Polyamide resin composition and molded article made from the same

Abstract

The present invention relates to a polyamide resin composition comprising polyamide 6; a long-chain polyamide; an impact resistance agent; and polyamide 66, an aromatic polyamide, or a combination thereof, and to a molded article made therefrom.

Description

[Technical Field]

[0001] The present invention relates to a polyamide resin composition and a molded article made from the same. [Background technology]

[0002] Recently, hydrogen vehicles, which use hydrogen as an energy source, have been attracting much attention as an environmentally friendly form of transportation. However, because hydrogen is explosive, various components used to store and transport hydrogen must be highly safe and functional.

[0003] Hydrogen tanks that store hydrogen are often made with a plastic liner, but these hydrogen tank liners must be highly rigid enough to withstand high-pressure hydrogen and durable enough to maintain their performance during repeated charging. Specifically, hydrogen tank liners must have excellent tensile elongation to withstand high-pressure hydrogen and gas barrier properties to prevent hydrogen permeation. They must also maintain excellent tensile elongation and durability even at low temperatures, which are created during hydrogen charging. Therefore, there is a need for the development of plastic materials that meet all of these physical properties. Summary of the Invention [Problem to be solved by the invention]

[0004] Provided are a polyamide resin composition having excellent mechanical properties at room temperature and low temperatures, high gas barrier properties, and excellent durability, and a molded article made from the composition. [Means for solving the problem]

[0005] In one embodiment, there is provided a polyamide resin composition comprising polyamide 6; a long-chain polyamide; an impact modifier; and polyamide 66, an aromatic polyamide, or a combination thereof, and a molded article comprising the same. [Effects of the Invention]

[0006] The polyamide resin composition according to one embodiment and molded articles produced therefrom exhibit excellent mechanical properties such as tensile elongation not only at room temperature but also at low temperatures of -40°C, and achieve excellent gas barrier properties, chemical resistance, and durability. DETAILED DESCRIPTION OF THE INVENTION

[0007] Although the present invention may be embodied in many different forms, it is not intended to be limited to the embodiments set forth herein.

[0008] The terms used herein are merely used to describe exemplary embodiments and are not intended to limit the present invention. The singular expressions include the plural expressions unless the context clearly indicates otherwise.

[0009] As used herein, "combinations thereof" refers to mixtures, laminates, composites, copolymers, alloys, blends, reaction products, and the like of compositions.

[0010] It should be understood that the terms "comprise," "comprise," or "have" are intended to specify the presence of embodied features, numbers, steps, components, or combinations thereof, but do not preclude the possible presence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0011] Furthermore, particle size and average particle size can be measured by methods well known to those skilled in the art, such as using a particle size analyzer, a transmission electron microscope (TEM), or a scanning electron microscope (SEM). Alternatively, dynamic light scattering (DLS) can be used to measure particle size, and data analysis can be performed to count the number of particles in each particle size range, after which the average particle size can be calculated based on the counted number. Unless otherwise defined, average particle size refers to the diameter (D50) of particles that make up 50% of the cumulative volume in the particle size distribution.

[0012] In one embodiment, a polyamide resin composition is provided that includes polyamide 6, a long-chain polyamide, an impact resistance agent, and polyamide 66, an aromatic polyamide, or a combination thereof. Such a polyamide resin composition has excellent mechanical properties, such as tensile elongation at room temperature and at low temperatures of -40°C, a high gas barrier property, and excellent durability.

[0013] Polyamide 6 Polyamide 6 (PA6) refers to a polyamide produced from ε-caprolactam or 6-aminocaproic acid, and may also be copolymerized with other monomers. Polyamide 6 has excellent mechanical strength, such as tensile elongation, as well as excellent chemical resistance and moldability.

[0014] The relative viscosity of the polyamide 6 may be 1.8 to 3.4, for example, 2.0 to 3.0, or 2.3 to 2.8. Here, the relative viscosity may be measured with a viscometer by adding 1 g of polyamide 6 to 100 ml of 96% sulfuric acid at 20° C. When the relative viscosity of the polyamide 6 satisfies the above range, it can exhibit excellent mechanical strength and maintain appropriate fluidity during injection.

[0015] The amount of amino terminal groups in the polyamide 6 is not particularly limited, but is preferably 1.0×10 -5 ~10.0×10 -5 mol / g, in which case a sufficient degree of polymerization can be obtained, thereby improving the mechanical strength and the like.

[0016] The polyamide 6 can be produced by a well-known method, or a commercially available one can be selected and used.

[0017] The polyamide 6 may be contained in an amount of 10 to 80% by weight, for example, 20 to 80% by weight, 30 to 80% by weight, 40 to 80% by weight, 45 to 75% by weight, or 50 to 70% by weight, based on 100% by weight of the polyamide resin composition. When the polyamide 6 is contained in this range, the polyamide resin composition can achieve excellent mechanical properties, durability, and moldability.

[0018] Long-chain polyamide A long-chain polyamide is a polyamide having a long carbon chain in the repeating unit, specifically a polyamide having 8 to 20 carbon atoms per nitrogen atom in one repeating unit. Here, the number of carbon atoms per nitrogen atom may be, for example, 8 to 18, 8 to 16, 8 to 14, or 8 to 12. The polyamide resin composition according to one embodiment may have improved mechanical properties, such as tensile elongation at low temperatures, by including a long-chain polyamide.

[0019] The long chain polyamide can include, for example, PA8, PA9, PA10, PA11, PA12, PA13, PA48, PA410, PA412, PA414, PA418, PA58, PA510, PA512, PA514, PA518, PA68, PA610, PA612, PA614, PA618, PA88, PA810, PA812, PA1010, PA1012, PA1014, PA1018, PA1210, PA1212, PA1214, PA1218, PA1410, PA1412, PA1414, PA1418, PA8T, PA9T, PA10T, PA12T, PA8I, PA9I, PA10I, PA12I, copolymers thereof, or combinations thereof. The long chain polyamide can be a homopolymer or a copolymer.

[0020] For example, the long-chain polyamide may include PA11, PA12, PA610, PA612, PA618, PA1010, PA1012, PA1212, copolymers thereof, or combinations thereof, in which case the polyamide resin composition may have significantly improved tensile elongation at low temperatures.

[0021] The long-chain polyamide may have a normal molecular weight, and the relative viscosity of the long-chain polyamide may be 1.8 to 4.0 when measured in a 98 wt % sulfuric acid solution at 25°C.

[0022] The content of the long-chain polyamide may be 1 to 25% by weight, for example, 1 to 20% by weight, 1 to 15% by weight, 1 to 10% by weight, 2 to 8% by weight, or 3 to 7% by weight, based on 100% by weight of the polyamide resin composition. When the content range is satisfied, the polyamide resin composition can exhibit excellent mechanical strength and durability at low temperatures.

[0023] Impact Resistant The polyamide resin composition according to one embodiment includes an impact modifier, which can provide a high-rigidity resin. The impact modifier may be, for example, a polyolefin-based rubber, such as ethylene-propylene rubber, ethylene-propylene-diene rubber, ethylene-octene rubber, ethylene-vinyl acetate rubber, or a combination thereof. These modifiers can significantly improve the impact strength of the polyamide resin composition without degrading other physical properties.

[0024] The impact modifier may be modified with maleic anhydride, such as a maleic anhydride-grafted polyolefin rubber, specifically a maleic anhydride-grafted ethylene-octene rubber, etc. When used, it can improve the compatibility of the impact modifier with resin components such as polyamide 6.

[0025] The content of the impact modifier may be 10% by weight to 50% by weight, for example, 10% by weight to 45% by weight, 10% by weight to 40% by weight, 15% by weight to 35% by weight, or 20% by weight to 30% by weight, relative to 100% by weight of the polyamide resin composition. When the content of the impact modifier satisfies the above range, the polyamide resin composition may exhibit excellent impact strength while improving tensile elongation at low temperatures, durability, chemical resistance, etc.

[0026] Polyamide 66, aromatic polyamide, or a combination of these The polyamide resin composition according to one embodiment further contains at least one of polyamide 66 and aromatic polyamide in addition to the above-mentioned components, thereby significantly improving tensile elongation at low temperatures of -40° C. Such a polyamide resin composition is suitable for use as a material for high-performance hydrogen tank liners.

[0027] Polyamide 66 Polyamide 66 (PA66) is a polyamide produced from hexamethylenediamine and adipic acid, and may optionally be copolymerized with other monomers. Polyamide 66 has excellent mechanical strength, chemical resistance, and moldability.

[0028] The relative viscosity of the polyamide 66 may be 1.7 to 3.1. In this case, the melt tension during the production of polyamide 66 is appropriate, allowing for continuous production, and the polyamide 66 has excellent miscibility with other components such as glass fiber. Here, the relative viscosity may be measured using a viscometer by adding 1 g of polyamide 66 to 100 ml of 96% sulfuric acid at 20°C.

[0029] The weight-average molecular weight of the polyamide 66 may be, for example, 11,000 g / mol to 21,000 g / mol. If it is less than this range, the thermal stability of the polyamide 66 may decrease, and if it exceeds this range, the screw torque of the extruder may increase, resulting in a decrease in productivity.

[0030] The polyamide 66 can be produced by a well-known method, or a commercially available product can be selected and used.

[0031] The polyamide 66 can be added to the polyamide resin composition in a certain amount to improve the tensile elongation at low temperatures.

[0032] aromatic polyamide The aromatic polyamide may refer to a semi-aromatic polyamide having an amide group structure and partially having an aromatic group, and may refer to a polyamide having six carbon atoms between amide groups and containing an aromatic structure that is a benzene bond structure.

[0033] Specific examples of the aromatic polyamide include polyamide 6I, polyamide 6I / 66, polyamide 6T / 6I / 66, polyamide 6T, polyamide 6T / 66, and, Polyamide 6T / D TFor example, the aromatic polyamide may be polyamide 6I. The polyamide 6I may be added to the polyamide resin composition in a certain amount to improve tensile elongation at low temperatures without deteriorating other physical properties.

[0034] The aromatic polyamide may have a melting point of approximately 280° C. to 330° C. and a glass transition temperature of approximately 80° C. to 180° C. The aromatic polyamide may have a normal molecular weight.

[0035] The content of the polyamide 66, aromatic polyamide, or a combination thereof may be 5% by weight to 20% by weight, for example, 5% by weight to 15% by weight, or 7% by weight to 13% by weight, relative to 100% by weight of the polyamide resin composition. When the content is within this range, the polyamide resin composition can achieve excellent mechanical strength at low temperatures, as well as excellent chemical resistance and durability.

[0036] Meanwhile, in the polyamide resin composition, the weight ratio of (long-chain polyamide):(polyamide 66, aromatic polyamide, or a combination thereof) may be 10:90 to 50:50, for example, 20:80 to 40:60, etc. When such a weight ratio is satisfied, tensile elongation at low temperatures can be maximized and price competitiveness can be achieved.

[0037] Other additives The polyamide resin composition may further contain other additives as needed, such as a plasticizer, a flame retardant, a heat resistance agent, an antioxidant, a reinforcing agent, a mold release agent, a dye, a pigment, an ultraviolet absorber, a nucleating agent, a lubricant, or a combination thereof.

[0038] The other additives may be included in an amount of 0 to 10% by weight, for example, 0.1 to 9%, 0.1 to 6%, 0.1 to 5%, 0.1 to 4%, 0.1 to 3%, 0.1 to 2%, or 0.2 to 1% by weight, based on the total weight of the polyamide resin composition, in which case the purpose of the additive can be achieved without affecting other physical properties.

[0039] The polyamide resin composition may contain, for example, 10% by weight to 80% by weight of polyamide 6; 1% by weight to 20% by weight of a long-chain polyamide; 10% by weight to 50% by weight of an impact resistance agent; 5% by weight to 20% by weight of polyamide 66, an aromatic polyamide, or a combination thereof; and 0% by weight to 10% by weight of other additives.

[0040] As a specific example, the polyamide resin composition may include 45% by weight to 75% by weight of polyamide 6; 1% by weight to 10% by weight of a long-chain polyamide; 15% by weight to 35% by weight of an impact resistance agent; 5% by weight to 15% by weight of polyamide 66, an aromatic polyamide, or a combination thereof; and 0% by weight to 5% by weight of other additives.

[0041] Such a polyamide resin composition has excellent mechanical properties, chemical resistance, and durability, and is particularly excellent in mechanical properties such as tensile elongation at low temperatures. Therefore, the polyamide resin composition is suitable as a material for hydrogen storage parts in devices that use hydrogen as an energy source. For example, the polyamide resin composition may be a polyamide resin composition for a hydrogen tank liner.

[0042] In one embodiment, a molded article is provided comprising the polyamide resin composition described above. The molded article may be, for example, a hydrogen storage device in a vehicle that uses hydrogen as an energy source, such as a hydrogen tank liner for a hydrogen vehicle.

[0043] The molded article according to one embodiment may have a tensile elongation of 70% or more at a low temperature of -40°C.

[0044] [Example] Examples of the present invention and comparative examples are described below. The following examples are merely examples of the present invention, and the present invention is not limited to the following examples.

[0045] Example 1 A polyamide resin composition is produced by mixing 60% by weight of polyamide 6 (PA6), 5% by weight of PA1012 as a long-chain polyamide, 25% by weight of ethylene-octene rubber (EOR) as an impact resistance agent, and 10% by weight of polyamide 66 (PA66) using an extruder.

[0046] The extrusion temperature is changed to 250°C to 280°C, and the screw speed is changed to 250 rpm to 450 rpm, and the polyamide resin composition is extruded and cooled to produce pellets. The obtained pellets are fed into an injection molding machine to produce a molded product in the form of a multipurpose test piece.

[0047] Example 2 A composition and a molded article are produced in the same manner as in Example 1, except that PA6I is used instead of PA66.

[0048] Example 3 The compositions and molded articles are prepared in the same manner as in Example 1, except that a PA66 and PA6I blend is used instead of the PA66 in Example 1.

[0049] Example 4 The composition and molded article are prepared in the same manner as in Example 2, except that 25% of the long-chain polyamide is used in Example 2.

[0050] Comparative Examples 1 and 2 A composition and a molded article are produced in the same manner as in Example 1, except that PA66 is not used and each component is mixed in the amounts shown in Table 1 below.

[0051] Comparative Example 3 A composition and a molded article are produced in the same manner as in Example 1, except that no long-chain polyamide is used and each component is mixed in the amounts shown in Table 1 below.

[0052] Comparative Example 4 A composition and a molded article were produced in the same manner as in Example 1, except that no impact resistance agent was used and the components were mixed in the amounts shown in Table 1 below.

[0053] [Table 1]

[0054] Evaluation example The molded articles produced in the examples and comparative examples were evaluated for tensile strength, tensile elongation, and impact strength at room temperature (23°C) and low temperature (-40°C) by the following methods, and the results are shown in Table 2 below.

[0055] The tensile strength and tensile elongation are evaluated according to ISO 527 at 50 mm / min.

[0056] The Izod impact strength is evaluated according to ISO 180 using a 3.2 mm thick specimen with a notch in the center at 23°C using a 5.5 J impact hammer.

[0057] For low-temperature properties, the specimens are aged at -40°C for 4 hours, and then the tensile strength, tensile elongation, Izod impact strength, etc. are evaluated in a chamber maintained at -40°C with liquid nitrogen.

[0058] [Table 2]

[0059] Referring to Table 2, it can be seen that Examples 1 to 4 are all excellent in physical properties such as tensile strength, tensile elongation, and impact strength at room temperature and low temperature. On the other hand, in Comparative Example 1, which did not use PA66 or PA6I, the tensile elongation at low temperature was significantly low, and in Comparative Example 2, which increased the content of long-chain polyamide, the tensile elongation increased compared to Comparative Example 1, but did not reach the level of the Examples. Comparative Example 3, which did not use a long-chain polyamide, also had the problem of significantly low tensile elongation at low temperature, and Comparative Example 4, which did not use an impact modifier, had significantly low impact strength at room temperature and low temperature, and significantly low tensile elongation at low temperature due to processing issues.

[0060] Although the preferred embodiment has been described in detail above, the scope of the present invention is not limited to this, and various modifications and improvements made by those skilled in the art using the basic concept defined in the claims also fall within the scope of the present invention.

Claims

1. A polyamide resin composition, comprising: Based on 100% by weight of the polyamide resin composition, 45% to 75% by weight of polyamide 6; 1% to 10% by weight of a long chain polyamide; 15% to 35% by weight of an impact modifier; 5% to 15% by weight of polyamide 66, aromatic polyamide, or a combination thereof; and 0% to 5% by weight of other additives Including, The long-chain polyamide is a homopolymer having 8 to 20 carbon atoms per nitrogen atom in one repeating unit, The weight ratio of (long chain polyamide):(polyamide 66, aromatic polyamide, or a combination thereof) is 20:80 to 40:

60. Polyamide resin composition.

2. 2. The polyamide resin composition according to claim 1, wherein the polyamide 6 has a relative viscosity of 1.8 to 3.

4.

3. The polyamide resin composition of claim 1, wherein the long-chain polyamide comprises PA8, PA9, PA10, PA11, PA12, PA13, PA48, PA410, PA412, PA414, PA418, PA58, PA510, PA512, PA514, PA518, PA68, PA610, PA612, PA614, PA618, PA88, PA810, PA812, PA1010, PA1012, PA1014, PA1018, PA1210, PA1212, PA1214, PA1218, PA1410, PA1412, PA1414, PA1418, PA8T, PA9T, PA10T, PA12T, PA8I, PA9I, PA10I, PA12I, or a mixture thereof.

4. 2. The polyamide resin composition of claim 1, wherein the long-chain polyamide comprises PA11, PA12, PA610, PA612, PA618, PA1010, PA1012, PA1212, or mixtures thereof.

5. 2. The polyamide resin composition of claim 1, wherein the impact modifier comprises ethylene-propylene rubber, ethylene-propylene-diene rubber, ethylene-octene rubber, ethylene-vinyl acetate rubber, or a combination thereof.

6. 2. The polyamide resin composition according to claim 1, wherein the polyamide 66 has a relative viscosity of 1.7 to 3.

1.

7. 2. The polyamide resin composition according to claim 1, wherein the aromatic polyamide has a melting point of 280°C to 330°C and a glass transition temperature of 80°C to 180°C.

8. 2. The polyamide resin composition according to claim 1, wherein the other additives include a plasticizer, a flame retardant, a heat resistance agent, an antioxidant, a reinforcing agent, a mold release agent, a dye, a pigment, an ultraviolet absorber, a nucleating agent, a lubricant, or a combination thereof.

9. A molded article made of the polyamide resin composition according to any one of claims 1 to 8.

10. The molded article of claim 9, wherein the molded article is a hydrogen tank liner.

Images