Polyamide resin composition and molded article comprising same

Abstract

An embodiment of the present specification provides a polyamide resin composition comprising: a polyamide resin including at least one selected from the group consisting of a chemically synthesized polyamide resin and a recycled polyamide resin; and glass fibers having a tensile modulus of 88 GPa or more, wherein the glass fibers contain 17 wt% to 24 wt% of calcium oxide and magnesia (with a content of the calcium oxide being 10 wt% or more and a content of the magnesia being 10 wt% or less) relative to 100 wt% of the glass fibers.

Description

Polyamide resin composition and molded article containing the same

[0001] The present invention relates to a polyamide resin composition and a molded article comprising the same. Specifically, it provides an environmentally friendly polyamide resin and a molded article that have excellent heat resistance and mechanical strength.

[0002] The present application claims the benefit of the filing dates of Korean Patent Application No. 10-2024-0175496 filed with the Korean Intellectual Property Office on November 29, 2024, and Korean Patent Application No. 10-2025-0101287 filed with the Korean Intellectual Property Office on July 25, 2025, the entire contents of which are incorporated herein by reference.

[0003] Recently, as awareness of environmental protection spreads globally, the use of recycled materials is surging. In particular, as efforts for the efficient utilization of resources and waste reduction intensify, the use of recycled materials is being actively promoted across various industrial sectors. Amidst this trend, efforts to increase the recycling and reuse rates of vehicle waste are also being treated as important.

[0004] In particular, in the automotive industry, the use of End-of-Life Vehicle (ELV) plastics recovered from scrapped vehicles and Post-Consumer Recycled (PCR) plastics recovered after consumer use is becoming an essential requirement. This is an important method for realizing a circular economy, reducing carbon emissions, and minimizing environmental pollution.

[0005] However, compared to conventional chemically synthesized products, recycled raw materials may not maintain consistent quality and may experience degradation in physical properties. In particular, to increase the content of ELV and / or PCR plastics while maintaining the quality of existing commercial products, new technical formulations are required to maximize the utilization of recycled resources without loss of physical properties. This is emerging as a critical research and development task, especially given the growing demand for eco-friendly products across various industries, not just the automotive sector.

[0006] This specification provides a polyamide resin composition and a molded article having excellent heat resistance and mechanical strength while containing recycled polyamide resin.

[0007] The problems of the present invention are not limited to those mentioned above, and other unmentioned technical problems will be clearly understood by those skilled in the art.

[0008] One embodiment of the present specification provides a polyamide resin composition comprising one or more selected from the group consisting of chemically synthesized polyamide resins and regenerated polyamide resins; and glass fibers having a tensile modulus of 88 GPa or more, wherein the glass fibers comprise 17% to 24% by weight of calcium oxide and magnesia (wherein the calcium oxide is 10% or more by weight and the magnesia is 10% or less by weight) relative to 100% by weight of the glass fibers.

[0009] The above polyamide resin includes a chemically synthesized polyamide resin and a recycled polyamide resin, and based on 100 weight% of the polyamide resin composition, the chemically synthesized polyamide resin may be included in an amount of 5 weight% or more and 60 weight% or less; and the recycled polyamide resin may be included in an amount of 10 weight% or more and 80 weight% or less.

[0010] The above recycled polyamide resin may include a first recycled polyamide resin derived from scrapped vehicle parts; and one or more selected from the group consisting of a second recycled polyamide resin derived from one or more selected from the group consisting of waste fishing nets, waste fishing nets, ropes, and airbags.

[0011] The above recycled polyamide resin includes a first recycled polyamide resin containing an inorganic filler, and the first recycled polyamide resin may be included in an amount of 1% to 50% by weight relative to 100% by weight of the polyamide resin composition.

[0012] The above inorganic filler is one or more selected from the group consisting of glass fiber, talc, kaolin, wollastonite, and carbon, and the first recycled polyamide resin may contain 27% to 35% by weight of the inorganic filler relative to 100% by weight of the first recycled polyamide resin.

[0013] The above polyamide resin composition may further include a heat stabilizer comprising two or more ether compounds.

[0014] The above heat stabilizer may be a masterbatch comprising the above two or more ether compounds and a carrier polymer.

[0015] The above carrier polymer may be a polyamide.

[0016] The above heat stabilizer may include a first ether compound having an acid value of 35 mgKOH / g to 40 mgKOH / g; and a second ether compound having an acid value of 1190 mgKOH / g to 1320 mgKOH / g.

[0017] The weight ratio of the first ether compound and the second ether compound may be 1:0.5 to 1:5.

[0018] Based on 100 weight% of the above polyamide resin composition, the polyamide resin may be included in 50 weight% to 85 weight%; the glass fiber in 10 weight% to 45 weight%; and the heat stabilizer in 1 weight% to 20 weight%.

[0019] The tensile strength of the above polyamide resin composition may be 177 MPa or higher.

[0020] One embodiment of the present specification provides a molded article comprising the aforementioned polyamide resin composition.

[0021] The above-mentioned molded product may be an automobile or electrical / electronic component.

[0022] The above-mentioned molded product may be a high-heat-resistant component for an automobile powertrain or an intake manifold.

[0023] A polyamide resin composition according to one embodiment of this specification is environmentally friendly as it includes recycled polyamide resin. Furthermore, it is possible to produce compositions and molded articles in a resource-recycling form.

[0024] In addition, a polyamide resin composition according to one embodiment of the present specification or a molded article containing the same has excellent weld strength and durability reliability.

[0025] In addition, a polyamide resin composition according to one embodiment of the present specification or a molded article containing the same has excellent heat resistance and mechanical strength and prevents whitening.

[0026] In addition, a polyamide resin composition according to one embodiment of the present specification or a molded article containing the same has a high maximum burst pressure.

[0027] In addition, a polyamide resin composition according to one embodiment of the present specification or a molded article containing the same exhibits properties equivalent to those of a synthetic resin or superior properties compared to those of a synthetic resin, even when including recycled resin.

[0028] The effects according to the embodiments are not limited to those exemplified above, and a wider variety of effects are included in this specification.

[0029] The present specification is described in detail below.

[0030] In this specification, when a part is described as "comprising" a certain component, it means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0031] Unless specifically stated otherwise in this specification, technical terms are used merely to refer to specific embodiments and are not intended to limit the invention.

[0032] The singular forms used in this specification include plural forms unless the phrases clearly indicate otherwise.

[0033] In this specification, "p to q" means a range of p or more and q or less.

[0034] Where measurement conditions and methods are not specifically described for the physical properties described in this specification, said physical properties are measured according to measurement conditions and methods generally used by a person skilled in the art.

[0035] In this specification, unless specifically otherwise specified, measurements of physical properties are performed at room temperature and atmospheric pressure.

[0036] In the present invention, "room temperature" refers to a natural temperature that has not been heated or cooled, for example, any temperature within the range of about 10°C to 30°C, for example, about 15°C, about 18°C, about 20°C, about 23°C, or about 25°C. Furthermore, unless otherwise specifically defined in the present invention, the unit of temperature is °C.

[0037] In the present invention, "atmospheric pressure" refers to natural pressure that is not pressurized or depressurized, and typically refers to about 1 atmosphere (about 700 to 800 mmHg).

[0038] In the present invention, "chemical synthesis" or "virgin" follows the definitions commonly used in the art to which the present invention belongs and, unless otherwise specified, refers to a polymerized petroleum-based polymer product.

[0039] In the present invention, "recycling" or "recycle" follows the definition commonly used in the art to which the present invention belongs and, unless otherwise specified, refers to a regenerated / recycled product derived from household waste of the virgin product or a regenerated / recycled product derived from scrapped vehicle parts.

[0040] Hereinafter, a polyamide resin composition according to one embodiment of the present specification and a molded article including the same will be described.

[0041] The polyamide resin composition and molded article according to one embodiment of this specification may include recycled resin but may have physical properties equivalent to those of existing products composed solely of virgin resin. Since recycled resin has already undergone product use and life cycles, it may exhibit greater degradation of physical properties (including in high-temperature environments) due to moisture absorption and aging processes compared to virgin resin. The polyamide resin composition according to one embodiment of this specification may include high-rigidity glass fibers to compensate for this.

[0042] One embodiment of the present specification provides a polyamide resin composition comprising one or more selected from the group consisting of chemically synthesized polyamide resins and regenerated polyamide resins; and glass fibers having a tensile modulus of 88 GPa or more, wherein the glass fibers comprise 17% to 24% by weight of calcium oxide and magnesia (wherein the calcium oxide is 10% or more by weight and the magnesia is 10% or less by weight) relative to 100% by weight of the glass fibers.

[0043] As for the polyamide resin, within the limits conforming to the definition of the present invention, one manufactured according to methods conventionally used in the technical field to which the present invention belongs or a commercially available one may be used, and is not particularly limited.

[0044] Polyamide resins are, for example, polyamide resin 6, polyamide resin 66, polyamide resin 46, polyamide resin 11, polyamide resin 12, polyamide resin 610, polyamide resin 612, polyamide resin 6 / 66, polyamide resin 6 / 612, polyamide resin MXD6, polyamide resin 6 / MXD6, polyamide resin 66 / MXD6, polyamide resin 6T, polyamide resin 6I, polyamide resin 6 / 6T, polyamide resin 6 / 6I, polyamide resin 66 / 6T, polyamide resin 66 / 6I, polyamide resin 6 / 6T / 6I, polyamide resin 9T, polyamide resin 9I, polyamide resin 6 / 9T, polyamide resin 6 / 9I, polyamide resin It may be one or more selected from the group consisting of 66 / 9T, polyamide resin 6 / 12 / 9T, polyamide resin 66 / 12 / 9T, polyamide resin 6 / 12 / 9I, and polyamide resin 66 / 12 / 6I, and more preferably may be a homopolymer or copolymer comprising one or more selected from polyamide resin 6, polyamide resin 66, polyamide resin 46, polyamide resin 11, and polyamide resin 12, and most preferably may comprise polyamide resin 6, in which case it has excellent heat resistance, moldability, and chemical resistance.

[0045] In one embodiment of the present specification, the polyamide resin comprises one or more selected from the group consisting of chemically synthesized polyamide resins and regenerated polyamide resins.

[0046] In one embodiment of the present specification, the polyamide resin comprises a chemically synthesized polyamide resin.

[0047] In one embodiment of the present specification, the polyamide resin comprises a recycled polyamide resin.

[0048] In one embodiment of the present specification, the polyamide resin comprises a chemically synthesized polyamide resin and a regenerated polyamide resin.

[0049] In one embodiment of the present specification, the polyamide resin comprises a regenerated polyamide resin and optionally further comprises a chemically synthesized polyamide resin.

[0050] In one embodiment of this specification, the relative viscosity (RV) of the chemically synthesized (virgin) polyamide resin may be 2.1 to 2.8, preferably 2.1 to 2.7, more preferably 2.2 to 2.6, and specifically, 2.3 to 2.8. The relative viscosity (RV) can be measured by applying methods commonly used in the art, and for example, based on the Sulfuric RV, the resin concentration in a 96 wt% sulfuric acid solution can be calculated as 1.0 w / v% according to ISO 307.

[0051] The above chemically synthesized polyamide resin is caprolactam (CH₃). 11 It can be synthesized using NO as the monomer through a ring-opening polymerization process. During this process, the caprolactam ring opens, and amide bonds are formed, resulting in the formation of long polymer chains. The basic unit of chemically synthesized polyamide resins is [-NH-(CH2)5-CO-] n It consists of.

[0052] The above chemically synthesized polyamide resin may have an amorphous region that occupies a significant portion, for example, the proportion of the amorphous region may be 50 to 65 weight percent. Since the alkyl chain (CH2) portion has a relatively flexible structure, the chains may not align and may form an amorphous region. As a result, a polyamide resin composition with an excellent balance of mechanical properties and moldability can be obtained.

[0053] In this specification, "amorphous" is defined as a polymer that does not produce crystallization (exothermic) or melting (endothermic) peaks during a Differential Scanning Calorimetry (DSC) test for a temperature range from below the glass transition temperature (Tg) to Tg+300°C; conversely, if such peaks are recorded in a DSC test, the polymer material is a crystalline or semicrystalline polymer. The DSC test is known to those skilled in the art.

[0054] In one embodiment of the present specification, the chemically synthesized polyamide resin is included in an amount of 5% by weight or more and 60% by weight or less relative to 100% by weight of the polyamide resin composition. Preferably, it is included in an amount of 10% by weight or more and 50% by weight or less, and more preferably in an amount of 13% by weight or more and 45% by weight or less. In the above range, the polyamide resin composition can be processed easily while maintaining somewhat uniform quality.

[0055] Recycled polyamide resin is produced by regenerating the aforementioned virgin polyamide resin. It is manufactured by collecting plastics that have reached the end of their product life or their intended use / expiration date, and subjecting them to chemical decomposition (C-PCR), mechanical decomposition, or grinding (M-PCR). Commercially available products may also be used.

[0056] Compared to chemically synthesized polyamide resins, recycled polyamide resins may exhibit non-uniform quality and fluctuating physical properties. During the recycling process, mechanical degradation, impurity incorporation, degradation of additives, oxidation, and moisture absorption affect the purity and molecular structure of the raw materials, which can result in reduced mechanical performance and durability compared to virgin resins.

[0057] In one embodiment of the present specification, the polyamide resin comprises a recycled polyamide resin.

[0058] In one embodiment of the present specification, the polyamide resin comprises a chemically synthesized polyamide resin and a regenerated polyamide resin.

[0059] In one embodiment of the present specification, the chemically synthesized polyamide resin is included in an amount of 5% by weight or more and 60% by weight or less relative to 100% by weight of the polyamide resin composition; and the recycled polyamide resin is included in an amount of 10% by weight or more and 80% by weight or less. Preferably, the chemically synthesized polyamide resin is included in an amount of 10% by weight or more and 50% by weight or less; and the recycled polyamide resin is included in an amount of 15% by weight or more and 70% by weight or less. More preferably, the chemically synthesized polyamide resin is included in an amount of 13% by weight or more and 45% by weight or less; and the recycled polyamide resin is included in an amount of 20% by weight or more and 65% by weight or less. In the above ranges, the polyamide resin composition may be easy to process while maintaining somewhat uniform quality.

[0060] In one embodiment of the present specification, the weight of the chemically synthesized polyamide resin is less than the weight of the recycled polyamide resin.

[0061] In one embodiment of the present specification, the weight of the recycled polyamide resin is 0.1 to 5 times the weight of the chemically synthesized polyamide resin. Preferably, it is 0.5 to 4 times. More preferably, it is 1.2 to 3.7 times. In the above range, the polyamide resin composition can be processed easily while maintaining somewhat uniform quality.

[0062] In one embodiment of the present specification, the relative viscosity (RV) of the regenerated polyamide resin is 2.40 to 3.20. The amorphous ratio of the regenerated polyamide resin may be greater than the amorphous ratio of the chemically synthesized polyamide resin. That is, due to degradation and impurities, the degree of crystallization of the regenerated polyamide resin may be lower than the degree of crystallization of the chemically synthesized polyamide resin.

[0063] In one embodiment of the present specification, recycled polyamide resins may be obtained from various waste materials such as scrapped vehicle parts, waste fishing nets, waste fishing nets, carpets, industrial films, packaging materials, ropes, bags, clothes, and airbags. In the present specification, among recycled polyamide resins, recycled resins derived from scrapped vehicle parts (ELV) may be referred to as PCR (Post-Consumer Recycled) resins. Recycled resin derived from scrapped vehicle parts may be referred to as the first recycled polyamide resin, and recycled resin derived from waste materials other than scrapped vehicle parts may be referred to as the second recycled polyamide resin.

[0064] In one embodiment of the present specification, the recycled polyamide resin comprises a first recycled polyamide resin containing an inorganic filler. The first recycled polyamide resin is derived from scrapped vehicle parts and may contain reinforcing materials or fillers included in vehicle parts. The first recycled polyamide resin may have a relatively stable quality compared to other PCR resins because the source of the raw material is specified. The inorganic filler may include, but is not limited to, glass fiber, talc, kaolin, wollastonite, mica, carbon, etc. In one embodiment, the first recycled polyamide resin comprises glass fiber as an inorganic filler. The glass fiber included as an inorganic filler in the first recycled polyamide resin may be distinguished from the high-rigidity glass fiber of the polyamide resin composition.

[0065] In one embodiment of the present specification, the first recycled polyamide resin comprises an inorganic filler in an amount of 25% to 40% by weight relative to 100% by weight of the first recycled polyamide resin. Preferably, the inorganic filler comprises 27% to 35% by weight. The first recycled polyamide resin used as a vehicle part comprises an inorganic filler to reinforce the rigidity of the chemically synthesized resin.

[0066] In one embodiment of the present specification, the first recycled polyamide resin is included in an amount of 1% to 50% by weight relative to 100% by weight of the polyamide resin composition. Preferably, it is included in an amount of 5% to 40% by weight, and more preferably in an amount of 7% to 30% by weight. In the above range, the quality of the polyamide resin composition can be maintained somewhat uniformly.

[0067] In one embodiment of the present specification, the first recycled polyamide resin is included in an amount of 10 weight% or more relative to 100 weight% of the recycled polyamide resin. Preferably, it is included in an amount of 10 weight% to 80 weight% relative to 100 weight% of the recycled polyamide resin, and more preferably in an amount of 15 weight% to 60 weight%. In the above range, the quality of the polyamide resin composition can be maintained somewhat uniformly.

[0068] In one embodiment of the present specification, the recycled polyamide resin comprises a second recycled polyamide resin which is a PCR (Post-Consumer Recycled) resin. The second recycled polyamide resin may be readily available and economical compared to the first recycled polyamide resin. In one embodiment, the second recycled polyamide resin is derived from one or more materials selected from the group consisting of discarded fishing nets, discarded fishing nets, ropes, and airbags.

[0069] In one embodiment of the present specification, the second recycled polyamide resin does not contain an inorganic filler, or contains an inorganic filler of 1 weight% or less relative to 100 weight% of the second recycled polyamide resin.

[0070] In one embodiment of the present specification, the regenerated polyamide resin may include the first regenerated polyamide resin and the second regenerated polyamide resin together, or may include only the second regenerated polyamide resin.

[0071] When the first regenerated polyamide resin and the second regenerated polyamide resin are included together, the weight ratio of the first regenerated polyamide resin and the second regenerated polyamide resin is 10:90 to 70:30. Preferably, it is 15:85 to 60:40.

[0072] In one embodiment of the present specification, the tensile modulus of the glass fiber is 88 GPa or higher, indicating high rigidity. The glass fiber can improve the mechanical properties and heat resistance of the polyamide resin composition.

[0073] In one embodiment of this specification, the tensile modulus of the glass fiber is 88 GPa to 92 GPa. The tensile modulus is measured by ASTMD2343 for a 17 µm-2400 text roving strand.

[0074] Glass fibers may be any conventional glass-based fibers known in the industry without limitation, and non-limiting examples include E-glass fibers, A-glass fibers, C-glass fibers, D-glass fibers, R-glass fibers, S-glass fibers, and E-glass fiber derivatives. The cross-section may be circular or non-circular, or it may be a flat type with a cross-section that is elliptical or non-circular, including irregular. These may be used individually or in combination of two or more types.

[0075] Circular refers to a case where the cross-section is circular and the ratio of the major axis to the secondary axis is close to 1 or is 1, but is not limited thereto. Elliptical refers to a case where the cross-section is elliptical and the ratio of the major axis to the secondary axis is 2 to 6, 3 to 6, or 3.5 to 5.0, but is not limited thereto. Irregular refers to a case where, for example, the cross-section is not circular or elliptical, but is not limited thereto.

[0076] The above glass fiber may have an aspect ratio expressed as the ratio of length (L) to diameter (D) (L / D), for example, 1:1 to 1:4, specifically 1:1 to 1:3, and more specifically 1:1.

[0077] In this specification, the diameter and length can be measured using a scanning electron microscope (SEM). Specifically, 20 strands of glass fiber are selected using a scanning electron microscope, and the diameter and length of each are measured using an icon bar that can measure the diameter, and then the average diameter and average length are calculated by arithmetically averaging them.

[0078] In one embodiment of the present specification, the diameter (D) of the glass fiber may be 6 to 16 μm, preferably an average diameter of 7 μm to 11 μm, and more preferably an average diameter of 10 μm to 11 μm. In the above range, the processability is improved, which has the effect of improving the tensile strength of a molded article manufactured by molding a polyamide resin composition.

[0079] In one embodiment of the present specification, the glass fiber comprises one or more selected from the group consisting of silica, alumina, calcium oxide, magnesia, titanium dioxide, sodium oxide, potassium oxide, and iron oxide.

[0080] In one embodiment of the present specification, the glass fiber comprises silica, alumina, calcium oxide, magnesia, titanium dioxide, sodium oxide, potassium oxide, and iron oxide.

[0081] In one embodiment of the present specification, the glass fiber comprises calcium oxide and magnesia. Calcium oxide can improve processability by lowering the melting point of the glass fiber and increasing flexibility, and magnesia reinforces mechanical performance and chemical resistance.

[0082] In one embodiment of the present specification, the content of calcium oxide included in the glass fiber is similar to or greater than the content of magnesia. In one embodiment, the glass fiber contains 17% to 24% by weight of calcium oxide and magnesia relative to 100% by weight of the glass fiber. At this time, the calcium oxide is contained in an amount of 10% by weight or more, and the magnesia is contained in an amount of 10% by weight or less. In this case, a polyamide resin composition with excellent balance of processability, specific gravity, mechanical properties, and heat resistance can be secured.

[0083] In one embodiment of the present specification, the glass fiber is boron-free and does not contain boron.

[0084] In one embodiment of the present specification, relative to 100 weight% of the glass fiber,

[0085] Silica is 50% to 80% by weight,

[0086] Alumina is 5% to 25% by weight,

[0087] Calcium oxide and magnesia are 10% by weight to 30% by weight,

[0088] Titanium dioxide is 0.1 wt% to 5 wt%,

[0089] Sodium oxide, potassium oxide, and iron oxide are included in an amount of 0.1% to 5% by weight.

[0090] In one embodiment of the present specification, relative to 100 weight% of the glass fiber,

[0091] Silica is 57% to 70% by weight,

[0092] Alumina is 10% to 20% by weight,

[0093] Calcium oxide and magnesia are 15% to 25% by weight,

[0094] Titanium dioxide is 0.5 weight% to 3 weight%,

[0095] Sodium oxide, potassium oxide, and iron oxide are included in an amount of 0.5% to 3% by weight.

[0096] In one embodiment of the present specification, relative to 100 weight% of the glass fiber,

[0097] Silica is 58% to 62% by weight,

[0098] Alumina is 14% to 18% by weight,

[0099] Calcium oxide and magnesia are 17% to 24% by weight,

[0100] Titanium dioxide is 0.5 weight% to 2 weight%,

[0101] Sodium oxide, potassium oxide, and iron oxide are included in an amount of 1.3 weight% or less.

[0102] In one embodiment of the present specification, the polyamide resin composition further comprises a heat stabilizer. The heat stabilizer may be applied in the form of a masterbatch, and the polyamide resin composition exhibits heat resistance at high temperatures of 180°C or higher. In addition, the heat stabilizer prevents whitening under automotive testing and usage environment conditions.

[0103] In one embodiment of the present specification, the heat stabilizer comprises two or more ether compounds.

[0104] In one embodiment of the present specification, the heat stabilizer comprises a first ether compound and a second ether compound that are different from each other.

[0105] The first ether compound may be a polymer in which a hydroxyl group (-OH) terminal is attached to a flexible ether chain. When the first ether compound is used with a polyamide resin, various interactions occur at the interface. The terminal -OH group of the first ether compound can form hydrogen bonds with the amide group (-CONH-) of the polyamide resin, thereby increasing the bonding strength and flexibility of the interface. Additionally, since both the first ether compound and the second ether compound have hydroxyl groups (-OH), hydrogen bonds can be formed between the ether compounds, and dispersion interactions are possible. This interfacial bonding and increased flexibility can prevent whitening of the molded product in the external surface layer and internally, and have a positive effect on the damping characteristics of the molded product. In an environment where ultrasonic vibration is applied, energy is easily absorbed and transmitted due to the first ether compound, and responsiveness to vibration energy during ultrasonic welding can be significantly improved. In addition, the impact resistance of the molded article can be increased due to the first ether compound, and the elongation at break can also be improved.

[0106] In addition, the second ether compound can improve the heat resistance of the polyamide resin composition together with the aforementioned first ether compound. The second ether compound may be a high-performance polyhydric alcohol compound having multiple hydroxyl groups (-OH). Since the polyamide resin contains amine groups (-NH2) and carboxyl groups (-COOH) at its ends, a strong hydrogen bond network can be formed between the -OH groups of the second ether compound and the terminal groups of the polyamide. This hydrogen bond network significantly increases the physical adhesion of the interface and provides a robust bonding structure within the molded article. This leads to improved long-term heat resistance and durability of the molded article. Finally, a molded article with excellent mechanical properties and durability can be realized.

[0107] In one embodiment of the present specification, the heat stabilizer comprises a first ether compound having an acid value of 35 mgKOH / g to 40 mgKOH / g; and a second ether compound having an acid value of 1190 mgKOH / g to 1320 mgKOH / g. The first compound has a relatively low acid value to provide flexibility, and the second compound has a relatively high acid value to increase crosslinking density and enhance heat resistance.

[0108] The above acid value (OH value) is not particularly limited if it is a value measured by a measurement method commonly used in the technical field to which the present invention belongs, and, for example, can be measured through standard methods such as ASTM D4274, ASTM D1899, ASTM D1957, ASTM D6321, ASTM D974 or ISO 660.

[0109] If the acid value of the first ether compound exceeds 40 mgKOH / g, the ether compound cannot sufficiently permeate to the surface, so the whitening phenomenon is not improved; therefore, it may preferably be in the range of 35 to 40 mgKOH / g. In this case, it is even more preferable as it can also improve the thermal bonding strength between the components constituting the polyamide resin composition.

[0110] In one embodiment of the present specification, the first ether compound is poly(tetramethylene ether) glycol. To the extent that it conforms to the definition of the present invention, the first ether compound may be manufactured according to a method commonly used in the art to which the present invention belongs or may be commercially available, and for example, PTMG3000, PTMG2000 products, etc. may be used.

[0111] In one embodiment of the present specification, the mass average molecular weight of the first ether compound is 1500 g / mol to 4000 g / mol, preferably 2500 g / mol to 3500 g / mol. In the above range, the first ether compound may have fluidity that allows it to move to a surface.

[0112] In one embodiment of the present specification, the second ether compound is dipentaerythritol.

[0113] In one embodiment of the present specification, the weight ratio of the first ether compound to the second ether compound is 1:0.5 to 1:5. Preferably, it is 1:0.7 to 1:3, and more preferably, 1:1 to 1:2.5. In the above range, the first ether compound can have appropriate mechanical strength while preventing whitening of the polyamide resin composition on the surface. The content of the second ether compound may vary depending on the average molecular weight (MW) of the first ether compound.

[0114] In one embodiment of the present specification, the heat stabilizer is a masterbatch comprising two or more ether compounds and a carrier polymer. Specifically, it is in the form of a masterbatch processed using two or more ether compounds and a carrier polymer.

[0115] The carrier polymer of the heat stabilizer is not limited as long as it is compatible with the polyamide resin composition used in the manufacture of the final product. Examples of carrier polymers may include, but are not limited to, polyethylene, polypropylene, polystyrene, polycarbonate, polyester, or polyamide. In one example, the carrier polymer is preferably polyamide 6, given that the main chain of the polyamide resin composition is polyamide 6.

[0116] The above heat stabilizer is not limited to the form of a master batch. Each of the above first ether compound, the above second ether compound, and the polyamide may be added to the above polyamide resin composition.

[0117] In one embodiment of the present specification, the heat stabilizer is, based on 100 weight% of the heat stabilizer,

[0118] The above carrier polymer is 50 weight% or more and 90 weight% or less,

[0119] The above first ether compound in an amount of 5% by weight or more and 20% by weight or less, and

[0120] The above second ether compound is included in an amount of 5% by weight or more and 45% by weight or less.

[0121] In one embodiment of the present specification, the heat stabilizer is, based on 100 weight% of the heat stabilizer,

[0122] The above carrier polymer is 65% by weight or more and 80% by weight or less,

[0123] The above first ether compound in an amount of 7% by weight or more and 15% by weight or less, and

[0124] The above second ether compound is included in an amount of 10% by weight or more and 30% by weight or less.

[0125] In one embodiment of the present specification, the heat stabilizer is, based on 100 weight% of the heat stabilizer,

[0126] The above carrier polymer is 65% by weight or more and 80% by weight or less,

[0127] The above first ether compound is 7% by weight or more and 13% by weight or less, and

[0128] The above second ether compound is included in an amount of 10% by weight or more and 20% by weight or less.

[0129] In one embodiment of the present specification, the polyamide resin composition further comprises an additive. The additive may be one or more selected from a lubricant and a heat stabilizer, and in this case, the necessary properties are well realized without degrading the inherent properties of the polyamide resin composition.

[0130] In one embodiment of the present specification, the lubricant may be a mineral wax derived from lignite or an olefin-based wax, and provides a role that enables excellent release properties and injection properties to be maintained in the polyamide resin composition.

[0131] The above olefin-based wax may be an oily solid with low melt viscosity and slipperiness and plasticity, and may be one or more selected from polyethylene wax and polypropylene wax, for example, and commercially available products may be used.

[0132] The above mineral wax may be one or more selected from OP and E grades, having high melting point and hardness and thermal stability, and commercially available products may be used as long as they comply with the definition of the present invention.

[0133] In one embodiment of the present specification, the heat stabilizer may be of various known types as long as it does not adversely affect the polyamide resin composition.

[0134] In one embodiment of the present specification, the heat stabilizer may include a metal-based compound, and the metal-based compound may be selected from one or more of copper-based compounds and potassium-based compounds, and in this case, there is an excellent effect of heat retention rate and discoloration resistance.

[0135] The copper-based compound mentioned above may be, for example, CuI, and the potassium-based compound mentioned above may be one or more selected from the group consisting of, for example, KI, KBr, etc.

[0136] In one embodiment of the present invention, the additive may be included in an amount of 5% or less, 0.05% to 3% by weight, preferably 0.01% to 2% by weight, relative to 100% by weight of the polyamide resin composition. If the above range is satisfied, excellent mold release and injection properties can be sufficiently provided.

[0137] In addition, additives may further include processing aids, pigments, colorants, etc., as needed.

[0138] In one embodiment of the present invention, the polyamide resin composition comprises, based on 100 weight% of the polyamide resin composition,

[0139] 50% to 85% by weight of the above polyamide resin;

[0140] 10% to 45% by weight of the above glass fibers; and

[0141] The above heat stabilizer is included in an amount of 1% to 20% by weight.

[0142] In one embodiment of the present invention, the polyamide resin composition comprises, based on 100 weight% of the polyamide resin composition,

[0143] 60% to 80% by weight of the above polyamide resin;

[0144] 20% to 40% by weight of the above glass fibers; and

[0145] The above heat stabilizer is included in an amount of 3% to 15% by weight.

[0146] In one embodiment of the present invention, the polyamide resin composition comprises, based on 100 weight% of the polyamide resin composition,

[0147] 60% to 70% by weight of the above polyamide resin;

[0148] 20% to 35% by weight of the above glass fibers; and

[0149] The above heat stabilizer is included in an amount of 3% to 12% by weight.

[0150] The present specification provides a method for manufacturing the aforementioned polyamide resin composition.

[0151] The polyamide resin composition according to the present invention can be manufactured by methods known in the art. For example, the polyamide resin composition can be manufactured in the form of pellets by melt-extruding a mixture of each component and other additives in an extruder, and the pellets can be used in injection and extrusion molded articles.

[0152] The method for manufacturing the above polyamide resin composition shares all the technical features of the aforementioned polyamide resin composition. Therefore, the description of overlapping parts is omitted.

[0153] In one embodiment of the present invention, the pellet is extruded at a temperature of 250°C to 280°C, wherein the temperature refers to the temperature set in the cylinder.

[0154] The above extrusion mixer is not particularly limited to any extrusion mixer commonly used in the technical field to which the present invention belongs, and preferably may be a twin-screw extrusion mixer.

[0155] It is preferable that the temperature of the mold during injection be in the range of 60°C to 120°C, preferably 80°C to 100°C.

[0156] The above injection process can be performed, for example, using an injection machine in which the hopper temperature or nozzle temperature is set to 255°C to 275°C, respectively.

[0157] The above polyamide resin composition may have a tensile strength of 177 MPa or higher according to the standard measurement ISO 527. In one embodiment, the tensile strength of the above polyamide resin composition is 177 MPa to 200 MPa. A polyamide resin composition having high tensile strength can have high strength even during ultrasonic welding or fusion.

[0158] The strength of the above polyamide resin composition can have a direct effect on the weld strength when the welding conditions are optimized. Generally, high-strength polyamide resins have excellent yield strength and fracture strength, allowing the welded joint to withstand a greater load. Due to these characteristics, the higher the mechanical strength of the resin itself, the greater the weld strength tends to be. Therefore, the polyamide resin composition according to the present invention can secure strength capable of withstanding high loads in the welded joint based on its excellent mechanical strength, which contributes significantly to improving the durability and reliability of the final product.

[0159] In one embodiment of the present specification, the tensile strength retention rate (residual rate) of the polyamide resin composition before and after aging is 84% ​​or more. At this time, the tensile strength retention rate before and after aging is calculated by measuring the tensile strength of a specimen before and after aging at 180°C for 1000 hours in accordance with ISO 527 using the following Equation 1.

[0160] [Mathematical Formula 1]

[0161] Tensile strength retention rate before and after aging (%) = [Tensile strength after aging / Tensile strength before aging] X 100

[0162] According to the above ISO 527, the specifications of the specimen are a thickness of 4 mm, a width of 10 mm, and a length of 170 mm (according to ISO 527-2 Type 1A).

[0163] A polyamide resin composition according to one embodiment of the present specification may have high impact strength. The impact strength was measured using a specimen of 80 mm × 10 mm × 4 mm in accordance with ISO 180 (Plastics - Determination of Isod impact strength) TYPE A.

[0164] The present specification provides a molded article comprising the aforementioned polyamide resin composition. The molded article may be processed from pellets made of the aforementioned polyamide resin composition.

[0165] The above-mentioned molded article may be a product for an application requiring rigidity, impact resistance, and heat resistance. The above-mentioned molded article may be an automotive or electrical / electronic component. For example, the above-mentioned molded article may be a high-heat-resistant component of an automotive powertrain, an engine cover, an intercooler, an intake manifold, etc. In this case, there is an advantage in that it can be provided with a high quality exceeding the quality required by the market through the polyamide resin composition.

[0166] The above-described molded article may have excellent physical properties even after welding or fusion. When the composition and molded article according to one embodiment of this specification are welded or fused, the tensile strength, impact strength, and / or heat resistance of the welded or fused portion are excellent. In addition, the composition and molded article according to one embodiment of this specification have a high maximum rupture pressure. Accordingly, the molded article has excellent pressure resistance characteristics in which fluid does not leak inside.

[0167] The above welding may be ultrasonic welding, and a weld specimen can be prepared by welding two flat plate specimens measuring 40 mm × 80 mm × 3 mm under settings of a welding pressure of 1 bar, an amplitude of 1.5 mm, and a weld depth of 1.0 mm. The tensile strength prior to welding is measured in accordance with the ISO 527 standard measurement. The weld strength after welding is measured using a Universal Testing Machine (UTM) at a speed of 5 mm / mm and a welding area of ​​120 mm 2 , it can be measured by tensile testing a welded specimen under conditions of a load cell capacity of at least 5kN, a test temperature of 23±2℃, and a humidity of 50±5% Rh.

[0168] In addition, in describing the polyamide resin compositions and molded articles of this specification, it is specified that other conditions or equipment not explicitly described may be appropriately selected within the scope of practices commonly carried out in the art and are not particularly limited.

[0169] Hereinafter, to specifically explain this specification, examples will be described in detail. However, the embodiments according to this specification may be modified in various different forms, and the scope of this specification is not to be interpreted as being limited to the embodiments described below. The embodiments of this specification are provided to more completely explain this specification to those with average knowledge in the art.

[0170] <Preparation Example>

[0171] Resin compositions of the examples and comparative examples are prepared as described in Table 1 below. At this time, each component is as follows, and each value in the composition of Table 1 represents weight %.

[0172] * PA6-V (Virgin Polyamide 6): Amorphous 50–60 wt%, Tm 215–225°C, Relative viscosity (RV) 2.2 to 2.5

[0173] * PA6-R2 (recycled polyamide 6 derived from discarded fishing nets), containing 1% or less of inorganic filler, relative viscosity (RV) 2.40 to 3.20

[0174] * Contains PA6-R1 (recycled polyamide 6 derived from scrapped vehicle parts) and inorganic filler (glass fiber) within 27 to 35 weight percent.

[0175] * GF1 (High-rigidity glass fiber): Glass fiber having a tensile modulus of 88 to 92 GPa as measured by ASTM D2343 for 17 µm-2400 text roving strands, and an aspect ratio of 1:1 (L / D, D: 10 µm).

[0176] GF1 (high-rigidity glass fiber) comprises, based on 100 weight%, 58 to 62 weight% silica, 14 to 18 weight% alumina, 17 to 24 weight% of a combined calcium oxide and magnesia (wherein the calcium oxide is 10 weight% or more, and the magnesia is 10 weight% or less), 0.5 to 2 weight% titanium dioxide, and the remainder 1.3 weight% or less. At this time, the remainder comprises sodium oxide, potassium oxide, and iron oxide.

[0177] * GF2: A general-purpose product with a tensile strength of 83 GPa was used. Based on 100 wt%, it contains 57 to 61 wt% silica, 11 to 15 wt% alumina, 22 to 29 wt% of the sum of calcium oxide and magnesia (wherein the calcium oxide is 20 wt% or more, and the magnesia is 5 wt% or less), 1.0 wt% or less titanium dioxide, and the remainder is 1.3 wt% or less. At this time, the remainder includes sodium oxide, potassium oxide, and iron oxide. The tensile modulus of GF2 measured by ASTM D2343 for a 17 µm-2400 dextroving strand is 83 to 87 GPa, and the aspect ratio of GF2 is 1:1 (L / D, D: 10~11 µm).

[0178] * Heat stabilizer: A masterbatch in which a first ether compound (product name PTMG 3000 of Korea PTG, with an OH value of 37 mgKOH / g) and a second ether compound (dipentaerythritol (DPE), with an OH value of 1190 to 1320 mgKOH / g) are mixed with polyamide. The first ether compound and the second ether compound are added in a weight ratio of 1:1 to 1:2.5, and the heat stabilizer (masterbatch) contains 50% by weight or more and 90% by weight or less of polyamide with respect to 100% by weight.

[0179] * Other additives 1: The lubricant Clariant LICOWAX-OP and the metal stabilizers KI and CuI were used.

[0180] * Other additives 2: The lubricant Clariant LICOWAX-OP product and a second ether compound (dipentaerythritol (DPE)) were used. General-purpose antioxidants or stabilizers may be additionally included.

[0181]

[0182] Each of the above components was added in the amounts listed in Table 1 below, and a resin composition in pellet form was prepared by melt-kneading in a twin-screw extruder heated to 250°C to 280°C. During injection, the mold temperature condition was 80°C to 100°C, and a specimen (thickness 4 mm, width 10 mm, and length 170 mm) was produced using a screw injection molding machine.

[0183]

[0184] <Evaluation Example 1>

[0185] The characteristics of the specimen prepared above were measured by the following method and are listed in Table 1 below.

[0186] * Tensile strength (MPa): Measured according to ISO 527 under conditions of a mark length of 50 mm, a test speed of 5.0 mm / min, and 23℃. A value of 177 MPa or higher was evaluated as having excellent mechanical strength.

[0187] * Tensile strength retention rate (%) before and after aging: The tensile strength of specimens aged for 1000 hours each at 180℃ was measured according to ISO 527 and calculated using the following mathematical formula 1. If the value was 84% ​​or higher, it was evaluated as OK, and if the value was less than 84%, it was evaluated as NG.

[0188] [Mathematical Formula 1]

[0189] Tensile strength retention rate before and after aging (%) = [Tensile strength after aging / Tensile strength before aging] X 100

[0190] * Whitening evaluation: O was evaluated if a whitening phenomenon occurred where the surface of the specimen turned white after aging for 4 weeks at 70℃ and 62RH%, and X was evaluated if there was no whitening phenomenon.

[0191] [Correction pursuant to Rule 91 Dec. 17, 2025]

[0192]

[0193] Looking at Table 1 above, it can be seen that in the case of an example containing glass fibers with a tensile modulus of 88 GPa or higher, the tensile strength of the specimen is high despite the inclusion of recycled polyamide resin. In addition, according to one embodiment of this specification, it can be seen that by including a heat stabilizer containing two or more ether compounds, the tensile strength is maintained and whitening does not occur despite heat aging.

[0194]

[0195] <Evaluation Example 2>

[0196] Impact strength was evaluated for the polyamide resin compositions of Examples 6 to 9 and Comparative Examples 5 to 6.

[0197] * Impact strength (kJ / m²) 2 Izod impact strength was measured using a specimen of 80mm × 10mm × 4mm in accordance with ISO 180 (Plastics - Determination of Izod impact strength) TYPE A.

[0198] In addition, ultrasonic welding was performed on the polyamide resin compositions of Examples 6 to 9 and Comparative Examples 5 to 6 using a Branson ultrasonic welder. The welding pressure was set to 1 bar, the amplitude to 1.5 mm, and the weld depth to 1.0 mm, and two flat plate specimens measuring 40 mm × 80 mm × 3 mm were welded to produce weld specimens. Subsequently, the tensile strength of the weld specimens was measured, and the strength ratio of the weld specimens to the tensile strength of the polyamide resin composition (base material) before welding was calculated.

[0199] * Strength ratio: Universal Testing Machine (UTM) speed 5 mm / mm, weld area 120 mm 2The weld strength was measured by tensile testing the weld specimen under conditions of a load cell capacity of at least 5 kN, a test temperature of 23 ± 2℃, and a humidity of 50 ± 5% Rh. The ratio of the weld strength of the weld specimen to the tensile strength of the base material measured in Evaluation Example 1 (strength ratio) was calculated. It was judged as excellent if the strength ratio was 20% or more, average if it was 10% or more but less than 20%, and poor if it was less than 10%.

[0200]

[0201] For the above Examples 6 to 9 and Comparative Examples 5 to 6, a molded intake manifold was manufactured by processing the composition, injection molding, and ultrasonic welding. The molded product included a plurality of passages and holes. The burst pressure of the part of the molded product was evaluated as follows.

[0202] * Component Burst Pressure: After completely sealing all passages and holes of the ultrasonically welded component, air or water is injected from one side to gradually increase the internal pressure. At this time, the maximum pressure that the component can withstand is measured. If the measured maximum pressure is 8.5 bar or higher, the component is judged as Pass, and if it is less than 8.5 bar, it is judged as Fail.

[0203] Example Comparative Example 678956 Composition Impact Strength (kJ / m²) 2 )15 17 16 15 13 14 Weld Specimen Strength Ratio Excellent Excellent Excellent Excellent Poor Average Part Part Burst Pressure (≥8.5 Bar) Pass Pass Pass Pass Fail Fail

[0204] Looking at Table 2 above, it can be seen that in the case of the example containing glass fiber with a tensile modulus of 88 GPa or higher, the strength is excellent even after welding. In addition, when applied as a part for vehicles, it can withstand high pressure and possesses strong durability. The polyamide resin composition according to one embodiment of this specification has welding strength and durability reliability equivalent to or better than that of a chemically synthesized polyamide resin-based composition, not only at the specimen (composition) level but also at the product level, despite the application of recycled polyamide resin.

Claims

1. A polyamide resin comprising one or more selected from the group consisting of chemically synthesized polyamide resins and regenerated polyamide resins; and It includes glass fibers with a tensile modulus of 88 GPa or higher, and A polyamide resin composition comprising, based on 100 weight% of glass fiber, 17 weight% to 24 weight% of calcium oxide and magnesia (wherein the calcium oxide is 10 weight% or more, and the magnesia is 10 weight% or less).

2. In Claim 1, The above polyamide resin includes chemically synthesized polyamide resin and regenerated polyamide resin, and Based on 100 weight% of the above polyamide resin composition, The above chemically synthesized polyamide resin is 5% by weight or more and 60% by weight or less; and A polyamide resin composition comprising the above-mentioned recycled polyamide resin in an amount of 10% by weight or more and 80% by weight or less.

3. In Claim 1, The above recycled polyamide resin is a first recycled polyamide resin derived from scrapped vehicle parts; and A polyamide resin composition comprising one or more selected from the group consisting of a second recycled polyamide resin derived from one or more selected from the group consisting of discarded fishing nets, discarded fishing nets, ropes, and airbags.

4. In Claim 1, The above-mentioned recycled polyamide resin includes a first recycled polyamide resin containing an inorganic filler, and The above-mentioned first recycled polyamide resin is a polyamide resin composition comprising 1% to 50% by weight relative to 100% by weight of the above-mentioned polyamide resin composition.

5. In Claim 4, The above inorganic filler is one or more selected from the group consisting of glass fiber, talc, kaolin, wollastonite, and carbon, and The above-mentioned first regenerated polyamide resin is a polyamide resin composition comprising 27% to 35% by weight of an inorganic filler relative to 100% by weight of the above-mentioned first regenerated polyamide resin.

6. In Claim 1, The above polyamide resin composition further comprises a heat stabilizer comprising two or more ether compounds.

7. In Claim 6, The above heat stabilizer is a polyamide resin composition comprising a master batch containing two or more ether compounds and a carrier polymer.

8. In Claim 7, A polyamide resin composition in which the above carrier polymer is a polyamide.

9. In Claim 6, The above heat stabilizer comprises a first ether compound having an acid value of 35 mgKOH / g to 40 mgKOH / g; and a second ether compound having an acid value of 1190 mgKOH / g to 1320 mgKOH / g, in a polyamide resin composition.

10. In Claim 9, A polyamide resin composition in which the weight ratio of the first ether compound and the second ether compound is 1:0.5 to 1:

5.

11. In Claim 6, Based on 100 weight% of the above polyamide resin composition, The above polyamide resin is 50% to 85% by weight; The above glass fibers are 10% to 45% by weight; and A polyamide resin composition comprising 1% to 20% by weight of the above heat stabilizer.

12. In Claim 1, A polyamide resin composition having a tensile strength of 177 MPa or higher.

13. A molded article comprising a polyamide resin composition according to any one of claims 1 to 12.

14. In Claim 13, The above-mentioned molded product is a molded product that is an automobile or electrical / electronic component.

15. In Claim 13, The above-mentioned molded product is a high-heat resistant part for an automobile powertrain, or a molded product that is an intake manifold.

Images