Application of polyurethane-based spraying materials and their composite insulation layers with EPDM

Abstract

The present invention relates to the technical field of thermal insulation materials, specifically disclosing a polyurethane-based spray material and its application in composite thermal insulation layers with EPDM. The polyurethane-based spray material comprises components A and B. Component A, by mass, comprises 50%-70% isocyanate prepolymer, 10%-20% liquid rubber, 10%-20% ablation-resistant resin, 5%-10% fiber filler, and 1%-5% plasticizer. Component B comprises 45%-70% amino-terminated polyether, 1%-3% vulcanization crosslinking agent, 2%-6% vulcanization activation accelerator, 5%-15% chain extender, 10%-15% fiber filler, 10%-15% ablation-resistant resin, and 1%-5% plasticizer. By introducing the liquid rubber curing system into the spray insulation material, the bonding strength between the polyurethane-based spray insulation material and the EPDM insulation material is enhanced, enabling the production of a polyurethane / EPDM rubber composite thermal insulation layer. This provides a new solution for the production of engine spray insulation layers.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal insulation and ablation-resistant materials for solid rocket engines, and in particular to a polyurethane-based spraying material and an application thereof in a composite thermal insulation layer with ethylene propylene diene monomer (EPDM). Background Art

[0002] Solid rocket engines use an insulation layer for heat insulation and ablation protection. Currently, the commonly used ablative insulation materials are nitrile, EPDM and silicone rubber insulation materials. This type of rubber insulation is made using patch or molding processes, which has problems such as low production efficiency and low product quality stability.

[0003] CN115028987 A discloses a sprayable polyurethane ablation-resistant material formulation, preparation method, and application. This material can be used to prepare thermal insulation materials through spray molding, improving work efficiency. Sprayable polyurethane materials have high molecular polarity and good bonding properties with nitrile thermal insulation materials, but their molecular polarity differs significantly from that of EPDM thermal insulation materials, resulting in lower bonding strength. The typical solution to interfacial bonding is to use adhesives. However, EPDM rubber vulcanizes at high temperatures of 150°C-160°C, while sprayable thermal insulation materials cure at room or medium temperatures (50°C-90°C). The curing temperatures used by these two thermal insulation materials differ significantly, making it difficult for the adhesive to cure at the same temperature range for both materials. Summary of the Invention

[0004] The present invention provides a polyurethane-based spraying material and an application thereof in an EPDM composite thermal insulation layer. A liquid rubber curing system is introduced into the spraying thermal insulation material, which can solve the problem of poor bonding quality between the polyurethane-based spraying thermal insulation material and the EPDM rubber thermal insulation material.

[0005] The technical solution of the present invention is to provide a polyurethane-based spray material, comprising component A and component B, wherein component A comprises, by mass fraction, 50% to 70% of isocyanate prepolymer, 10% to 20% of liquid rubber, 10% to 20% of ablation-resistant resin, 5% to 10% of fiber filler and 1% to 5% of plasticizer.

[0006] Component B: 45%~70% amino-terminated polyether, 1%~3% vulcanization crosslinking agent, 2%~6% vulcanization activation accelerator, 5%~15% chain extender, 10%~15% fiber filler, 10%~15% ablation-resistant resin and 1%~5% plasticizer.

[0007] Optionally, the isocyanate prepolymer is one or more of hexamethylene diisocyanate (HDI) and diphenylmethane-4,4-diisocyanate (MDI).

[0008] Optionally, the liquid rubber is one or more of maleic anhydride grafted liquid isoprene rubber, maleic anhydride grafted liquid EPDM rubber and maleic anhydride grafted liquid polybutadiene.

[0009] Alternatively, maleic anhydride grafting onto liquid rubber can be performed using maleic anhydride (MAH) as the grafting agent, an anionic initiator or a peroxide initiator, and a solution grafting method. The ratio of maleic anhydride to liquid rubber in the preparation of the maleic anhydride grafted liquid rubber is 100:(2-6), diisopropylbenzene peroxide is used as the initiator, and the reaction temperature is 120 min to 160°C, and the reaction time is 30 min to 120 min.

[0010] Optionally, component A and component B meet at least one of the following conditions: the ablation-resistant resin is one or both of polyimide resin and phenolic resin; the fiber filler is one or both of carbon fiber and basalt fiber; and the plasticizer is dioctyl phthalate.

[0011] Optionally, the amino-terminated polyether is one or both of CGA-D2000 and CGA-T5000.

[0012] Optionally, the B component meets at least one of the following conditions: the vulcanization crosslinking agent is one or more of diisopropylbenzene peroxide, di-tert-butyl diisopropylbenzene peroxide or dimethyl di-tert-butyl peroxide; the vulcanization activation accelerator is one or more of zinc oxide, stearic acid, zinc stearate, N,N-dicyclohexyl-2-benzothiazole sulfenamide (CZ), N-tert-butyl-2-benzothiazole sulfenamide (NS), tetrapentamethylenethiuram tetrasulfide (TRA) and zinc dimethyldithiocarbamate (PZ); the chain extender is one or more of 3,3-dichloro-4,4-diaminodiphenylmethane (MOCA), diethyltoluenediamine (DETDA) and N,N-dialkylphenylenediamine.

[0013] The present invention also relates to a method for preparing the polyurethane-based spray material, comprising preparing component A and component B according to a ratio, mixing component A and component B uniformly before use, and placing them in a spraying device for spraying.

[0014] The present invention also relates to the application of the polyurethane-based spraying material in the preparation of a thermal insulation layer of a solid rocket engine.

[0015] Optionally, the thermal insulation layer is a polyurethane / ethylene propylene diene monomer rubber composite thermal insulation layer.

[0016] The present invention has the following beneficial effects:

[0017] 1. Liquid rubber is added to the polyurethane-based spray material provided by the present invention, wherein the liquid rubber is grafted with maleic anhydride polar functional groups to increase a part of the polarity of the liquid rubber, so that it has a certain compatibility with the polyurethane-based resin, increases the "interface affinity", and makes the mixing and dispersion more uniform. At the same time, the long-chain structure of the liquid rubber has similar properties to EPDM rubber. Adding it to the polyurethane-based spray material improves the interface bonding performance between the spray material and EPDM rubber, which can effectively solve the problem of poor bonding quality between the polyurethane-based spray insulation material and the EPDM rubber insulation material.

[0018] 2. The polyurethane-based spray material of the present invention also introduces a rubber peroxide vulcanization system to form a "dual-curing" network system with the spray polyurethane system, so that when the material is bonded with the EPDM insulation material, a co-"vulcanization bond" is formed at the interface, thereby improving the interfacial bonding performance between the polyurethane-based spray insulation material and the EPDM insulation layer. DETAILED DESCRIPTION

[0019] 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.

[0020] The polyurethane-based spray material provided by the present invention comprises components A and B. Component A comprises, by mass, 50% to 70% isocyanate prepolymer, 10% to 20% liquid rubber, 10% to 20% ablation-resistant resin, 5% to 10% fiber filler, and 1% to 5% plasticizer. Component B comprises 45% to 70% amino-terminated polyether, 1% to 3% vulcanization crosslinking agent, 2% to 6% vulcanization activation accelerator, 5% to 15% chain extender, 10% to 15% fiber filler, 10% to 15% ablation-resistant resin, and 1% to 5% plasticizer.

[0021] In some embodiments, the isocyanate prepolymer is one or more of hexamethylene diisocyanate (HDI) and diphenylmethane-4,4-diisocyanate (MDI).

[0022] In some embodiments, the ablation-resistant resin is one or both of a polyimide resin and a phenolic resin.

[0023] In some embodiments, the fibrous filler is one or both of carbon fiber and basalt fiber.

[0024] In some embodiments, the plasticizer is dioctyl phthalate.

[0025] In some embodiments, the amino-terminated polyether is one or both of CGA-D2000 and CGA-T5000.

[0026] In some embodiments, the vulcanization crosslinking agent is one or more of diisopropylbenzene peroxide, diisopropyldimethylperoxide, or dimethyldi-tert-butylperoxide.

[0027] In some embodiments, the vulcanization activation accelerator is one or more of zinc oxide, stearic acid, zinc stearate, N,N-dicyclohexyl-2-benzothiazolesulfenamide (CZ), N-tert-butyl-2-benzothiazolesulfenamide (NS), dipentamethylenethiuram tetrasulfide (TRA), and zinc dimethyldithiocarbamate (PZ).

[0028] In some embodiments, the chain extender is one or more of 3,3-dichloro-4,4-diaminodiphenylmethane (MOCA), diethyltoluenediamine (DETDA), and N,N-dialkylphenylenediamine.

[0029] The liquid rubber in the present invention is one or more of maleic anhydride grafted liquid isoprene rubber, maleic anhydride grafted liquid EPDM rubber and maleic anhydride grafted liquid polybutadiene.

[0030] In a preferred embodiment, the maleic anhydride-grafted liquid rubber is prepared using maleic anhydride (MAH) as the grafting agent, an anionic initiator or a peroxide initiator, and a solution grafting method. The weight ratio of maleic anhydride to liquid rubber in the preparation of the maleic anhydride-grafted liquid rubber is (2-5):100, and diisopropylbenzene peroxide is used as the initiator in an amount of 1-2.5 parts. The reaction temperature is 130°C to 150°C, and the reaction time is 30 min to 120 min.

[0031] The present invention is described in detail below with reference to specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0032] Example 1

[0033] The formula of polyurethane-based spray material is shown in Table 1.

[0034] Table 1

[0035]

[0036] When preparing the liquid rubber maleic anhydride grafted product, the feeding ratio of liquid EPDM rubber to maleic anhydride is 100:5, the amount of initiator diisopropylbenzene peroxide is 2.5 parts, the reaction temperature is 150° C., and the reaction time is 120 minutes.

[0037] To prepare the polyurethane-based spray material, first prepare component A and component B separately according to the mixing ratio. Before use, mix components A and B thoroughly and place them in the spray equipment for spraying. The mass ratio of component A to component B is 1.02:1.

[0038] Example 2

[0039] The formula of polyurethane-based spray material is shown in Table 2.

[0040] Table 2

[0041]

[0042] When preparing the liquid rubber maleic anhydride grafted product, the feeding ratio of liquid isoprene rubber to maleic anhydride is 100:2, the amount of initiator diisopropylbenzene peroxide used is 1 part, the reaction temperature is 130° C., and the reaction time is 30 minutes.

[0043] The preparation of the polyurethane-based spray material is the same as in Example 1.

[0044] Example 3

[0045] The formula of polyurethane-based spray material is shown in Table 3.

[0046] Table 3

[0047]

[0048] When preparing the liquid rubber maleic anhydride grafted product, the feeding ratio of liquid polybutadiene rubber to maleic anhydride is 100:3, the amount of initiator diisopropylbenzene peroxide used is 1.5 parts, the reaction temperature is 130° C., and the reaction time is 60 minutes.

[0049] The preparation of the polyurethane-based spray material is the same as in Example 1.

[0050] Example 4

[0051] The formula of polyurethane-based spray material is shown in Table 4.

[0052] Table 4

[0053]

[0054] The specific preparation method of the liquid rubber maleic anhydride grafted material and the preparation of the polyurethane-based spray material are the same as those in Example 1.

[0055] Comparative Example 1:

[0056] Taking Example 1 as the object, the mass of maleic anhydride grafted liquid EPDM rubber in component A was replaced by hexamethylene diisocyanate, and the diisopropyl peroxide, zinc oxide, stearic acid and N-tert-butyl-2-benzothiazolesulfenamide in component B were replaced with CGA-D2000 in the same proportion. The other components and proportions remained unchanged, and the polyurethane spray material was prepared as in Example 1.

[0057] Comparative Example 2

[0058] Based on Example 1, the only difference is that the mass of maleic anhydride grafted liquid EPDM rubber is replaced by liquid EPDM rubber (ie, no maleic anhydride grafting modification is performed).

[0059] Comparative Example 3

[0060] Based on Example 1, diisopropylbenzene peroxide, zinc oxide, stearic acid and N-tert-butyl-2-benzothiazolesulfenamide in component B were replaced with CGA-D2000 in the same proportion, and the other components and proportions remained unchanged. A polyurethane spray material was prepared in the same manner as in Example 1.

[0061] The polyurethane spray materials obtained in the above examples and comparative examples were sampled and tested in accordance with relevant test standards. The oxygen-acetylene wire ablation rate test was in accordance with GJB 323A, the pull-off strength test was in accordance with aerospace industry standard QJ 2038.1, and the peel strength test was in accordance with GB / T 2791. The specific performance of the test results is shown in Table 5.

[0062] Table 5

[0063]

[0064] The above embodiments describe preferred embodiments of the present invention, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent of the present invention shall be based on the appended claims.

Claims

1. A polyurethane-based spray material, characterized in that: The invention comprises component A and component B, wherein, by mass fraction, component A comprises 50% to 70% of isocyanate prepolymer, 10% to 20% of liquid rubber, 10% to 20% of ablation-resistant resin, 5% to 10% of fiber filler, and 1% to 5% of plasticizer; the liquid rubber is one or more of maleic anhydride-grafted liquid isoprene rubber, maleic anhydride-grafted liquid EPDM rubber, and maleic anhydride-grafted liquid polybutadiene. Component B: 45%~70% amino-terminated polyether, 1%~3% vulcanization crosslinking agent, 2%~6% vulcanization activation accelerator, 5%~15% chain extender, 10%~15% fiber filler, 10%~15% ablation-resistant resin and 1%~5% plasticizer.

2. The polyurethane-based spray material according to claim 1, characterized in that: The isocyanate prepolymer is one or more of hexamethylene diisocyanate (HDI) and diphenylmethane-4,4-diisocyanate (MDI).

3. The polyurethane-based spray material according to claim 1, characterized in that: When maleic anhydride is grafted onto liquid rubber, maleic anhydride (MAH) is used as the grafting agent, an anionic initiator or a peroxide initiator is used, and the grafting is carried out by a solution grafting method.

4. The polyurethane-based spray material according to claim 1, characterized in that: Component A and component B meet at least one of the following conditions: the ablation-resistant resin is one or both of polyimide resin and phenolic resin; the fiber filler is one or both of carbon fiber and basalt fiber; and the plasticizer is dioctyl phthalate.

5. The polyurethane-based spray material according to claim 1, characterized in that: The amino-terminated polyether is one or both of CGA-D2000 and CGA-T5000.

6. The polyurethane-based spray material according to claim 1, characterized in that: The B component meets at least one of the following conditions: the vulcanization crosslinking agent is one or more of diisopropylbenzene peroxide, di-tert-butyl diisopropylbenzene peroxide or dimethyl di-tert-butyl peroxide; the vulcanization activation accelerator is one or more of zinc oxide, stearic acid, zinc stearate, N,N-dicyclohexyl-2-benzothiazole sulfenamide (CZ), N-tert-butyl-2-benzothiazole sulfenamide (NS), dipentamethylenethiuram tetrasulfide (TRA) and zinc dimethyldithiocarbamate (PZ); the chain extender is one or more of 3,3-dichloro-4,4-diaminodiphenylmethane (MOCA), diethyltoluenediamine (DETDA) and N,N-dialkylphenylenediamine.

7. The method for preparing the polyurethane-based spraying material according to any one of claims 1 to 6, characterized in that: Prepare component A and component B respectively according to the ratio. Before use, mix component A and component B evenly and place them in the spraying equipment for spraying.

8. Use of the polyurethane-based spray material according to any one of claims 1 to 6 in the preparation of a thermal insulation layer of a solid rocket motor.

9. The use according to claim 8, characterized in that: The heat insulating layer is a polyurethane / ethylene propylene diene monomer rubber composite heat insulating layer.

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