RU2070903C1 - Siloxane composition absorbing mechanical energy - Google Patents

Abstract

FIELD: absorption of mechanical energy in shock-absorbing and braking devices. SUBSTANCE: composition comprises (wt parts): 100 dimethyl diethyl siloxane rubber; 10-30 aerosil; 7-23 asbestos; 75-150 oligodiethyl siloxane fluid with viscosity of 1.5-5.0 poise; methyl-3,3,3- trifluoropropyl siloxanediol containing 3-10 wt% hydroxyl groups or dimethyl methylphenyl siloxanediol containing at least 3 wt % hydroxy groups and 4-20 wt% methylphenyl siloxane units. EFFECT: improved properties of the siloxane composition. 2 tbl

Description

 The invention relates to the field of production of elastomeric compositions for absorbing mechanical energy based on dimethyldiethylsiloxane rubber and can be used in depreciation and braking devices in the railway, aviation and other sectors of the economy.

 Siloxane compositions are known for absorbing mechanical energy, which contain, in addition to organosilicon oligomers, aliphatic alcohols with different contents of hydroxyl groups, mineral oils, polyisobutylenes with a molecular weight of 5000,000, fillers of various nature [Japan, Application No. 54-41957, publication of 04/03/79] however, they energy intensity does not exceed 60 kJ.

The composition that is closest in composition to the invention is a composition based on boron-containing copolymers of polydimethyl-, methylphenyl-, methylvinylsiloxanediols, containing silica gel with a specific surface area of 10,400 m ² / g, titanium white pigment, plasticizing additives methylsiloxane oil or glycerin as a filler, benzoyl peroxide curing agent [Polish patent N 108635, C 08 L 83/12, 1981

The disadvantage of this composition is the relatively low energy consumption. The specified composition is used in the depreciation device of railway cars (KZE shock absorber), the performance of which is limited by an energy intensity of 72 kJ at a collision speed of 10 12 km / h and a car weight of 80-90 tons [Prospect f. Kolmex Co. LTd, Poland, KZE Shock Absorber]
However, for the conditions of long-distance transportation in order to reduce their cost, a significantly higher carrying capacity of vehicles and an increase in speed and, therefore, an increase in the energy intensity of elastomeric compositions absorbing mechanical energy are required.

In connection with the foregoing objective of the present invention is the creation of an elastomeric composition with an energy intensity of up to 200 kJ, operable in the temperature range from minus 60 to plus 130 ^o C.

This problem is solved in such a way that SKTEM-1 dimethyldiethylsiloxane rubber is used as the elastomeric base of the siloxane composition that absorbs mechanical energy, aerosil and asbestos are fillers, the composition contains anti-structuring and plasticizing additives in the following ratio of components:
dimethyldiethylsiloxane rubber 100
Aerosil 10 30
asbestos 7 23
anti-structuring additive 1 4
methyl-3,3,3-trifluoropropylsiloxanediol or dimethylmethylphenylsiloxanediol plasticizing agent oligodiethylsiloxane liquid 75 150
Upon receipt of the composition, the following components are used: rubber SKTEM-1, containing 25 to 35 mol%. diethylsiloxane units (TU 38.403441-82), highly dispersed silica aerosil A-300 (GOST 14922-77), asbestos (TU 6-05-1379-86), anti-structuring additive - methyl 3,3,3-trifluoropropylsiloxanediol (TU 38.403674 -90) or dimethylmethylphenylsiloxanediol containing at least 3 mol. hydroxyl groups and from 4 to 20 mol. methylphenylsiloxane units, plasticizing additive oligoethylsiloxane liquid PES-5 (GOST 13004-77).

The mixing process is carried out in a low-speed paddle mixer 3Sh-4VRK-01 at a temperature of (23 ± 5) ^o C for 20 minutes, introducing successively rubber, aerosil A-300, anti-structuring additive, plasticizing additive, asbestos.

After the specified mixing time, the resulting composition is removed from the mixer, kept in air for 3 hours at a temperature of (23 ± 5) ^o C and rheological and low-temperature characteristics of the composition, as well as its energy intensity under the action of compressive stress, are determined.

Additionally determine the rheological characteristics of the composition after exposure for 3 days at (23 ± 5) ^o C and 130 ^o C.

 Example 1. Compositions are made as described above, varying the ingredients in the amounts indicated in table 1 under codes 2 to 6, within the scope of the claimed formula. Low-temperature, rheological characteristics of the compositions and their energy intensity are given in table 2 under the codes 2 6.

 Example 2. Compositions are made analogously to example 1, varying the amount of fluorosiloxane diol from zero to 5.0 mass. parts per 100 mass. parts of rubber (table 1, codes 7-8). Low-temperature, rheological characteristics of the compositions, energy intensity are given in table 2, codes 7 8.

 The exclusion of fluorosiloxane diol or an increase in its content in the formulation leads to instability of rheological characteristics, a decrease in the energy intensity of the composition, and a deterioration in its low temperature properties.

 Example 3. Compositions are made analogously to example 1, varying the content of oligoethylsiloxane liquid (PES-5) in the amounts indicated in table 1 under codes 10. The low-temperature, rheological characteristics of the compositions, their energy intensity are given in table 2, codes 9-10.

 Changing the content of PES-5 above and below the optimum (according to the proposed formula) leads to a decrease in the energy intensity of the composition and the deterioration of low temperature properties.

Example 4. Compositions are made according to example 1, varying the content of Aerosil A-300 and asbestos in the amounts indicated in table 1 under codes 11
14. The characteristics of the compositions are shown in table 2, codes 11-14.

 Changes in the content of Aerosil A-300 and asbestos fillers outside the proposed formulation lead to instability of rheological characteristics and a decrease in the energy intensity of the composition.

 From the above data it follows that the set of required properties of the composition is achieved using cipher formulations 2 6. Changing the content of components (cipher formulations 7 14) leads to instability of the rheological parameters of the composition, worsening low-temperature properties (cipher formulations 7, 8, 9, 10) and reducing energy intensity.

The proposed composition, corresponding to formulations 2 to 6, for the absorption of mechanical energy ensures the performance of brake and depreciation devices of vehicles at temperatures from minus 60 ^o to 130 ^o C with an energy intensity of 2.8 ^o C 3.0 times the energy intensity of the prototype.

Claims (1)

 Siloxane composition, absorbing mechanical energy, including an organosiloxane polymer, a filler and a plasticizing additive, characterized in that it contains dimethyldiethylsiloxane rubber with 25 to 35 mol. diethylsiloxane units, as a filler aerosil and asbestos, as a plasticizing additive - oligodiethylsiloxane fluid with a viscosity of 1.5 5.0 Poise and an additional anti-structuring additive methyl-3,3,3-trifluoropropylsiloxane diol with 3 10 mol. hydroxyl groups or dimethylmethylphenylsiloxane diol containing at least 3 mol. hydroxyl groups and 4 to 20 mol. methylphenylsiloxylates in the following ratio of components, parts by weight Dimethyldiethylsiloxane rubber 100
Aerosil 10 30
Asbestos 7 23
Oligodiethylsiloxane Liquid 75 150
with viscosity 1.5 5.0 Poise
Anti-structuring additive methyl-3,3,3-trifluoropropylsiloxanediol with 3 to 10 mol. hydroxyl groups or dimethylmethylphenylsiloxane diol containing at least 3 wt. hydroxyl groups and 4 to 20 wt. methylphenylsiloxylates 1 4

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