Encapsulant material suitable for use under conditions of prolonged vacuum
AssigneeE M I Limited
InventorsAgathangelos Hajimichael, Sidney Hopper, Peter K. Smith
Life of this patent
Estimating the term…
Abstract
An encapsulant material suitable for use in space applications a polyurethane having according to the ESTEC specification a total mass loss of not greater than 1% and condensible volatiles content of not greater than 0.1% combined with a vibration performance characterised by a Q of from 4 to 15 and a peak frequency of 200 to 400 Hz when vibrated at 1g.
Claims15
An encapsulant material suitable for use in space applications which comprises a polyurethane formed from the reaction of a polyoxypropylene glycol of molecular weight between 3500 and 5000 and a chemical structure such that the ratio of molecular weight to hydroxyl number is at least 90 with a molar excess of a diisocyanate selected from the group consisting of toluene diisocyanate and isophorone diisocyanate under conditions that will give a prepolymer containing from 3.5% to 5.0% of free isocyanate groups, with an equivalent amount of a triol or diol having a molecular weight of from 90 to 190, said polyurethane when cured having according to the European Space Research and Technology Centre (ESTEC) specification a total mass loss not greater than 1% and condensible volatiles content of not greater than 0.1% combined with a vibration performance characterised by a Q of from 4 to 15 and a peak frequency of 200 to 400 Hz when vibrated at 1 g.
A process for the preparation of a polyurethane encapsulant material suitable for use in space applications which process comprises reacting a polyoxypropylene glycol of molecular weight between 3500 and 5000 and a chemical structure such that the ratio of molecular weight to hydroxyl number is at least 90 with a molar excess of a diisocyanate selected from the group consisting of toluene diisocyanate and isophorone diisocyanate under conditions that will give a prepolymer containing from 3.5% to 5.0% of free isocyanate groups and then reacting said prepolymer with an equivalent amount of a triol or diol having a molecular weight of from 90 to 190, and thereafter curing the resultant reaction product.
A method of encapsulating an object or apparatus in a polyurethane material which material has a total mass loss of not greater than 1% and a condensible volatiles content of not greater than 0.1% combined with a vibration performance characterised by a Q of from 4 to 15 and a peak frequency of 200 to 400 Hz when vibrated at 1 g which method comprises reacting in situ while in contact with said object or apparatus to be encapsulated a prepolymer, formed from the reaction of a polyoxypropylene glycol of molecular weight between 3500 and 5000 and a chemical structure such that the ratio of molecular weight to hydroxyl number is at least 90 with a molar excess of a diisocyanate selected from the group consisting of toluene diisocyanate and isophorone diisocyanate under conditions that will give a prepolymer containing from 3.5% to 5.0% of free isocyanate groups, with an equivalent amount of a triol or diol having a molecular weight of from 90 to 190, and thereafter curing the resultant reaction product.
Dependencies are inferred from the claim text.