CN105585848B - Solid propellant rocket liner molding silicone rubber air capsule material and preparation method thereof - Google Patents

Abstract

The invention relates to a long-life, high-temperature vulcanized silicone rubber material that is resistant to high temperature and anti-degradation under the complex working conditions of EPDM thermal insulation material molding, and is specially used for preparing auxiliary airbags for lining molding of aerospace solid rocket motors. The formula components (by weight) are 100 parts of silicone rubber compound, 30-50 parts of fumed silica, 5-10 parts of anti-aging additive A, 1-3 parts of anti-aging additive B, and 5-10 parts of anti-aging additive C , 5-10 parts of silazane, 1-3 parts of vulcanizing agent, the process of preparing an airbag mold with the silicone rubber is mixing, re-milling, molding, one-stage vulcanization, bonding, and two-stage vulcanization. In the sealed state, the temperature is 150°C, the pressure is 0.5MPa, and the EPDM rubber insulation layer composite material exists, it will not fail after 200 hours of use. It can be used as an auxiliary airbag material for lining molding of various types of pressure vessels such as aerospace solid rocket motors. .

Description

Silicone rubber airbag material for solid rocket motor lining molding and preparation method thereof

technical field

The invention belongs to the technical field of aerospace solid rocket motors, and in particular relates to a silicone rubber composite material for forming a solid rocket motor inner lining, such as a solid rocket motor inner heat insulation layer, and a preparation method thereof.

Background technique

A silicone rubber airbag-assisted molding process is commonly used in the lining molding of solid rocket motors for aerospace. Curing and forming. Silicone rubber airbag core mold is flexible. Compared with compression molding, it is easy to realize the overall molding of complex structural parts. It is simple and quick to assemble and demould, which can save a lot of man-hours and simplify the molding process. Compared with traditional metal and other polymer core molds, It has obvious cost advantages.

The special silicone rubber material used in the airbag-assisted molding process requires high thermal stability and comprehensive aging resistance, resistance to deterioration or softening under heat and pressure, stable dimensions, high tensile modulus, and high tearing after repeated use burst strength, high elongation at break, etc. For example, the silicone rubber airbag used in the lining of solid rocket motors has to withstand the complex composition of lining materials (including rubber, various inorganic fillers, etc.) , compatibilizers, additives, flame retardants, catalysts, cross-linking agents, etc.) repeated physical and chemical actions, put forward a lot of comprehensive aging resistance properties such as heat resistance, chemical resistance, peroxide resistance, pressure resistance, etc. high demands. The current commercialized related products are made of 110-2 glue as the matrix material, with fillers and additives such as white carbon black and ferric oxide added. After 6 hours of aging in this environment, it is found that the silicone rubber has Severely sticky, a degradation reaction has occurred.

In addition, in the prior art, there are many vulcanized silicone rubbers that are resistant to high temperatures, do not age, and do not degrade. For example, in the Chinese patent "Anti-Degradation Room Temperature Vulcanized Silicone Rubber", the authorized announcement number is CN1410487A, which discloses a potting compound that can withstand a high temperature of 150°C for 24 hours in a sealed state without aging or degradation, but it has not yet been found to meet the requirements of similar solid rocket motors. This kind of solid rocket motor lining molding working environment (sealed state, temperature 150 ℃, pressure 0.1~0.7MPa, EPDM insulation layer material and its decomposition products) and long-life vulcanized silicone rubber material that can be used for 200 hours technology. In addition, the use of polytetrafluoroethylene, modified carbon nanotubes, chitosan and transition metal oxides as anti-aging additives for silicone rubber materials has not been reported so far.

SUMMARY OF THE INVENTION

Aiming at the deficiencies of the prior art, the present invention solves the problem by providing a formula and preparation method of a silicone rubber airbag material for solid rocket motor lining molding, so as to greatly prolong the service life of the silicone rubber airbag material in a closed and complex working environment , to improve the reliability of solid rocket motor lining molding. The silicone rubber airbag mold material provided by the invention is suitable for lining molding of solid rocket motors.

The silicone rubber airbag material of the present invention can be fixed on the surface of the inner lining of the solid rocket motor by a certain air pressure to support the molding of the inner lining to ensure the integrity of the inner lining and the reliability of the work. The silicone rubber airbag material for solid rocket motor inner lining molding includes the following components according to the weight ratio:

(1) Silicone rubber material 100-120 parts;

(2) Anti-aging additive A 5-10 parts;

(3) 1~3 parts of anti-aging additive B;

(4) Anti-aging additive C 5~10 parts;

(5) 30-50 parts of reinforcing filler;

(6) Vulcanizing agent 0.5-3 parts;

(7) 5-12 parts of structural control agent;

(8) 1~5 parts of coupling agent.

(9) Process additive 5~10 parts.

Further, the silicone rubber compound is one or both of methyl vinyl silicone rubber and phenyl silicone rubber.

Furthermore, the anti-aging additive A is a single or composite oxide of manganese, iron, and cerium.

Another object of the present invention is to provide a kind of preparation method of above-mentioned silicone rubber airbag material, the technological process of using silicone rubber airbag material is:

Firstly, at room temperature, the matrix resin, reinforcing filler, and peroxide-resistant additives are put into an open mixer in sequence according to the weight ratio and mixed at room temperature.

After breaking the rubber, adjust the roller distance to 2mm; slowly add silane coupling agent and structure control agent after wrapping the roller; add vulcanizing agent after mixing, and release the film after mixing.

Then, according to the model requirements, the rubber material is pressed into a rubber block with a certain thickness through the screw extruder and the press, and the rubber block is discharged on the two-roller machine (thickness 2mm);

Finally, make a mold according to the requirements of the container model, wrap the above-mentioned silicone rubber green sheet on the mold, and make the size of the airbag meet the requirements of the drawing through processes such as shaping and calendering lap edges, and then carry out a period of vulcanization under normal pressure, and the heat transfer medium is hot air. , the vulcanization temperature is 160~170°C, and the vulcanization time is 30 minutes; check the airtightness of the airbag, and if it is qualified, proceed to the second-stage vulcanization.

The present invention has the following beneficial effects:

(1) The silicone rubber airbag material of the present invention replaces existing products, prolongs the life of the airbag formed by the solid rocket motor lining to 200 hours, and reduces the cost of the airbag in the molding process from 100,000 yuan per 100 times to 15,000 yuan In addition, the vulcanized rubber is easy to use, easy to maintain, and easy to obtain raw materials.

(2) Using the silicone rubber airbag material, high-temperature vulcanized silicone rubber can be placed in a sealed state to undergo high-temperature degradation reactions, which solves quality problems, prevents product scrapping, and greatly improves product reliability and life.

Detailed ways

The technical solutions of the present invention will be further described below in conjunction with the examples.

The silicone rubber airbag material for solid rocket motor lining molding of the present invention comprises the following components according to the weight ratio:

(1) Silicone rubber material 100-120 parts;

(2) Anti-aging additive A 5-10 parts;

(3) 1~3 parts of anti-aging additive B;

(4) Anti-aging additive C 5~10 parts;

(5) 30-50 parts of reinforcing filler;

(6) Vulcanizing agent 0.5-3 parts;

(7) 5-12 parts of structural control agent;

(8) 1~5 parts of coupling agent.

(9) Process additive 5~10 parts.

Furthermore, the silicone rubber compound is one or two of methyl vinyl silicone rubber and phenyl silicone rubber (including low, medium and high), and is the base compound of the silicone rubber airbag mold material. The silicone rubber with a special structure can increase the steric hindrance of the main chain of raw rubber, prevent the rearrangement and degradation of the main chain of silicone rubber, and thus greatly improve the temperature resistance of the silicone rubber composite material.

Preferably, the anti-aging additive A is a transition metal mixed oxide. This type of compound can reduce the attack of active oxygen on the side groups of silicone rubber by preventing the chain growth of free radicals, thereby significantly reducing the thermal decomposition and aging of silicone rubber. By preparing the compound of these several types of compounds, their synergistic effect on aging resistance under complex working conditions can be effectively exerted. The preparation process is as follows: at room temperature, the sol-gel method is used to prepare two or more composite oxide gels such as nickel, cobalt, copper, tin, manganese, iron, cerium, and lanthanum, and the gel is placed at 110 ° C. Dry overnight, pre-calcine at 400°C for 1 hour, and calcinate at 800°C for 2 hours. After cooling, the composite oxide sample is obtained and stored in a sealed and dry place at 0-30°C.

Further, the anti-aging additive B is one or both of hydroxyl- or amino-modified multi-walled carbon nanotube materials or low-molecular-weight chitosan. Carbon nanotube materials are difficult to disperse in silicone rubber, so the following pre-dispersion process needs to be used first: add carbon nanotubes to an appropriate amount of xylene, and ultrasonically disperse for about 1 hour. Add a small amount of polyvinyl liquid silicone rubber into the xylene solution, stir and dissolve it fully, then add the xylene solution of the above-mentioned carbon nanotubes in a small amount and several times while stirring and sonicating, and continue to sonicate for 30 minutes after the addition is completed. Then quickly remove the xylene and seal it up for later use. Low-molecular-weight chitosan is superior to high-molecular-weight chitosan in terms of clearing superoxide anions and hydroxyl radicals, and can be directly added or used in conjunction with modified carbon nanotubes in silicone rubber.

Further, the anti-aging additive C is one or both of polytetrafluoroethylene emulsion or polytetrafluoroethylene ultrafine powder. These materials have high dispersibility and can be evenly blended with other materials. Resistant to strong acid, strong alkali and strong oxidizing agent.

Further, the reinforcing filler is fumed silica, high-strength silica, acetylene carbon black, diatomaceous earth, montmorillonite and other fillers, wherein the grades of silica include M5, Ts720, S-600, HB -One or more of 612 or HB-620, nano-silica and Jibisheng silanized silica. The reinforcing effect of white carbon black on silicone rubber is considered to be that the raw rubber molecules of silicone rubber are more easily adsorbed on the surface of the dispersed _Si02 particles, so that the distance between the particles is smaller than the diameter of the particle body, and some chain links of the raw rubber molecules are arranged in sequence, resulting in The crystallization effect strengthens the attraction between molecules in the adsorption layer; in addition, the Si-O bond in the raw rubber molecule or its terminal hydroxyl group can form a physical or chemical combination with the Si-OH group on the surface of SiO ₂ , making the vulcanized rubber Improved physical and mechanical properties. Different types of fillers with different particle sizes have very different reinforcing effects on silicone rubber.

Further, the vulcanizing agent is benzoyl peroxide, dicumyl peroxide, 2,4-dichlorobenzoyl peroxide (DCEP), tert-butyl perbenzoate, di-tert-butyl peroxide, 2 , 5-dimethyl-2, 5-di-tert-butylperoxy-hexane or one or both of them can transform the high-viscosity plastic state silicone rubber raw rubber into three-dimensional network structure elastic state silicon rubber material.

Further, the structural control agent is one or two of hexamethylcyclotrisilazane, octamethylcyclotetrasilazane, diphenyldisilanol, and hydroxyl silicone oil, as a reinforcing filler surface structure The use of special treatment agents can effectively adjust the hydroxyl content between the filler surfaces, and inhibit the thermal rearrangement degradation of silicone rubber caused by excessive Si-OH content at high temperatures.

Further, the coupling agent is an epoxy coupling agent and an acryloxy coupling agent, and the epoxy coupling agent and the acryloxy coupling agent are Nanda-42 silane coupling agent, A-151 silane coupling agent One or both of γ-glycidyl ether propyl trimethoxysilane and γ-methacryloxypropyl trimethoxysilane, epoxy, acryloxy coupling agent Form a stable chemical covalent bond, greatly improve the bonding durability and stability between the filler and the matrix resin, thereby improving the process performance and aging resistance.

The silicon rubber airbag material for forming the inner lining of the solid rocket motor of the present invention may also include process additives and EPDM heat insulation layer materials.

Process additives refer to stearic acid, zinc stearate, zinc oxide, dioctyl sebacate, dibutyl phthalate, triethyl citrate, chlorinated paraffin-42, tricresyl phosphate, acetyl One or several kinds of tributyl citrate are used to improve the process performance of the mixed rubber, to prevent the sticking of the roller and the phenomenon that it cannot be formed.

The EPDM insulation layer material is based on EPDM rubber, adding flame retardant, carbon fiber or aramid fiber, white carbon black, curing agent and other additives in proportion, mixing at room temperature and vulcanizing under normal pressure The resulting elastomer composite material is one of the most common materials for the inner heat insulation layer of solid rocket motors.

The silicone rubber matrix undergoes ring-opening, hydrolysis, condensation, and esterification reactions under the action of coupling agents and vulcanizing agents.

Please refer to the 5 silicone rubber airbag material formulations of the present invention enumerated in Table 1.

Table 1 Silicone rubber airbag material for solid rocket motor lining molding of the present invention and comparative ratio proportioning (single bits: %) raw material name Recipe 1 Recipe 2 Recipe 3 Recipe 4 Recipe 5 comparative example Phenyl Silicone Rubber Resin 100 100 100 100 100 0 Methyl vinyl silicone rubber / / / / / 100 Hydrophobic silica 30 40 25 40 35 / Fumed silica 20 10 25 / 15 40 composite metal oxide 10 5 8 6 3 10 Amino-modified carbon nanotubes 1 / 0.5 / 0.8 / Hydroxyl-modified carbon nanotubes / 1 0.5 / 1 / Low Molecular Chitosan / 1 1 2 1.5 / PTFE emulsion 5 5 8 10 4 / Dioctyl sebacate / / 3 / 1.5 2.5 Zinc oxide / 5 / 5 / / stearic acid 5 / / / / Zinc stearate / / / / 5 5 A silane coupling agent 2.5 2.5 3 5 5 2.5 Silazane 3 3 5 5 5 3 Vulcanizing agent 3 3 3 3 3 3

Example 1

High-temperature vulcanized silicone rubber raw rubber is processed in an open double-roller rubber mixing machine at room temperature. First, add methylphenyl silicone rubber resin raw rubber to the roller according to formula 1 in Table 1. After starting the machine to cover the roller with rubber, gradually add fillers (white carbon black, peroxide-resistant additives, coupling agents, etc.) . After uniform mixing, the rubber material is thinly passed 8 to 10 times, rolled and lowered, and the mixed rubber is stored in a desiccator for later use. The mixed rubber is left for 24 hours and then re-milled on an open double-roller rubber mixer. When the rubber material becomes soft, the surface is smooth and flat, and it is thinned 5 to 10 times, the material can be unloaded and released. Then roll the silicone rubber compound on the open double-roller rubber mixing machine, add crosslinking agent, catalyst, etc., and pass it about 10 times, and then the rubber block is released on the two-roller machine (thickness 2mm). Prepare the capsule mold according to the requirements of the pressure vessel model (the head, tail, and cylinder are made separately), and then wrap the silicone rubber green sheet on the capsule mold, and make the capsule size meet the requirements through processes such as shaping and calendering lap joints , and cover the silicone rubber with cloth, fix the silicone rubber raw rubber capsule, and perform a stage of vulcanization under normal pressure. The heat transfer medium is hot air, the vulcanization temperature is 160~170°C, and the vulcanization time is about 30 minutes. Finally, the capsules of different parts are bonded together by adhesive for two-stage vulcanization (condition 150°C×120min).

The manufactured airbag is artificially accelerated aging under the conditions of the molding simulation test based on the use conditions of the material and the national standard GB/T 7141-1992 in a closed environment with a temperature of 150°C and an internal pressure of 0.1~0.7MPa. After 200 hours After the test treatment, the appearance of the airbag remained unchanged, and samples were taken after dissection for mechanical performance testing. To simulate the pressure of silicone rubber in practical applications, it can be obtained by processing equipment, and the amount of applied pressure can be expressed by controlling the strain of the sample. Taking the hardness change of 15 degrees and the elongation at break change of -50% as the rubber failure criterion, the results show that the formula material of the implementation case 1 can fully meet the requirements of working for 200 hours under the conditions of 150°C and internal pressure of 0.1~0.7MPa.

Example 2

The silicone rubber airbag 2 for solid rocket motor lining auxiliary molding was prepared according to the formula 2 in Table 1, and its preparation method was the same as that of Example 1. The properties of the obtained airbag material of the present invention are shown in Example 2 of Table 2.

Example 3

The silicone rubber airbag 3 for solid rocket motor liner auxiliary molding was prepared according to the formula 3 in Table 1, and its preparation method was the same as that of Example 1. The properties of the obtained airbag material of the present invention are shown in Example 3 of Table 2.

Example 4

Prepare the silicone rubber airbag 4 for auxiliary molding of the solid rocket motor lining according to the formula 4 in Table 1, and its preparation method is the same as that of Example 1. The properties of the obtained airbag material of the present invention are shown in Example 4 of Table 2.

Example 5

Prepare solid rocket motor liner auxiliary molding silicone rubber airbag 5 according to formula 5 in table 1, and its preparation method is the same as embodiment 1. The properties of the obtained airbag material of the present invention are shown in Example 5 of Table 2.

comparative example

The silicone rubber airbag material was prepared according to the formula of the comparative example in Table 1. The preparation method was the same as in Example 1, and the performance of the obtained airbag material of the present invention was shown in the comparative example in Table 2.

Table 2 Mechanical properties of the silicone rubber airbag material of the present invention before and after aging and comparison with existing materials.

*Aging time is 200 hours.

(According to GB/T528-1998 "Determination of Tensile Stress-Strain Properties of Vulcanized Rubber or Thermoplastic Rubber", GB/T529-1999 "Determination of Tear Strength of Vulcanized Rubber or Thermoplastic Rubber", GB/T15254-94 "Vulcanized Rubber and Metal Bonding 180 °Peel test" requires cutting into the desired shape.

Claims (5)

1. a kind of solid propellant rocket liner molding silicone rubber air capsule material, which is characterized in that the silicone rubber component packet It includes by weight are as follows:

Silicone rubber compounds, 100 parts；

Ageing-resistant additive A, 5-10 parts；

Ageing-resistant additive B, 1 ~ 3 part；

Ageing-resistant addition of C, 5 ~ 10 parts

Reinforced filling, 30-50 parts；

Vulcanizing agent, 0.5-3 parts；

Antistructurizing agent, 5 ~ 12 parts；

Coupling agent, 1 ~ 5 part；

The ageing-resistant additive B is hydroxyl, amino or carboxy-modified carbon nano-tube material, low-molecular weight chitoglycan and its derivative Object is therein any one or more of；

The silicone rubber compounds are one or both of methyl vinyl silicone rubber, phenyl siloxane rubber；

The ageing-resistant additive A is the single or composite oxides of manganese, iron, cerium；

The reinforced filling be fume colloidal silica Ts720, M5, HB-612 or HB-620, silanization white carbon black it is single or mixed Close object；The ageing-resistant addition of C is the single or mixture of ptfe emulsion, superfine powder of polytetrafluoroethylene.

2. a kind of method for preparing solid propellant rocket liner molding silicone rubber air capsule material described in claim 1, It is characterized in that, comprises the following steps that:

High-temperature sulfuration silicon rubber raw rubber is machined in open type dual-roller cylinder refining glue at room temperature, and silicone rubber compounds are added to roller first On, after sizing material packet roller of machining, it is gradually added reinforced filling, ageing-resistant additive, coupling agent；Sizing material after being kneaded uniformly is thin After logical 8 ~ 10 times, clot bottom sheet, obtain rubber compound deposit in it is spare in drier；Rubber compound carries out back mixing after placing 24 hours, It is carried out on open type dual-roller cylinder rubber mixing machine, when sizing material limbers up, surface is smooth, Bao Tong 5 ~ 10 times, can blanking slice；

Then by silicon rubber gross rubber on open type dual-roller cylinder rubber mixing machine packet roller, be added crosslinking agent, catalyst, 10 left sides Bao Tong The right side, by blob of viscose on two roller machine slice；Pressing force container model requirement prepares capsule die, then by silicon rubber raw cook packet in glue On capsule mold, by shaping, calendering overlap edge process, capsule size is made to meet the requirements, and in silicon rubber top covering cloth, fixed silicon Rubber raw rubber capsule, carries out one step cure under normal pressure, and heat transfer medium is hot-air, and curing temperature is 160 ~ 170 DEG C, when vulcanization Between about 20min；The capsule of different piece is finally bonded together carry out post vulcanization by adhesive.

3. a kind of method for preparing solid propellant rocket liner molding silicone rubber air capsule material as claimed in claim 2, It is characterized in that, by blob of viscose on two roller machine slice with a thickness of 2mm.

4. a kind of method for preparing solid propellant rocket liner molding silicone rubber air capsule material as claimed in claim 2, It is characterized in that, the capsule die is fabricated separately according to head, tail portion, shell portion.

5. a kind of method for preparing solid propellant rocket liner molding silicone rubber air capsule material as claimed in claim 2, It is characterized in that, the condition of the post vulcanization is at 150 DEG C, the progress time is 120min.