Nylon composite material suitable for rotational molding of hydrogen storage bottle and preparation method of nylon composite material

Abstract

The invention discloses a nylon composite material suitable for a rotational molding hydrogen storage bottle and a preparation method thereof. The nylon composite material is prepared from the following components in percentage by mass: 61-91.5% of polyamide; 3 to 10 percent of phenoxy resin; 5-25% of a toughening agent; 0.3 to 0.8 percent of a dendritic polymer; 0.1 to 0.6 percent of an antioxidant; 0.1%-0.6% of a lubricating agent; and 0-2% of other auxiliary agents. According to the invention, the defects of material shortage, cavity and hydrogen leakage at the position of a thin runner at the periphery of an insert and a joint line can be effectively improved, and the prepared nylon material has excellent performances of strong bonding force, low hydrogen permeability, high fluidity and the like, and is suitable for a rotational molding grade IV type hydrogen storage bottle liner product.

Description

TECHNICAL FIELD

[0001] The present application relates to a nylon composite material suitable for rotational molding hydrogen storage bottles and a preparation method thereof. BACKGROUND

[0002] With the development of energy, hydrogen has become an important part of new energy industry with the advantages of low carbon, environmental protection, large energy density, and renewable energy. Among them, hydrogen storage technology is an important part of the development of hydrogen energy technology. From the aspects of hydrogen storage technology maturity, safety and economy, high-pressure gaseous hydrogen storage is still the best choice for current hydrogen storage methods. As an important equipment for high-pressure gaseous hydrogen storage, hydrogen storage bottles have experienced four generations of innovations: all-metal gas cylinders (type I), metal liner fiber ring winding gas cylinders (type II), metal liner fiber full winding gas cylinders (type III), and non-metal liner fiber full winding gas cylinders (type IV). Type I and type II bottles are heavy, have low hydrogen storage density, and have a pressure resistance of less than 30 MPa, which are not suitable for vehicle use. Type III bottle is a metal liner carbon fiber winding, which can increase the pressure resistance to 35 MPa, and is the main hydrogen storage bottle used in China at present, but has problems such as low hydrogen storage density, high cost, and hydrogen embrittlement of the metal liner. Type IV bottle is a plastic liner carbon fiber full winding, which is light in weight, low in cost, high in hydrogen storage density, and can store gas at a pressure of 70 MPa, which is suitable for vehicle hydrogen storage and has been widely used internationally. It is a research hotspot at home and abroad at present.

[0003] In type IV hydrogen storage bottle, the plastic liner is responsible for the gas tightness, and the outer carbon fiber composite winding layer is responsible for the strength and deformation of the hydrogen storage bottle. However, the bottle mouth structure still needs to use metal material as the valve seat to connect the plastic liner of the hydrogen storage bottle and the external valve due to the insufficient strength and rigidity of the plastic. However, this structure has the disadvantages of poor adhesion between the plastic liner and the metal valve seat, insufficient bonding strength, etc., which leads to the fact that the contact surface between the existing type IV bottle liner and the metal valve seat is easy to produce a small gap, which has the risk of hydrogen leakage. In severe cases, the plastic liner may peel off from the metal bottle mouth, which seriously threatens the safety and reliability of the type IV hydrogen storage bottle.

[0004] The materials used for the plastic liner at present are mainly HDPE and PA. For example, CN113124309A discloses a plastic liner for a high-pressure hydrogen storage bottle and a preparation method thereof. The plastic liner comprises, from the outside to the inside, an outer layer, an outer transition layer, a barrier layer, an inner transition layer and an inner layer. The outer layer and the inner layer are polyamide, polyester or high-density polyethylene. The barrier layer is ethylene vinyl alcohol copolymer or a modified product thereof. The inner / outer transition layer is a mixture of the materials used for the inner / outer layer and ethylene vinyl alcohol copolymer. The method adopts a rotational molding process, which is complex and requires multiple feeding for preparation. CN118755258A discloses a special rotational molding polyamide material for a hydrogen storage bottle liner, a preparation method and application thereof. The addition of a carbon radical trapping agent improves the problems of micropore defects caused by the surface oxidation and degradation of the polyamide material during the rotational molding process and performance decay caused by the long rotational molding cycle. However, no improvement scheme is provided for the poor adhesion between the material and the metal.

[0005] To solve the problem of poor sealing between the metal valve seat and the liner material, the technical solutions are more focused on the design of the bottle mouth structure. For example, the sandwich structure, BOSS structure, conical sealing, interference fit, thread sealing and labyrinth sealing are adopted. CN213236962U achieves sealing by pressing the plastic liner and the metal valve seat and extruding the sealing ring. CN111998220A and CN111649223A adopt a combination sealing type of thread connection and sealing ring. CN113775926A uses a buckle structure formed by the cooperation of the gland, plastic liner and valve seat, as well as labyrinth sealing and conical sealing to improve the reliability and sealing performance of the bottle mouth. However, these methods still have problems such as complex sealing structure, poor impact resistance, insufficient stability, poor sealing effect, insufficient bonding strength between different materials, etc. SUMMARY

[0006] The main purpose of the present application is to provide a nylon composite material suitable for rotational molding hydrogen storage bottles. The nylon composite material improves the adhesion, air tightness and flowability of the liner material through the synergistic effect of ultra-high molecular weight phenoxy resin and dendritic polymer. It is suitable for the integrated molding of IV type hydrogen storage bottle liners with good inner surface flow leveling and low outer surface porosity through the rotational molding process, and realizes effective sealing between the liner material and the metal valve seat.

[0007] The technical scheme adopted by the present application to solve the technical problems is as follows:

[0008] The present application is realized by the following technical scheme:

[0009] One of the purposes of the present application is to provide a nylon composite material suitable for rotational molding hydrogen storage bottles. The raw materials of the nylon composite material contain, by mass percentage:

[0010] Polyamide: 61-91.5%

[0011] Phenoxy resin: 3-10%

[0012] Toughening agent: 5-25%

[0013] Dendrimer: 0.3-0.8%

[0014] Antioxidant: 0.1-0.6%

[0015] Lubricant: 0.1-0.6%

[0016] Other auxiliary agents: 0-2%

[0017] The polyamide is a mixture of one or several aliphatic polyamide resins, preferably the polyamide is selected from at least one of PA6, PA66, PA6 / 66, PA11, PA12, PA610 and / or PA612, and the polyamide has a relative viscosity of 2.0-2.8;

[0018] The phenoxy resin is an ultrahigh molecular weight phenoxy resin containing a large number of ether bonds and hydroxyl groups in the molecule; preferably YP-50S series from Japan Iron Chemical.

[0019] The toughening agent is ethylene-octene copolymer grafted maleic anhydride POE-g-MAH or ternary ethylene-propylene rubber grafted maleic anhydride EPDM-g-MAH.

[0020] The dendrimer is a special functional polymer; preferably CYD-701 series from Weihai Chen Yuan and HL-10 series from Guangzhou Jian Da.

[0021] The antioxidant is one or several of organic or inorganic copper salt, hindered phenol, hindered amine, thioester, phosphite and composite antioxidant.

[0022] The lubricant is one or more of stearic acid, stearate, pentaerythritol stearate, TAF, silicone powder, PE wax, ethylene bis-stearamide, fluoropolymer.

[0023] The other processing aid is one or several of wear-resistant agent, coupling agent, antistatic agent, anti-hydrolysis agent, pigment.

[0024] The second object of the present application is to provide a preparation method of a nylon composite material suitable for a rotational molding hydrogen storage bottle, comprising the following steps:

[0025] (1) Dry the polyamide in a desiccator at 80-100℃ for 6-8 hours, control the moisture content <0.03% or less;

[0026] (2) the polyamide, phenoxy resin, toughening agent, dendritic polymer, antioxidant, lubricant and other auxiliaries are weighed by weight percentage, and then all are put into a high-speed stirrer to stir for 2-3 minutes to prepare a premix;

[0027] (3) the premix prepared above is added from a main feeding loss-in-weight metering scale of a double-screw extruder, and is subjected to melt plasticization, meshing mixing through the double-screw extruder, and is extruded into a strip through a head die, and is cooled through a cooling water tank and dried through a drying machine, and is cut and granulated through a granulator to obtain a granular hydrogen storage bottle special nylon composite material;

[0028] (4) the granular nylon composite material prepared above is subjected to cryogenic liquid nitrogen powder grinding to freeze and grind the powder after preliminary grinding, and the powder is classified and screened through a high-precision airflow auxiliary rotary screen to effectively control the powder particle size, and finally a 20-60 mesh nylon powder suitable for a rotational molding hydrogen storage bottle is obtained.

[0029] Further, the preparation method of the nylon composite material suitable for the rotational molding hydrogen storage bottle, the length-diameter ratio of the double-screw extruder is required to be greater than or equal to 48:1, for example (48-60):1, the extruder temperature range is 220-290℃, and the screw rotation speed is 450-550rpm; wherein the processing temperatures of each section of the double-screw extruder are as follows: the temperature of the first section is 150-200℃, the temperature of the second section is 230-270℃, the temperature of the third section is 250-280℃, the temperature of the fourth section is 250-280℃, the temperature of the fifth section is 250-270℃, the temperature of the sixth section is 250-270℃, the temperature of the seventh section is 250-270℃, the temperature of the eighth section is 250-270℃, the temperature of the ninth section is 250-270℃, the temperature of the tenth section is 250-270℃, and the head temperature is 250-270℃.

[0030] The equipment, reagents, processes, parameters and the like involved in the present application are conventional equipment, reagents, processes, parameters and the like unless otherwise specified, and will not be described in the examples.

[0031] All the ranges listed in the present application include all the point values in the range.

[0032] Compared with the background art, the technical solution has the following advantages:

[0033] The nylon composite material prepared by the application is suitable for the roto-molding hydrogen storage bottle, the phenoxy resin used is BPA type ultrahigh molecular weight phenoxy resin, the molecule contains a large number of flexible ether bonds, benzene rings and hydroxyl groups, the flexible propyl ether can give the polymer good toughness, the existence of a large number of benzene ring structures can improve the rigidity and heat resistance of the material, and the polar hydroxyl groups in the molecule can participate in the reaction, have good compatibility and infiltration with the nylon, and can increase the adhesion of the nylon composite material and the metal material; at the same time, under the action of the dendritic polymer, the barrier property and flowability of the material are significantly improved, the penetration path of the gas molecules is increased, the hydrogen molecule diffusion is slow, the defects of material voids and hydrogen leakage at the positions of the insert and the mold line periphery thin flow channel can be effectively improved, under the synergistic action of the above raw material components, the prepared nylon composite material has excellent properties such as strong adhesion, low hydrogen permeability and high flowability, and is suitable for the roto-molding type IV hydrogen storage bottle inner liner product. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 The metal adhesion test strip of the application. DETAILED DESCRIPTION

[0035] The raw materials in the embodiments and comparative examples of the application are as follows:

[0036] Polyamide: PA6, Haiyang HY2500A

[0037] Phenoxy resin: JFE Chemical YP-50S;

[0038] Toughening agent: DuPont N495

[0039] Dendritic polymer: Weihai Chen Yuan CYD-701D;

[0040] Antioxidant: Bruggemann H318, Matsubayashi Songnox6280

[0041] Lubricant: Honeywell AC540A.

[0042] Example 1

[0043] Polyamide 80.7%, phenoxy resin 3%, dendritic polymer 0.3%, toughening agent 15%, antioxidant 0.5%, lubricant 0.5%.

[0044] Example 2

[0045] Polyamide 78.7%, phenoxy resin 5%, dendritic polymer 0.3%, toughening agent 15%, antioxidant 0.5%, lubricant 0.5%.

[0046] Example 3

[0047] Polyamide 78.5%, phenoxy resin 5%, dendrimer 0.3%, toughening agent 0.5%, antioxidant 0.5%, lubricant 0.5%.

[0048] Example 4

[0049] Polyamide 73.5%, phenoxy resin 10%, dendrimer 0.5%, toughening agent 15%, antioxidant 0.5%, lubricant 0.5%.

[0050] Example 5

[0051] Polyamide 73.2%, phenoxy resin 10%, dendrimer 0.8%, toughening agent 15%, antioxidant 0.5%, lubricant 0.5%.

[0052] Comparative Example 1

[0053] Polyamide 84.0%, phenoxy resin 0, dendrimer 0%, toughening agent 15%, antioxidant 0.5%, lubricant 0.5%.

[0054] Comparative Example 2

[0055] Polyamide 83.0%, phenoxy resin 1%, dendrimer 0%, toughening agent 15%, antioxidant 0.5%, lubricant 0.5%.

[0056] Comparative Example 3

[0057] Polyamide 83.9%, phenoxy resin 1%, dendrimer 0.1%, toughening agent 15%, antioxidant 0.5%, lubricant 0.5%.

[0058] Comparative Example 4

[0059] Polyamide 82.9%, phenoxy resin 1%, dendrimer 2.0%, toughening agent 15%, antioxidant 0.5%, lubricant 0.5%.

[0060] Comparative Example 5

[0061] Polyamide 62.0%, phenoxy resin 20%, dendrimer 0.1%, toughening agent 15%, antioxidant 0.5%, lubricant 0.5%.

[0062] The preparation method of each of the above examples and comparative examples,

[0063] (1) The polyamide is dried in a dehumidifying dryer at 100°C for 8 hours, and the moisture content is controlled to be less than 0.03% for use;

[0064] (2) The polyamide, phenoxy resin, toughening agent, dendrimer, antioxidant, lubricant and other additives are weighed according to the percentage by weight, and then all are put into a high-speed mixer and stirred for 3 minutes to prepare a premix.

[0065] (3) The premix prepared above is added into the main feeding loss-in-weight metering scale of the twin-screw extruder, and the premix is subjected to melt plasticizing and meshing mixing through the twin-screw extruder, and then the extruded strip is extruded through the head die, cooled in a cooling water tank, and dried in a air-drying machine, and then the strip is cut and granulated through a granulator to obtain granular hydrogen storage bottle special nylon material;

[0066]

[0067] (4) The granular nylon material prepared above is subjected to cryogenic grinding through a low-temperature liquid nitrogen grinding machine, and the preliminarily ground powder is classified and screened through a high-precision airflow-assisted rotary screen to effectively control the powder particle size, and finally 20-60 mesh nylon powder suitable for rotational molding hydrogen storage bottles is obtained.

[0068] The length-diameter ratio of the twin-screw extruder is 48:1, the extruder temperature range is 220-290℃, and the screw rotation speed is 450-550rpm; wherein the processing temperatures of each section of the twin-screw extruder are as follows: the temperature of the first section is 150-200℃, the temperature of the second section is 230-270℃, the temperature of the third section is 250-280℃, the temperature of the fourth section is 250-280℃, the temperature of the fifth section is 250-270℃, the temperature of the sixth section is 250-270℃, the temperature of the seventh section is 250-270℃, the temperature of the eighth section is 250-270℃, the temperature of the ninth section is 250-270℃, the temperature of the tenth section is 250-270℃, and the temperature of the head is 250-270℃.

[0069] Performance test:

[0070] The tensile strength is tested in accordance with the standard ISO 527, the notched impact strength is tested in accordance with the standard ISO 179, the melt flow rate MVR is tested in accordance with the standard ISO 1133 under the condition of 275℃ / 5kg, and the gas permeation coefficient is tested in accordance with the standard GB / T 1038;

[0071] The metal adhesion test method is as follows: a plurality of metal copper blocks are prepared according to the blue part in the table, the pre-prepared copper blocks are placed into a 4mm*10mm*150mm mold cavity before injection molding, and each nylon composite material prepared is injected into the mold cavity according to the same injection molding process to form a plurality of test strips with copper blocks and nylon adhered to each other, and then the copper block-nylon peeling force test is carried out by referring to the tensile test method as a characterization method of metal adhesion. Figure 1

[0072] Table 1: Overview of each experimental group

[0073]

[0074] Table 2: Overview of test results of each experimental group

[0075] ​​

[0076]

[0077] As can be seen from Table 2, under the action of the phenoxy resin, the tensile strength, flowability and hydrogen permeability of the prepared nylon composite material are reduced, but the metal adhesion is significantly improved, which can significantly improve the poor adhesion between the metal valve seat and the plastic liner of the type IV hydrogen storage bottle. However, if the amount is too large, it will cause the prepared product to be difficult to demold after rotational molding. Under the action of the dendritic polymer, the tensile strength, impact performance and metal adhesion of the prepared nylon composite material are reduced, and the flowability is significantly improved, which can obviously improve the hollow defects formed by the difficulty of melt flow filling at the fine flow channel around the embedded part. In addition, the improvement of flowability is conducive to the regular arrangement and crystallization of nylon molecular chain, prolongs the penetration path of gas molecules, and further improves the hydrogen permeability. However, if the amount is too large, it will significantly reduce the adhesion between the bottle mouth metal material and the plastic liner and the mechanical properties of the material. Therefore, only by adding appropriate proportions of phenoxy resin and dendritic polymer, can the nylon composite material suitable for rotational molding hydrogen storage bottle with strong adhesion, low permeability and high flow be prepared, and the effective sealing between the liner material and the metal valve seat can be realized.

[0078] The above description is only the preferred embodiment of the present application, and therefore cannot limit the scope of the present application. Any equivalent changes and modifications made according to the scope and content of the present patent should still be within the scope of the present application.

Claims

1. A nylon composite suitable for use in a rotomolded hydrogen storage vessel, characterized in that: The nylon composite raw material contains, by mass percentage: Polyamide: 61-91.5% Phenoxy resin: 3-10% Toughening agent: 5-25% Dendritic polymer: 0.3-0.8% Antioxidant: 0.1-0.6% Lubricant: 0.1-0.6% Other additives: 0-2%.

2. The nylon composite material for rotomolded hydrogen storage bottle according to claim 1, characterized in that: The polyamide is a mixture of one or more aliphatic polyamide resins, and the polyamide has a relative viscosity of 2.0-2.

8.

3. The nylon composite material for rotomolded hydrogen storage bottle according to claim 1, characterized in that: The polyamide is selected from at least one of PA6, PA66, PA6 / 66, PA11, PA12, PA610, or PA612.

4. The nylon composite material for rotomolded hydrogen storage bottle according to claim 1, wherein: The phenoxy resin is an ultrahigh molecular weight phenoxy resin, and the phenoxy resin is Nippon Steel Chemical YP-50S.

5. The nylon composite material for rotomolded hydrogen storage bottle according to claim 1, wherein: The toughening agent is ethylene-octene copolymer grafted maleic anhydride POE-g-MAH or ethylene-propylene-diene rubber grafted maleic anhydride EPDM-g-MAH.

6. The nylon composite material for rotomolded hydrogen storage bottle according to claim 1, wherein: The dendritic polymer is a special functional polymer selected from Weihai Chen Yuan CYD-701 or Guangzhou Jian Da HL-10.

7. The nylon composite material for rotomolded hydrogen storage bottle according to claim 1, wherein: The antioxidant is one or more of organic or inorganic copper salts, hindered phenols, hindered amines, thioesters, phosphites, and composite antioxidants.

8. Use of the nylon composite material according to any one of claims 1 to 7 in the preparation of a roving molding hydrogen storage bottle inner liner.

9. A method for preparing a nylon material suitable for a roving molding hydrogen storage bottle, comprising the following steps: (1) drying the polyamide in a desiccator at 80-100°C for 6-8 hours, and controlling the moisture content to be less than 0.03% or lower; (2) weighing the polyamide, phenoxy resin, toughening agent, dendritic polymer, antioxidant, lubricant, and other additives according to the weight percentage, and then putting all of them into a high-speed mixer to stir for 2-3 minutes to prepare a premix; wherein the premix contains, by mass percentage, polyamide: 61-91.5%; phenoxy resin: 3-10%; toughening agent: 5-25%; dendritic polymer: 0.3-0.8%; antioxidant: 0.1-0.6%; lubricant: 0.1-0.6%; and other additives: 0-2%; (3) feeding the prepared premix into a double-screw extruder through a main feeding loss-in-weight metering scale, melting and plasticizing through the double-screw extruder, meshing and mixing, extruding a strip through a die head, cooling in a cooling water tank, and drying in a air dryer, and then cutting and granulating through a granulator to obtain a granular hydrogen storage bottle special nylon material; (4) freezing and grinding the prepared granular nylon material using a low-temperature liquid nitrogen grinding machine, and then classifying and screening the preliminarily ground powder through a high-precision airflow-assisted rotary screen to effectively control the powder particle size, and finally obtaining a 20-60 mesh nylon powder suitable for a roving molding hydrogen storage bottle.

10. The method of claim 9, wherein: The length-diameter ratio of the double screw extruder is greater than or equal to 48:1, the extruder temperature range is 220-290 DEG C, the screw rotation speed is 450-550 rpm; wherein the processing temperature of each section of the double screw extruder is respectively: the first zone temperature is 150-200 DEG C, the second zone temperature is 230-270 DEG C, the third zone temperature is 250-280 DEG C, the fourth zone temperature is 250-280 DEG C, the fifth zone temperature is 250-270 DEG C, the sixth zone temperature is 250-270 DEG C, the seventh zone temperature is 250-270 DEG C, the eighth zone temperature is 250-270 DEG C, the ninth zone temperature is 250-270 DEG C, the tenth zone temperature is 250-270 DEG C, and the head temperature is 250-270 DEG C.

Images