Hydrogen-resistant toughening material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of hydrogen storage, in particular to a hydrogen-resistant toughening material and a preparation method and application thereof. The hydrogen-resistant toughening material is prepared from the following components in percentage by mass: 95%-60% of PA6 resin, 5%-40% of a modifier, 0.1%-0.5% of a lubricant and 0.1%-0.8% of an antioxidant. The modifier containing the maleic anhydride group has high compatibility with PA6 resin, and a PA6 modified material prepared through blending modification has high hydrogen barrier property, excellent toughness, good processability, excellent moisture resistance and balanced comprehensive performance. The raw materials are sufficient and easy to obtain, the process is simple and feasible, the price is relatively appropriate, compared with a rotational molding process and a blow molding process, the prepared liner material can realize high-precision rapid molding of a compact product under high pressure through an injection molding process, the boiling process of a PA6 hydrogen storage cylinder liner is omitted, large-scale production is facilitated, and the production cost is reduced. The preparation method has wide prospects in development and application of IV-type hydrogen storage cylinder liner materials.

Description

Technical Field

[0001] This invention relates to the field of hydrogen storage technology, and in particular to a hydrogen-barrier toughening material, its preparation method, and its application. Background Technology

[0002] The information disclosed in the background section of this invention is intended only to enhance the understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Carbon fiber wound hydrogen storage cylinders (Type IV) represent an inevitable trend in hydrogen storage. The application of composite material layers and plastic inner liners significantly increases the hydrogen storage density of these cylinders. The inner liner primarily functions to seal the gas and support the carbon fiber layers; commonly used materials include high-density polyethylene and polyamide.

[0004] Polyamides, as an important class of engineering plastics, occupy a significant position in materials science due to their diverse properties and wide range of applications. Among them, PA6 resin is one of the most widely used polyamide varieties because of its excellent mechanical strength, outstanding barrier properties, good heat resistance, and relatively low cost. However, PA6 resin faces several technical challenges in the application of hydrogen storage cylinder liners: First, its low-temperature toughness is insufficient, making it prone to brittle fracture in extreme environments; second, the material is highly sensitive to notches, posing a risk of stress concentration; and third, its high water absorption leads to fluctuations in dimensional stability and mechanical properties. These characteristics make it easy to generate significant internal stress during the processing of hydrogen storage cylinder liners when directly using PA6 resin. A complex boiling process is necessary to relieve stress, balance moisture absorption, and improve toughness, increasing the complexity of the production process.

[0005] To address these issues, material modification has become a necessary approach. Currently, PA6 modified materials specifically for hydrogen storage cylinder liners have been developed on the international market. While these materials have been validated in laboratories and achieved small-scale applications, they still face industrialization bottlenecks such as high costs and immature large-scale production processes. In contrast, domestic research and development in this field lags behind, mature products are scarce, and most research remains in the laboratory stage, without achieving large-scale production or practical engineering applications. This technological gap makes the development of high-performance, low-cost PA6 modified materials suitable for large-scale production a current research focus and challenge. Summary of the Invention

[0006] In view of this, the present invention provides a hydrogen-barrier toughening material, its preparation method, and its application. The hydrogen-barrier toughening material prepared by the present invention has high hydrogen barrier performance, excellent toughness, good processability, and excellent moisture resistance. The process is simple, the price is relatively reasonable, and the overall performance is balanced. It can be used to achieve high-precision rapid molding of dense products under high pressure through injection molding, and has broad prospects in the development and application of Type IV hydrogen storage cylinder liner materials.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solution: In a first aspect, the present invention provides a hydrogen-barrier toughening material, wherein the material is composed of the following components by mass fraction: 60%~95% PA6 resin, 5%~40% modifier, 0.1%~0.5% lubricant, and 0.1%~0.8% antioxidant.

[0008] Furthermore, the hydrogen-barrier toughening material is composed of the following components by mass fraction: 70%~90% PA6 resin, 10%~30% modifier, 0.2%~0.5% lubricant, and 0.1%~0.6% antioxidant.

[0009] Furthermore, the melt index of the PA6 resin is 15-40 g / 10min.

[0010] Furthermore, the modifier comprises one or more of the following: maleic anhydride-grafted POE (POE-g-MAH), maleic anhydride-grafted LLDPE (LLDPE-g-MAH), maleic anhydride-grafted HDPE (HDPE-g-MAH), maleic anhydride-grafted EPDM (EPDM-g-MAH), maleic anhydride-grafted EVA (EVA-g-MAH), and maleic anhydride-grafted SEBS (SEBS-g-MAH).

[0011] Furthermore, the lubricant comprises one or more of silicone oil, ethylene bis-stearamide, zinc stearate, calcium stearate, and pentaerythritol stearate (PETS).

[0012] Furthermore, the antioxidants include hindered phenolic antioxidants and phosphite antioxidants.

[0013] Further, the antioxidant is one or a combination of two or more of antioxidant 1010, antioxidant 168, and antioxidant 1098.

[0014] PA6 matrix has excellent hydrogen barrier properties, and the modifier has excellent toughness. The maleic anhydride group in the modifier is chemically combined with the amino group in the PA6 molecular chain, so that the two have good compatibility. The toughness (especially low temperature toughness), moisture resistance and processability of the blend are improved.

[0015] Secondly, the present invention provides a method for preparing the above-mentioned hydrogen-barrier toughening material, comprising the following steps: S1. Weigh out PA6 resin, modifier, antioxidant, and lubricant according to their respective mass fractions, and set aside for later use; S2. Vacuum dry the PA6 resin in S1 at 70-90℃ for 4-10 hours, and then mix the PA6 resin, modifier, antioxidant and lubricant evenly. S3. Add the raw materials mixed in S2 into a twin-screw extruder. After melt blending and extrusion, the blend is drawn, water-cooled, and pelletized to obtain PA6 modified material. S4. The PA6 modified material obtained in S3 is vacuum dried at 70-90 ℃ for 20-36 hours to obtain a hydrogen-barrier toughened material.

[0016] Furthermore, the temperatures of each zone and the die head of the twin-screw extruder are set to 210-230 ℃, 220-240 ℃, 230-250 ℃, 230-250 ℃, 230-250 ℃, 230-250 ℃, and 230-250 ℃, respectively.

[0017] Furthermore, the main engine speed of the twin-screw extruder during blending is set to 290-310 r / min.

[0018] Thirdly, the present invention provides the application of the hydrogen-barrier toughening material described in the first aspect or the hydrogen-barrier toughening material prepared in the second aspect in the preparation of the inner liner of a type IV hydrogen storage cylinder.

[0019] Fourthly, the present invention provides a method for preparing a hydrogen-barrier and toughened Type IV hydrogen storage cylinder liner, wherein the molding process is injection molding, and includes the following steps: S1. Vacuum dry the hydrogen-barrier toughening material at 70-90℃ for 4-10 hours; S2. Add the dried material from S1 into the barrel of the injection molding machine and heat it to melt and plasticize it under segmented temperature control. S3. The material plasticized in S2 is injected into the cavity of the inner liner mold of the type IV hydrogen storage cylinder under high pressure; S4. Dynamically cool and demold the mold to obtain the hydrogen-barrier and toughened Type IV hydrogen storage bottle liner.

[0020] Furthermore, the temperatures of each zone and the injection molding head of the injection molding machine described in S2 are controlled at 175-195℃, 210-230℃, 230-250℃, 240-260℃, 230-250℃, and 230-250℃, respectively.

[0021] Furthermore, the pressure in S3 is set to 80-120 bar.

[0022] Compared with the prior art, the present invention has achieved the following beneficial effects: (1) The modifier containing maleic anhydride groups described in this invention has strong compatibility with PA6 resin. The PA6 modified material prepared by blending modification has high hydrogen barrier properties, excellent toughness, good processing performance and excellent moisture resistance. The overall performance is balanced and can meet the material performance requirements of the inner liner of type IV hydrogen storage cylinder.

[0023] (2) The raw materials of this invention are abundant and readily available, the process is simple and easy to implement, and the price is relatively reasonable. Compared with rotational molding and blow molding, the prepared inner liner material can be molded into a high-precision and rapid dense product under high pressure through injection molding, eliminating the need for the boiling process of PA6 hydrogen storage bottle inner liner, which is conducive to large-scale production. It has broad prospects in the development and application of Type IV hydrogen storage bottle inner liner material. Detailed Implementation

[0024] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0025] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0026] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments and comparative examples.

[0027] Example 1 This embodiment provides a hydrogen-barrier toughening material, the preparation method of which is as follows: S1. Weigh PA6 resin, modifier POE-g-MAH, antioxidant 168, antioxidant 1098, and lubricant PETS according to their mass fractions, and set aside for later use; wherein PA6 resin accounts for 84.4%, modifier POE-g-MAH accounts for 14.8%, antioxidant 168 accounts for 0.4%, antioxidant 1098 accounts for 0.2%, and lubricant PETS accounts for 0.2%.

[0028] S2. Dry the PA6 resin in S1 in a vacuum oven at 80 ℃ for 6 hours. Add the PA6 resin, modifier POE-g-MAH, antioxidant 168, antioxidant 1098, and lubricant PETS to a mixer and mix evenly.

[0029] S3. Add the raw materials mixed in S2 to a twin-screw extruder. Set the temperatures of each zone and the die head of the twin-screw extruder to 220 ℃, 230 ℃, 240 ℃, 240 ℃, 240 ℃, 240 ℃, and 240 ℃, respectively. Set the main extruder speed to 300 r / min. After melt blending and extrusion, the blend is traction, water cooling, and pelletizing to obtain PA6 modified material.

[0030] S4. The PA6 modified material obtained in S4 is dried in a vacuum oven at 80 ℃ for 24 hours to obtain the PA6 / POE-g-MAH modified material for the inner liner of the hydrogen storage bottle of type IV with hydrogen barrier toughening.

[0031] Example 2 This embodiment provides a hydrogen-barrier toughening material, the preparation method of which is as follows: S1. Weigh PA6 resin, LLDPE-g-MAH modifier, antioxidant 168, antioxidant 1010, and ethylene bis-stearamide lubricant according to their respective mass fractions, and set aside for later use; wherein PA6 resin accounts for 74.4%, LLDPE-g-MAH modifier accounts for 24.8%, antioxidant 168 accounts for 0.4%, antioxidant 1010 accounts for 0.2%, and ethylene bis-stearamide lubricant accounts for 0.2%.

[0032] S2. Dry the PA6 resin in S1 in a vacuum oven at 80 ℃ for 6 hours. Add the PA6 resin, modifier LLDPE-g-MAH, antioxidant 168, antioxidant 1010, and lubricant ethylene bis-stearamide to a mixer and mix evenly.

[0033] S3. Add the raw materials mixed in S2 to a twin-screw extruder. Set the temperatures of each zone and the die head of the twin-screw extruder to 220 ℃, 230 ℃, 240 ℃, 240 ℃, 240 ℃, 240 ℃, and 240 ℃, respectively. Set the main extruder speed to 300 r / min. After melt blending and extrusion, the blend is traction, water cooling, and pelletizing to obtain PA6 modified material.

[0034] S4. The PA6 modified material obtained in S4 is dried in a vacuum oven at 80℃ for 24 hours to obtain the PA6 / LLDPE-g-MAH modified material for the inner liner of the hydrogen storage bottle of type IV with hydrogen barrier toughening.

[0035] Example 3 This embodiment provides a hydrogen-barrier toughening material, the preparation method of which is as follows: S1. Weigh out PA6 resin, modifier HDPE-g-MAH, antioxidant 168, antioxidant 1010, and lubricant ethylene bis-stearamide according to their respective mass fractions, and set aside for later use; wherein PA6 resin accounts for 74.4%, modifier HDPE-g-MAH accounts for 24.8%, antioxidant 168 accounts for 0.4%, antioxidant 1010 accounts for 0.2%, and lubricant ethylene bis-stearamide accounts for 0.2%.

[0036] S2. Dry the PA6 resin in S1 in a vacuum oven at 80 ℃ for 6 hours. Add the PA6 resin, modifier HDPE-g-MAH, antioxidant 168, antioxidant 1010, lubricant ethylene bis-stearamide, etc. into a mixer and mix evenly.

[0037] S3. Add the raw materials mixed in S2 to a twin-screw extruder. Set the temperatures of each zone and the die head of the twin-screw extruder to 220 ℃, 230 ℃, 240 ℃, 240 ℃, 240 ℃, 240 ℃, and 240 ℃, respectively. Set the main extruder speed to 300 r / min. After melt blending and extrusion, the blend is traction, water cooling, and pelletizing to obtain PA6 modified material.

[0038] S4. The PA6 modified material obtained in S4 is dried in a vacuum oven at 80 ℃ for 24 hours to obtain the PA6 / HDPE-g-MAH modified material for the inner liner of the hydrogen storage bottle of type IV with hydrogen barrier toughening.

[0039] Comparative Example 1 This comparative example provides a material whose preparation method is as follows: S1. Weigh PA6 resin, antioxidant 168, antioxidant 1098, and lubricant PETS according to their mass fractions, and set aside for later use; wherein PA6 resin is 99.2%, antioxidant 168 is 0.4%, antioxidant 1098 is 0.2%, and lubricant PETS is 0.2%.

[0040] S2. Dry the PA6 resin in S1 in a vacuum oven at 80°C for 6 hours. Add the PA6 resin, antioxidant 168, antioxidant 1098, lubricant PETS, etc. into a mixer and mix evenly.

[0041] S3. Add the raw materials mixed in S2 to a twin-screw extruder. Set the temperatures of each zone and the die head of the twin-screw extruder to 220 ℃, 230 ℃, 240 ℃, 240 ℃, 240 ℃, 240 ℃, and 240 ℃, respectively. Set the main extruder speed to 300 r / min. After melt blending and extrusion, the blend is traction, water cooling, and pelletizing to obtain PA6 modified material.

[0042] S4. The PA6 modified material obtained in S4 is dried in a vacuum oven at 80℃ for 24 hours to obtain PA6 material as the inner liner of the type IV hydrogen storage bottle.

[0043] Preparation of injection molded inner liner S1. The prepared hydrogen-barrier toughening material was vacuum dried at 80 °C for 24 hours; S2. Add the dried hydrogen-resistant toughening material from S1 into the barrel of the injection molding machine, and heat and melt it under segmented temperature control. The temperatures of each zone and the die head of the injection molding machine are set to 185 ℃, 220 ℃, 240 ℃, 250 ℃, 240 ℃, and 240 ℃, respectively. S3. The material plasticized in S2 is injected into the cavity of the type IV hydrogen storage cylinder inner liner mold under a pressure of 100 bar. S4. Dynamically cool and demold the mold to obtain the hydrogen-barrier and toughened Type IV hydrogen storage bottle liner.

[0044] Impact strength test The PA6 modified materials prepared in Comparative Example 1 and Examples 1-3 were tested for impact strength according to GB / T 1043-2018 "Determination of Impact Properties of Simply Supported Beams in Plastics".

[0045] Table 1 Impact strength of PA6 modified materials prepared in Comparative Example 1 and Examples 1-3 at -30℃ and room temperature

[0046] The toughness of PA6 material, especially its toughness under low-temperature conditions, is a key performance indicator for its use as the inner liner material of hydrogen storage cylinders. Excellent toughness can effectively inhibit the initiation and propagation of microcracks, thereby significantly improving the fatigue life of the material under high-pressure hydrogen cycling conditions and effectively preventing low-temperature brittle fracture. Furthermore, good toughness can improve the material's processing performance, reduce the tendency for stress cracking during molding, and decrease the occurrence of welding defects. Impact strength test results show that, with the addition of the modifier, the impact strength of the PA6 modified materials prepared in Examples 1-3 shows an increasing trend compared to PA6 resin. In Example 1, the PA6 / POE-g-MAH modified material showed an increase of 5.4 times in room temperature impact strength and 14.8 times in impact strength at -30°C compared to PA6 resin. In Example 2, the PA6 / LLDPE-g-MAH modified material showed an increase of 0.71 times in room temperature impact strength and 2.8 times in impact strength at -30°C compared to PA6 resin. In Example 3, the PA6 / HDPE-g-MAH modified material showed an increase of 0.51 times in room temperature impact strength and 2.4 times in impact strength at -30°C compared to PA6 resin. From a molecular structure perspective, this is because the molecular chain of POE-g-MAH has more branched structures compared to LLDPE-g-MAH and HDPE-g-MAH. Therefore, the impact strength of the modified materials prepared by POE-g-MAH modifier can be significantly improved. However, on the other hand, precisely because the molecular chain structures of LLDPE-g-MAH and HDPE-g-MAH are more regular, their gas barrier properties are better than POE-g-MAH under the same composition, but this can only improve the impact strength of the blend to a certain extent. Meanwhile, since the maleic anhydride graft modifiers all react chemically with the amino groups of PA6 through maleic anhydride groups, the compatibility between the two is enhanced. POE and PE resins themselves have good impact properties, and the blend exhibits improved impact strength. Therefore, the PA6 modified materials prepared in Examples 1-3 show excellent impact resistance (especially low-temperature impact resistance).

[0047] Melt Flow Index Test The PA6 modified materials prepared in Comparative Example 1 and Examples 1-3 were tested for melt index according to GB / T 3682-2018 "Determination of melt mass flow rate (MFR) and melt volume flow rate (MVR) of thermoplastic plastics".

[0048] Table 2 Melt index of PA6 modified materials prepared in Comparative Example 1 and Examples 1-3

[0049] Melt flow index (MFI) is a crucial parameter for measuring the flow properties of thermoplastics in the molten state and is one of the core parameters for evaluating processing performance. In the development and manufacturing of PA6 hydrogen storage cylinder liners, controlling the MFI is particularly critical. The MFI results show that with the addition of the modifier, the MFI of the PA6 modified materials prepared in Examples 1-3 decreases relative to PA6 resin. This is because the maleic anhydride groups in the modifier react chemically with the amino groups of PA6 resin, forming a micro-crosslinked structure. The PA6 modified materials prepared in Examples 1-3 exhibit good flow properties, are suitable for injection molding, and can be used to prepare Type IV hydrogen storage cylinder liners.

[0050] Water absorption test The PA6 modified materials prepared in Comparative Example 1 and Examples 1-3 were tested according to GB / T 1034-2008 "Determination of water absorption of plastics" for 24 hours in an environment of 23 ℃ and 50% relative humidity and for 24 hours in water at 23 ℃.

[0051] Table 3. Water absorption of PA6 modified materials prepared in Comparative Example 1 and Examples 1-3

[0052] When PA6 is used as the inner liner material of hydrogen storage cylinders, its absorbency is a crucial characteristic that must be considered, as it directly affects the material's mechanical properties, dimensional stability, and hydrogen permeability. Water absorption test results show that, with the addition of modifiers, the water absorption rate of the PA6 modified materials prepared in Examples 1-3 decreases compared to PA6 resin. In Example 1, the water absorption mass fraction of the PA6 / POE-g-MAH modified material, compared to PA6 resin, decreased from 0.58% to 0.29% in an environment of 23°C and 50% relative humidity after 24 hours of storage, and decreased from 5.48% to 2.5% in water at 23°C. In Example 2, the water absorption mass fraction of the PA6 / LLDPE-g-MAH modified material, compared to PA6 resin, decreased from 0.58% to 0.28% in an environment of 23°C and 50% relative humidity after 24 hours of storage, and decreased from 5.48% to 2.11% in water at 23°C. In Example 3, the water absorption mass fraction of the PA6 / HDPE-g-MAH modified material, compared to PA6 resin, decreased from 0.58% to 0.27% in an environment of 23°C and 50% relative humidity after 24 hours, and from 5.48% to 2.09% in water at 23°C. This is because POE and PE resins themselves have excellent low water absorption, and the blend exhibits a reduction in water absorption rate. Therefore, it can be seen that the PA6 modified materials prepared in Examples 1-3 have excellent moisture resistance.

[0053] Hydrogen permeability test The hydrogen permeability coefficients of the PA6 modified materials prepared in Comparative Example 1 and Examples 1-3 were tested at 15°C and 55°C according to GB / T 1038-2022 "Test Method for Gas Permeability of Plastic Products Films and Sheets".

[0054] Table 4 Hydrogen permeability coefficients of PA6 modified materials prepared in Comparative Example 1 and Examples 1-3

[0055] Hydrogen permeability is a core indicator of the inner liner material of hydrogen storage cylinders, directly affecting hydrogen storage efficiency, safety, and system lifespan. Hydrogen permeability coefficient test results show that with the addition of modifiers, the hydrogen permeability of the PA6 modified materials prepared in Examples 1-3 shows an increasing trend compared to PA6 resin, but the increase is limited. For example, at 15℃, compared to PA6 resin, the hydrogen permeability coefficient of the PA6 / POE-g-MAH modified material in Example 1 increased by 26.9%; the hydrogen permeability coefficient of the PA6 / LLDPE-g-MAH modified material in Example 2 increased by 32.1%; and the hydrogen permeability coefficient of the PA6 / HDPE-g-MAH modified material in Example 3 increased by 19.5%. This is because POE and PE themselves have lower hydrogen barrier properties than PA6, but the PA6 modified materials, with PA6 as the continuous phase, exhibit a slight increase in hydrogen permeability coefficient. The hydrogen permeability coefficients of Examples 1-3 meet the requirements of GB / T42610-2023 "Test Method for Compatibility of Plastic Liners and Hydrogen in High-Pressure Hydrogen Cylinders" and GB / T 42612-2023 "Carbon Fiber Fully Wound Gas Cylinders with Plastic Liners for Compressed Hydrogen in Vehicles". The hydrogen permeability coefficients of the samples at (15℃±1) and (55±1)℃ do not exceed 9.0×10-16 and 4.5×10~15mol·m / (m2·s·Pa), respectively. It can be seen that the PA6 modified materials prepared in Examples 1-3 have excellent hydrogen barrier properties.

[0056] In summary, the PA6 modified materials in Examples 1-3 possess characteristics such as high hydrogen barrier properties, excellent toughness, good processability, and superior moisture resistance. They are simple to process, relatively affordable, and have balanced overall performance, meeting the material performance requirements of Type IV hydrogen storage cylinder liners. They can be rapidly and precisely molded into dense products under high pressure using injection molding, showing broad prospects in the development and application of Type IV hydrogen storage cylinder liner materials.

[0057] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A hydrogen-barrier toughening material, characterized in that, The material, by mass fraction, comprises the following components: 60%~95% PA6 resin, 5%~40% modifier, 0.1%~0.5% lubricant, and 0.1%~0.8% antioxidant; The modifier includes one or more of the following: maleic anhydride-grafted POE, maleic anhydride-grafted LLDPE, maleic anhydride-grafted HDPE, maleic anhydride-grafted EPDM, maleic anhydride-grafted EVA, and maleic anhydride-grafted SEBS.

2. The hydrogen-barrier toughening material as described in claim 1, characterized in that, The hydrogen-barrier toughening material is composed of the following components by mass fraction: 70%~90% PA6 resin, 10%~30% modifier, 0.2%~0.5% lubricant, and 0.1%~0.6% antioxidant.

3. The hydrogen-barrier toughening material according to any one of claims 1-2, characterized in that, The lubricant includes one or more of silicone oil, ethylene bis-stearamide, zinc stearate, calcium stearate, and pentaerythritol stearate. The antioxidant is one or a combination of two or more of antioxidants 1010, antioxidant 168, and antioxidant 1098.

4. The method for preparing the hydrogen-barrier toughening material as described in claim 1, characterized in that, Includes the following steps: S1. Weigh out PA6 resin, modifier, antioxidant, and lubricant according to their respective mass fractions, and set aside for later use; S2. Vacuum dry the PA6 resin in S1 at 70-90℃ for 4-10 hours, and then mix the PA6 resin, modifier, antioxidant and lubricant evenly. S3. Add the raw materials mixed in S2 into a twin-screw extruder. After melt blending and extrusion, the blend is traction, water cooling, and pelletizing to obtain PA6 modified material. S4. The PA6 modified material obtained in S3 is vacuum dried at 70-90℃ for 20-36 hours to obtain a hydrogen-barrier toughened material.

5. The preparation method according to claim 4, characterized in that, The main engine speed of the twin-screw extruder during blending is set to 290-310 r / min.

6. The preparation method according to claim 4, characterized in that, The temperatures of each zone and the die head of the twin-screw extruder are set to 210-230 ℃, 220-240 ℃, 230-250 ℃, 230-250 ℃, 230-250 ℃, 230-250 ℃, and 230-250 ℃, respectively.

7. The preparation method according to claim 4, characterized in that, The lubricant comprises one or more of silicone oil, ethylene bis-stearamide, zinc stearate, calcium stearate, and pentaerythritol stearate; the antioxidant is one or more of antioxidant 1010, antioxidant 168, and antioxidant 1098.

8. The application of the hydrogen-barrier toughening material as described in any one of claims 1-3 or the hydrogen-barrier toughening material prepared by any one of claims 4-7 in the preparation of the inner liner of a type IV hydrogen storage cylinder.

9. A method for preparing a hydrogen-barrier and toughened type IV hydrogen storage cylinder inner liner, characterized in that, Includes the following steps: S1. Vacuum dry the hydrogen-barrier toughening material at 70-90 ℃ for 4-10 hours; S2. Add the dried material from S1 into the barrel of the injection molding machine and heat it to melt and plasticize it under segmented temperature control. S3. The material plasticized in S2 is injected into the cavity of the inner liner mold of the type IV hydrogen storage cylinder under high pressure; S4. Dynamically cool and demold the mold to obtain the hydrogen-barrier and toughened Type IV hydrogen storage bottle liner.

10. The preparation method according to claim 9, characterized in that, In S2, the temperatures of each zone and the injection molding head of the injection molding machine are controlled at 175-195℃, 210-230℃, 230-250℃, 240-260℃, 230-250℃, and 230-250℃, respectively; in S3, the pressure is set to 80-120 bar.

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