RU2563036C1 - Thermal protection material - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: thermal protection material based on ethylenepropylenediene cauotchouc contains vulcanising agents, vulcanisation accelerator -benzothiazole derivative, vulcanisation activators, filler, technological additives and modifying additive, material is characterised by the fact that as ethylenepropylenediene cauotchouc it contains SKEPT-40 rubber, as vulcanisation accelerator it contains 2-mercaptobenzothiazole, as modifying additive it contains mixture of phosphorus-boron-containing oligomer PBO and magnesium hydroxide, with the following component ratio, wt. p.: cauotchouc SKEPT-40 - 100.0, sulphur - 2.0, dithiodimorpholine - 2.0, thiuram D - 0.75, 2-mercaptanobenzothiazole (captax) - 1.5, zinc oxide - 5.0, stearine - 1.0, technical carbon P-324 - 2.0, pine rosin - 3.0, white soot WS-100 - 30.0, magnesium hydroxide - 10,0, phosphorus-boron-containing oligomer PBO - 10.0.

EFFECT: reduction of rate of thermal-protective material heating.

2 tbl, 1 ex

Description

The invention relates to heat-protective materials based on ethylene propylene diene rubbers that can be used in aircraft and rocket science.

Known heat-protective material AR-998 (TU 38.1051211-83), which is a composition comprising a reinforcing heat-resistant filler of asbestos fabric with a double-sided lining with a rubber mixture based on synthetic ethylene propylene diene rubber.

A significant drawback of this material is that asbestos fabric has a higher coefficient of thermal conductivity than the rubber compound, which in turn leads to an increase in the heating rate of the heat-shielding material and, as a consequence, to a decrease in its heat-shielding characteristics.

Known heat-shielding material (Pat. 2404209 RF, IPC C08L 23/16, B32B 25/10, F16L 59/00, F02K 9/34, 11/20/2010) made of a formed layer of aramid fiber non-woven structure, laid between two layers of rubber mixtures of brand 51-2110 (TU 38.10551177-88) based on ethylene propylene diene rubber with subsequent vulcanization as part of the product.

The disadvantage of this heat-shielding material is that during its operation, the rubber layer is destroyed and the substance is carried away from the surface of the heat-shielding material, which, in turn, leads to an increase in the heating rate of the heat-shielding material, a decrease in its heat-shielding characteristics, and a decrease in the service life of the product or unit in whole.

The closest is a heat-shielding material based on ethylene propylene diene rubber (Pat. 2486215 RF, IPC C08L 23/16, June 27, 2013), which includes a vulcanizing group, a filler and processing aids, additionally contains a polyvinylidene chloride or adamantane modifying additive.

The disadvantage of this heat-shielding material is that it does not provide a decrease in the heating rate of the heat-shielding material based on ethylene propylene diene rubber.

The task of the invention is to obtain materials with high thermal characteristics.

The technical result of the claimed invention is to reduce the heating rate of the heat-shielding material.

The technical result is achieved in that the heat-protective material based on ethylene propylene diene rubber, containing vulcanizing agents, a vulcanization accelerator - a benzothiazole derivative, vulcanization activators, a filler, processing aids and a modifying additive, is characterized in that it contains SKEPT-40 rubber as an ethylene propylene diene rubber vulcanization accelerator contains 2-mercaptobenzothiazole, and as a modifying additive contains a mixture of phosphorus-containing oligomer TSF and hydroxide and magnesium, in the following ratio of components, parts by weight: rubber SKEPT-40 - 100.0, sulfur - 2.0, dithiodimorpholine - 2.0, thiuram D - 0.75, 2-mercaptobenzothiazole (captax) - 1, 5, zinc oxide - 5.0, stearin - 1.0, carbon black P-324 - 2.0, pine rosin - 3.0, white soot BS-100 - 30.0, magnesium hydroxide - 10.0, phosphorus-containing TSF oligomer - 10.0.

In the proposed heat-shielding material, the following components are used:

SKEPT-40 ethylene propylene diene rubber containing dicyclopentadiene as the diene copolymer (TU 2294-087-05766563-2010).

Vulcanizing group, including:

vulcanizing agents - sulfur (GOST 127-76), dithiodimorpholine (TU 2478-033-05807983-2002), thiuram D (TU 6-14-943-79);

vulcanization accelerator - captax (2-mercaptobenzothiazole) (TU 113-00-05761631-23-91);

vulcanization activators - zinc oxide (GOST 202-84), stearin (GOST 6484-96).

Filler - white soot BS-100 (GOST 18307-78).

Pine rosin (GOST 19113-84) and P-324 carbon black (GOST 7885-86) are used as technological additives.

As modifying additives, a mixture of the phosphorus-containing oligomer of the TSF and magnesium hydroxide (MgOH) is used (TU 6-09-3759-86). At the same time, the TSF increases fire resistance, heat resistance, and resistance to thermo-oxidative degradation of synthetic fibers (Pat. 2481428 of the Russian Federation, IPC D06M 15/41, May 10, 2003).

The use of a mixture of the phosphorus-containing oligomer of the TSF and magnesium hydroxide MgOH as a modifying additive gives the heat-shielding material based on ethylene-propylene diene rubber increased heat resistance, since under the influence of high temperatures, the presence of magnesium hydroxide in the mixture during decomposition contributes to a greater release of water, which in turn leads to cooling of the surface of the material, and the resulting foam layer covers the surface from the heat flow, which limits the flow of oxygen to the combustion source, reducing the rate of destruction of the material.

In this case, the separate introduction of the components of the modifying additive significantly impairs the physico-mechanical properties of the heat-shielding material.

The claimed amount of the modifying additive in combination with the vulcanization accelerators used and other components of the rubber composition allows to obtain a heat-shielding material with improved heat-shielding characteristics.

Example

The rubber mixture is prepared on rollers at a roll temperature of 65-70 ° C.

Mixing time 25 minutes. Then the vulcanization of the rubber mixture is carried out at a temperature of 165 ° C for 25 minutes. Then, the obtained samples are subjected to the necessary tests.

Table 1 shows the compositions of the prepared mixtures and prototype.

The rate of heating of the heat-shielding material during high-temperature heating (heat resistance) was estimated as follows: the time of heating the reverse side of a sample made in the form of a washer with a diameter of 30 mm and a thickness of 6 mm was determined to a temperature of 100 and 120 ° C.

The sample was heated by an open flame of a gas burner (a temperature of 1200 ° C was created on the surface). The sample was mounted in a tripod at an angle of 45 ° to the burner flame. To reduce the heat sink and reduce the experimental error, the sample was insulated with asbestos along the edge.

To measure the temperature on the unheated surface of the sample, a S-300.3 Photon pyrometer was used (GOST 28243-96 Pyrometers. General Technical Requirements). The principle of operation of the pyrometer is based on measuring the thermal radiation power of the measurement object mainly in the ranges of infrared radiation and visible light; and contact chromel-kopel thermocouple of the Aries regulator TRM-1.

Thermal protective properties of the proposed thermal protective material are given in table.2.

As can be seen from the data presented, the proposed heat-shielding material in comparison with the prototype has higher heat-shielding properties.

Thus, the introduction of SKEPT-40 rubber mixture based on ethylene propylene diene rubber as a modifying additive to a mixture of the phosphorus-containing oligomer of the TSF and magnesium hydroxide MgOH, the vulcanization accelerator - captax, reduces the heating rate of the heat-shielding material, which makes it possible to increase its heat-shielding properties.

Claims (1)

Thermoprotective material based on ethylene propylene diene rubber containing vulcanizing agents, vulcanization accelerator - benzothiazole derivative, vulcanization activators, filler, processing aids and modifying additive, characterized in that it contains SKEPT-40 rubber as ethylene propylene diene rubber and contains 2 vulcanization accelerator , and as a modifying additive contains a mixture of phosphorus-containing oligomer of the TSF and magnesium hydroxide, in the following ratio Nentov, parts by weight:
Rubber SKEPT-40 100.0 Sulfur 2.0 Dithiodimorpholine 2.0 Tiuram D 0.75 2-Mercaptobenzothiazole (Captax) 1,5 Zinc oxide 5,0 Stearin 1,0 Carbon black P-324 2.0 Pine Rosin 3.0 White soot BS-10 30,0 Magnesium hydroxide 10.0 Phosphorus TSF oligomer 10.0