Polyamide resin composition and molded article comprising the same

Abstract

An exemplary embodiment of this disclosure provides a polyamide resin composition comprising: a polyamide resin comprising at least one selected from chemically synthesized polyamide resins and recycled polyamide resins; and glass fibers having a tensile modulus of 88 GPa or more, wherein, based on 100% by weight of the glass fibers, the glass fibers comprise 17% by weight to 24% by weight of calcium oxide and magnesium oxide (wherein the calcium oxide content is 10% by weight or more and the magnesium oxide content is 10% by weight or less).

Description

Technical Field

[0001] This disclosure relates to a polyamide resin composition and a molding article comprising the thereof. Specifically, this disclosure relates to a polyamide resin composition having excellent heat resistance and mechanical rigidity and being environmentally friendly, and a molding article comprising the thereof.

[0002] This application claims the benefit of Korean Patent Application No. 10-2024-0175496 filed on November 29, 2024, and Korean Patent Application No. 10-2025-0101287 filed on July 25, 2025, the entire disclosure of which is incorporated herein by reference. Background Technology

[0003] Recently, with the growing awareness of environmental protection worldwide, the use of recycled materials is rapidly increasing. In particular, with the increasing efforts to effectively utilize resources and reduce waste, the use of recycled materials is being actively promoted in various industrial sectors. Under this trend, efforts to improve the recycling rate of automotive waste are also receiving attention.

[0004] In particular, within the automotive industry, the use of end-of-life (ELV) plastics recovered from discarded vehicles and post-consumer recycled (PCR) plastics is becoming an essential requirement. This is a crucial pathway to achieving a circular economy of resources, reducing carbon emissions, and minimizing environmental pollution.

[0005] However, compared to existing chemically synthesized products, recycled raw materials may not maintain uniform 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 technological formulations are needed to maximize the use of recycled resources without sacrificing physical properties. This is becoming an important research and development task due to the increasing demand for environmentally friendly products across various industries, including the automotive sector. Summary of the Invention

[0006] Technical issues

[0007] This disclosure aims to provide a polyamide resin composition comprising recycled polyamide resin and having excellent heat resistance and mechanical rigidity, and a molding article comprising the same.

[0008] The problems addressed in this disclosure are not limited to those described above, and other technical issues not mentioned will be readily apparent to those skilled in the art.

[0009] Technical solution

[0010] An exemplary embodiment of this disclosure provides a polyamide resin composition comprising: a polyamide resin comprising at least one selected from chemically synthesized polyamide resins and recycled polyamide resins; and glass fibers having a tensile modulus of 88 GPa or more, wherein, based on 100% by weight of the glass fibers, the glass fibers comprise 17% by weight to 24% by weight of calcium oxide and magnesium oxide (wherein the calcium oxide content is 10% by weight or more and the magnesium oxide content is 10% by weight or less).

[0011] The polyamide resin may include chemically synthesized polyamide resin and recycled polyamide resin, and based on a 100% by weight polyamide resin composition, the polyamide resin composition may contain 5% to 60% by weight of chemically synthesized polyamide resin and 10% to 80% by weight of recycled polyamide resin.

[0012] The recycled polyamide resin may include at least one of the following: a first recycled polyamide resin derived from scrapped automotive parts; and a second recycled polyamide resin derived from at least one of waste fishing nets, waste netting, ropes, and airbags.

[0013] The recycled polyamide resin may include a first recycled polyamide resin containing inorganic fillers, and the content of the first recycled polyamide resin may be from 1% to 50% by weight based on 100% by weight of the polyamide resin composition.

[0014] The inorganic filler may be at least one selected from glass fiber, talc, kaolin, wollastonite and carbon, and based on 100% by weight of the first recycled polyamide resin, the first recycled polyamide resin may contain an amount of 27% to 35% by weight of the inorganic filler.

[0015] The polyamide resin composition may further include a heat stabilizer containing two or more ether compounds.

[0016] Heat stabilizers can be masterbatches containing two or more ether compounds and carrier polymers.

[0017] The carrier polymer can be polyamide.

[0018] The heat stabilizer may contain a first ether compound with an acid value of 35 mg KOH / g to 40 mg KOH / g and a second ether compound with an acid value of 1190 mg KOH / g to 1320 mg KOH / g.

[0019] The weight ratio of the first ether compound to the second ether compound can be from 1:0.5 to 1:5.

[0020] Based on a 100% by weight polyamide resin composition, the polyamide resin composition may comprise: 50% to 85% by weight of polyamide resin; 10% to 45% by weight of glass fiber; and 1% to 20% by weight of heat stabilizer.

[0021] Polyamide resin compositions can have tensile strengths of 177 MPa or higher.

[0022] An exemplary embodiment of this disclosure provides a molding article comprising the above-described polyamide resin composition.

[0023] Molded parts can be automotive parts or electrical / electronic components.

[0024] The molded parts can be high heat-resistant components of automotive powertrains or intake manifolds.

[0025] Beneficial effects

[0026] The polyamide resin composition according to one exemplary embodiment of this disclosure contains recycled polyamide resin and is therefore eco-friendly. Furthermore, resource-recycling compositions and molding articles can be produced.

[0027] Furthermore, the polyamide resin composition according to an exemplary embodiment of this disclosure, or the molded article containing it, has excellent weld strength and durability.

[0028] In addition, the polyamide resin composition or molding article containing the polyamide resin composition according to an exemplary embodiment of the present disclosure has excellent heat resistance and mechanical rigidity and prevents whitening.

[0029] In addition, the polyamide resin composition or molding article containing it according to an exemplary embodiment of this disclosure has a high maximum burst pressure.

[0030] Furthermore, the polyamide resin composition or molding article containing the polyamide resin according to an exemplary embodiment of the present disclosure exhibits physical properties comparable to or superior to those of synthetic resins, even if it contains recycled resin.

[0031] The advantages of the exemplary embodiments disclosed herein are not limited to those described above, and a wider variety of effects are included in this specification. Detailed Implementation

[0032] This disclosure will be explained in detail below.

[0033] Throughout this specification, unless the context specifically states otherwise, when a part is described as "containing" a component, this does not exclude the presence of another component, but rather implies that other components may be included.

[0034] Unless otherwise specifically stated in this specification, the terminology is intended to refer to a particular embodiment only and is not intended to limit this disclosure.

[0035] The singular forms used in this specification also include the plural forms, unless the phrase clearly indicates the opposite meaning.

[0036] In this specification, "p to q" refers to the range above p and below q.

[0037] When the measurement conditions and methods are not specifically described for the physical properties described in this specification, the physical properties shall be measured according to the measurement conditions and methods commonly used by those skilled in the art.

[0038] Unless otherwise stated, physical properties are measured at room temperature and ambient pressure in this specification.

[0039] In this disclosure, "room temperature" means the natural temperature without heating or cooling, and refers to any temperature in the range of about 10°C to about 30°C, such as about 15°C, about 18°C, about 20°C, about 23°C, or about 25°C. Furthermore, unless otherwise stated in this disclosure, the unit of temperature is °C.

[0040] In this disclosure, "ambient pressure" is natural pressure without pressurization and depressurization, and about 1 atm (about 700 mmHg to 800 mmHg) is generally referred to as ambient pressure.

[0041] In this disclosure, "chemically synthesized" or "native" follows the common definition in the technical field to which this disclosure pertains, and unless otherwise specified, refers to petroleum-based polymer products manufactured by polymerization.

[0042] In this disclosure, “recycled” or “recovered” follows the common definition in the technical field to which this disclosure pertains, and unless otherwise specified, refers to recycled / recovered products derived from virgin products of household waste or from scrapped vehicle parts.

[0043] In the following, a polyamide resin composition and a molding article comprising the present disclosure according to an exemplary embodiment will be explained.

[0044] The polyamide resin composition and molding article comprising it according to an exemplary embodiment of this disclosure, even when containing recycled resin, can have physical properties comparable to existing products containing only virgin resin. Recycled resin has undergone use and life cycles and may experience significant physical property degradation compared to virgin resin due to moisture absorption and aging (including high-temperature environments). The polyamide resin composition according to an exemplary embodiment of this disclosure further comprises high-rigidity glass fibers, thus mitigating this problem.

[0045] In one exemplary embodiment of this disclosure, a polyamide resin composition is provided, comprising: a polyamide resin comprising at least one selected from chemically synthesized polyamide resins and recycled polyamide resins; and glass fibers having a tensile modulus of 88 GPa or more, wherein, based on 100% by weight of the glass fibers, the glass fibers comprise 17% by weight to 24% by weight of calcium oxide and magnesium oxide (wherein the calcium oxide content is 10% by weight or more and the magnesium oxide content is 10% by weight or less).

[0046] Hereinafter, within the scope of the definitions consistent with this disclosure, polyamide may be a polyamide prepared by methods commonly used in the technical field to which this disclosure pertains, or may be a commercially available polyamide, without particular limitation.

[0047] For example, the polyamide resin can be selected from 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 66 / 6T / 6I, polyamide resin 66 / 6T / 6I, polyamide resin The resin may be at least one of resin 9T, polyamide resin 9I, polyamide resin 6 / 9T, polyamide resin 6 / 9I, polyamide resin 66 / 9T, polyamide resin 6 / 12 / 9T, polyamide resin 66 / 12 / 9T, polyamide resin 6 / 12 / 9I, and polyamide resin 66 / 12 / 6I. More preferably, it may be a homopolymer or copolymer comprising at least one selected from polyamide resin 6, polyamide resin 66, polyamide resin 46, polyamide resin 11, and polyamide resin 12. Most preferably, it may comprise polyamide resin 6, and this provides excellent heat resistance, molding and processing properties, and chemical resistance.

[0048] In one exemplary embodiment of this disclosure, the polyamide resin includes at least one selected from chemically synthesized polyamide resins and recycled polyamide resins.

[0049] In one exemplary embodiment of this disclosure, the polyamide resin includes a chemically synthesized polyamide resin.

[0050] In one exemplary embodiment of this disclosure, the polyamide resin includes recycled polyamide resin.

[0051] In one exemplary embodiment of this disclosure, the polyamide resin includes chemically synthesized polyamide resin and recycled polyamide resin.

[0052] In one exemplary embodiment of this disclosure, the polyamide resin includes recycled polyamide resin and optionally includes chemically synthesized polyamide resin.

[0053] In one exemplary embodiment of this disclosure, the chemically synthesized (virgin) polyamide resin may have a relative viscosity (RV) of 2.1 to 2.8, preferably 2.1 to 2.7, more preferably 2.2 to 2.6, and particularly 2.3 to 2.8. The relative viscosity (RV) can be determined using methods conventionally used in the art. For example, the relative viscosity can be based on sulfuric acid RV, calculated according to ISO 307 by taking the resin concentration in a 96% by weight sulfuric acid solution as 1.0 w / v%.

[0054] Chemically synthesized polyamide resins can be achieved by using caprolactam (CH2O3). 11 Caprolactam is synthesized using a ring-opening polymerization process with NO as the unit. In this process, the caprolactam ring is opened, and a long polymer chain is formed simultaneously with the formation of amide bonds. The basic unit for the chemical synthesis of polyamide resins includes [-NH-(CH2)5-CO-]. n .

[0055] In chemically synthesized polyamide resins, amorphous segments constitute a significant proportion, for example, ranging from 50% to 65% by weight. Because the alkyl chain (CH2) moiety is a relatively soft structure, the chains are not aligned but rather form amorphous segments. Therefore, an excellent balance between mechanical properties and moldability can be ensured in the polyamide resin composition.

[0056] In this disclosure, "amorphous" is defined as a polymer that does not produce crystallization (exothermic) or melting (endothermic) peaks when subjected to differential scanning calorimetry (DSC) testing in a temperature range from below the glass transition temperature (Tg) to Tg+300°C. Conversely, if such peaks are recorded in the DSC test, the polymer material is a crystalline or semi-crystalline polymer. DSC testing is known to those skilled in the art.

[0057] In one exemplary embodiment of this disclosure, the content of chemically synthesized polyamide resin is from 5% to 60% by weight, based on 100% by weight of the polyamide resin composition. Preferably, the content of chemically synthesized polyamide resin is from 10% to 50% by weight, more preferably from 13% to 45% by weight, based on 100% by weight of the polyamide resin composition. Within the above-defined range, the polyamide resin composition is easy to process while maintaining relatively uniform quality.

[0058] Recycled polyamide resin is obtained by regenerating the aforementioned virgin polyamide resin. It is commercialized through chemical decomposition (C-PCR (post-consumer recycling)) or mechanical decomposition or pulverization (M-PCR) after collecting end-of-life, end-of-use, or expired plastics. Recycled polyamide resin can be commercially available.

[0059] Compared to chemically synthesized polyamide resins, recycled polyamide resins may have uneven quality and exhibit variable physical properties. Compared to virgin resins, recycled polyamide resins may exhibit lower mechanical properties and durability because the purity and molecular structure of the original material are affected by mechanical degradation, impurity contamination, additive degradation, oxidation, and moisture absorption during the recycling process.

[0060] In one exemplary embodiment of this disclosure, the polyamide resin includes recycled polyamide resin.

[0061] In one exemplary embodiment of this disclosure, the polyamide resin includes chemically synthesized polyamide resin and recycled polyamide resin.

[0062] In one exemplary embodiment of this disclosure, a 100% by weight polyamide resin composition comprises: 5% to 60% by weight of chemically synthesized polyamide resin and 10% to 80% by weight of recycled polyamide resin. Preferably, a 100% by weight polyamide resin composition comprises: 10% to 50% by weight of chemically synthesized polyamide resin and 15% to 70% by weight of recycled polyamide resin. More preferably, a 100% by weight polyamide resin composition comprises: 13% to 45% by weight of chemically synthesized polyamide resin and 20% to 65% by weight of recycled polyamide resin. Within the above-defined ranges, the polyamide resin composition is easy to process while maintaining relatively uniform quality.

[0063] In one exemplary embodiment of this disclosure, the weight of the chemically synthesized polyamide resin is less than the weight of the recycled polyamide resin.

[0064] In one exemplary embodiment of this disclosure, the weight of the recycled polyamide resin is 0.1 to 5 times that of the chemically synthesized polyamide resin. Preferably, the weight of the recycled polyamide resin is 0.5 to 4 times that of the chemically synthesized polyamide resin. More preferably, the weight of the recycled polyamide resin is 1.2 to 3.7 times that of the chemically synthesized polyamide resin. Within the above-defined ranges, the polyamide resin composition is easy to process while maintaining relatively uniform quality.

[0065] In one exemplary embodiment of this disclosure, the recycled polyamide resin has a relative viscosity of 2.40 to 3.20. The amorphous proportion of the recycled polyamide resin can be greater than that of the chemically synthesized polyamide resin. In other words, due to the effects of degradation and impurities, the crystallinity of the recycled polyamide resin may be lower than that of the chemically synthesized polyamide resin.

[0066] In one exemplary embodiment of this disclosure, the recycled polyamide resin can be obtained from various wastes, such as end-of-life vehicle parts, waste fishing nets, waste netting, carpets, industrial films, packaging materials, ropes, bags, clothing, and airbags. In this disclosure, the recycled polyamide resin may be referred to as PCR (post-consumer recycled) resin, except for recycled resin derived from end-of-life vehicle (ELV) parts. Recycled resin derived from end-of-life vehicle parts may be referred to as first recycled polyamide resin, and recycled resin derived from waste other than end-of-life vehicle parts may be referred to as second recycled polyamide resin.

[0067] In one exemplary embodiment of this disclosure, the recycled polyamide resin includes a first recycled polyamide resin containing inorganic fillers. The first recycled polyamide resin is derived from end-of-life automotive parts and may contain reinforcing materials or fillers found in the vehicle parts. Because the raw material source of the first recycled polyamide resin is well-defined, it may have relatively stable quality compared to other PCR resins. Inorganic fillers may include, but are not limited to, glass fibers, talc, kaolin, wollastonite, mica, carbon, etc. For example, the first recycled polyamide resin contains glass fibers as an inorganic filler. The glass fibers contained as the inorganic filler in the first recycled polyamide resin can be distinguished from the high-rigidity glass fibers in the polyamide resin composition.

[0068] In one exemplary embodiment of this disclosure, based on 100% by weight of a first recycled polyamide resin, the first recycled polyamide resin comprises 25% by weight to 40% by weight of inorganic filler. Preferably, the first recycled polyamide resin comprises 27% by weight to 35% by weight of inorganic filler. The first recycled polyamide resin used as a vehicle component comprises inorganic filler to enhance the rigidity of the chemically synthesized polyamide resin.

[0069] In one exemplary embodiment of this disclosure, the content of the first recycled polyamide resin is from 1% to 50% by weight based on 100% by weight of the polyamide resin composition. Preferably, the content of the first recycled polyamide resin is from 5% to 40% by weight, more preferably from 7% to 30% by weight based on 100% by weight of the polyamide resin composition. Within the above-defined ranges, the polyamide resin composition can maintain relatively uniform mass.

[0070] In one exemplary embodiment of this disclosure, the content of the first recycled polyamide resin is 10% by weight or more based on 100% by weight of the recycled polyamide resin. Preferably, the content of the first recycled polyamide resin is from 10% by weight to 80% by weight, more preferably from 15% by weight to 60% by weight, based on 100% by weight of the recycled polyamide resin. Within the above-defined range, the polyamide resin composition can maintain relatively uniform mass.

[0071] In one exemplary embodiment of this disclosure, the recycled polyamide resin includes a second recycled polyamide resin as a PCR (post-consumer recycled) resin. Compared to the first recycled polyamide resin, the second recycled polyamide resin is more readily available and more economical. For example, the second recycled polyamide resin is derived from at least one selected from waste fishing nets, waste netting, ropes, and airbags.

[0072] In one exemplary embodiment of this disclosure, the second recycled polyamide resin is free of inorganic fillers, or the inorganic filler content is less than 1% by weight based on 100% by weight of the second recycled polyamide resin.

[0073] In one exemplary embodiment of this disclosure, the recycled polyamide resin may comprise a combination of a first recycled polyamide resin and a second recycled polyamide resin, or it may comprise only the second recycled polyamide resin.

[0074] When the recycled polyamide resin comprises a combination of a first recycled polyamide resin and a second recycled polyamide resin, the weight ratio of the first recycled polyamide resin to the second recycled polyamide resin is 10:90 to 70:30, preferably 15:85 to 60:40.

[0075] In one exemplary embodiment of this disclosure, the glass fiber has a tensile modulus of 88 GPa or higher, thereby determining high rigidity. The glass fiber can improve the mechanical properties and heat resistance of the polyamide resin composition.

[0076] In one exemplary embodiment of this disclosure, the glass fiber has a tensile modulus of 88 GPa to 92 GPa. The tensile modulus is determined according to ASTM D2343 for 17 μm-2400 tex rovings.

[0077] Any conventional glass-based fiber known in the art can be used as a glass fiber without particular limitation. Non-limiting examples of glass fibers include E-glass fiber, A-glass fiber, C-glass fiber, D-glass fiber, R-glass fiber, S-glass fiber, E-glass fiber derivatives, etc. Glass fibers can have a circular, non-circular, or elliptical cross-section, or can have a flat cross-section, including non-circular types such as atypical cross-sections. Such glass fibers can be used alone or in combination.

[0078] A circular cross-section refers to a cross-section that displays a circular shape and whose ratio of the primary cross-section axis to the secondary cross-section axis is 1 or approximately 1, but is not limited to this. An elliptical cross-section refers to a cross-section that displays an elliptical shape and whose ratio of the primary cross-section axis to the secondary cross-section axis is 2:6, 3:6, or 3.5:5.0, but is not limited to this. An irregular cross-section refers to a cross-section that does not display a circular or elliptical shape, but is not limited to this.

[0079] For example, glass fibers can have an aspect ratio (L / D) defined as the ratio of length (L) to diameter (D), ranging from 1:1 to 1:4, specifically from 1:1 to 1:3, and more specifically 1:1.

[0080] In this disclosure, the diameter and length can be determined using a scanning electron microscope (SEM). Specifically, 20 glass fiber strands are selected using a scanning electron microscope, and the diameter and length of each strand are measured using a diameter-measuring icon bar, and their arithmetic mean is calculated to obtain the average diameter and average length.

[0081] In one exemplary embodiment of this disclosure, the glass fibers may have a diameter (D) of 6 μm 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. Within the above-described range, it is possible to mold a polyamide resin composition with improved processing properties and to provide improved tensile strength of molded articles made from the polyamide resin composition.

[0082] In one exemplary embodiment of this disclosure, the glass fiber includes at least one selected from silicon dioxide, aluminum oxide, calcium oxide, magnesium oxide, titanium dioxide, sodium oxide, potassium oxide, and iron oxide.

[0083] In one exemplary embodiment of this disclosure, the glass fiber comprises silicon dioxide, aluminum oxide, calcium oxide, magnesium oxide, titanium dioxide, sodium oxide, potassium oxide, and iron oxide.

[0084] In one exemplary embodiment of this disclosure, the glass fiber comprises calcium oxide and magnesium oxide. Calcium oxide lowers the melting point of the glass fiber and increases its flexibility, thereby improving its processing performance. Magnesium oxide enhances mechanical properties and chemical resistance.

[0085] In one exemplary embodiment of this disclosure, the glass fiber contains a calcium oxide content similar to or higher than the magnesium oxide content. For example, based on 100% by weight of glass fiber, the glass fiber contains 17% to 24% by weight of calcium oxide and magnesium oxide. Here, the calcium oxide content is 10% by weight or more, and the magnesium oxide content is 10% by weight or less. In this case, a polyamide resin composition that achieves a good balance between processing performance, specific gravity, mechanical and physical properties, and heat resistance is ensured.

[0086] In one exemplary embodiment of this disclosure, the glass fiber is boron-free glass fiber.

[0087] In one exemplary embodiment of this disclosure, based on 100% by weight of glass fiber, the glass fiber comprises: 50% to 80% by weight of silicon dioxide, 5% to 25% by weight of alumina, 10% to 30% by weight of calcium oxide and magnesium oxide, 0.1% to 5% by weight of titanium dioxide, and Sodium oxide, potassium oxide and iron oxide, 0.1% to 5% by weight.

[0088] In one exemplary embodiment of this disclosure, based on 100% by weight of glass fiber, the glass fiber comprises: 57% to 70% by weight of silicon dioxide, 10% to 20% by weight of alumina, 15% to 25% by weight of calcium oxide and magnesium oxide, 0.5% to 3% by weight of titanium dioxide, and Sodium oxide, potassium oxide and iron oxide, 0.5% to 3% by weight.

[0089] In one exemplary embodiment of this disclosure, based on 100% by weight of glass fiber, the glass fiber comprises: 58% to 62% by weight of silicon dioxide, 14% to 18% by weight of alumina, 17% to 24% by weight of calcium oxide and magnesium oxide, 0.5% to 2% by weight of titanium dioxide, and Sodium oxide, potassium oxide, and iron oxide less than 1.3% by weight.

[0090] In one exemplary embodiment of this disclosure, the polyamide resin composition further comprises a heat stabilizer. The heat stabilizer can be applied in the form of a masterbatch, and the polyamide resin composition exhibits heat resistance at temperatures above 180°C. Furthermore, the heat stabilizer prevents whitening under vehicle testing and usage environmental conditions.

[0091] In one exemplary embodiment of this disclosure, the heat stabilizer comprises two or more ether compounds.

[0092] In one exemplary embodiment of this disclosure, the heat stabilizer comprises a first ether compound and a second ether compound that are different from each other.

[0093] The first ether compound can be a polymer containing a soft ether chain terminated with a hydroxyl group (-OH). When the first ether compound is used with a polyamide resin, they induce various interactions 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 enhancing interfacial bonding and flexibility. Furthermore, both the first and second ether compounds have hydroxyl groups (-OH), which can form hydrogen bonds between the ether compounds and facilitate dispersion interactions. This increased interfacial bonding and flexibility can prevent whitening of the molded article on both the outer surface layer and the interior, and can positively influence the damping properties of the molded article. Under ultrasonic vibration, the first ether compound facilitates energy absorption and transfer, and can significantly improve the response to vibrational energy during ultrasonic welding. Furthermore, the first ether compound can enhance the impact resistance and elongation at break of the molded article.

[0094] Furthermore, the second ether compound, together with the first ether compound, can improve the heat resistance of the polyamide resin composition. The second ether compound can be a highly functional polyol 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 end groups of the polyamide and the -OH groups of the second ether compound. This hydrogen bond network significantly increases interfacial physical adhesion and provides a rigid bonding structure within the molded article. This leads to improved long-term heat resistance and durability. Ultimately, molded articles with excellent mechanical properties and durability can be achieved.

[0095] In one exemplary embodiment of this disclosure, the heat stabilizer comprises: a first ether compound with an acid value of 35 mg KOH / g to 40 mg KOH / g; and a second ether compound with an acid value of 1190 mg KOH / g to 1320 mg KOH / g. The first ether compound has a relatively low acid value to provide flexibility, and the second ether compound has a relatively high acid value to increase crosslinking density and enhance heat resistance.

[0096] There are no particular restrictions on the acid value (OH value), as long as it is a value determined by methods conventionally used in the art. For example, the acid value can be determined by standard methods such as ASTM D4274, ASTM D1899, ASTM D1957, ASTM D6321, ASTM D974, or ISO 660.

[0097] When the first ether compound has an acid value higher than 40 mg KOH / g, the corresponding ether compound cannot sufficiently diffuse to the surface, thus failing to improve the whitening phenomenon. Therefore, the first ether compound preferably has an acid value of 35 mg KOH / g to 40 mg KOH / g. In this case, it is also preferable to improve the thermal bonding between the components forming the polyamide resin composition.

[0098] In one exemplary embodiment of this disclosure, the first ether compound is poly(tetramethylene ether) glycol. Within the scope defined herein, the first ether compound may be an ether compound prepared according to methods conventionally used in the art or a commercially available ether compound, such as PTMG3000 or PTMG2000.

[0099] In one exemplary embodiment of this disclosure, the first ether compound may have a weight-average molecular weight of 1500 g / mol to 4000 g / mol, preferably 2500 g / mol to 3500 g / mol. Within the above-defined range, the first ether compound may have fluidity, through which it can migrate to a surface.

[0100] In one exemplary embodiment of this disclosure, the second ether compound is dipentaerythritol.

[0101] In one exemplary embodiment of this disclosure, the weight ratio of the first ether compound to the second ether compound is 1:0.5 to 1:5, preferably 1:0.7 to 1:3, and more preferably 1:1 to 1:2.5. Within the above-defined range, the first ether compound prevents surface whitening of the polyamide resin composition while achieving suitable mechanical rigidity. The content of the second ether compound can vary depending on the average molecular weight (MW) of the first ether compound.

[0102] In one exemplary embodiment of this disclosure, the heat stabilizer is a masterbatch containing two or more ether compounds and a carrier polymer. Specifically, it is a masterbatch processed using two or more ether compounds and a carrier polymer.

[0103] There are no particular limitations on the carrier polymer for the heat stabilizer, as long as it is compatible with the polyamide resin composition used to manufacture the final product. Specific examples of carrier polymers include, but are not limited to, polyethylene, polypropylene, polystyrene, polycarbonate, polyester, or polyamide. For example, given that the main chain of the polyamide resin composition is polyamide 6, the carrier polymer is preferably polyamide 6.

[0104] The heat stabilizer is not limited to a single masterbatch. Each of the first ether compound, the second ether compound, and the polyamide can be introduced individually into the polyamide resin composition.

[0105] In one exemplary embodiment of this disclosure, based on 100% by weight of a heat stabilizer, the heat stabilizer comprises: 50% to 90% by weight of carrier polymer, 5% to 20% by weight of the first ether compound, and 5% to 45% by weight of the second ether compound.

[0106] In one exemplary embodiment of this disclosure, based on 100% by weight of a heat stabilizer, the heat stabilizer comprises: 65% to 80% by weight of carrier polymer, 7% to 15% by weight of the first ether compound, and 10% to 30% by weight of a second ether compound.

[0107] In one exemplary embodiment of this disclosure, based on 100% by weight of a heat stabilizer, the heat stabilizer comprises: 65% to 80% by weight of carrier polymer, 7% to 13% by weight of the first ether compound, and 10% to 20% by weight of the second ether compound.

[0108] In one exemplary embodiment of this disclosure, the polyamide resin composition further comprises an additive. The additive may be at least one selected from lubricants and heat stabilizers. In this case, it provides an effect of appropriately achieving the desired physical properties without causing degradation of the inherent physical properties of the polyamide resin composition.

[0109] In one exemplary embodiment of this disclosure, the lubricant may be a mineral wax or olefin wax derived from lignite, which serves to maintain the polyamide resin composition's excellent release properties and injection performance.

[0110] Olefin waxes can be polymers with low melt viscosity and can be oily solids with sliding and plastic properties. For example, olefin waxes can be at least one selected from polyethylene waxes and polypropylene waxes, and can be commercially available.

[0111] The mineral wax exhibits a high melting point and high hardness and has thermal stability, and may be selected from at least one of OP and E grades, and may be a commercially available product without departing from the definition in accordance with this disclosure.

[0112] In one exemplary embodiment of this disclosure, various known types of heat stabilizers may be used, provided they do not adversely affect the polyamide resin composition.

[0113] In one exemplary embodiment of this disclosure, the heat stabilizer may include a metal compound, which may be at least one selected from copper-based compounds and potassium-based compounds. In this case, excellent heat retention and colorfastness are provided.

[0114] Copper-based compounds can be exemplified by CuI, and potassium-based compounds can be exemplified by at least one selected from KI, KBr, etc.

[0115] In one exemplary embodiment of this disclosure, based on 100% by weight of the polyamide resin composition, the content of the additive can be less than 5% by weight, from 0.05% by weight to 3% by weight, preferably from 0.01% by weight to 2% by weight. When the above-defined ranges are met, excellent mold release properties and injection performance can be adequately provided.

[0116] In addition, additives may include processing aids, pigments, colorants, etc., if necessary.

[0117] In one exemplary embodiment of this disclosure, based on 100% by weight of a polyamide resin composition, the polyamide resin composition comprises: 50% to 85% by weight of polyamide resin; 10% to 45% by weight of glass fiber; and 1% to 20% by weight of heat stabilizer.

[0118] In one exemplary embodiment of this disclosure, based on 100% by weight of a polyamide resin composition, the polyamide resin composition comprises: 60% to 80% by weight of polyamide resin; 20% to 40% by weight of glass fiber; and 3% to 15% by weight of heat stabilizer.

[0119] In one exemplary embodiment of this disclosure, based on 100% by weight of a polyamide resin composition, the polyamide resin composition comprises: 60% to 70% by weight of polyamide resin; 20% to 35% by weight of glass fiber; and 3% to 12% by weight of heat stabilizer.

[0120] In one exemplary embodiment of this disclosure, a method for preparing the above-described polyamide resin composition is provided.

[0121] The polyamide resin composition according to this disclosure can be prepared by methods known in the art. For example, the polyamide resin composition can be produced in granular form by melt extrusion of a mixture of the components and other additives in an extruder, the granules being used for injection molding or extrusion molding articles.

[0122] The method for preparing the polyamide resin composition has all the technical features of the polyamide resin composition described above. Therefore, the description of overlapping parts will be omitted.

[0123] In one exemplary embodiment of this disclosure, the pellets are extruded at a temperature of 250°C to 280°C, wherein the temperature refers to the temperature set in the barrel.

[0124] There are no particular restrictions on the extrusion kneader, as long as it is an extrusion kneader commonly used in the art, and preferably, it can be a twin-screw extrusion kneader.

[0125] During injection, the mold temperature is preferably 60°C to 120°C, more preferably 80°C to 100°C.

[0126] For example, the injection process can be performed using an injection molding machine with either the hopper temperature or the nozzle temperature set to 255°C to 275°C.

[0127] Polyamide resin compositions can have a tensile strength of 177 MPa or higher, as determined by standard testing ISO 527. For example, polyamide resin compositions have a tensile strength of 177 MPa to 200 MPa. Polyamide resin compositions with high tensile strength can exhibit high strength even when welded or fused.

[0128] When optimizing weld strength, the strength of the polyamide resin composition directly affects the weld strength. Generally, high-strength polyamide resins exhibit high yield strength and high tensile strength, thus allowing the welded portion to withstand higher loads. Therefore, the higher the mechanical strength of the resin itself, the higher the weld strength. Consequently, the polyamide resin composition according to this disclosure can ensure high load strength even at welded portions due to its excellent mechanical strength, which significantly contributes to improved durability and reliability of the final product.

[0129] In one exemplary embodiment of this disclosure, the polyamide resin composition exhibits a tensile strength retention rate (residual strength) of over 84% before and after aging. Here, the tensile strength retention rate before and after aging is calculated according to the following mathematical formula 1, after measuring the tensile strength of the specimen before and after aging at 180°C for 1000 hours based on ISO 527: [Mathematical Expression 1] Tensile strength retention rate before and after aging (%) = [Tensile strength after aging / Tensile strength before aging] x 100 When measuring tensile strength based on ISO 527, the specimen has dimensions of 4 mm thickness, 10 mm width, and 170 mm length (according to ISO 527-2 1A type).

[0130] The polyamide resin composition according to an exemplary embodiment of this disclosure can have high impact strength. The impact strength is determined using a specimen with dimensions of 80 mm × 10 mm × 4 mm according to ISO 180A (Plastics – Determination of cantilever beam impact strength).

[0131] In one exemplary embodiment of this disclosure, a molding article comprising the above-described polyamide resin composition is provided. The molding article can be processed from granules prepared from the above-described polyamide resin composition.

[0132] Molded parts can be used for all applications requiring rigidity, impact resistance, and heat resistance. Molded parts can be automotive components or electrical / electronic components. For example, molded parts can be high-heat-resistant components for automotive powertrain systems (powertrain assemblies), engine covers, intercoolers, intake manifolds, etc. In such cases, polyamide resin compositions can provide the advantages of molded parts that meet or exceed market-required quality standards.

[0133] Even after welding or fusion, the molded article can exhibit excellent physical properties. When the composition and molded article according to an exemplary embodiment of the present disclosure are subjected to welding or fusion, the welded or fused portions exhibit excellent tensile strength, impact strength, and / or heat resistance. Furthermore, the composition and molded article according to an exemplary embodiment of the present disclosure have a high maximum burst pressure. Therefore, excellent pressure resistance without fluid leakage inside the molded article can be achieved.

[0134] Ultrasonic welding can be used to weld two planar specimens measuring 40mm × 80mm × 3mm under conditions of 1 bar welding pressure, 1.5mm amplitude, and 1.0mm welding depth. The tensile strength before welding is determined according to ISO 527 standard. The weld strength after welding can be determined using a universal testing machine (UTM) to tensile the welded specimen under conditions of 5mm / min speed, 120mm² weld area, load cell capacity of 5kN or higher, test temperature of 23±2℃, and humidity of 50%RH.

[0135] Furthermore, in describing the polyamide resin compositions and molding articles of this disclosure, other conditions or equipment not explicitly described may be appropriately selected within the scope of conventional practice in the art, and there are no particular limitations.

[0136] The present disclosure is described in detail below by way of examples. However, embodiments of the present disclosure may be varied in several different forms, and the scope of the present disclosure should not be construed as limited to the embodiments described below. Examples of this specification are provided to more fully describe the present disclosure to those skilled in the art.

[0137] Preparation Example

[0138] The compositions of the examples and comparative examples were prepared according to Table 1 below. Here, each component is described below, and the numbers in Table 1 refer to weight percent.

[0139] PA6-V (virgin polyamide 6): 50% to 60% amorphous segments, Tm 215°C to 225°C, relative viscosity (RV) 2.2 to 2.5. PA6-R2 (recycled polyamide 6 derived from waste nets and fishing nets) contains less than 1% inorganic filler and has a relative viscosity (RV) of 2.40 to 3.20. PA6-R1 (recycled polyamide 6 derived from end-of-life automotive parts) contains 27% to 35% by weight of inorganic filler (glass fiber). GF1 (High-rigidity glass fiber): Glass fiber with a tensile strength of 88 GPa to 92 GPa and an aspect ratio of 1:1 (L / D, D: 10 μm) for 17 μm-2400 tex rovings, as determined by ASTM D2343. GF1 (high-rigidity glass fiber) is based on 100% GF1 comprising 58% to 62% silica, 14% to 18% alumina, 17% to 24% calcium oxide and magnesium oxide (where calcium oxide content is more than 10% by weight and magnesium oxide content is less than 10% by weight), 0.5% to 2% titanium dioxide, and the balance being less than 1.3% by weight. The balance includes sodium oxide, potassium oxide, and iron oxide.

[0140] GF2: Uses commercially available products with a tensile strength of 83 GPa. GF2 is based on 100 wt% comprising 57 wt% to 61 wt% silica, 11 wt% to 15 wt% alumina, 22 wt% to 29 wt% calcium oxide + magnesium oxide (where calcium oxide content is more than 20 wt% and magnesium oxide content is less than 5 wt%), less than 1.0 wt% titanium dioxide, and the balance less than 1.3 wt%. Here, the balance includes sodium oxide, potassium oxide, and iron oxide. GF2 is determined according to ASTM D2343 for 17 μm-2400 tex rovings, having a tensile modulus of 83 GPa to 87 GPa and exhibiting a 1:1 aspect ratio (L / D, D: 10 μm to 11 μm).

[0141] Heat stabilizer: A masterbatch of polyamide is used, comprising a mixture of a first ether compound (PTMG 3000 from PTG Corporation of Korea, OH value 37 mg KOH / g) and a second ether compound (dipentaerythritol (DPE) with OH value 1190 mg KOH / g to 1320 mg KOH / g). The first and second ether compounds are introduced at a weight ratio of 1:1 to 1:2.5, and the heat stabilizer (masterbatch) contains 50% to 90% polyamide per 100% by weight.

[0142] Other additives 1: Clariant's LICOWAX-OP is used as a lubricant, and KI and CuI products are used as metal stabilizers.

[0143] Other additive 2: Clariant's LICOWAX-OP is used as a lubricant, along with a second ether compound (dipentaerythritol (DPE)). Commercially available antioxidants or stabilizers may be further used.

[0144] The components were added according to the amounts shown in Table 1, and melt-blended in a twin-screw extruder heated to 250°C to 280°C to obtain a granular resin composition. Samples (4 mm thickness, 10 mm width, 170 mm length) were manufactured using a screw injection molding machine at an injection mold temperature of 80°C to 100°C.

[0145] Experimental Example 1

[0146] The properties of the samples obtained above were determined as follows. The results are shown in Table 1.

[0147] Tensile strength (MPa): The tensile strength was determined according to ISO 527 under the conditions of a mark distance of 50 mm, a test speed of 5.0 mm / min, and a temperature of 23 °C. Specimens with a tensile strength of 177 MPa or higher are considered to have excellent mechanical rigidity.

[0148] Tensile strength retention rate before and after aging (%): The tensile strength of the specimen before and after aging at 180°C for 1000 hours is determined according to ISO 527, and the tensile strength retention rate is calculated according to the following mathematical formula 1. Specimens with a tensile strength retention rate of 84% or higher are evaluated as "OK", and specimens with a tensile strength retention rate of less than 84% are evaluated as "NG". [Mathematical Expression 1] Tensile strength retention rate before and after aging (%) = [Tensile strength after aging / Tensile strength before aging] x 100 Whitening test: The sample is aged at 70℃ and 62%RH for 4 weeks. When whitening occurs and the sample surface turns white, the sample is rated as "O". When no whitening occurs, the sample is rated as "X".

[0149] [Table 1]

[0150] As can be seen from Table 1, in the embodiments containing glass fibers with a tensile modulus of 88 GPa or higher, the samples exhibit high tensile strength even when containing recycled polyamide resin. Furthermore, it can be seen that, according to an exemplary embodiment of this disclosure, a heat-resistant stabilizer containing two or more ether compounds is used, thus maintaining tensile strength and preventing whitening despite heat aging.

[0151] Experimental Example 2

[0152] The impact strength of the polyamide resin compositions of Examples 6 to 9, as well as Comparative Examples 5 and 6, was evaluated.

[0153] Impact strength (kJ / m²): The cantilever beam impact strength of a specimen with dimensions of 80mm × 10mm × 4mm is determined according to ISO 180 (Plastics - Determination of cantilever beam impact strength) Type A.

[0154] In addition, the polyamide resin compositions of Examples 6 to 9, as well as Comparative Examples 5 and 6, were ultrasonically welded using a Branson ultrasonic welding machine. Two planar specimens measuring 40 mm × 80 mm × 3 mm were welded together under conditions set to a welding pressure of 1 bar, an amplitude of 1.5 mm, and a welding depth of 1.0 mm to prepare welded specimens. The tensile strength of the welded specimens was then determined, and the strength ratio of the welded specimens based on the tensile strength of the polyamide resin composition (base material) before welding was calculated.

[0155] Strength ratio: The weld strength was determined using a universal testing machine (UTM) to tensile weld specimens under the conditions of a speed of 5 mm / min, a weld area of ​​120 mm², a load cell capacity of 5 kN or more, a test temperature of 23 ± 2 °C, and a humidity of 50% RH. The weld strength ratio (strength ratio) of the weld specimens was calculated based on the tensile strength of the base material determined in Test Example 1. When the strength ratio was 20% or more, the specimen was rated as "excellent". When the strength ratio was 10% or more but less than 20%, the specimen was rated as "moderate". Furthermore, when the strength ratio was less than 10%, the specimen was rated as "poor".

[0156] The compositions of Examples 6 to 9, as well as Comparative Examples 5 and 6, were processed, injection molded, and subjected to ultrasonic welding to obtain intake manifold molded articles. The molded articles include multiple channels and holes. The burst pressure of the molded article component was evaluated as follows.

[0157] Component burst pressure: All channels and holes of the component undergoing ultrasonic welding are completely sealed, and then air or water is injected into one side to gradually increase the internal pressure. Here, the maximum pressure the component can withstand is determined. When the determined maximum pressure is above 8.5 bar, the corresponding component is judged as "passed". When the maximum pressure is below 8.5 bar, the component is judged as "failed".

[0158] [Table 2]

[0159] As can be seen from Table 2, in the examples containing glass fibers with a tensile modulus of 88 GPa or higher, excellent strength is still exhibited after welding. Furthermore, when applied to vehicle parts, etc., they are able to withstand high pressure to achieve strong durability. The polyamide resin composition according to an exemplary embodiment of this disclosure, not only in sample (composition) form but also in product units, even when using recycled polyamide resin, possesses weld strength and durability reliability comparable to or higher than compositions based on chemically synthesized polyamide resins.

Claims

1. A polyamide resin composition comprising: A polyamide resin comprising at least one selected from chemically synthesized polyamide resins and recycled polyamide resins; and Glass fiber with a tensile modulus of 88 GPa or higher. The glass fiber comprises 17% to 24% calcium oxide and magnesium oxide, with the calcium oxide content being more than 10% by weight and the magnesium oxide content being less than 10% by weight.

2. The polyamide resin composition according to claim 1, wherein The polyamide resin includes chemically synthesized polyamide resin and recycled polyamide resin, and Based on 100% by weight of the polyamide resin composition, the polyamide resin composition comprises 5% to 60% by weight of the chemically synthesized polyamide resin and 10% to 80% by weight of the recycled polyamide resin.

3. The polyamide resin composition according to claim 1, wherein The recycled polyamide resin comprises at least one selected from the following: First recycled polyamide resin derived from end-of-life automotive parts; and The second recycled polyamide resin is derived from at least one of waste fishing nets, waste netting, ropes and airbags.

4. The polyamide resin composition according to claim 1, wherein The recycled polyamide resin comprises a first recycled polyamide resin containing inorganic fillers, and Based on 100% by weight of the polyamide resin composition, the content of the first recycled polyamide resin is from 1% by weight to 50% by weight.

5. The polyamide resin composition according to claim 4, in, The inorganic filler is selected from at least one of glass fiber, talc, kaolin, wollastonite, and carbon, and Based on 100% by weight of the first recycled polyamide resin, the first recycled polyamide resin contains 27% to 35% by weight of the inorganic filler.

6. The polyamide resin composition according to claim 1, It further includes heat-resistant stabilizers containing two or more ether compounds.

7. The polyamide resin composition according to claim 6, in, The heat stabilizer is a masterbatch containing the two or more ether compounds and the carrier polymer.

8. The polyamide resin composition according to claim 7, in, The carrier polymer is polyamide.

9. The polyamide resin composition according to claim 6, in, The heat stabilizer comprises a first ether compound with an acid value of 35 mg KOH / g to 40 mg KOH / g and a second ether compound with an acid value of 1190 mg KOH / g to 1320 mg KOH / g.

10. The polyamide resin composition according to claim 9, in, The weight ratio of the first ether compound to the second ether compound is 1:0.5 to 1:

5.

11. The polyamide resin composition according to claim 6, Based on 100% by weight of the polyamide resin composition, it comprises: 50% to 85% by weight of the polyamide resin; 10% to 45% by weight of the glass fiber; and 1% to 20% by weight of the heat stabilizer.

12. The polyamide resin composition according to claim 1, It has a tensile strength of over 177 MPa.

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

14. The molded article according to claim 13, For automotive parts or electrical / electronic components.

15. The molded article according to claim 13, High heat-resistant components for automotive powertrains or intake manifolds.

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