Sealing material for aircraft fuel tank as well as preparation method and application of sealing material

Abstract

The invention provides a sealing material for an aircraft fuel tank as well as a preparation method and application thereof, the sealing material is prepared from an isocyanate component and an amine curing agent component, and the weight ratio of the isocyanate component to the amine curing agent component is 100: (5-15); the isocyanate component is an isocyanate prepolymer prepared from the following components: an isocyanate monomer, a polymer polyol, a diluent and a catalyst; the amine curing agent component comprises a mixture of an amine chain extender, a long-chain polyamine compound and an auxiliary agent. The sealing material provided by the invention has relatively good physical properties, mechanical properties, environment resistance, temperature resistance, aging resistance and flame retardance, and has a relatively good sealing effect when being applied to an aircraft fuel tank.

Description

Technical Field

[0001] The present invention relates to the technical field of sealing materials. Further, it relates to a sealing material for aircraft fuel tanks, its preparation method and application. Background Art

[0002] The fuel used in aero-engines is mainly aviation kerosene RP-3, which is a mixture of various hydrocarbons, and its light components have strong volatility. During the storage and use of aviation kerosene, some of the lighter liquid components will inevitably vaporize and escape from the fuel tank. For example, the fuel tank structure of an unmanned aerial vehicle has a relatively complex space, many corners and hard materials, making it common for fuel tanks to leak and seep oil.

[0003] Generally, BFJ-1650 is selected as the anti-corrosion protection coating inside the fuel tank for the overall mating surface of the aircraft fuel tank, and is sealed with a modified polysulfide sealant (HM116C8) with high adhesion. Since the sealant is in direct contact with moisture, salt and dielectric oil in the fuel tank, it will cause the sealant to expand, resulting in foaming and peeling of the sealing system, causing leakage of aviation kerosene vapor. To achieve good sealing and anti-corrosion effects for the overall aircraft fuel tank, polysulfide sealants are often used in combination with sealing materials for aircraft fuel tanks. Among them, polysulfide sealants are mainly used for sealing mating surfaces, fillets, screws and other parts, and then a layer of sealing material for aircraft fuel tanks is brushed on the inner surface of the fuel tank as a whole to achieve the best double-insurance sealing. Therefore, the sealing material for aircraft fuel tanks is required to not only have good fuel resistance, temperature resistance and other properties, but also have good adhesion to the fuel tank substrate and polysulfide sealants. At present, the protective sealing coating for aircraft fuel tanks generally uses a solvent-based glue solution prepared from nitrile rubber. Since nitrile rubber is an amorphous random copolymer, the peel strength from polysulfide sealants and metal substrates is not high. During flight, affected by factors such as vibration, pressure and temperature, gaps may appear in the sealed parts, leading to fuel leakage and posing serious safety hazards. At the same time, nitrile rubber requires solvents such as toluene and xylene during construction, which are volatile, harmful to the human body and easy to pollute the environment, restricting its application.

[0004] Therefore, to meet the requirements of new-generation aircraft, a sealing material for aircraft fuel tanks with better physical properties, mechanical properties, environmental resistance, temperature resistance, aging resistance, flame retardancy and other properties is needed to meet the application requirements of aircraft fuel tanks. Summary of the Invention

[0005] To solve the above problems, the present invention provides a sealing material for aircraft fuel tanks and its preparation method. The sealing material has good physical properties, mechanical properties, environmental resistance, temperature resistance, aging resistance and flame retardancy, and has a good sealing effect when applied to aircraft fuel tanks.

[0006] First, one of the objectives of the present invention is to provide a sealing material for aircraft fuel tanks.

[0007] Specifically, the sealing material is prepared from an isocyanate component and an amine curing agent component, and the weight ratio of the isocyanate component to the amine curing agent component is 100:5 to 15, preferably 100:6 to 10.

[0008] More specifically, the isocyanate component is an isocyanate prepolymer prepared from components including an isocyanate monomer, a polymer polyol, a diluent, and a catalyst.

[0009] Furthermore, in the isocyanate component, based on a total weight of 100 parts by weight, the mass percentages of the respective components are as follows:

[0010] Isocyanate monomer: 10 to 30 parts by weight, preferably 15 to 25 parts by weight;

[0011] Polymer polyol: 25 to 45 parts by weight, preferably 30 to 40 parts by weight;

[0012] Diluent: 40 to 60 parts by weight, preferably 42 to 55 parts by weight;

[0013] Catalyst: 0.5 to 1.5 parts by weight, preferably 0.8 to 1.2 parts by weight.

[0014] Furthermore, the functionality of the isocyanate monomer is 2 to 3; preferably, the isocyanate monomer is selected from aliphatic isocyanate monomers, more preferably one or a combination of 4,4'-dicyclohexylmethane diisocyanate (HMDI), isophorone diisocyanate (IPDI), and 1,4-cyclohexane diisocyanate (CHDI); the sealing material prepared from the above-mentioned aliphatic isocyanates has good aging resistance and a slow reaction rate, which is more conducive to construction.

[0015] Furthermore, the functionality of the polymer polyol is 2 to 3, the hydroxyl equivalent is 500 to 2500, preferably 500 to 1500, and particularly preferably 500 to 1000; preferably, the polymer polyol is selected from the combination of at least one of polytetrahydrofuran ether glycol, polycaprolactone diol, and polycarbonate diol and a reactive flame retardant; preferably, the reactive flame retardant is selected from one of flame retardant FR780, flame retardant FR750, and flame retardant FR830; wherein, the dosage of the reactive flame retardant accounts for 50 to 70% of the total dosage of the polymer polyol; preferably 60 to 65%.

[0016] It is worth mentioning that polymer polyol constitutes the soft segment part of the polyurethane coating, which can improve the elasticity, elongation rate and medium resistance of the sealing coating; and when the reactive flame retardant is used in combination with the polymer polyol and isocyanate components, it not only takes into account the flame retardant performance of the coating, but also takes into account the mechanical properties of the coating and keeps them from decreasing.

[0017] Further, the diluent is selected from one or a combination of butyl acetate and ethyl acetate.

[0018] Further, the catalyst is selected from one or a combination of dibutyltin dilaurate, stannous octoate and bismuth octoate.

[0019] More specifically, the amine curing agent component is formulated from components including an amine chain extender, a long-chain polyamine compound and an auxiliary agent. The present invention adjusts the physical and chemical properties such as the molecular structure, molecular chain regularity, molecular weight and viscosity of the polyurethane sealing coating by adding the amine curing agent component.

[0020] Further, in the amine curing agent component, based on 100 parts by weight in total, the mass ratios of the respective components are as follows:

[0021] The amine chain extender is 35-60 parts by weight, preferably 40-55 parts by weight;

[0022] The long-chain polyamine compound is 35-60 parts by weight, preferably 40-55 parts by weight;

[0023] The auxiliary agent is 0.5-5.5 parts by weight, preferably 1.5-5.5 parts by weight.

[0024] Further, the amine chain extender is selected from one or a combination of primary amine chain extenders and secondary amine chain extenders, preferably selected from one or a combination of diethyltoluenediamine (DETDA), methylene bis-o-phenylenediamine (MOCA), dimethylthiotoluenediamine (DMTDA), bis(sec-butylamino)diphenylmethane (MDBA).

[0025] Further, the long-chain polyamine compound is selected from one or a combination of polyaspartate and polytetramethylene ether glycol.

[0026] Further, the auxiliary agent is one or more of an antifoaming agent, a dispersant, a coupling agent, a leveling agent, an antioxidant, an ultraviolet stabilizer and an adhesion promoter. In this case, the added auxiliary agent is not limited and is an auxiliary agent conventionally used in the art.

[0027] Secondly, the second object of the present invention is to provide a preparation method of the sealing material for an aircraft fuel tank for the first object of the present invention.

[0028] Specifically, the method includes the following steps:

[0029] Step 1: Preheat the isocyanate monomer. While stirring, add dropwise a mixture of a polymeric polyol, a diluent, and a catalyst. After the addition is complete, raise the temperature and carry out a holding reaction to form an isocyanate prepolymer;

[0030] Step 2: Mix and disperse an amine chain extender, a long-chain polyamine compound, and an auxiliary agent in accordance with a ratio to obtain an amine curing agent;

[0031] Step 3: Mix the isocyanate prepolymer and the amine curing agent to obtain a sealing material.

[0032] More specifically, the method includes the following steps:

[0033] Step 1: Preheat the isocyanate monomer. While stirring, add dropwise a mixture of a polymeric polyol, a diluent, and a catalyst. After the addition is complete, raise the temperature and carry out a holding reaction to form an isocyanate prepolymer;

[0034] Step 2: Add an amine chain extender, a long-chain polyamine compound, and an auxiliary agent into a paint mixing tank in accordance with a ratio, and then use a high-speed shear dispersion device to disperse them until uniform to obtain an amine curing agent;

[0035] Step 3: Mix the isocyanate prepolymer and the amine curing agent to obtain a sealing material.

[0036] Preferably, in Step 1, the preheating temperature is 50 - 80 °C; preferably 60 - 70 °C.

[0037] Preferably, in Step 1, the conditions for the holding reaction are: the temperature is 90 - 100 °C, preferably 93 - 97 °C, and the reaction time is 2 - 4 h; preferably 2.5 - 3.5 h.

[0038] Preferably, in Step 1, the termination condition for the holding reaction is: the content of free isocyanate groups in the isocyanate prepolymer is 1 - 3%.

[0039] Preferably, in Step 3, the molar ratio of the isocyanate groups in the isocyanate prepolymer to the amine groups in the amine curing agent is 1.00 - 1.15.

[0040] Furthermore, the third object of the present invention is to provide an application of the sealing material for an aircraft fuel tank of the first object of the present invention.

[0041] Specifically, the application method includes the following steps: Mix the isocyanate component and the amine curing agent component in accordance with a ratio, and then spray them on the aircraft fuel tank area to cure into a film.

[0042] Compared with the prior art, the beneficial effects of the present invention are:

[0043] 1. The sealing material for aircraft fuel tanks of the present invention is obtained by spraying with an ordinary spray gun. After curing, it has good physical properties, mechanical properties, environmental resistance, temperature resistance, aging resistance, flame retardancy and other properties, and has a high fuel vapor isolation efficiency, being suitable for application in the area of aircraft fuel tanks to achieve the effect of preventing fuel vapor leakage.

[0044] 2. The sealing material for aircraft fuel tanks provided by the present invention is a sealing material prepared by synthesizing a series of isocyanate prepolymers from aliphatic isocyanates and different polymer polyols, and cooperating with long-chain polyamine compounds and amine chain extenders. After curing, it has a good fuel vapor isolation efficiency, being suitable for application in the area of aircraft fuel tanks to achieve the effect of preventing fuel vapor leakage.

[0045] 3. The sealing material for aircraft fuel tanks provided by the present invention has a tensile strength of more than 22 Mpa and an elongation at break of more than 400%. It has good physical properties and mechanical properties, and can effectively protect aircraft fuel tanks from fuel vapor leakage.

[0046] 4. The sealing material for aircraft fuel tanks provided by the present invention has excellent environmental resistance, temperature resistance and aging resistance.

[0047] 5. The sealing material for aircraft fuel tanks provided by the present invention can self-extinguish within 2 seconds after leaving the fire and has excellent flame retardancy. Specific Embodiments

[0048] The present invention will be specifically described below in conjunction with specific embodiments. It is necessary to point out here that the following embodiments are only for further illustration of the present invention and should not be construed as limiting the protection scope 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 still fall within the protection scope of the present invention.

[0049] In the following examples and comparative examples, the raw materials are all commercially available products. Among them, flame retardant FR780, flame retardant FR750, and flame retardant FR830 are purchased from Qingdao Ruinuo Chemical Co., Ltd.

[0050] Example 1

[0051] This example is used to illustrate the preparation of the sealing coating, and the specific steps are as follows:

[0052] Step 1: Preheat 12 parts by weight of 4,4 - dicyclohexylmethane diisocyanate (HMDI) at 60°C. Under stirring, add dropwise 13 parts by weight of polytetrahydrofuran ether glycol (P1000) (hydroxyl equivalent is 500), 25 parts by weight of flame retardant FR - 780 (hydroxyl equivalent is 1200), 1 part by weight of dibutyltin dilaurate, and 49 parts by weight of butyl acetate. After the dropwise addition is completed, keep the reaction at 95°C for 3 h to obtain an isocyanate prepolymer with an NCO% content of 1.9%.

[0053] Step 2: Add 49 parts by weight of diethyltoluenediamine (E-100), 49 parts by weight of polyaspartate (F420), and 2 parts by weight of additives (including 0.5 part of defoamer BYK-A530, 0.5 part of leveling agent Levaslip466, 0.5 part of antioxidant 1076, and 0.5 part of ultraviolet stabilizer UV-531) into a paint mixing tank, and disperse them evenly at high speed using a high-speed shear dispersion device to obtain an amine curing agent.

[0054] Step 3: Mix the isocyanate prepolymer and the amine curing agent (weight ratio is 100:6, and the ratio of isocyanate groups to amine groups is 1.1), and then apply it to the surface of a tinplate mold through an ordinary spray gun to produce a standard test sample.

[0055] Among them, the mechanical property test is only carried out on the sample. The thickness of the sample is 300 μm, and the mechanical property test method is GB / T528; when conducting the wet resistance, salt resistance, fog resistance, oil resistance and flame retardancy tests, it is all compounded with the YMS2502Ⅰ type primer. The thickness of the sealing material is 300 μm, and the test method for the double-layer liquid of salt water / fuel oil is GJB 1390; the flame retardancy test method is Method F2 in BSS 7230; the test for fuel oil penetration pressure is combined with the technical requirements for the fuel tank isolation coating product in the product specification document BMS 5-81J "Secondary Isolation Layer for Fuel Tanks" of The Boeing Company in the United States; the wet heat resistance test method is GB / T 1740; the neutral salt fog resistance test method is GB / T 1771; the low temperature resistance test method is 2 h at -55 °C, and visually inspect after rapid bending; the artificial weathering test standard is GB / T 1865.

[0056] Table 1 shows the test data of the performance of the sample in this example.

[0057] Table 1:

[0058]

[0059] Example 2

[0060] This example is used to illustrate the preparation of the sealing coating, and the specific steps are as follows:

[0061] Step 1: Preheat 12 parts by weight of isophorone diisocyanate (IPDI) at 60 °C. Under stirring, dropwise add 13 parts by weight of polycarbonate ether diol (C1100) (hydroxyl equivalent is 500), 25 parts by weight of flame retardant FR-750 (hydroxyl equivalent is 1500), 1 part by weight of dibutyltin dilaurate, and 49 parts by weight of butyl acetate. After the dropping is completed, keep the reaction at 95 °C for 3 h to obtain an isocyanate prepolymer with an NCO% content of 1.9%.

[0062] Step 2: Add 49 parts by weight of dimethylthiotoluenediamine (E-300), 49 parts by weight of polyaspartate (F420), and 2 parts by weight of additives (including 0.5 part of defoamer BYK-A530, 0.5 part of leveling agent Levaslip 466, 0.5 part of antioxidant 1076, and 0.5 part of UV stabilizer UV-531) into a paint mixing tank, and use a high-speed shear dispersion device to disperse them evenly at high speed to obtain an amine curing agent;

[0063] Step 3: Mix the isocyanate prepolymer and the amine curing agent (weight ratio is 100:8, and the ratio of isocyanate groups to amine groups is 1.1), and then apply it to the surface of a tinplate mold through an ordinary spray gun to make a standard test sample.

[0064] The test method for the sample in this example is the same as that for the sample in Example 1.

[0065] Table 2 shows the test data of the performance of the sample in this example.

[0066] Table 2:

[0067]

[0068] Example 3

[0069] This example is used to illustrate the preparation of a sealing coating, and the specific steps are as follows:

[0070] Step 1: Preheat 13 parts by weight of 1,4-cyclohexane diisocyanate (CHDI) at 60°C. Under stirring, dropwise add 12 parts by weight of polycaprolactone diol (PCL-1000) (hydroxyl equivalent is 500), 25 parts by weight of flame retardant FR-830 (hydroxyl equivalent is 1000), 1 part by weight of dibutyltin dilaurate, and 49 parts by weight of butyl acetate. After the dropping is completed, keep the reaction at 95°C for 3 h to obtain an isocyanate prepolymer with an NCO% content of 1.9%.

[0071] Step 2: Add 45 parts by weight of methylene bis-o-phenylenediamine (MOCA), 53 parts by weight of polytetramethylene ether glycol (PTEG1000), and 2 parts by weight of additives (including 0.5 part of defoamer BYK-A530, 0.5 part of leveling agent Levaslip 466, 0.5 part of antioxidant 1076, and 0.5 part of UV stabilizer UV-531) into a paint mixing tank, and use a high-speed shear dispersion device to disperse them evenly at high speed to obtain an amine curing agent;

[0072] Step 3: Mix the isocyanate prepolymer and the amine curing agent (weight ratio is 100:10, and the ratio of isocyanate groups to amine groups is 1.1), and then apply it to the surface of a tinplate mold through an ordinary spray gun to make a standard test sample.

[0073] The sample testing method of this embodiment is the same as that of Embodiment 1.

[0074] Table 3 shows the test data of the performance of the sample in this embodiment.

[0075] Table 3:

[0076]

[0077] Embodiment 4

[0078] This embodiment is used to illustrate the preparation of the sealing coating, and the specific steps are as follows:

[0079] Step 1: Preheat 11 parts by weight of 4,4 - dicyclohexylmethane diisocyanate (HMDI) at 60 °C. Under stirring, add dropwise 14 parts by weight of polytetrahydrofuran ether glycol (P - 1000) (hydroxyl equivalent is 500), 25 parts by weight of flame retardant FR - 780 (hydroxyl equivalent is 1200), 1 part by weight of dibutyltin dilaurate, and 49 parts by weight of butyl acetate. After the addition is complete, keep the reaction at 95 °C for 3 h to obtain an isocyanate prepolymer with an NCO% content of 1.9%.

[0080] Step 2: Add 40 parts by weight of bis(sec - butylamino)diphenylmethane (MDBA), 58 parts by weight of polytetramethylene ether glycol (PTEG 1000), and 2 parts by weight of additives (including 0.5 part of defoamer BYK - A530, 0.5 part of leveling agent Levaslip 466, 0.5 part of antioxidant 1076, and 0.5 part of ultraviolet stabilizer UV - 531) into the paint mixing tank, and disperse them evenly using a high - speed shear dispersion device to obtain an amine curing agent;

[0081] Step 3: Mix the isocyanate prepolymer and the amine curing agent (weight ratio is 100:10, and the ratio of isocyanate groups to amine groups is 1.1), and then apply it to the surface of a tinplate mold through an ordinary spray gun to make a standard test sample.

[0082] The sample testing method of this embodiment is the same as that of Embodiment 1.

[0083] Table 4 shows the test data of the performance of the sample in this embodiment.

[0084] Table 4:

[0085]

[0086] Comparative Example 1

[0087] This comparative example is used to illustrate the preparation of the sealing coating, and the specific steps are as follows:

[0088] Step 1: Preheat 12 parts by weight of 4,4'-dicyclohexylmethane diisocyanate (HMDI) at 60°C first. Under stirring, dropwise add a mixture of 13 parts by weight of polyether polyol (DL-1000D) (hydroxyl equivalent weight is 500), 25 parts by weight of flame retardant FR-780 (hydroxyl equivalent weight is 1200), 1 part by weight of dibutyltin dilaurate, and 49 parts by weight of butyl acetate. After the dropping is completed, keep the reaction at 95°C for 3 h to obtain an isocyanate prepolymer with an NCO% content of 1.9%.

[0089] Step 2: Add 49 parts by weight of diethyltoluenediamine (E-100), 49 parts by weight of polyaspartate (F420), and 2 parts by weight of additives (including 0.5 part of defoamer BYK-A530, 0.5 part of leveling agent Levaslip466, 0.5 part of antioxidant 1076, and 0.5 part of ultraviolet stabilizer UV-531) into a paint mixing tank, and use a high-speed shear dispersion device to disperse evenly to obtain an amine curing agent;

[0090] Step 3: Mix the isocyanate prepolymer and the amine curing agent (weight ratio is 100:6, and the ratio of isocyanate groups to amine groups is 1.1), and then apply it to the surface of a tinplate mold through an ordinary spray gun to produce a standard test specimen.

[0091] The test method for the sample of this comparative example is the same as that of the sample in Example 1.

[0092] Table 5 shows the test data of the performance of the sample of this comparative example.

[0093] Table 5:

[0094]

[0095] Comparative Example 2

[0096] This comparative example is used to illustrate the preparation of a sealing coating, and the specific steps are as follows:

[0097] Step 1: Preheat 11 parts by weight of 4,4'-dicyclohexylmethane diisocyanate (HMDI) at 60°C first. Under stirring, dropwise add 24 parts by weight of polytetrahydrofuran ether glycol (P1000) (hydroxyl equivalent weight is 500), 15 parts by weight of flame retardant FR-780 (hydroxyl equivalent weight is 1200), 1 part by weight of dibutyltin dilaurate, and 49 parts by weight of butyl acetate. After the dropping is completed, keep the reaction at 95°C for 3 h to obtain an isocyanate prepolymer with an NCO% content of 2.1%.

[0098] Step 2: Add 49 parts by weight of diethyltoluenediamine (E-100), 49 parts by weight of polyaspartate (F420), and 2 parts by weight of additives (including 0.5 part of defoamer BYK-A530, 0.5 part of leveling agent Levaslip 466, 0.5 part of antioxidant 1076, and 0.5 part of ultraviolet stabilizer UV-531) into a paint mixing tank, and use a high-speed shear dispersion device to disperse evenly at high speed to obtain an amine curing agent;

[0099] Step 3: Mix the isocyanate prepolymer and the amine curing agent (weight ratio is 100:6, and the ratio of isocyanate groups to amine groups is 1.1), and then apply it to the surface of a tinplate mold through an ordinary spray gun to produce a standard test sample.

[0100] The test method for the sample of this comparative example is the same as that of the sample in Example 1.

[0101] Table 6 shows the test data of the performance of the sample of this comparative example.

[0102] Table 6:

[0103]

[0104] Comparative Example 3

[0105] This comparative example is used to illustrate the preparation of a sealant coating, and the specific steps are as follows:

[0106] Step 1: Preheat 12 parts by weight of 4,4'-dicyclohexylmethane diisocyanate (HMDI) at 60 °C. Under stirring, dropwise add 13 parts by weight of polytetrahydrofuran ether glycol (P1000) (hydroxyl equivalent is 500), 25 parts by weight of flame retardant FR-780 (hydroxyl equivalent is 1200), 1 part by weight of dibutyltin dilaurate, and 49 parts by weight of butyl acetate. After the dropwise addition is completed, keep the reaction at 95 °C for 3 h to obtain an isocyanate prepolymer with an NCO% content of 1.9%.

[0107] Step 2: Add 98 parts by weight of diethyltoluenediamine (E-100) and 2 parts by weight of additives (including 0.5 part of defoamer BYK-A530, 0.5 part of leveling agent Levaslip 466, 0.5 part of antioxidant 1076, and 0.5 part of ultraviolet stabilizer UV-531) into a paint mixing tank, and use a high-speed shear dispersion device to disperse evenly at high speed to obtain an amine curing agent;

[0108] Step 3: Mix the isocyanate prepolymer and the amine curing agent (weight ratio is 100:5, and the ratio of isocyanate groups to amine groups is 1.1), and then apply it to the surface of a tinplate mold through an ordinary spray gun to produce a standard test sample.

[0109] The sample test method of this comparative example is the same as that of Example 1.

[0110] Table 7 shows the test data of the performance of the sample of this comparative example.

[0111] Table 7:

[0112]

[0113] From the data in Tables 1-7, it can be seen that Examples 1-4 provide a sealing coating with relatively excellent comprehensive performance. Among them, after using dimethylthiotoluenediamine (E-300) as a chain extender in Example 2, the pot life and surface drying time of the material are both extended, delaying the reaction rate of the material and providing sufficient construction time.

[0114] Furthermore, by comparing Example 1 with Comparative Example 1, it can be seen that when polyether polyol (DL-1000D) is used to replace polytetrahydrofuran ether glycol (P1000) in Comparative Example 1, although the mechanical properties of the material are improved, the paint film has blistering phenomenon and the effect of resisting double-layer liquid becomes worse.

[0115] Furthermore, by comparing Example 1 with Comparative Example 2, it can be seen that after reducing the dosage of the flame retardant in Comparative Example 2, the mechanical properties are improved, but the flame retardancy drops significantly.

[0116] Furthermore, by comparing Example 1 with Comparative Example 3, it can be seen that after Comparative Example 3 does not add long-chain polyamine compounds and only uses amine chain extenders, the elongation at break of the material drops to 380%, and the pot life and surface drying time of the material are significantly reduced, indicating that the reaction rate of the material is too fast and is not conducive to the requirements of actual construction use.

[0117] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A sealing material for aircraft fuel tanks, which is prepared from an isocyanate component and an amine curing agent component, and the weight ratio of the isocyanate component to the amine curing agent component is 100:5 to 15; The isocyanate component is an isocyanate prepolymer prepared from components including an isocyanate monomer, a polymer polyol, a diluent, and a catalyst; The amine curing agent component is prepared from components including an amine chain extender, a long-chain polyamine compound, and an auxiliary agent.

2. The sealing material for aircraft fuel tanks according to claim 1, characterized in that, The weight ratio of the isocyanate component to the amine curing agent component is 100:6 to 10.

3. The sealing material for aircraft fuel tanks according to claim 1, characterized in that In the isocyanate component, based on a total weight of 100 parts by weight, the mass ratio of each component is: Isocyanate monomer: 10 to 30 parts by weight, preferably 15 to 25 parts by weight; Polymer polyol: 25 to 45 parts by weight, preferably 30 to 40 parts by weight; Diluent: 40 to 60 parts by weight, preferably 42 to 52 parts by weight; Catalyst: 0.5 to 1.5 parts by weight, preferably 0.8 to 1.2 parts by weight.

4. The sealing material for aircraft fuel tanks according to claim 3, wherein The functionality of the isocyanate monomer is 2 to 3; Preferably, the isocyanate monomer is selected from aliphatic isocyanate monomers; More preferably, the isocyanate monomer is selected from one or a combination of 4,4'-dicyclohexylmethane diisocyanate, isophorone diisocyanate, and 1,4-cyclohexane diisocyanate; And / or, The functionality of the polymer polyol is 2 to 3, and the hydroxyl equivalent is 500 to 2500, preferably 500 to 1500; Preferably, the polymer polyol is selected from a combination of at least one of polytetrahydrofuran ether diol, polycaprolactone diol, and polycarbonate diol and a reactive flame retardant; Preferably, the reactive flame retardant is selected from one or a combination of flame retardant FR780, flame retardant FR750, and flame retardant FR830; Preferably, the amount of the reactive flame retardant accounts for 50 to 70% of the total amount of the polymer polyol; More preferably 60 to 65%; And / or, The diluent is selected from one or a combination of butyl acetate and ethyl acetate; And / or, The catalyst is selected from one or a combination of dibutyltin dilaurate, stannous octoate, and bismuth octoate.

5. The sealing material for aircraft fuel tanks according to claim 1, wherein, In the amine curing agent component, based on a total weight of 100 parts by weight, the mass ratio of each component is: Amine chain extender: 35 to 60 parts by weight, preferably 40 to 55 parts by weight; Long-chain polyamine compound: 35 to 60 parts by weight, preferably 40 to 55 parts by weight; Auxiliary agent: 0.5 to 5.5 parts by weight, preferably 1.5 to 5.5 parts by weight.

6. The sealing material for aircraft fuel tanks according to claim 5, wherein The amine chain extender is selected from one or a combination of primary amine chain extenders and secondary amine chain extenders; Preferably, the amine chain extender is selected from one or a combination of diethyltoluenediamine, methylene bis-o-phenylenediamine, dimethylthiotoluenediamine, and bis-sec-butylaminodiphenylmethane; And / or, The long-chain polyamine compound is selected from one or a combination of polyaspartate and polytetramethylene ether glycol.

7. The preparation method of the sealing material for aircraft fuel tanks according to any one of claims 1 to 6 includes the following steps: Step 1: Preheat the isocyanate monomer. Under stirring, dropwise add a mixture of a polymeric polyol, a diluent, and a catalyst. After the dropwise addition is completed, raise the temperature and then carry out a heat preservation reaction to generate an isocyanate prepolymer; Step 2: Mix and disperse an amine chain extender, a long-chain polyamine compound, and an auxiliary agent in accordance with the ratio to obtain an amine curing agent; Step 3: Mix the isocyanate prepolymer with the amine curing agent to obtain a sealing material.

8. The preparation method of the sealing material for aircraft fuel tanks according to claim 7, characterized in that, In the said Step 1, the preheating temperature is 50 - 80 °C; preferably 60 - 70 °C; and / or, the conditions for the heat preservation reaction are: the temperature is 90 - 100 °C, preferably 93 - 97 °C, and the reaction time is 2 - 4 h; preferably 2.5 - 3.5 h; and / or, the termination condition for the heat preservation reaction is: the content of free isocyanate groups in the isocyanate prepolymer is 1 - 3%.

9. The preparation method of the sealing material for aircraft fuel tanks according to claim 7, characterized in that, in the said Step 2, the auxiliary agent is one or more of an antifoaming agent, a dispersant, a coupling agent, a leveling agent, an antioxidant, an ultraviolet stabilizer, and an adhesion promoter; and / or, in the said Step 3, the molar ratio of the isocyanate groups in the isocyanate prepolymer to the amine groups in the amine curing agent is 1.00 - 1.

15.

10. Application of the sealing material for aircraft fuel tanks according to any one of claims 1 to 6, wherein the application method comprises the following steps: Mix the isocyanate component and the amine curing agent component in proportion, and spray them on the aircraft fuel tank area to cure into a film.

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