the balance of physical properties between dimensional stability, heat resistance, and specific gravity is excellent.

[0219] On the other hand, in Comparative Example 1, which does not contain polyethylene terephthalate but contains glass fibers with a calcium content outside the scope of the present invention, the melt flow index is poor.

[0220] Furthermore, in Comparative Example 2, which contained glass fibers with a calcium content outside the scope of this invention, the melt flow index and impact strength decreased. In the case of containing an excessive amount of resin obtained from processing waste mineral water bottles, the impact strength was very low.

[0221] Furthermore, in Comparative Examples 4 and 5, where excessive amounts of glass fiber were used despite the calcium content being within the scope of the present invention, the flexural strength decreased depending on the amount of polybutylene terephthalate used. Additionally, the flexural modulus, heat distortion temperature, and impact strength also decreased.

[0222] In addition, when the sample was prepared using the same procedure as in Example 1, except that the polyethylene terephthalate resin (B2) obtained from processing waste mineral water bottles was replaced with virgin PET (B1) and glass fiber 3 (C3) was replaced with glass fiber 1 (C1), and the physical properties of the sample were measured using the same method, the sample exhibited a melt flow index of 24.8 g / 10 min and a melt flow rate of 1,330 kgf / cm³. 2 Tensile strength, 3.5% elongation at break, 1,980 kgf / cm² 2 Flexural strength, 79,950 kgf / cm 2 The flexural modulus, impact strength of 7.3 kgf·cm / cm, and heat distortion temperature of 206°C were measured. Based on these results, it can be seen that the sample exhibits similar physical properties to those of Examples 1 to 4.

[0223] In summary, although inexpensive PBT materials and recycled PET materials with high crystallization temperatures and unstable mechanical properties such as dimensional stability are incorporated, similar mechanical properties, particularly injection molding performance, to conventional PBT-reinforced resin compositions can be obtained, while improving eco-friendliness and heat resistance. Therefore, the compositions of this invention are suitable for internal motor insulation components requiring dimensional stability, heat resistance, and injection molding performance.

Claims

1. A polyester resin composition, comprising, based on a total weight of 100% by weight of the polyester resin composition: 26.7% to 54% by weight of polybutylene terephthalate resin; 10% to 37.5% by weight of polyethylene terephthalate resin; and 15% to 35% by weight of glass fiber, in, The weight ratio of the polybutylene terephthalate resin to the polyethylene terephthalate resin is 1:0.7 to 1:3; The glass fiber contains 13% to 24% by weight of calcium oxide.

2. The polyester resin composition according to claim 1, wherein, The polyethylene terephthalate resin is a resin obtained by processing mineral water bottles.

3. The polyester resin composition according to claim 1, wherein, The intrinsic viscosity of the polyethylene terephthalate resin, as measured according to ASTM D2857, is 0.5 to 1.

0.

4. The polyester resin composition according to claim 1, wherein, The intrinsic viscosity of the polybutylene terephthalate resin, as measured according to ASTM D2857, is 0.6 to 1.

8.

5. The polyester resin composition according to claim 1, wherein, The polyester resin composition comprises one or more additives selected from lubricants, transesterification inhibitors, antioxidants, heat stabilizers, flame retardants, flame retardant additives, colorants, release agents, pigments, dyes, antistatic agents, antibacterial agents, metal passivators, smoke inhibitors, fluorinated anti-drip agents, anti-friction agents, anti-wear agents, and coupling agents.

6. The polyester resin composition according to claim 1, wherein, The polyester resin composition is a polyester resin composition for use in internal motor insulation.

7. The polyester resin composition according to claim 1, wherein, The polyester resin composition exhibits a flexural strength of 1,700 kgf / cm², measured according to ASTM D790 using 1 / 8-inch molded article specimens at a span of 50 mm and a speed of 1.3 mm / min. 2 The above has a flexural modulus of 70,000 kgf / cm. 2 above.

8. The polyester resin composition according to claim 1, wherein, The polyester resin composition has a cantilever beam impact strength of ≥7.0 kgf·cm / cm measured using notched specimens at 23°C according to ASTM D256, and a heat distortion temperature of ≥200°C measured under a load of 18.6 kg according to ASTM D648.

9. A method for preparing a polyester resin composition, comprising, based on a total weight of 100 wt% of the polyester resin composition, melting-kneading and extruding 26.7 wt% to 54 wt% of polybutylene terephthalate resin, 10 wt% to 37.5 wt% of polyethylene terephthalate resin, and 15 wt% to 35 wt% of glass fiber, in, The weight ratio of the polybutylene terephthalate resin to the polyethylene terephthalate resin is 1:0.7 to 1:3; The glass fiber contains 13% to 24% by weight of calcium oxide.

10. A molded article comprising a polyester resin composition according to any one of claims 1 to 6.

11. The molded article according to claim 10, wherein, The molded product is an insulator component for internal use in motors.

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