Polyamide resin composition and molded article produced using the same

Abstract

Provided is a polyamide resin composition comprising 38 to 82% by weight of polyamide 6 (PA6), 1 to 30% by weight of a long-chain polyamide, 15 to 35% by weight of an impact resistance agent containing a polyolefin-based rubber, 0.1 to 1.0% by weight of an antioxidant containing a phenol-based antioxidant, an amine-based antioxidant, a phosphite-based antioxidant, or a mixture thereof, and 0.1 to 1.0% by weight of a mold release agent containing ethylene bisstearamide.

Description

[Technical Field]

[0001] The present disclosure relates to a polyamide resin composition and a molded article for a pressure vessel liner produced using the same. [Background technology]

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

[0003] Hydrogen tanks that store hydrogen may have a plastic interior liner, but such hydrogen tank liners must be highly rigid to withstand high-pressure hydrogen and durable enough to maintain their performance during repeated hydrogen filling. Specifically, hydrogen tank liners must have excellent tensile elongation to withstand high-pressure hydrogen and gas barrier properties to prevent hydrogen permeation. Furthermore, since a low-temperature environment is created during hydrogen filling, the liner must also have excellent tensile elongation and durability even at such low temperatures. Therefore, there is a need for the development of a plastic material that simultaneously satisfies all of these physical properties. Summary of the Invention [Problem to be solved by the invention]

[0004] In one aspect, the present invention provides a polyamide resin composition that contains a small amount of long-chain polyamide but has excellent mechanical properties at room temperature and low temperature, high gas barrier properties, and excellent durability.

[0005] Another aspect of the embodiment provides a molded article for a pressure vessel liner produced using the polyamide resin composition. [Means for solving the problem]

[0006] According to one embodiment, there is provided a polyamide resin composition comprising 38 to 82% by weight of polyamide 6 (PA6), 1 to 30% by weight of a long-chain polyamide, 15 to 35% by weight of an impact resistance agent including a polyolefin-based rubber, 0.1 to 1.0% by weight of an antioxidant including a phenol-based antioxidant, an amine-based antioxidant, a phosphite-based antioxidant, or a mixture thereof, and 0.1 to 1.0% by weight of a mold release agent including ethylene bisstearamide.

[0007] The relative viscosity of polyamide 6 may be between 1.8 and 3.4.

[0008] Long chain polyamides can be polyamides having from 8 to 20 carbon atoms per nitrogen atom in a repeating unit.

[0009] The long chain polyamide can include 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 mixtures thereof.

[0010] The long chain polyamide may include PA11, PA12, PA610, PA612, PA618, PA1010, PA1012, PA1212, copolymers thereof, or mixtures thereof.

[0011] The polyamide resin composition may contain 15 to 25 wt % of the long chain polyamide based on the total weight of the polyamide resin composition.

[0012] The impact modifier may further comprise ethylene-propylene rubber, ethylene-propylene-diene rubber, ethylene-vinyl acetate rubber, or mixtures thereof.

[0013] The release agent may further comprise a polyethylene-based release agent, an ester-based release agent, or a mixture thereof.

[0014] The polyamide resin composition has a tensile elongation (ISO527, measurement speed: 50 mm / min) of 30% or more at low temperature (-40°C), and an impact strength (ISO180, IZOD) of 20 kJ / m 2 It could be more than that.

[0015] According to another embodiment, there is provided a molded article for a pressure vessel liner manufactured using the polyamide resin composition. [Effects of the Invention]

[0016] The polyamide resin composition according to the embodiment contains a small amount of long-chain polyamide, yet has high tensile elongation (ISO527, measurement speed: 50 mm / min) not only at room temperature but also at low temperature (-40°C), and has excellent impact strength (ISO180, IZOD) at low temperature (-40°C). It also exhibits excellent mechanical properties such as tensile elongation, and can realize excellent gas barrier properties, chemical resistance, and durability, and can therefore be used as a molding material for pressure vessel liners. DETAILED DESCRIPTION OF THE INVENTION

[0017] The advantages and features of the technology described below, and methods for achieving them, will become clearer with reference to a series of examples described in detail below. However, the embodiments are not limited to the series of examples disclosed below. Unless otherwise defined, all terms (including technical and scientific terms) used in this specification should be used in a manner commonly understood by those skilled in the art. Furthermore, terms defined in commonly used dictionaries should not be interpreted as ideal or excessive unless specifically defined.

[0018] Throughout this specification, when a part "comprises" a certain element, this does not mean excluding other elements, but may further include other elements, unless otherwise specified. Also, the singular form includes the plural form unless the wording specifically states otherwise.

[0019] The polyamide resin composition according to one embodiment includes polyamide 6, a long-chain polyamide, an impact modifier, an antioxidant, and a mold release agent.

[0020] Long-chain polyamides have the advantage of maintaining tensile elongation and impact strength at low temperatures (-40°C). However, to achieve this effect, the long-chain polyamide must be used in an amount of 10% by weight or more based on the total weight of the polyamide resin composition.

[0021] According to one embodiment, the polyamide resin composition contains 38 to 82% by weight of polyamide 6 (PA6), 1 to 30% by weight of a long-chain polyamide, 15 to 30% by weight of an impact resistance agent including a polyolefin-based rubber, 0.1 to 1.0% by weight of an antioxidant including a phenol-based antioxidant, an amine-based antioxidant, a phosphite-based antioxidant, or a mixture thereof, and 0.1 to 1.0% by weight of a release agent including ethylene bisstearamide. Therefore, despite the low content of long-chain polyamide, the polyamide resin composition has excellent mechanical properties at room and low temperatures, high gas barrier properties, and excellent durability.

[0022] Polyamide 6 (PA6) refers to a polyamide produced from ε-caprolactam or 6-aminocaproic acid, and may be copolymerized with other monomers in some cases. Polyamide 6 has excellent mechanical strength, such as tensile elongation, as well as excellent chemical resistance and moldability.

[0023] The relative viscosity of 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 polyamide 6 satisfies this range, it can exhibit excellent mechanical strength and maintain appropriate fluidity during injection.

[0024] There is no particular limitation on the amount of amino terminal groups in polyamide 6. -5 mol / g~10.0X10 -5 mol / g, in which case a sufficient degree of polymerization can be obtained, and the mechanical strength and the like can be improved.

[0025] Polyamide 6 can be produced by a known method or commercially available polyamide 6 can be selected and used.

[0026] The polyamide 6 may be included in an amount of 38 to 82 wt % of the total weight of the polyamide resin composition, for example, 39.5 to 79.5 wt %. When the polyamide 6 is included in this range, the polyamide resin composition may exhibit excellent mechanical properties, durability, and moldability.

[0027] Long-chain polyamides are polyamides having long carbon chains in their repeating units, specifically polyamides 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. By including a long-chain polyamide, the polyamide resin composition can improve mechanical properties such as tensile elongation at low temperatures.

[0028] 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 mixtures thereof. The long chain polyamide can be a homopolymer or a copolymer.

[0029] For example, the long-chain polyamide may include PA11, PA12, PA610, PA612, PA618, PA1010, PA1012, PA1212, copolymers thereof, or mixtures thereof, which can significantly improve the tensile elongation of the polyamide resin composition at low temperatures.

[0030] The long chain polyamide may have a conventional molecular weight, and the relative viscosity of the long chain polyamide may be from 1.8 to 4.0 when measured in a 98% by weight sulfuric acid solution at 25°C.

[0031] The content of the long-chain polyamide may be 1 to 30% by weight, for example, 1 to 25% by weight, 5 to 25% by weight, 10 to 25% by weight, or 15 to 25% by weight, based on 100% by weight of the polyamide resin composition. When this content range is satisfied, the polyamide resin composition can exhibit excellent mechanical strength and durability at low temperatures.

[0032] For example, the polyamide resin composition has a tensile elongation (ISO527, measurement speed: 50 mm / min) of 30% or more at low temperature (-40°C) and an impact strength (ISO180, IZOD) of 20 kJ / m 2 It could be more than that.

[0033] The polyamide resin composition may contain an impact modifier, thereby realizing a resin with high rigidity. The impact modifier may be, for example, a polyolefin 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 deteriorating other physical properties.

[0034] The impact modifier may be modified with maleic anhydride, for example, a polyolefin rubber grafted with maleic anhydride, specifically, an ethylene-octene rubber grafted with maleic anhydride. For example, the impact modifier may include an ethylene-octene copolymer and a compound grafted with one or more of an α,β-unsaturated carboxylic acid, an α,β-unsaturated anhydride, and derivatives thereof in an amount of 0.5 to 5 parts by weight per 100 parts by weight of the ethylene-octene copolymer.

[0035] When this is used, the kneading characteristics of the resin component such as polyamide 6 and the impact resistance agent can be improved.

[0036] The content of the impact modifier may be 15 to 35 wt %, for example, 15 to 30 wt %, based on the total weight of the polyamide resin composition. When the content of the impact modifier satisfies this range, the polyamide resin composition can exhibit excellent impact strength while improving tensile elongation at low temperatures, durability, chemical resistance, etc.

[0037] The antioxidant prevents deterioration of physical properties due to heat that can occur during the manufacturing of molded hydrogen tank liners, and exerts a synergistic effect in improving heat resistance.

[0038] The antioxidant may include a phenolic, an amine, a phosphite antioxidant, or mixtures thereof.

[0039] The content of the antioxidant may be 0.1 wt% to 1.0 wt%, for example, 0.1 wt% to 0.3 wt%, based on the total weight of the polyamide resin composition. If the content of the antioxidant is less than 0.1 wt%, the effect of improving heat resistance may be insufficient, while if it exceeds 1.0 wt%, gas generation during injection molding may cause poor surface condition.

[0040] The release agent may include an ethylene bisstearamide-based, polyethylene-based, ester-based release agent, or a mixture thereof.

[0041] The content of the release agent may be 0.1 wt% to 1.0 wt%, for example, 0.1 wt% to 0.5 wt%, based on the total weight of the polyamide resin composition. If the content of the release agent is less than 0.1 wt%, the release properties during molding may be poor, and if it exceeds 0.5 wt%, slippage and gas generation may occur during extrusion and injection processing.

[0042] Optionally, the polyamide resin composition may further contain at least one of polyamide 66 and aromatic polyamide in addition to the above-mentioned components, thereby dramatically improving the 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.

[0043] Optionally, the polyamide resin composition may further contain other additives as needed, such as a plasticizer, a flame retardant, an antioxidant, a reinforcing agent, a dye, a pigment, an ultraviolet absorber, a nucleating agent, a lubricant, or a combination thereof.

[0044] Other additives may be included in an amount of 0 to 10 wt % based on the total weight of the polyamide resin composition, for example, 0.1 to 9 wt %, 0.1 to 6 wt %, 0.1 to 5 wt %, 0.1 to 4 wt %, 0.1 to 3 wt %, 0.1 to 2 wt %, or 0.2 to 1 wt %, such that the purpose of the additive can be achieved without affecting other physical properties.

[0045] The polyamide resin composition can be produced by any of the general methods for producing polyamide resin compositions, and an example thereof is a method using a single-screw or twin-screw extruder.

[0046] In another embodiment, there is provided a molded pressure vessel liner manufactured using the polyamide resin composition described above.

[0047] The method for producing a molded article for a pressure vessel liner using the polyamide resin composition is not particularly limited, and any of the general methods for producing a polyamide resin molded article can be used.

[0048] The molded article for a pressure vessel liner can be, for example, a hydrogen storage device in a transportation system that uses hydrogen as energy, and one example is a hydrogen tank liner for a hydrogen automobile.

[0049] The molded article for pressure vessel liners can have a tensile elongation of 70% or more at a low temperature of −40° C. That is, because the molded article for pressure vessel liners is produced using the polyamide resin described above, it has excellent gas barrier properties, and good tensile elongation at a low temperature (−40° C.) and impact resistance at a low temperature (−40° C.).

[0050] Specific examples of the present invention will be presented below. However, the examples described below are merely for the purpose of specifically illustrating and explaining the present invention, and should not be construed as limiting the scope of the present invention.

[0051] [Production Example: Production of Polyamide Resin Composition] Example 1 A polyamide resin composition is produced using an extruder by mixing 79.5% by weight of polyamide 6 (PA6), 5% by weight of PA1012 as a long-chain polyamide, 25% by weight of ethylene-octene rubber (493D) as an impact resistance agent, 0.3% by weight of ethylene bisstearamide (EBS) as a mold release agent, and 0.2% by weight of an antioxidant (a mixture of a phenolic antioxidant and a phosphite-based antioxidant).

[0052] The polyamide resin composition is extruded at an extrusion temperature of 250 to 280°C and a screw speed of 250 to 450 rpm, and cooled to produce pellets. The obtained pellets are fed into an injection molding machine to produce molded products in the form of multipurpose test pieces.

[0053] (Examples 2 to 8) As shown in Table 1, compositions and molded articles were produced in the same manner as in Example 1, except that the contents of polyamide 6, long-chain polyamide, and impact resistance agent were changed.

[0054] (Comparative Example 1) A polyamide resin composition is produced using an extruder by mixing 89.5 wt% of polyamide 6 (PA6), 5 wt% of PA1012 as a long-chain polyamide, 5 wt% of ethylene-octene rubber (493D) as an impact resistance agent, 0.3 wt% of ethylene bisstearamide (EBS) as a mold release agent, and 0.2 wt% of an antioxidant (a mixture of a phenolic antioxidant and a phosphite antioxidant).

[0055] The polyamide resin composition is extruded at an extrusion temperature of 250 to 280°C and a screw speed of 250 to 450 rpm, and then cooled to produce pellets. The obtained pellets are then fed into an injection molding machine to produce molded products in the form of multipurpose test specimens.

[0056] (Comparative Example 2) A polyamide resin composition was produced using an extruder by mixing 84.5% by weight of polyamide 6 (PA6), 15% by weight of ethylene-octene rubber (493D) as an impact resistance agent, 0.3% by weight of ethylene bisstearamide (EBS) as a mold release agent, and 0.2% by weight of an antioxidant (a mixture of a phenol-based antioxidant and a phosphite-based antioxidant).

[0057] The polyamide resin composition is extruded at an extrusion temperature of 250 to 280°C and a screw speed of 250 to 450 rpm, and then cooled to produce pellets. The obtained pellets are then fed into an injection molding machine to produce molded products in the form of multipurpose test specimens.

[0058] (Comparative Example 3) 69.5% by weight of polyamide 6 (PA6), 30% by weight of ethylene-octene rubber (493D) as an impact resistance agent, 0.3% by weight of ethylene bisstearamide (EBS) as a mold release agent, and 0.2% by weight of an antioxidant (a mixture of a phenol-based antioxidant and a phosphite-based antioxidant) are mixed together, and a polyamide resin composition is produced using an extruder.

[0059] The polyamide resin composition is extruded at an extrusion temperature of 250 to 280°C and a screw speed of 250 to 450 rpm, and then cooled to produce pellets. The obtained pellets are then fed into an injection molding machine to produce molded products in the form of multipurpose test specimens.

[0060] Comparative Example 4 A polyamide resin composition is produced using an extruder by mixing 34.5% by weight of polyamide 6 (PA6), 25% by weight of PA1012 as a long-chain polyamide, 40% by weight of ethylene-octene rubber (493D) as an impact resistance agent, 0.3% by weight of ethylene bisstearamide (EBS) as a mold release agent, and 0.2% by weight of an antioxidant (a mixture of a phenol-based antioxidant and a phosphite-based antioxidant).

[0061] The polyamide resin composition is extruded at an extrusion temperature of 250 to 280°C and a screw speed of 250 to 450 rpm, and then cooled to produce pellets. The obtained pellets are then fed into an injection molding machine to produce molded products in the form of multipurpose test specimens.

[0062] [Table 1]

[0063] (unit: weight %) 1) PA6: Polyamide 6 (Hyosung 1031BRT product) 2) PA1012: Long-chain polyamide (Sandongdongcheon's PA1012 product) 3) Impact resistance agent: ethylene-octene rubber (DUPONT FUSAMOND N493 product) 4) Release agent: Ethylene bisstearamide (HI-LUBE product of Shinwan Chemical Co., Ltd.) 5) Antioxidant: A mixture of phenolic and phosphite antioxidants (ASC BB98240 product)

[0064] [Experimental example: Measurement of physical properties of polyamide resin molded products] 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.

[0065] The tensile strength and tensile elongation are evaluated according to ISO527 at 50 mm / min.

[0066] The Izod impact strength is evaluated according to ISO 180 using a 3.2 mm thick test piece with a notch in the center at 23°C using a 5.5 J impact hammer.

[0067] For low-temperature properties, test pieces 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.

[0068] [Table 2]

[0069] 1)nb:non-breakable

[0070] Referring to Table 2, it can be seen that Examples 1 to 8 have excellent physical properties such as tensile strength, tensile elongation, and impact strength at room temperature and low temperature. In particular, Examples 1 and 2 have excellent physical properties at low temperature even when containing only 5 wt% long-chain polyamide.

[0071] In Comparative Examples 2 and 3, the absence of long-chain polyamide resulted in poor physical properties at low temperatures, and in Comparative Example 1, the impact modifier content should be 15 wt % or more. Also, in Comparative Example 4, when the impact modifier content was too high, the tensile elongation and impact strength at low temperatures were excellent, but the tensile strength was significantly low.

[0072] Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concept of the present invention defined in the following claims also fall within the scope of the present invention. [Industrial Applicability]

[0073] The present disclosure relates to a polyamide resin composition for hydrogen tank liners and a molded article produced using the same, and provides a polyamide resin composition that contains a small amount of long-chain polyamide but has excellent mechanical properties at room temperature and low temperature, high gas barrier properties, and excellent durability.

Claims

1. Polyamide 6 (PA6) 38% to 82% by weight, 1% to 30% by weight of a long-chain polyamide, 15% to 35% by weight of an impact resistance agent including a polyolefin rubber; 0.1% to 1.0% by weight of an antioxidant, including a phenolic antioxidant, an amine antioxidant, a phosphite antioxidant, or a mixture thereof; and A polyamide resin composition comprising 0.1% by weight to 1.0% by weight of a mold release agent comprising ethylene bisstearamide.

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. 2. The polyamide resin composition according to claim 1, wherein the long-chain polyamide is a polyamide having 8 to 20 carbon atoms per nitrogen atom in one repeating unit.

4. 4. The polyamide resin composition according to claim 3, 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, copolymers thereof, or mixtures thereof.

5. 5. The polyamide resin composition according to claim 4, wherein the long-chain polyamide comprises PA11, PA12, PA610, PA612, PA618, PA1010, PA1012, PA1212, copolymers thereof, or mixtures thereof.

6. The polyamide resin composition according to claim 1, wherein the polyamide resin composition contains 15 to 25 wt% of the long-chain polyamide based on the total weight of the polyamide resin composition.

7. 2. The polyamide resin composition according to claim 1, wherein the impact modifier further comprises ethylene-propylene rubber, ethylene-propylene-diene rubber, ethylene-vinyl acetate rubber, or a mixture thereof.

8. 2. The polyamide resin composition according to claim 1, wherein the release agent further comprises a polyethylene-based release agent, an ester-based release agent, or a mixture thereof.

9. The polyamide resin composition comprises The tensile elongation at low temperature (-40°C) (ISO527, measurement speed: 50 mm / min) is 30% or more, Impact strength (ISO180, IZOD) at low temperature (-40°C) is 20kJ / m ２ The polyamide resin composition according to claim 1 .

10. A molded product for a pressure vessel liner, produced using the polyamide resin composition according to any one of claims 1 to 9.

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