Prepolymer lining material and preparation method thereof

Abstract

The invention belongs to the technical field of solid rocket engine lining materials, and particularly discloses a prepolymer lining material and a preparation method thereof.The prepolymer lining material comprises a component A and a component B. The component A comprises, by weight, 1-10 parts of a component B, 1-10 parts of a component C and 1-10 parts of a component D, the component A is prepared from the following raw materials: 100 parts of an adhesive matrix material, 14 to 30 parts of isocyanate, 0 to 2 parts of a cross-linking agent, 12 to 30 parts of powdery reinforcing filler, 0.5 to 1 part of an anti-aging agent, 0.3 to 1 part of a bonding agent, 0 to 4 parts of a plasticizer and 0 to 1 part of a catalyst; and the component B is 6-8 parts of a curing agent. According to the invention, the component A is prepared into two components and can be stored for a long time, and meanwhile, the component A and the component B can be molded in an engine shell after being mixed according to a ratio when the component A is pre-polymerized and the lining is constructed, so that a sagging-free state is quickly achieved, the process time and the process cost are further saved, and the lining molding efficiency is improved; the interface performance of the lining layer is ensured to meet the requirement through raw material control and process control.

Description

Technical Field

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

[0002] The liner is an important component of the solid rocket engine charge. It is a transition layer that achieves the 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 liner is to achieve effective bonding between the insulation layer and the propellant interface, and its interface strength can still meet the design requirements during long-term storage, so that the interface can withstand all possible stresses and ensure the structural integrity and safety and reliability of the engine.

[0003] The traditional lining commonly uses the HTPB adhesive system, which has the advantages of good adhesion to the propellant, good resistance to small molecule migration and easy molding. However, due to the one-step curing of HTPB and isocyanate, it has the following two problems. First, the lining needs to be mixed and prepared before each batch of engine charging. The preparation process requires the gradual addition of matrix materials, cross-linking agents, chain extenders, curing agents, fillers, etc., and then mixed one by one. The preparation process is time-consuming. Second, because the adhesive is in an uncured state, the viscosity is too low and it is easy to sag. It is necessary to carry out a pre-curing process before charging, that is, the engine casing coated with the lining is placed in an oven and heated and rotated continuously. By performing a certain degree of curing reaction under the condition of heating, the lining reaches a state of basically non-flowing and then the casting process is carried out. The pre-curing process takes several hours, which takes up the engine manufacturing time. In addition, the different degrees of pre-curing reaction affect the interface chemical cross-linking between the lining and the propellant, which may lead to risks such as interface debonding.

[0004] The prepolymer of polyurethane is obtained by reacting polyisocyanate and polyol in a certain proportion, and is a reactive semi-finished product. However, there has been no report on the use of polyurethane prepolymer technology in solid rocket engine linings so far. If polyurethane prepolymer technology is used for the preparation of linings, there are many problems that need to be solved. For example, problem 1: if the reactivity of the prepolymer lining is too high at room temperature, the viscosity of the material increases too fast after the two components A and B are mixed, and it will be difficult to form in the shell through scraping or spraying molding process; if the reactivity of the prepolymer lining is too low at 50℃~70℃, the lining will still sag after pre-curing for 5h, which will lead to unstable interface thickness and insufficient interface bonding strength after the propellant is cured. Problem 2: If the curing rate of the prepolymer lining does not match that of the propellant during the heating and curing process, sufficient chemical bonding may not occur at the interface between the propellant and the lining, resulting in insufficient interfacial bonding strength. Problem 3: In addition to the polyurethane prepolymer, component A of the lining also requires the addition of bonding agents, antioxidants, and reinforcing powder fillers. If the addition process of the above materials is not suitable, it will cause the material to absorb water and the bonding agent to lose its activity, which will seriously affect the interfacial bonding strength between the lining and the propellant.

[0005] In summary, it is of great significance to solve the above problems and develop a solid rocket engine prepolymer lining material. Summary of the invention

[0006] The present invention provides a prepolymer lining material and a preparation method thereof. The prepolymer lining material is prepared into two components and can be stored for a long time. At the same time, since component A has been prepolymerized, when the lining is constructed, components A and B can be mixed in proportion and formed in an engine casing, and a non-sagging state can be quickly achieved, thereby further saving process time and process costs and improving lining forming efficiency. The present invention also ensures that the lining interface performance meets the requirements through raw material control and process control.

[0007] The technical solution of the present invention is to provide a prepolymer lining material, which includes component A and component B. Component A includes the following raw materials in parts by weight: 100 parts of adhesive matrix material, 14 to 30 parts of isocyanate, 0 to 2 parts of cross-linking agent, 12 to 30 parts of powdered reinforcing filler, 0.5 to 1 part of antioxidant, 0.3 to 1 part of bonding agent, 0 to 4 parts of plasticizer and 0 to 1 part of catalyst; component B is 6 to 8 parts of curing agent.

[0008] Optionally, the adhesive matrix material is one or more of hydroxyl-terminated polybutadiene, epoxidized hydroxyl-terminated polybutadiene and carboxyl-terminated polybutadiene.

[0009] Optionally, the isocyanate is toluene diisocyanate, isophorone diisocyanate or dimer acid diisocyanate.

[0010] Optionally, the raw material of the prepolymer lining material satisfies at least one of the following conditions: 1) The cross-linking agent is one or more of diethanolamine, triethanolamine, glycerol, trimethylolpropane or phloroglucinol; 2) The powdered reinforcing filler is one or more of precipitated silicon oxide, titanium dioxide, zinc oxide, zinc silicate, aluminum hydroxide, and magnesium hydroxide.

[0011] 3) The antioxidant is antioxidant H, α-naphthylamine or diphenylamine; 4) The bonding agent is one or more of LBA-603, MAPO, and T313.

[0012] 5) The plasticizer is one or more of diisooctyl sebacate, dibutyl phthalate and diisooctyl adipate; 6) The catalyst is dibutyltin dilaurate, iron acetylacetonate or triphenylbismuth.

[0013] Optionally, the curing agent is an amine or hydroxyl curing agent.

[0014] Optionally, the hydroxyl curing agent is N,N-bis(2-hydroxypropyl)aniline (Lap-101); the amine curing agent is one or two of 3,5-dimethylthiotoluenediamine (DMTDA) and 3,3'-dichloro-4,4'-diphenyltoluenediamine (MOCA).

[0015] The present invention also relates to a method for preparing the prepolymer lining material, comprising the following steps: S1. After heating the adhesive matrix material, vacuum dehydration is performed, isocyanate is added at a temperature below 50°C, and the material is discharged after the temperature is raised to react to obtain a polyurethane prepolymer; S2. Under the conditions of room temperature of 10°C to 30°C, relative humidity of no more than 65%, and absolute moisture content of no more than 15g water / kg dry air, the raw materials of component A are mixed manually or by machine to obtain component A; S3. Mix component A and component B at room temperature of 10°C to 30°C, relative humidity of no more than 70%, and absolute moisture content of no more than 19g water / kg dry air to obtain a prepolymer lining material for painting.

[0016] Optionally, the adhesive matrix material in S1 is heated to 120±5° C. for post-vacuum dehydration; and after adding isocyanate, the temperature is raised to 80±5° C. for reaction.

[0017] Optionally, each raw material in S2 is added and mixed before adding the next raw material; the total effective mixing time for manual mixing is more than 30 minutes; the total effective mixing time for machine mixing is more than 50 minutes; the powdered reinforcing filler is sieved and dried before being added and placed in an oven for standby use.

[0018] Optionally, component A and component B are mixed manually for more than 5 minutes; component A and component B are mixed by machine for more than 10 minutes.

[0019] The present invention has the following beneficial effects: The present invention preforms the lining material into two components, A and B. Component A is usually obtained by chain extension reaction of polyester or polyether diol, wherein the prepolymer with NCO end group has high reaction characteristics; component B is also called curing agent, and the active hydrogen therein reacts with the NCO end group in component A to form a polyurethane elastomer. When the lining is prepared, components A and B are mixed and formed, which can greatly extend the shelf life of the lining material. The original full-component lining slurry process has a usable period of only a few hours, while the prepared component A prepolymer can be sealed and stored for 3 to 12 months. Moreover, the lining construction can be carried out after the A and B components are mixed. Since the A component has been prepolymerized in advance, it can reach a non-sagging state within 3 hours at 50°C after being mixed with the B component, effectively improving the manufacturing efficiency of the engine lining.

[0020] When preparing the prepolymer lining, in order to avoid the viscosity of components A and B increasing too fast after mixing and affecting the scraping or spraying molding, the present invention selects suitable isocyanate and curing agent types, wherein in order to meet the matching of the curing reaction rate of the lining and the propellant, the isocyanate is selected from toluene diisocyanate, isophorone diisocyanate or dimer acid diisocyanate, so that the lining and the propellant can be cured synchronously, and the interface bonding performance does not fail to meet the requirements due to the excessive difference in curing rate; at the same time, the curing agent of component B is selected from N, N-bis (2-hydroxypropyl) aniline (Lap-101), 3, 5-dimethylthiotoluenediamine (DMTDA) or 3, 3'-dichloro-4, 4' diphenyl toluenediamine (MOCA), and the curing agent has appropriate reaction activity with component A, and the viscosity of the two components will not increase too fast after mixing due to the too fast curing reaction. In addition, during the preparation of the prepolymer lining, the moisture content of each raw material and the process conditions are controlled, and a moderate excess of isocyanate is used to avoid the material from losing its activity due to water absorption, ensuring that sufficient chemical bonding can occur at the interface between the propellant and the lining so that the interface bonding strength meets the requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The present invention is a process flow chart for preparing the prepolymer lining.

[0022] Figure 2 The lining test piece is prepared using the prepolymer lining material in Example 1. DETAILED DESCRIPTION

[0023] 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.

[0024] 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.

[0025] The present invention provides a prepolymer lining material, which comprises an A component and a B component. The A component comprises the following raw materials by weight: 100 parts of an adhesive matrix material, 14 to 30 parts of an isocyanate, 0 to 2 parts of a crosslinking agent, 12 to 30 parts of a powdered reinforcing filler, 0.5 to 1 part of an antioxidant, 0.3 to 1 part of a bonding agent, 0 to 4 parts of a plasticizer and 0 to 1 part of a catalyst; and the B component comprises 6 to 8 parts of a curing agent. By separately preparing the A component containing the prepolymer and the B component containing the curing agent, the material not only has the effects of low preparation cost and long-term storage, but also maintains the original bonding strength, mechanical properties and process properties.

[0026] In a preferred embodiment, the adhesive matrix material is one or more of terminal hydroxyl polybutadiene, epoxidized terminal hydroxyl polybutadiene and terminal carboxyl polybutadiene. The isocyanate is toluene diisocyanate, isophorone diisocyanate or dimer acid diisocyanate. The crosslinking agent is one or more of diethanolamine, triethanolamine, glycerol, trimethylolpropane or phloroglucinol. The powdered reinforcing filler is one or more of precipitated silica, titanium dioxide, zinc oxide, zinc silicate, aluminum hydroxide and magnesium hydroxide. The antioxidant is antioxidant H, α-naphthylamine or diphenylamine. The bonding agent is one or more of LBA-603, MAPO and T313. The plasticizer is one or more of diisooctyl sebacate, dibutyl phthalate and diisooctyl adipate, and the catalyst is dibutyltin dilaurate, iron acetylacetonate or triphenylbismuth.

[0027] The curing agent of component B is an amine or hydroxyl curing agent. The hydroxyl curing agent is N,N-bis(2-hydroxypropyl)aniline (Lap-101); the amine curing agent is one of 3,5-dimethylthiotoluenediamine (DMTDA) and 3,3'-dichloro-4,4'-diphenyltoluenediamine (MOCA).

[0028] The specific preparation comprises the following steps: S1. The adhesive matrix material is heated to 120±5°C for post-vacuum dehydration, isocyanate is added below 50°C, the temperature is raised to 80±5°C for reaction, and then the polyurethane prepolymer is obtained; S2. Under the conditions of room temperature of 10°C to 30°C, relative humidity of no more than 65%, and absolute moisture content of no more than 15g water / kg dry air, the raw materials of component A are mixed manually or by machine to obtain component A; When mixing manually, the total effective mixing time is more than 30 minutes; when mixing by machine, the effective mixing time is more than 50 minutes; the powdered reinforcing filler is sieved and dried before being added and placed in an oven for use.

[0029] The order of mixing the raw materials can be bonding agent → polyurethane prepolymer → cross-linking agent → antioxidant → reinforcing filler → plasticizer → catalyst, or it can be prepolymer → cross-linking agent → antioxidant → reinforcing filler → bonding agent → plasticizer → catalyst. The specific order of addition is not limited to this and is subject to uniform mixing.

[0030] S3. Mix component A and component B at room temperature of 10°C to 30°C, relative humidity of no more than 70%, and absolute moisture content of no more than 19g water / kg dry air; the mixing time is more than 5 minutes when mixing manually and more than 10 minutes when mixing by machine. After mixing, the prepolymer lining material for painting is obtained.

[0031] Example 1 A method for preparing a prepolymer lining for a rocket engine charge comprises 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 aluminum hydroxide and magnesium hydroxide powders through a 60-mesh sieve, dry them in an electric blast drying oven at 80°C, and store them.

[0032] Preparation of component A: Add 2000g of hydroxyl-terminated polybutadiene to a three-necked flask, heat to 120℃, vacuum dehydrate for 2.5h, wait until the temperature drops below 50℃, add 320g of toluene diisocyanate, heat to 80℃, react for 2h, then drop to below 40℃ to discharge, and obtain polyurethane prepolymer. At room temperature of 20℃ and relative humidity of no more than 50%, add 10g of propylene glycol and 2000g of polyurethane prepolymer to the hopper of a horizontal mixer by the reduction method, mix for 4min in the "forward direction", and then mix for 4min in the "reverse direction"; continue to add 8g of T313 bonding agent to the hopper by the reduction method, mix for 4min in the "forward direction", and then mix for 4min in the "reverse direction"; continue to add 12g of antioxidant H weighed to the hopper, mix for 4min in the "forward direction", and then mix for 4min in the "reverse direction"; continue to add 16 0g precipitated silica, mix for 4min in "forward" mode, and then mix for 4min in "reverse" mode; continue to add weighed 120g zinc oxide to the hopper, mix for 4min in "forward" mode, and then mix for 4min in "reverse" mode; continue to add 40g aluminum hydroxide and 20g magnesium hydroxide premixed manually to the hopper, mix for 4min in "forward" mode, and then mix for 4min in "reverse" mode; finally, add 40g dibutyl phthalate to the hopper using the reduction method, mix for 4min in "forward" mode, and then mix for 4min in "reverse" mode. The component A prepared by the above steps is sealed and stored in a HDPE plastic bottle.

[0033] Liner mixing: At room temperature of 22°C and relative humidity of 50%, weigh 200g of component A from a HDPE plastic bottle into a mixing container by incremental method, add 12g of Lap-101 to the container by incremental method, and mix manually for more than 5 minutes. The lining slurry obtained after mixing is a uniform light gray color, without dark or light particles visible to the naked eye, and can be used for spraying or scraping molding of solid rocket engines.

[0034] The properties of the rocket engine prepolymer lining material prepared in this embodiment are shown in Table 1:

[0035] Table 1

[0036] Example 2 A method for preparing a prepolymer lining for rocket engine propellant comprises the following steps: Raw material processing: Analytical pure titanium dioxide and analytical pure zinc oxide were sieved through a 100-mesh sieve, dried in an electric blast drying oven at 110°C for 4 hours, and then stored at 80°C.

[0037] Preparation of component A: Add 1000g of hydroxy-terminated polybutadiene to a three-necked flask, heat to 120℃, vacuum dehydrate for 2h, wait until the temperature drops below 50℃, add 204.32g of isophorone diisocyanate, heat to 80℃, react for 1.5h, then drop to below 40℃ to discharge, and obtain polyurethane prepolymer. At room temperature of 25℃ and relative humidity of no more than 55%, add 1.2g of MAPO to a stainless steel basin by addition method, continue to add 300g of polyurethane prepolymer to the stainless steel basin by addition method, and mix manually for 5min; continue to add 1.5g of triethanolamine to the stainless steel basin by addition method, and mix manually for 5min; continue to add 3g of α-naphthylamine H to the stainless steel basin by addition method, and mix manually for 5min; continue to add 60g of titanium dioxide to the stainless steel basin by addition method, and mix manually for 5min; continue to add 15g of zinc oxide to the stainless steel basin by addition method, and mix manually for 5min. The component A prepared by the above steps was sealed and stored in a HDPE plastic bottle.

[0038] Weighing and mixing of lining: Under the conditions of room temperature 22°C and relative humidity 50%, weigh 250g of component A from a HDPE plastic bottle into a mixing container by incremental method, add 19.32g, 3'-dichloro-4,4'-diphenyltoluenediamine (MOCA) into the container by incremental method, and mix for more than 8 minutes using a pneumatic stirrer. The lining slurry obtained after mixing is a uniform light gray color, without dark or light particles visible to the naked eye, and can be used for spraying or scraping molding of solid rocket engines.

[0039] The properties of the rocket engine prepolymer lining material prepared in this embodiment are shown in Table 2: Table 2

[0040] The lining layer formulations of the following embodiments and comparative examples are shown in Table 3.

[0041] Table 3

[0042] According to the ratio in the above table, each raw material was weighed to prepare component A and mix the lining. The lining slurry obtained after mixing Examples 3, 4, 5 and Comparative Examples 2 and 3 was a uniform light brown to light gray slurry. The only difference between Comparative Example 1 and Example 1 was that the isocyanate was not added enough, resulting in the curing of component A at room temperature after preparation and inability to mix with component B. The only difference between Comparative Example 2 and Example 4 was that the isocyanate was added excessively in the preparation of component A, and the lining was difficult to cure during the vulcanization process, and the test could not be carried out.

[0043] The above materials were tested and their properties are shown in Table 4.

[0044] Table 4

[0045] As can be seen from Table 4, the performances of Examples 3, 4, and 5 are relatively good. The only difference between Comparative Example 3 and Example 1 is that the vacuum dehydration process of the adhesive matrix material and the filler drying process are not carried out in the preparation of Component A, resulting in excessive moisture content in Component A. Since the moisture consumes isocyanate and generates gas, the mechanical properties of the lining body and the interface bonding properties are relatively poor.

[0046] Compared with Example 1, the only difference in Comparative Example 4 is that the curing agent selected for component B is not the curing agent of the present application, and the reaction activity of the used DETDA (3,5-diethyltoluenediamine) is too high, and the viscosity of the lining increases too quickly at room temperature, resulting in a large number of pores in the lining test pieces and the interface test pieces, and it is difficult to coat them uniformly, resulting in poor mechanical properties of the lining body and poor interface bonding properties.

[0047] 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 prepolymer lining material, characterized in that: The prepolymer lining material comprises component A and component B, wherein component A comprises the following raw materials in parts by weight: 100 parts of adhesive matrix material, 14-30 parts of isocyanate, 0-2 parts of crosslinking agent, 12-30 parts of powdered reinforcing filler, 0.5-1 parts of antioxidant, 0.3-1 parts of bonding agent, 0-4 parts of plasticizer and 0-1 parts of catalyst; Component B is 6 to 8 parts of curing agent.

2. The prepolymer lining material according to claim 1, characterized in that: The adhesive matrix material is one or more of hydroxyl-terminated polybutadiene, epoxidized hydroxyl-terminated polybutadiene and carboxyl-terminated polybutadiene.

3. The prepolymer lining material according to claim 1, characterized in that: The isocyanate is toluene diisocyanate, isophorone diisocyanate or dimer acid diisocyanate.

4. The prepolymer lining material according to claim 1, characterized in that The raw material of the prepolymer lining material meets at least one of the following conditions: 1) The cross-linking agent is one or more of diethanolamine, triethanolamine, glycerol, trimethylolpropane or phloroglucinol; 2) The powdered reinforcing filler is one or more of precipitated silicon oxide, titanium dioxide, zinc oxide, zinc silicate, aluminum hydroxide, and magnesium hydroxide. 3) The antioxidant is antioxidant H, α-naphthylamine or diphenylamine; 4) The bonding agent is one or more of LBA-603, MAPO, and T313. 5) The plasticizer is one or more of diisooctyl sebacate, dibutyl phthalate and diisooctyl adipate; 6) The catalyst is dibutyltin dilaurate, iron acetylacetonate or triphenylbismuth.

5. The prepolymer lining material according to any one of claims 1 to 4, characterized in that: The curing agent is an amine or hydroxyl curing agent.

6. The prepolymer lining material according to claim 5, characterized in that: The hydroxy curing agent is N,N-bis(2-hydroxypropyl)aniline (Lap-101); the amine curing agent is 3,5-dimethylthiotoluenediamine (DMTDA) and / or 3,3'-dichloro-4,4'-diphenyltoluenediamine (MOCA).

7. The method for preparing the prepolymer lining material according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1. After heating the adhesive matrix material, vacuum dehydration is performed, isocyanate is added at a temperature below 50°C, and the material is discharged after the temperature is raised to react to obtain a polyurethane prepolymer; S2. Under the conditions of room temperature of 10°C to 30°C, relative humidity of no more than 65%, and absolute moisture content of no more than 15g water / kg dry air, the raw materials of component A are mixed manually or by machine to obtain component A; S3. Mix component A and component B at room temperature of 10°C to 30°C, relative humidity of no more than 70%, and absolute moisture content of no more than 19g water / kg dry air to obtain a prepolymer lining material for painting.

8. The preparation method according to claim 7, characterized in that: The adhesive matrix material in S1 is heated to 120±5°C for post-vacuum dehydration; after adding isocyanate, the temperature is raised to 80±5°C for reaction.

9. The preparation method according to claim 7, characterized in that: When manually mixing in S2, the total effective mixing time is more than 30 minutes; when mixing by machine, the effective mixing time is more than 50 minutes; the powdered reinforcing filler is sieved and dried before being added and placed in an oven for use.

10. The preparation method according to claim 7, characterized in that: Component A and component B are mixed manually for more than 5 minutes; component A and component B are mixed by machine for more than 10 minutes.

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