Long-pot-life lining material and preparation method thereof

Abstract

The invention relates to the technical field of solid rocket engine lining materials, and particularly discloses a long-pot-life lining material and a preparation method thereof.The long-pot-life lining material is prepared from, by weight, 100 parts of hydroxyl-terminated polybutadiene, 12-20 parts of an isocyanate curing agent, 3-5 parts of 2, 4-TDI dimer, 0.5-2 parts of a cross-linking agent, 0.5-1 part of N, N-dimethylformamide, 0.5-1 part of a coupling agent, 0.5-1 part of a coupling agent and 0.5-1 part of a coupling agent. The adhesive is prepared from the following components in parts by weight: 3-6 parts of N, N-bis (2-hydroxypropyl) aniline, 15-30 parts of powder filler, 0.5-1 part of an anti-aging agent, 0.4-1 part of a bonding agent, 0-4 parts of a plasticizer and 0-1.5 parts of a catalyst. By adding the 2, 4-TDI dimer and adjusting the formula of the lining, the working life of the solid rocket launch lining material can be successfully prolonged to 7 days or above.

Description

Technical Field

[0001] The invention relates to the technical field of solid rocket engine lining materials, and in particular to a lining material with a long service life and a preparation method thereof. Background Art

[0002] The lining is a transition layer that achieves bonding between the insulation layer (or shell) and the propellant. It is formed between the insulation layer (or shell) and the propellant. The main function of the lining is to achieve effective bonding between the insulation layer and the propellant interface. Generally, after the lining is formed and a semi-curing reaction occurs under elevated temperature conditions, it is transported and temporarily stored under normal temperature conditions, and then placed in a heated pouring cylinder for pouring. After the pouring is completed, it is transferred to the vulcanization process. During the vulcanization process, the lining and the propellant are cured together. At the interface between the lining and the propellant, the isocyanate group reacts chemically with the hydroxyl group to generate chemicals such as carbamate, thereby achieving effective bonding of the interface.

[0003] During the turnover cycle from semi-curing to the completion of pouring, the interfacial bonding strength between the liner and the propellant can remain relatively stable, and the length of time that the interfacial bonding meets the design requirements is also called the applicability period of the liner, which is one of the key process performances of the liner. During the turnover cycle, due to the continuous reaction between the isocyanate groups on the surface of the liner and the hydroxyl groups in the liner and the moisture in the environment, the isocyanate groups decrease, which can easily affect the chemical reaction between the liner and the propellant after pouring, and reduce the interfacial bonding strength between the liner and the propellant. When the turnover cycle is within 3 days, the interfacial bonding strength between the liner and the propellant can generally meet the design index requirements. In the batch production of large-scale and large-size solid rocket engines, according to the production arrangement and process requirements, the turnover cycle from liner molding to completion of pouring may be as long as 5 to 7 days, which requires the applicability period of the liner to be extended from about 3 days to more than 7 days, so as to ensure that the interfacial bonding strength between the liner and the grain meets the design requirements.

[0004] An effective way to extend the service life of the lining is to protect the isocyanate groups in the lining with blocking agents such as alcohols, amines and inorganic salts, so that the isocyanate groups are not easily consumed during the turnover cycle. However, due to the high deblocking temperature of the blocking agent and the fact that the introduced blocking agent easily affects the interfacial curing reaction, the method of using a blocking agent is not well suited for use in lining materials.

[0005] 2,4-TDI dimer is a polymer of two 2,4-TDI molecules. It has good stability at room temperature and is not easy to react with water. At about 140℃, its four-membered ring can be opened by alcohol to generate urethane compounds. The isocyanate group is protected by self-capping of isocyanate, and no blocking agent is introduced into the material. However, when 2,4-TDI dimer is used in the lining, its activity is too low below the depolymerization temperature, and the depolymerization temperature is as high as 140℃. If the engine is vulcanized at 140 degrees Celsius to achieve dimer depolymerization, it is easy to cause the energetic propellant in the engine to explode, bringing a high safety risk. In addition, the addition of 2,4-TDI dimer consumes reactive groups such as hydroxyl groups in the system, which is easy to affect the balance of the curing reaction at the interface between the lining and the propellant, resulting in a decrease in the interfacial bonding strength. In addition, solvents such as pyridine are often used in the application of 2,4-TDI dimer. The volatilization of the solvent may cause defects at the interface between the lining and the propellant, affecting the product quality. Summary of the invention

[0006] The present invention provides a lining material with a long applicability period and a preparation method thereof. By adding 2,4-TDI dimer and adjusting the lining formula, the applicability period of the solid rocket starting lining material can be successfully extended to more than 7 days.

[0007] The technical solution of the present invention is to provide a long-applicable-life lining material, which includes the following raw materials in parts by weight: 100 parts of terminal hydroxyl polybutadiene (HTPB), 12 to 20 parts of isocyanate curing agent, 3 to 5 parts of 2,4-TDI dimer, 0.5 to 2 parts of cross-linking agent, 3 to 6 parts of N, N-bis(2-hydroxypropyl)aniline (LAP-101), 15 to 30 parts of powder filler, 0.5 to 1 part of antioxidant, 0.4 to 1 part of bonding agent, 0 to 4 parts of plasticizer and 0 to 1.5 parts of catalyst.

[0008] Optionally, the isocyanate curing agent is toluene diisocyanate, isophorone diisocyanate or dimer acid diisocyanate.

[0009] Optionally, the cross-linking agent is one or more of diethanolamine, triethanolamine, glycerol, trimethylolpropane or phloroglucinol.

[0010] Optionally, the powder filler is one or more of precipitated silicon oxide, titanium dioxide, analytically pure zinc oxide, zinc silicate, 4A molecular sieve or 5A molecular sieve.

[0011] Optionally, the antioxidant is antioxidant H, α-naphthylamine or diphenylamine.

[0012] Optionally, the bonding agent is one or more of MAPO, T313 or BA-A5.

[0013] Optionally, the plasticizer is one or more of diisooctyl sebacate, dibutyl phthalate and diisooctyl adipate.

[0014] Optionally, the catalyst is dibutyltin dilaurate, iron acetylacetonate or triphenylbismuth.

[0015] The present invention also relates to a method for preparing the long-usable period lining material, comprising the following steps: The powder filler is sieved and dried for later use. The bonding agent, HTPB, cross-linking agent and LAP-101 are mixed and preheated to dissolve the LAP-101. Then, isocyanate curing agent, 2,4-TDI dimer, antioxidant, powdered reinforcing filler, plasticizer and catalyst are added in sequence and mixed to obtain a long-usable-life lining material with uniform color and no dark or light particles visible to the naked eye.

[0016] Optionally, the preparation operation is carried out at room temperature of 10°C to 30°C, relative humidity of no more than 80%, and absolute moisture content of no more than 19g water / kg dry air; when the outdoor temperature is below 10°C, the terminal hydroxyl polybutadiene is preheated to a glue temperature of 35°C before use.

[0017] The present invention has the following beneficial effects: In view of the problem of high depolymerization temperature of 2,4-TDI dimer, the present invention simultaneously introduces 2,4-TDI dimer and LAP-101 into the lining material. Through the catalytic effect of LAP-101 in the hydroxy-terminated polybutadiene polyurethane system, the 2,4-TDI dimer in the lining reacts with the active hydrogen component in the system to generate polyurethane at the conventional engine vulcanization temperature of 50 to 70 degrees Celsius, and slowly undergoes a ring-opening reaction, thereby significantly improving the reaction activity of the 2,4-TDI dimer and reducing the depolymerization temperature from about 140°C to about 50°C. After the lining is semi-cured, the 2,4-TDI dimer in the lining is stable at room temperature and is not easily consumed due to a long turnover cycle; and during the engine pouring and temperature-raising vulcanization process, the reaction activity of the 2,4-TDI dimer is improved under the temperature-raising condition, and it effectively participates in the curing reaction system, so that a polymer three-dimensional network is formed at the interface between the lining and the propellant, and the interface bonding strength meets the index requirements. At the same time, the reaction rate of chain extender LAP-101 with isocyanate monomers such as TDI is controlled, and it will not be over-consumed during the semi-curing process and the applicable period, avoiding affecting its catalytic activity under conditions of 50 to 70 degrees Celsius.

[0018] In addition, the present invention screens suitable isocyanate monomers and 2,4-TDI dimer dosages through formula debugging to ensure the balance of the curing reaction; the TDI dimer powder can function after being mixed and dispersed in the lining system, and there is no need to use TDI dimer solvents such as pyridine, thereby realizing the research on solvent-free lining formulas and avoiding the risk of interface bonding quality caused by the introduction of solvents.

[0019] The long-usable-life lining obtained by the present invention can meet the batch production requirements of large-volume and large-size engines, and the lining still has the performance of achieving effective interface bonding with the propellant after a 7-day turnover cycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A process flow chart of the preparation of a lining layer with a long applicable period is provided for the present invention.

[0021] Figure 2 The lining test piece is prepared using the long-applicable-life lining material in Example 2. DETAILED DESCRIPTION

[0022] The present invention is described in detail below in conjunction with specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and a specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0023] The experimental methods in the following examples are conventional methods unless otherwise specified. The raw materials, reagents, etc. used in the following examples are commercially available products unless otherwise specified.

[0024] The invention provides a lining material with a long application period, which comprises the following raw materials in parts by weight: 100 parts of terminal hydroxyl polybutadiene, 12-20 parts of isocyanate curing agent, 3-5 parts of 2,4-TDI dimer, 0.5-2 parts of crosslinking agent, 3-6 parts of N,N-bis(2-hydroxypropyl)aniline, 15-30 parts of powder filler, 0.5-1 parts of antioxidant, 0.4-1 parts of bonding agent, 0-4 parts of plasticizer and 0-1.5 parts of catalyst.

[0025] In some embodiments, the isocyanate curing agent is preferably toluene diisocyanate, isophorone diisocyanate or dimer acid diisocyanate. The cross-linking agent is preferably one or more of diethanolamine, triethanolamine, glycerol, trimethylolpropane or phloroglucinol. The powder filler is preferably one or more of precipitated silica, titanium dioxide, analytical pure zinc oxide, zinc silicate, 4A molecular sieve or 5A molecular sieve. The antioxidant is preferably antioxidant H, α-naphthylamine or diphenylamine. The bonding agent is preferably one or more of MAPO, T313 or BA-A5. The plasticizer is preferably one or more of diisooctyl sebacate, dibutyl phthalate and diisooctyl adipate. The catalyst is preferably dibutyltin dilaurate, iron acetylacetonate or triphenylbismuth.

[0026] The specific preparation process flow chart is as follows Figure 1 , including the following steps: Step 1: sieve and dry the powder filler for later use; Step 2: Weigh and mix the lining at room temperature of 10℃~30℃, relative humidity not more than 80%, and absolute moisture content not more than 19g water / kg dry air. When the outdoor temperature is below 10℃, the hydroxyl-terminated polybutadiene needs to be preheated to a temperature of 35℃ or above before use. Add bonding agent, hydroxyl-terminated polybutadiene, crosslinking agent, and LAP-101 to the mixing container in the appropriate order (i.e., mixing 1), then preheat in a 70℃ oven for 15 to 30 minutes to dissolve LAP-101, and then take it out of the oven and add curing agent, 2,4-TDI dimer, antioxidant, powdered reinforcing filler, plasticizer and catalyst according to the formula (i.e., mixing 2). The mixing method can be manual mixing. In the above steps, each raw material needs to be mixed for more than 3 minutes until the slurry is uniform, and the total effective mixing time is not less than 30 minutes. The lining slurry obtained after mixing should be uniform in color, without dark or light particles visible to the naked eye.

[0027] Example 1 A method for preparing a long-usable-life lining for rocket engine propellant, comprising the following steps: Raw material processing: sieve the precipitated silicon oxide and analytical pure zinc oxide through a 100-mesh sieve, dry them in an electric blast drying oven at 110°C for 4 hours, and store them at 80°C. Sift the antioxidant H through a 60-mesh sieve and store them in a desiccator.

[0028] Lining mixing: At room temperature of 22°C and relative humidity of 50%, weigh 4g MAPO, 1000g HTPB, 5g propylene glycol, and 40g LAP-101 in sequence using the incremental method, preheat in an oven at 70°C for 20 minutes, then add 162.4g toluene diisocyanate, 40g 2,4-TDI dimer, 100g precipitated silica, 50g analytical grade zinc oxide, 5g antioxidant H, and 20g diisooctyl sebacate. In the above operation, each component is added and mixed by hand for about 4 minutes. The lining slurry obtained after mixing is a uniform light gray color without dark or light particles visible to the naked eye.

[0029] After the rocket engine long-usable period lining material prepared in this embodiment was semi-cured, it was placed under the conditions of 20-22 degrees Celsius and 55% relative humidity for 7 days and then subjected to performance testing. The main test results are shown in Table 1: Table 1

[0030] Example 2 A method for preparing a long-usable-life lining for rocket engine propellant, comprising the following steps: Raw material processing: Analytical pure titanium dioxide, analytical pure zinc oxide and 4A molecular sieve were sieved through a 100 mesh screen, dried in an electric blast drying oven at 110°C for 4 hours and then stored at 80°C. Diphenylamine was sieved through a 60 mesh screen and stored in a desiccator.

[0031] Lining mixing: At room temperature of 24°C and relative humidity of 55%, 5g BA-A5 (produced by Liming Chemical Research Institute, diethanolamine and boron trifluoride complex), 500g HTPB, 10g trimethylolpropane, and 30g LAP-101 were weighed in sequence using the incremental method, and preheated in an oven at 70°C for 20 minutes. Subsequently, 83.5g isophorone diisocyanate, 15g 2,4-TDI dimer, 100g analytically pure titanium dioxide, 30g analytically pure zinc oxide, 20g 4A molecular sieve, 5g diphenylamine, 20g dibutyl phthalate, and 7.5g triphenyl bismuth were added. In the above operation, each component was added and mixed by hand for about 4 minutes. The lining slurry obtained after mixing was a uniform light gray color without dark or light particles visible to the naked eye.

[0032] After the rocket engine long-usable period lining material prepared in this embodiment is semi-cured, it is placed at 20-22 degrees Celsius and 55% relative humidity for 7 days and subjected to main performance tests. The test results are shown in Table 1: Table 2

[0033] The lining formulations of the following examples and comparative examples are shown in Table 3 Table 3

[0034] According to the proportions in the table above, each raw material was weighed to prepare component A and mix the lining layer. The obtained lining slurry was uniform light brown to light gray slurry. It was placed at 20-22 degrees Celsius and relative humidity of 50%-60% for 7 days and the main performance tests were carried out. The performance is shown in Table 4.

[0035] Table 4

[0036] Embodiments 1 to 5 have good performance and meet the general requirements of solid rocket engine propellants.

[0037] Compared with Example 1, Comparative Example 1 differs only in that 2,4-TDI dimer is not added, and the interfacial bonding strength with the propellant is significantly decreased after 7 days; Compared with Example 2, Comparative Example 2 differs only in that LAP-101 is not added, and the interfacial bonding strength with the propellant is significantly decreased after 7 days; Compared with Example 3, Comparative Example 3 differs only in that the addition amount of 2,4-TDI dimer is too low, and the interfacial bonding strength with the propellant is significantly decreased after 7 days; Compared with Example 4, Comparative Example 4 differs only in that the chain extender LAP-101 is replaced with a chain extender 1,4-butanediol with an equal molar amount of hydroxyl groups, and the interfacial bonding strength with the propellant is significantly decreased after 7 days. At the same time, in the above comparative examples, the lining layer, the propellant and the insulation layer are all broken at the interface, and it can be seen that the interfacial bonding performance of the lining layer is significantly decreased after 7 days, and the applicable period of the lining layer is less than 7 days.

[0038] The above embodiments describe the preferred implementation of the present invention, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A lining material with a long service life, characterized in that: The invention comprises the following raw materials in parts by weight: 100 parts of terminal hydroxyl polybutadiene, 12-20 parts of isocyanate curing agent, 3-5 parts of 2,4-TDI dimer, 0.5-2 parts of crosslinking agent, 3-6 parts of N,N-bis(2-hydroxypropyl)aniline, 15-30 parts of powder filler, 0.5-1 parts of antioxidant, 0.4-1 parts of bonding agent, 0-4 parts of plasticizer and 0-1.5 parts of catalyst.

2. The long-usable-life lining material according to claim 1, characterized in that: The isocyanate curing agent is toluene diisocyanate, isophorone diisocyanate or dimer acid diisocyanate.

3. The long-usable-life lining material according to claim 1, characterized in that: The cross-linking agent is one or more of diethanolamine, triethanolamine, glycerol, trimethylolpropane or phloroglucinol.

4. The long-usable-life lining material according to claim 1, characterized in that: The powder filler is one or more of precipitated silicon oxide, titanium dioxide, analytically pure zinc oxide, zinc silicate, 4A molecular sieve or 5A molecular sieve.

5. The long-usable-life lining material according to claim 1, characterized in that: The antioxidant is antioxidant H, α-naphthylamine or diphenylamine.

6. The long-usable-life lining material according to claim 1, characterized in that: The bonding agent is one or more of MAPO, T313 or BA-A5.

7. The long-usable-life lining material according to claim 1, characterized in that: The plasticizer is one or more of diisooctyl sebacate, dibutyl phthalate and diisooctyl adipate.

8. The long-usable-life lining material according to claim 1, characterized in that: The catalyst is dibutyltin dilaurate, iron acetylacetonate or triphenylbismuth.

9. The method for preparing a long-usable-life lining material according to any one of claims 1 to 8, characterized in that: The following steps are involved: The powder filler is sieved and dried for later use. The bonding agent, terminal hydroxyl polybutadiene, crosslinking agent and N, N-bis(2-hydroxypropyl)aniline are mixed and preheated to dissolve LAP-101. Then, isocyanate curing agent, 2,4-TDI dimer, antioxidant, powdered reinforcing filler, plasticizer and catalyst are added in sequence and mixed to obtain a long-usable-life lining material with uniform color and no dark or light particles visible to the naked eye.

10. The preparation method according to claim 9, characterized in that: The preparation operation is carried out at room temperature of 10°C to 30°C, relative humidity of no more than 80%, and absolute moisture content of no more than 19g water / kg dry air; when the outdoor temperature is lower than 10°C, the terminal hydroxyl polybutadiene is preheated to a glue temperature of 35°C before use.

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