JP2011038456A - Insulation material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an insulation material capable of enhancing the actual carbon ratio, by reducing a burnt speed, by restraining pyrolysis. <P>SOLUTION: This insulation material includes vulcanizable elastomer, a filler and an additive. The additive includes fullerene (C<SB>60</SB>). The blending ratio of the fullerene (C<SB>60</SB>) to elastomer 100 pts.wt. can be set, for example, to 1-5 pts.wt. or 1-10 pts.wt. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an insulation material, and more particularly to an insulation material provided on the inner surface of a solid rocket motor case.

  A solid rocket motor is a rocket engine that generates propulsion with solid fuel (also called a solid propellant), and is a propulsion engine for a rocket for defense, a missile, or a satellite launch vehicle, an rocket for observation, or attitude control. Widely used as a rocket for vehicles.

  FIG. 1 shows a configuration of a conventional example of a solid rocket motor. The solid rocket motor 1 includes a motor case 2, a solid propellant 3, a nozzle 4, an igniter 5, and an insulation material 6. When the solid propellant 3 filled in the motor case 2 is ignited by the igniter 5, high-temperature and high-pressure combustion gas is generated inside the motor case 2, and this combustion gas flows out from the nozzle 4 at a high speed. Propulsion is generated by. Insulation material 6 is provided on the inner surface of the motor case 2 in order to thermally protect the motor case 2 from the high-temperature, high-pressure, and high-speed combustion gas.

  Since the insulation material 6 does not contribute to the generation of the propulsive force of the solid rocket motor 1, in order to improve the performance of the solid rocket motor 1, it is necessary to reduce its weight to the limit. Further, since the insulation material 6 is present between the motor case 2 and the solid propellant and also functions as an intermediary material for holding the solid propellant in the motor case 2, an appropriate strength is obtained. In addition, it is required to have an elongation, and an adhesive layer having sufficient strength can be formed between the motor case 2 and the insulation material 6 and between the insulation material 6 and the solid propellant 3. It has been.

  Therefore, the characteristics required for the insulation material include that it is difficult to transfer heat to the outer motor case, that it is difficult to be burned down, that strength and elongation are high, and that the density is low. Further, from the viewpoint of workability when the insulation material is vulcanized and bonded to the motor case, the sheeting property is good and the pasting workability is good. Furthermore, good adhesion between the motor case and the propellant is also required.

Here, ablation means that when the insulation material is exposed to high-temperature, high-pressure, high-speed combustion gas, the insulation material is thermally decomposed by this combustion gas.
The pyrolyzed cracked gas is discharged together with the combustion gas, so that heat generated by the combustion is discharged outside the motor case, and the motor case is thermally protected.
Ablation rate refers to the thickness per unit time at which the insulation material burns and erodes when exposed to high-temperature, high-pressure, high-speed combustion gas, and carbonization occurs due to thermal decomposition. This is the thickness per unit time that is added to the thickness per unit time.

  In addition, as a prior art document regarding an insulation material, there exist the following patent documents 1 and 2, for example.

JP 2006-96823 A JP 2006-95733 A

  As described above, in order to improve the performance of a solid rocket motor, it is necessary to reduce its weight to the limit. However, since the conventional insulation material is quickly burnt down by thermal decomposition, the consumption amount of the insulation material within the combustion time increases. Therefore, it is necessary to increase the thickness of the insulation material. As a result, the weight of the solid rocket motor is increased, which hinders improvement in performance.

  This invention is made | formed in view of said problem, and makes it a subject to provide the insulation material which can suppress the burning out at the time of thermal decomposition and can raise a residual-carbon rate.

In order to solve the above problem, the present invention is an insulation material comprising a vulcanizable elastomer, a filler, and an additive, wherein the additive contains fullerene (C ₆₀ ). .
In such an insulation material, 1 to 5 parts by weight of fullerene (C ₆₀ ) or 1 to 10 parts by weight may be blended with 100 parts by weight of elastomer.

When fullerene (C ₆₀ ) was added to the insulation material, as described later, it was confirmed that burnout due to thermal decomposition was suppressed and the residual coal rate increased. Since the remaining charcoal rate increases and the burnout rate on a weight basis decreases, the weight of the insulation material in the solid rocket motor can be reduced, thereby reducing the weight of the solid rocket motor and improving the performance of the solid rocket motor. Is possible.

It is a figure which shows the structure of the prior art example of a solid rocket motor. It is a figure which shows the relationship between the addition amount of fullerene, and a heating loss.

Hereinafter, preferred embodiments of the present invention will be described in detail.
Insulation materials for solid rocket motors generally consist of an elastomer that functions as a binder, fillers that improve mechanical properties such as strength and ablation characteristics, and additives that perform various functions. Is. In the present invention, the insulation material includes at least a vulcanizable elastomer, a filler, and an additive.

  The vulcanizable elastomer includes an ethylene-propylene-diene terpolymer (hereinafter referred to as EPDM) having an unsaturated bond and capable of sulfur crosslinking, and a natural rubber having a polyisoprene structure (hereinafter referred to as NR). ), Isoprene rubber having the same polyisoprene structure as natural rubber (hereinafter referred to as IR), acrylonitrile butadiene rubber (hereinafter referred to as NBR), which is a copolymer of acrylonitrile and butadiene, liquid butadiene rubber ( (Hereinafter referred to as BR) (1,2-BR, 1,4-BR), liquid IR (1,4-IR), liquid NBR rubber, liquid SBR rubber, liquid polybutene, liquid urethane rubber and other liquid rubber are used. Is done. These elastomers can be used alone or in a blend of these rubbers in order to utilize the advantages of each rubber.

  As the filler, aromatic polyamide fibers (hereinafter referred to as aramid fibers), aromatic polyamide pulp fibers (hereinafter referred to as pulp aramid fibers), carbon fibers, glass fibers, carbon black, asbestos, granular silica, and the like are used. These can be used alone or in a blend of two or more.

  Here, the pulp-like aramid fiber is a very short and highly fibrillated fiber. The fiber is finely cleaved into an aggregated state, and the fiber surface is activated compared to normal fibers. The surface area is greatly increased. Therefore, by using such a pulp-like aramid fiber as a filler for an insulation material, the bonding strength between the filler and the elastomer is increased, and mechanical properties such as strength and ablation characteristics can be greatly improved. Such pulp-like aramid fibers are commercially available, for example, as KEVLAR dry pulp (trade name of Toray DuPont), TWARON pulp (trade name of TEIJIN), and the like.

  Determine the compounding ratio of vulcanizable elastomers, additives, and fillers from the viewpoint of properties required for insulation materials such as heat insulation properties, burnout properties, density, ablation properties, workability, workability, and adhesiveness. There is a need.

  The compounding ratio of the vulcanizable elastomer is preferably 30 to 75% by weight, more preferably 40 to 70% by weight, based on the total weight of the insulation material. Furthermore, the blending ratio of the filler is preferably 10 to 45% by weight, more preferably 15 to 40% by weight, based on the total weight of the insulation material. The compounding ratio of the additive is preferably 1 to 30% by weight, more preferably 2 to 20% by weight, based on the total weight of the insulation material.

  Additives added to insulation materials include vulcanizing or crosslinking compounding agents for forming chain rubber molecules into a three-dimensional structure, and adjusting the hardness of rubber products to improve kneadability and processability Softeners and plasticizers or processing aids, anti-aging agents to prevent rubber deterioration, processing aids to improve workability during rubber kneading and rolling, and to obtain appropriate tackiness These are selected from combinations of elastomers and fillers used, and additives suitable for the rubber production method.

In the insulation material of the present invention, fullerene (C ₆₀ ) is further added as an additive. Fullerene (C ₆₀ ) is a fullerene having a truncated icosahedron (soccer ball-like) structure composed of 60 carbon atoms.
Here, the blending ratio of fullerene (C ₆₀ ) with respect to 100 parts by weight of the elastomer can be, for example, 1 to 5 parts by weight, or 1 to 10 parts by weight.

[Example]
Vulcanizable elastomer components, fillers and various additives were mixed and kneaded at high temperature using a Barbary mixer. The additive contains fullerene (C ₆₀ ). Then, a vulcanizing agent was added and kneaded using an open roll. The obtained rubber product was sheeted by a calender roll machine to produce the insulation material of the present invention. In this embodiment, an insulation material (Example 1) in which 2 parts by weight of fullerene (C ₆₀ ) is added to 100 parts by weight of elastomer, and 5 parts by weight of fullerene (C ₆₀ ) to 100 parts by weight of elastomer. An added insulation material (Example 2) was produced. The blending ratio of fullerene (C ₆₀ ) in the insulation material is 0.8 wt% in Example 1 and 2.0 wt% in Example 2.
As a comparative example, the insulation material is not added fullerene (C ₆₀₎ was prepared by procedures similar to those described above.

  FIG. 2 is a diagram showing the relationship between the amount of fullerene added and the heating loss for the comparative example and the insulation material of the present invention (Examples 1 and 2). In FIG. 2, the measurement result of the heating loss when the insulation material of the comparative example, Example 1 and Example 2 is heated to 600 ° C. at a temperature increase rate of 10 ° C./mm in an argon atmosphere is shown.

Here, the loss on heating is an index indicating how much gasification is lost with respect to the weight before heating when the sample is gradually heated under a certain atmosphere, and is measured by, for example, a thermobalance. be able to. The loss on heating is expressed by the following formula (1), where W1 is the weight before heating and W2 is the weight after heating.
Heat loss = {(W1-W2) / W1] × 100 (1)

2 that Example 1 and Example 2 in which fullerene (C ₆₀ ) is added to the insulation material have less heat loss than the comparative example. This result shows that thermal decomposition is suppressed and the residual coal rate increases. Here, the remaining carbon ratio is the mass percentage of the residue when the object to be measured is heated and the entire amount is carbonized.

  As described above, according to the insulation material of the present invention, the residual charcoal ratio increases and the burnout rate on the weight basis decreases, so that the weight of the insulation material can be reduced in the solid rocket motor, thereby reducing the solid rocket motor. It is possible to reduce the weight and improve the performance of the solid rocket motor.

Moreover, it can be seen from FIG. 2 that the heating loss decreases as the amount of fullerene (C ₆₀ ) added increases. Therefore, the addition amount of fullerene (C ₆₀ ) is within the range of an appropriate blending ratio of the above-mentioned additives (preferably 1 to 30% by weight, more preferably 2 to 20% by weight), and the desired effect of reducing weight loss by heating is obtained. It is good to set so that it can be obtained. However, even when the blending ratio of fullerene (C ₆₀ ) with respect to 100 parts by weight of the elastomer is in the range of 1 to 5 parts by weight or 1 to 10 parts by weight, a sufficient effect of reducing the heat loss can be obtained.

  Although the embodiments and examples of the present invention have been described above, the embodiments of the present invention disclosed above are merely examples, and the scope of the present invention is the embodiments of these inventions. It is not limited to. The scope of the present invention is indicated by the description of the scope of claims, and further includes meanings equivalent to the description of the scope of claims and all modifications within the scope.

1 Solid Rocket Motor 2 Motor Case 3 Solid Propellant 4 Nozzle 5 Igniter

Claims (3)

An insulation material comprising a vulcanizable elastomer, a filler, and an additive,
An insulation material, wherein the additive contains fullerene (C ₆₀ ). The insulation material according to claim 1, wherein 1 to 5 parts by weight of fullerene (C ₆₀ ) is blended with respect to 100 parts by weight of the elastomer. The insulation material according to claim 1, wherein 1 to 10 parts by weight of fullerene (C ₆₀ ) is blended with respect to 100 parts by weight of the elastomer.

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