Claims for Patent: 9,480,652

Summary for Patent: 9,480,652

Title:	Aerosol valve
Abstract:	A steam-sterilizable aerosol valve has a valve body of polymeric material such as polyphenylene sulfone (PPSU) having an HDT (heat deflection temperature) at 1.8 MPa stress in the range of 200-275.degree. C. Such a valve has the ability to survive steam sterilization without significant degradation of properties or appearance.
Inventor(s):	Harman; Anthony David (Henley-on-thames, GB)
Assignee:	BTG INTERNATIONAL LIMITED (London, GB)
Application Number:	12/083,871
Patent Claims:	1. A steam-sterilizable aerosol valve for an aerosol dispenser comprising: a valve body with external slots; a valve insert comprising gas channels formed on to the bottom of the insert which create two internal gas metering slots that are in communication with the external slots when preassembled into the valve body; and a stem valve; wherein the valve body, the valve insert and the stem valve consist of polymeric material having an HDT (heat deflection temperature) at 1.8 MPa stress in the range of 200-275.degree. C. 2. An aerosol valve as claimed in claim 1, wherein the valve body, stem valve and valve insert consist of the same material. 3. An aerosol valve as claimed in claim 1, wherein the HDT of the valve body at 1.8 MPa stress is in the range of 200-250.degree. C. 4. An aerosol valve as claimed in claim 3, wherein the HDT is in the range of 200-210.degree. C. 5. An aerosol valve as claimed in claim 1, wherein the glass transition temperature (Tg) of the valve body material is in the range of 200-330.degree. C. 6. An aerosol valve as claimed in claim 5, wherein the Tg is in the range of 210-230.degree. C. 7. An aerosol valve as claimed in claim 1, wherein the moisture absorption (after 24 hours in moist air) of the valve body material is below 0.75%. 8. An aerosol valve as claimed in claim 7, wherein the moisture absorption is below 0.6%. 9. An aerosol valve as claimed in claim 1, wherein the water take-up at saturation in liquid of the valve body material is below 3%. 10. An aerosol valve as claimed in claim 9, wherein the water take-up is below 2.5%. 11. An aerosol valve as claimed in claim 1, wherein the Izod impact strength of the valve body material is 0.8 J cm.sup.-1 or greater. 12. An aerosol valve as claimed in claim 11, wherein the Izod impact strength is above 1.0 J cm.sup.-1. 13. An aerosol valve as claimed in claim 1, wherein the tensile stiffness of the valve body material is below 4.0 GPa. 14. An aerosol valve as claimed in claim 13, wherein the tensile stiffness is below 3.0 GPa. 15. An aerosol valve as claimed in claim 1, wherein the valve body material consists of PEI (polyetherimide), PES (polyethersulphone), PPSU (polyphenylsulphone), PI (polyimide) or LCP (liquid crystal polymer). 16. A steam-sterilizable aerosol valve according to claim 1 having a valve body of polymeric material, wherein the valve body consists of a polymer of formula: ##STR00007## where a is 0 or 1 and Ar is 1,4-phenylene or 4,4'-biphenylene. 17. A steam-sterilizable aerosol valve according to claim 1 having a valve body of polymeric material, wherein the valve body consists of a copolymer between compounds of formula: ##STR00008## where Ar is 1,4-phenylene or 4,4'-biphenylene and X is fluorine or chlorine. 18. A method for producing a microfoam suitable for use in scleropathy of blood vessels, comprising introducing a physiologically acceptable blood-dispersible gas into a container holding an aqueous sclerosant liquid and releasing the mixture of blood-dispersible gas and sclerosant liquid, whereby upon release of the mixture the components of the mixture interact to form a microfoam, the container being provided with the steam-sterilizable aerosol valve according to claim 1. 19. A method as claimed in claim 18, wherein the sclerosant liquid is a solution of polidocanol or sodium tetradecyl sulfate in an aqueous carrier. 20. A method as claimed in claim 19, wherein the solution is from 0.25 to 5% vol/vol polidocanol. 21. A method as claimed in claim 18, wherein the mixture of blood-dispersible gas and sclerosant liquid is pressurized to a predetermined level in the range 800 mbar to 4.5 bar gauge (1.8 bar to 5.5 bar absolute). 22. A method as claimed in any claim 21, wherein the pressure is in the range of 1 bar to 2.5 bar gauge. 23. A method as claimed in claim 18, wherein the microfoam is such that less than 20% of the bubbles are less than 30 .mu.m diameter, greater than 75% are between 30 and 280 .mu.m diameter, less than 5% are between 281 and 500 .mu.m diameter, and there are substantially no bubbles greater than 500 .mu.m diameter. 24. A method as claimed in claim 18, wherein the gas/liquid ratio in the mix is controlled such that the density of the microfoam is 0.07 g/ml to 0.19 g/ml. 25. A method as claimed in claim 18, wherein the microfoam has a half-life of at least 2 minutes. 26. An aerosol valve as claimed in claim 1, wherein valve body material consists of PPSU (polyphenylsulphone). 27. A device for producing a microfoam suitable for use in scleropathy of blood vessels, including a steam-sterilizable aerosol valve comprising a valve body with external slots and: a valve insert comprising gas channels formed on to the bottom of the insert which create two internal gas metering slots that are in communication with the external slots when preassembled into the valve body; and a stem valve; wherein the valve body, the valve insert and the stem valve consist of polymeric material having an HDT (heat deflection temperature) at 1.8 MPa stress in the range of 200-275.degree. C. 28. A device as claimed in claim 27, wherein the device comprises a housing in which is situated a pressurizable chamber containing a solution of the sclerosing agent in a physiologically acceptable solvent; a pathway with one or more outlet orifices by which the solution may pass from the pressurizable chamber to the exterior of the device through said one or more outlet orifices and a mechanism by which the pathway from the chamber to the exterior can be opened or closed such that, when the container is pressurized and the pathway is open, fluid will be forced along the pathway and through the one or more outlet orifices; said housing incorporating an inlet for the admission of a pressurized source of physiologically acceptable gas that is dispersible in blood; the gas being in contact with the solution on activation of the mechanism such as to produce a gas-solution mixture; said pathway to the exterior of the housing including one or more foaming elements. 29. A device as claimed in claim 28, wherein the foaming element(s) comprise one or more passages of cross sectional dimension 0.1 .mu.m to 30 .mu.m, through which the solution and gas mixture is passed to reach the exterior of the device, said passing of said mixture through the passages forming a microfoam of 0.07 to 0.19 g/ml density and of half-life at least 2 minutes.