An epoxy resin composition for a winding layer of a type IV hydrogen storage cylinder, and a preparation method and applications thereof

Abstract

The application provides an epoxy resin composition for a winding layer of a type IV hydrogen storage bottle and a preparation method and application thereof. The epoxy resin composition comprises the following components: an epoxy resin, a diluent, a curing agent and an accelerator; the epoxy resin is a liquid epoxy resin. The formula system has small viscosity, slow reaction at room temperature and can meet the requirement of a winding process on a pot life. The required curing temperature of the epoxy resin system is not higher than a softening temperature of a polyethylene inner liner. The glass transition temperature of a cured product after curing of the epoxy resin system is higher than a standard requirement. The impact strength of the cured product after curing of a cast body of the epoxy resin system is also greatly improved.

Description

Technical Field

[0001] This invention relates to the field of hydrogen storage technology, and more specifically, to an epoxy resin composition for the winding layer of a type IV hydrogen storage cylinder, its preparation method, and its application. Background Technology

[0002] Hydrogen exists primarily in combined form on Earth and is the most abundant substance in the universe, constituting 75% of the universe's mass. It is a secondary energy source. Hydrogen has a high calorific value, three times that of gasoline, 3.9 times that of alcohol, and 4.5 times that of coke. The combustion product of hydrogen is water, making it one of the cleanest energy sources in the world. Hydrogen energy is poised to become a crucial energy source on the global energy stage. The hydrogen energy industry chain can be divided into three main segments: hydrogen production, hydrogen storage and transportation, and hydrogen application. Among these, storage and transportation are key to the efficient utilization of hydrogen energy and are crucial for its large-scale development. Hydrogen storage serves as a bridge between hydrogen production and utilization, playing an irreplaceable role in the development of hydrogen energy.

[0003] Hydrogen storage cylinders generally come in four types: Type I cylinders are made entirely of steel, with a pressure resistance not exceeding 30 MPa. Their main drawback is their weight, making them unsuitable for vehicle use; they are better suited for stationary hydrogen storage at hydrogen refueling stations. Type II and Type III cylinders have a metal liner with carbon fiber winding, which are also relatively heavy, but lighter than Type I cylinders, and their pressure resistance can be increased to 70 MPa. Type IV cylinders have a plastic liner with fully wrapped carbon fiber, making them the lightest and suitable for vehicle use. They have a storage pressure of 70 MPa and represent the mainstream technology internationally, widely used globally.

[0004] The biggest change in Type IV bottles compared to Type III bottles is the replacement of the aluminum alloy inner liner with a plastic one. This change in liner material necessitates consideration of heat resistance, which involves three aspects: First, the plastic liner material itself must have a maximum operating temperature higher than the temperature limit caused by filling and releasing gas. Second, the heat resistance of the composite material winding layer surrounding the liner; for safety, its glass transition temperature must be at least 30°C higher than the temperature limit caused by filling and releasing gas. Third, the curing temperature of the winding layer must be considered; it must be lower than the operating temperature of the plastic liner. A high curing temperature can cause deformation of the plastic liner, posing a safety hazard.

[0005] On October 8, 2020, the group standard "Carbon Fiber Fully Wound Compressed Hydrogen Cylinders with Plastic Liners for Vehicles" officially came into effect. This standard mainly specifies the type, parameters, and technical requirements of carbon fiber fully wound compressed hydrogen cylinders with plastic liner for vehicles, such as a nominal working pressure not exceeding 70 MPa, a nominal volume not exceeding 450 L, a storage medium of compressed hydrogen, and an operating temperature not lower than -40℃ and not higher than 85℃. Considering that the cylinders may operate in high-temperature environments, the U.S. Department of Transportation's DOTCFFC 2007 standard explicitly requires the cylinders to withstand 20 cycles of thermal cycling from -51.6℃ to 93.3℃, ​​and if the glass transition temperature of the resin system is below 102℃, a high-temperature creep test is also required. If 93.3℃ is considered the operating temperature, from a materials science perspective, the glass transition temperature must be at least 30℃ higher than the operating temperature to meet the usage requirements. Taking all factors into account, the glass transition temperature of the composite material winding layer of the cylinder must be at least higher than 115℃.

[0006] The current problem is that the curing temperature of the winding layer cannot be high, but the heat resistance temperature must be high. The composite winding layer is composed of a resin matrix and fibers. The resin matrix material used in the gas cylinder is an epoxy resin system, and the heat resistance problem of the winding layer is essentially the heat resistance problem of the epoxy resin system. Generally, the higher the curing temperature of epoxy resin, the higher its glass transition temperature will be. For example, when phthalic anhydride curing agent cures bisphenol A epoxy resin, the curing temperature is around 160℃, and the T of the cured product... g Around 130℃. The lower the curing temperature, the lower the glass transition temperature. For example, when aliphatic amine curing agents cure bisphenol A epoxy resin, the curing reaction can occur at room temperature, but the glass transition temperature of the cured product is lower. g Around 50℃.

[0007] On the other hand, it's important to consider that epoxy resin systems requiring high curing temperatures tend to have poor toughness. Insufficient toughness in the matrix resin will worsen the impact resistance of the entire composite winding, potentially leading to safety accidents after collisions or impacts. In practice, toughening agents are generally added to improve the toughness of epoxy resins. Liquid rubber toughening and polyurethane toughening are commonly used methods, but while improving toughness, they also significantly reduce the glass transition temperature.

[0008] In summary, the curing temperature of the epoxy resin system should not exceed 100℃, but the glass transition temperature should be higher than 115℃. Summary of the Invention

[0009] To address the aforementioned problems in the prior art, this invention proposes an epoxy resin composition for the winding layer of a Type IV hydrogen storage cylinder. Specifically, it relates to an epoxy resin composition for the winding layer of a Type IV hydrogen storage cylinder, its preparation method, and its application.

[0010] After long-term and in-depth research, the inventors discovered that increasing the amount of epoxy resin curing accelerator added to a certain level can not only significantly reduce the curing temperature of the resin, but also improve the impact strength of the cured product.

[0011] The resin formulation system described in this invention has low viscosity and reacts slowly at room temperature, which can meet the requirements of the winding process for the pot life.

[0012] The resin formulation system described in this invention can meet the requirements for heat resistance during the production and use of hydrogen storage cylinders.

[0013] One objective of this invention is to provide an epoxy resin composition for the winding layer of a Type IV hydrogen storage cylinder, which may contain the following components: epoxy resin, diluent, curing agent, and accelerator.

[0014] The epoxy resin is a liquid epoxy resin, specifically selected from at least one of liquid bisphenol A type epoxy resin, liquid hydrogenated bisphenol A type epoxy resin, liquid bisphenol F type epoxy resin, liquid glycidyl ester type epoxy resin, and liquid glycidyl amine type epoxy resin. Preferably, it is at least one of liquid bisphenol A type epoxy resin and liquid bisphenol F type epoxy resin.

[0015] The diluent may be a non-reactive diluent, a reactive diluent, or a combination thereof.

[0016] The inactive diluent is epoxy-free and may be selected from at least one of acetone, ethanol, toluene, xylene, ethyl acetate, dibutyl phthalate, dioctyl phthalate, styrene, diallyl phthalate, and benzyl alcohol. And / or,

[0017] The reactive diluent may contain at least one low-viscosity substance with an epoxy group; the reactive diluent may be selected from at least one of polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, butyl glycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, furan methyl glycidyl ether, ethylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, allyl glycidyl ether, phenyl glycidyl ether, o-tolyl glycidyl ether, benzyl glycidyl ether, resorcinol diglycidyl ether, octyl glycidyl ether, C12-14 alkyl glycidyl ether (AGE), glycidyl tert-carbonate, glycidyl neodecanoate, and glycidyl methacrylate.

[0018] The diluent is preferably one or a combination of benzyl alcohol (BA), 1,4-butanediol diglycidyl ether (622), and C12-14 alkyl glycidyl ether (AGE);

[0019] The amount of the diluent is preferably 3 to 15 wt% of the epoxy resin weight, more preferably 5 to 10 wt% (such as 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, or any value between the above values ​​or a range between any two of the above values).

[0020] The curing agent can be selected from acid anhydride curing agents or amine curing agents;

[0021] The anhydride curing agent may be selected from at least one of methyltetrahydrophthalic anhydride, liquid methylhexahydrophthalic anhydride, and liquid methylnadic anhydride.

[0022] The amount of the anhydride curing agent added can be measured according to a calculation formula commonly used in the industry. For example, it can be calculated using the following formula:

[0023] The dosage of anhydride curing agents is usually calculated using the following formula:

[0024] W = A E ×E×K

[0025] Where: W --- the mass of anhydride curing agent required for every 100g of epoxy resin, in grams;

[0026] AE --- Molar mass of acid anhydride, g / mol;

[0027] E --- Epoxy value of epoxy resin;

[0028] K --- The amount of acid anhydride required per mole of epoxy group, in mol. Empirical data shows it varies within the range of 0.5 to 1.1, but is generally taken as 0.85.

[0029] The amine curing agent is preferably diethyltoluenediamine / or montananediamine.

[0030] The amount of the amine curing agent added can be measured according to the stoichiometric ratio.

[0031] The calculation method for the dosage of amine curing agents is based on the interaction between an active hydrogen atom and an epoxy group on the amine group. The dosage of various primary and secondary amines can be calculated using the following formula:

[0032]

[0033] Where: W --- the mass of amine curing agent required for every 100g of epoxy resin, in grams;

[0034] M --- Molecular weight of amine curing agents;

[0035] Hn --- the number of active hydrogen atoms on the amine group in a curing agent molecule;

[0036] E --- Epoxy value of epoxy resin.

[0037] The accelerator may be selected from at least one of triethanolamine, tris(dimethylaminopropyl)amine, 2,4,6-tris(dimethylaminomethyl)phenol, 2-ethyl-4-methylimidazole, and 2-methylimidazole; preferably at least one of 2-ethyl-4-methylimidazole and 2-methylimidazole.

[0038] The amount of the accelerator is preferably 3 to 10 wt% of the sum of the weights of the epoxy resin and the diluent, more preferably 5 to 8 wt%. (e.g., 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, or any value between the above values ​​or a range between any two of the above values)

[0039] The present invention may also include a defoamer, wherein the defoamer may be selected from one or more of aliphatic defoamers, polyether defoamers, silicone defoamers, polyether-modified silicone defoamers, and fluorine-modified silicone defoamers; preferably a polyether defoamer;

[0040] The amount of the defoamer is preferably 0.3 to 1.2 wt% of the epoxy resin weight, more preferably 0.5 to 1.0 wt%. (e.g., 0.5 wt%, 0.8 wt%, 1.0 wt%, or any value between the above values ​​or any two of the above values) can be adjusted according to the actual situation.

[0041] The curing temperature of the epoxy resin composition is not higher than the softening temperature of the polyethylene liner; specifically, the curing temperature of the epoxy resin composition is not higher than 110°C.

[0042] The second objective of this invention is to provide a method for preparing the epoxy resin composition for the winding layer of a Type IV hydrogen storage cylinder, which may include the following steps:

[0043] Step 1: Prepare component A: Stir the liquid epoxy resin, add diluent, and optionally add defoamer. Stir at high speed, then stop stirring and let stand for later use.

[0044] The preferred speed of the high-speed stirring is 2000–3000 r / min;

[0045] The preferred high-speed stirring time is 10 to 15 minutes.

[0046] Step 2: Prepare Component B: Mix the curing agent and accelerator, heat and stir, then cool and set aside; preferably, heat to 60-145°C; preferably, stir at 300-1000 rpm for 10-20 minutes.

[0047] Step 3: Pour component B into component A and stir. The stirring is carried out at a speed not exceeding 300-1000 r / min for 10-20 min.

[0048] More specifically, the preparation method may include the following steps:

[0049] Step 1: Prepare Component A: Pour the liquid epoxy resin into a container and stir slowly using a mechanical stirrer. Weigh the diluent and pour it into the container. Then weigh the defoamer and pour it into the container. Stir at a high speed of 2000-3000 r / min for 10-15 minutes, then stop stirring and let it stand for later use.

[0050] Step 2: Prepare component B: Weigh the curing agent and pour it into a container equipped with a condenser. Then weigh the accelerator and pour it into the same container. Heat the mixture to 60-145°C, stir at 300 rpm for 10 minutes, then stop and let it cool before use.

[0051] Step 3: Slowly pour component B into component A and stir at a speed not exceeding 300 rpm for 10 minutes. Then pour it into the glue tank for use.

[0052] A third objective of this invention is to provide the application of the epoxy resin composition for the winding layer of a type IV hydrogen storage cylinder as described in the first objective of this invention, or the epoxy resin composition prepared by the preparation method described in the second objective of this invention, preferably in the application of hydrogen storage cylinders.

[0053] The beneficial effects of this invention are as follows: the system has low viscosity and reacts slowly at room temperature, meeting the pot life requirements of the winding process. The curing temperature required for the epoxy resin system is not higher than the softening temperature of the polyethylene liner. The glass transition temperature of the cured epoxy resin system is higher than various standard requirements (e.g., U.S. Department of Transportation DOTCFFC 2007). The impact strength of the cured epoxy resin system casting is also significantly improved. Attached Figure Description

[0054] Figure 1 The images show the non-isothermal DSC scan curves of the epoxy resin compositions of Example 1 and Comparative Example 1. Detailed Implementation

[0055] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0056] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0057] Source of raw materials

[0058] Unless otherwise specified, the raw materials used in the examples and comparative examples are all disclosed in the prior art, such as those that can be directly purchased or prepared according to the preparation methods disclosed in the prior art.

[0059] Example 1

[0060] Weigh the following components by weight: 100 parts E54 epoxy resin, 5 parts 1,4-butanediol diglycidyl ether, 85 parts methyltetrahydrophthalic anhydride, 5 parts 2-ethyl-4-methylimidazolium, and 0.5 parts polyether defoamer BYK054. Pour the above components into a three-necked flask, maintain the temperature at 30°C and stir, then degas under vacuum at 60 kPa for 5 min. Pour the mixture into a mold and cure at 80°C for 1 h and 100°C for 4 h.

[0061] Example 2

[0062] Weigh the following components by weight: 100 parts liquid bisphenol F type epoxy resin (F-170), 5 parts 1,4-butanediol diglycidyl ether, 95 parts methyltetrahydrophthalic anhydride, 5 parts 2-ethyl-4-methylimidazolium, and 0.5 parts polyether type defoamer BYK054. Pour the above components into a three-necked flask, maintain 30°C and stir, and degas under vacuum at 60 kPa for 5 min. Pour the mixture into a mold and cure at 80°C for 1 h and 100°C for 4 h.

[0063] Example 3

[0064] Weigh the following components by weight: 50 parts E54 epoxy resin, 50 parts liquid bisphenol F epoxy resin (F-170), 5 parts 1,4-butanediol diglycidyl ether, 90 parts methyltetrahydrophthalic anhydride, 5 parts 2-ethyl-4-methylimidazolium, and 0.5 parts BYK054 polyether defoamer. Pour the above components into a three-necked flask, maintain the temperature at 30°C and stir, and degas under vacuum at 60 kPa for 5 min. Pour the mixture into a mold and cure at 80°C for 1 h and 100°C for 4 h.

[0065] Example 4

[0066] In Example 1, 5 parts of 1,4-butanediol diglycidyl ether were replaced with 10 parts of 1,4-butanediol diglycidyl ether, while the rest remained unchanged.

[0067] Example 5

[0068] Weigh the following components by weight: 50 parts E54 epoxy resin, 50 parts liquid bisphenol F epoxy resin (F-170), 5 parts 1,4-butanediol diglycidyl ether, 95 parts methylnadic phthalic anhydride, 5 parts 2-ethyl-4-methylimidazole, and 0.5 parts polyether defoamer BYK054. Pour the above components into a three-necked flask, maintain the temperature at 30°C and stir, and degas under vacuum at 60 kPa for 5 min. Pour the mixture into a mold and cure at 80°C for 1 h and 100°C for 4 h.

[0069] Example 6

[0070] In Example 1, 5 parts of 2-ethyl-4-methylimidazole were replaced with 8 parts of 2-ethyl-4-methylimidazole, while the rest remained unchanged.

[0071] Example 7

[0072] Weigh the following components by weight: 50 parts E54 epoxy resin, 50 parts liquid bisphenol F epoxy resin (F-170), 5 parts 1,4-butanediol diglycidyl ether, 90 parts methyltetrahydrophthalic anhydride, 5 parts 2-methylimidazole, and 0.5 parts polyether defoamer. First, pour the methyltetrahydrophthalic anhydride and 2-methylimidazole into a three-necked flask equipped with a condenser, heat to 145℃ and stir for 10 minutes. After cooling to 30℃, add the remaining components to the three-necked flask and degas under vacuum at 60 kPa for 5 minutes. Pour the mixture into a mold and cure at 80℃ for 1 hour and 100℃ for 4 hours.

[0073] Example 8

[0074] In Example 1, 85 parts of methyltetrahydrophthalic anhydride were replaced with 27 parts of diethyltoluenediamine, while the rest remained unchanged.

[0075] Example 9

[0076] In Example 1, 5 parts of 2-ethyl-4-methylimidazole were replaced with 10 parts of 2-ethyl-4-methylimidazole, while the rest remained unchanged.

[0077] Comparative Example 1

[0078] In Example 1, 5 parts of 2-ethyl-4-methylimidazole were replaced with 1 part of 2-ethyl-4-methylimidazole, while the rest remained unchanged.

[0079] Comparative Example 2

[0080] In Example 1, 5 parts of 2-ethyl-4-methylimidazol were replaced with 5 parts of 2,4,6-tris(dimethylaminomethyl)phenol (DMP-30), while the rest remained unchanged.

[0081] The products obtained from Examples 1 to 9 and Comparative Examples 1 to 2 were subjected to performance testing, and the results are shown in Table 1 below.

[0082] Table 1

[0083]

[0084]

[0085] From the appendix Figure 1 As can be seen, by increasing the amount of imidazole accelerator in Example 1 of this application, the curing temperature of the system is significantly reduced, allowing curing to be carried out below the softening temperature of the polyethylene liner.

[0086] As shown in Table 1 above, the epoxy resin composition for the winding layer of Type IV hydrogen storage cylinders described in this application achieves a curing temperature lower than the softening temperature of the polyethylene liner by varying the amount of accelerator, and the cured product has a glass transition temperature higher than the standard requirement, while also improving impact resistance. The system has low viscosity, which facilitates resin wetting of fibers, and the reaction is slow at room temperature, meeting the pot life requirements of the winding process.

Claims

1. An epoxy resin composition for use in the winding layer of a type IV hydrogen storage cylinder, comprising the following components: epoxy resin, diluent, curing agent, accelerator, and defoamer; The epoxy resin is a liquid epoxy resin; the epoxy resin is selected from at least one of liquid bisphenol A type epoxy resin, liquid hydrogenated bisphenol A type epoxy resin, liquid bisphenol F type epoxy resin, liquid glycidyl ester type epoxy resin, and liquid glycidyl amine type epoxy resin. The accelerator is selected from at least one of 2-ethyl-4-methylimidazole and 2-methylimidazole; The amount of the accelerator is 3-10 wt% of the sum of the weights of the epoxy resin and the diluent; The amount of the diluent used is 3 to 15 wt% of the epoxy resin weight; The defoamer is selected from one or more of aliphatic defoamers, polyether-based defoamers, and polyether-modified silicone defoamers; the amount of the defoamer is 0.3 to 1.2 wt% of the epoxy resin weight. The curing temperature of the epoxy resin composition is not higher than 100°C, but the glass transition temperature is higher than 115°C.

2. The epoxy resin composition for the winding layer of a type IV hydrogen storage cylinder according to claim 1, characterized in that: The epoxy resin is at least one of liquid bisphenol A type epoxy resin and liquid bisphenol F type epoxy resin.

3. The epoxy resin composition for the winding layer of a type IV hydrogen storage cylinder according to claim 1, characterized in that: The diluent is selected from at least one of non-reactive diluents and reactive diluents; The inactive diluent is free of epoxy groups; and / or, The reactive diluent contains a low-viscosity substance with at least one epoxy group.

4. The epoxy resin composition for the winding layer of a type IV hydrogen storage cylinder according to claim 3, characterized in that: The inactive diluent is selected from at least one of acetone, ethanol, toluene, xylene, ethyl acetate, dibutyl phthalate, dioctyl phthalate, styrene, diallyl phthalate, and benzyl alcohol; and / or, The active diluent is selected from at least one of polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, butyl glycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, furan methyl glycidyl ether, ethylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, allyl glycidyl ether, phenyl glycidyl ether, o-tolyl glycidyl ether, benzyl glycidyl ether, resorcinol diglycidyl ether, octyl glycidyl ether, C12-14 alkyl glycidyl ether, glycidyl tert-carbonate, glycidyl neodecanoate, and glycidyl methacrylate.

5. The epoxy resin composition for the winding layer of a type IV hydrogen storage cylinder according to claim 4, characterized in that: The diluent is selected from at least one of benzyl alcohol, 1,4-butanediol diglycidyl ether, and C12-14 alkyl glycidyl ether.

6. The epoxy resin composition for the winding layer of a type IV hydrogen storage cylinder according to claim 1, characterized in that: The amount of the diluent used is 5 to 10 wt% of the epoxy resin.

7. The epoxy resin composition for the winding layer of a type IV hydrogen storage cylinder according to claim 1, characterized in that: The curing agent is selected from acid anhydride curing agents or amine curing agents.

8. The epoxy resin composition for the winding layer of a type IV hydrogen storage cylinder according to claim 7, characterized in that: The anhydride curing agent is selected from at least one of methyltetrahydrophthalic anhydride, liquid methylhexahydrophthalic anhydride, and liquid methylnadic anhydride; and / or The amine curing agent is selected from diethyltoluene diamine and / or montanane diamine.

9. The epoxy resin composition for the winding layer of a type IV hydrogen storage cylinder according to claim 1, characterized in that: The amount of the accelerator is 5 to 8 wt% of the sum of the weights of the epoxy resin and the diluent.

10. The epoxy resin composition for the winding layer of a type IV hydrogen storage cylinder according to claim 1, characterized in that: The defoamer is selected from polyether-type defoamers; The amount of the defoamer is 0.5 to 1.0 wt% of the epoxy resin.

11. The method for preparing the epoxy resin composition for the winding layer of a type IV hydrogen storage cylinder according to any one of claims 1 to 10, characterized in that... Includes the following steps: Step 1: Prepare component A: Stir the epoxy resin, add the diluent, and optionally add the defoamer. After stirring, stop stirring and let it stand for later use. Step 2: Prepare Component B: Mix the curing agent and accelerator, heat and stir, then cool and set aside. Step 3: Pour component B into component A and stir.

12. The method for preparing the epoxy resin composition for the winding layer of a type IV hydrogen storage cylinder according to claim 11, characterized in that: In step two, the heating is performed to 60–145°C.

13. The use of the epoxy resin composition for the winding layer of a type IV hydrogen storage cylinder according to any one of claims 1 to 10, or the epoxy resin composition prepared by the preparation method according to claim 11 or 12.

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