Seal for a dispensing apparatus
A seal for a valve for use in a pharmaceutical dispensing device, which seal is formed from a blend comprising: a thermoplastic elastomer including a propylene component with isotactic crystallinity; and a polymer selected from one or more of polypropylene, polyethylene and copolymers thereof.
1. A seal for a valve for use in a pharmaceutical dispensing device, which seal is formed from a blend comprising:
a thermoplastic elastomer including at least 80% a propylene component with isotactic crystallinity in which all or substantially all of the substituent groups lie on the same side of the carbon chain; and
a polymer selected from one or more of polypropylene, polyethylene, copolymer of propylene, and copolymer of ethylene, wherein the polymer has a melting point that is greater than the melting point of the thermoplastic polymer.
2. A seal as claimed in claim 1 , wherein the thermoplastic elastomer comprises a copolymer or terpolymer of propylene and one or more alpha-olefin (s).
3. A seal as claimed in claim 2 , wherein the alpha-olefin in the thermoplastic elastomer is selected from one or more of ethylene, butene, hexene, octene and decene.
4. A seal as claimed in claim 1 , wherein the propylene component in the thermoplastic elastomer has from 2 to 25% isotactic crystallinity.
5. A seal as claimed in claim 1 , wherein the thermoplastic elastomer has a molecular weight (Mw) of at least 100,000.
6. A seal as claimed in claim 1 , wherein said polymer increases the peak crystalline melting point of the blend.
7. A seal as claimed in claim 1 , wherein said polymer has a molecular weight that is greater than the molecular weight of the thermoplastic elastomer.
8. A seal as claimed in claim 1 , wherein said polymer comprises polypropylene.
9. A seal as claimed in claim 8 , wherein said polymer comprises a copolymer of polypropylene.
10. A seal as claimed in claim 1 , wherein said polymer comprises LDPE or HDPE.
11. A seal as claimed in claim 1 , wherein said polymer is present in the blend an amount of from 2 to 30 wt. %.
12. A seal as claimed in claim 1 , wherein the seal material comprises an additional thermoplastic component.
13. A seal as claimed in claim 12 , wherein the additional thermoplastic component comprises one or more polymers selected from styrene-ethylene-ethylene-propylene, styrene-ethylene-propylene, styrene-butadiene-styrene, polyether block polyamide, polyether-polyester, ethylene-diene, polydimethylsiloxane/urea copolymers, and/or cyclo-olefin copolymers, including combinations of two or more thereof.
14. A seal as claimed in claim 1 , wherein the seal material further comprises a mineral and/or inorganic filler.
15. A seal as claimed in claim 14 , wherein the filler is clay.
16. A seal as claimed in claim 14 , wherein the filler is present in the seal material in an amount of from 1 to 40 wt. %.
17. A seal as claimed in claim 1 , wherein the seal material is essentially free of a cross-linking agent.
18. A seal as claimed in claim 1 , wherein the seal material is essentially free of a plasticizer.
19. A seal as claimed in claim 1 , wherein the seal material is essentially free of a processing aid.
20. A seal as claimed in claim 1 , wherein the seal material is essentially free of a compatiblising agent.
21. A valve for use in a pharmaceutical dispensing device having a seal formed from a blend comprising:
a thermoplastic elastomer including at least 80% a propylene component with isotactic crystallinity in which all or substantially all of the substituent groups lie on the same side of the carbon chain; and
a polymer selected from one or more of polypropylene, polyethylene, copolymer of propylene, and copolymer of ethylene, wherein the polymer has a melting point that is greater than the melting point of the thermoplastic polymer.
22. A pharmaceutical dispensing device having a valve having a seal formed from a blend comprising:
a thermoplastic elastomer including at least 80% a propylene component with isotactic crystallinity in which all or substantially all of the substituent groups lie on the same side of the carbon chain; and
a polymer selected from one or more of polypropylene, polyethylene, copolymer of propylene, and copolymer of ethylene, wherein the polymer has a melting point that is greater than the melting point of the thermoplastic polymer.
23. A pharmaceutical dispensing device as claimed in claim 22 which is a pharmaceutical metered dose aerosol inhaler device.
24. A dispensing apparatus for dispensing pressurised fluid comprising a valve body defining a chamber, a valve member extending movably through the chamber and through at least one annular seal co-operating with the valve member and the body to regulate the discharge of fluid, wherein the at least one annular seal is formed from a blend comprising:
a thermoplastic elastomer including at least 80% a propylene component with isotactic crystallinity in which all or substantially all of the substituent groups lie on the same side of the carbon chain; and
a polymer selected from one or more of polypropylene, polyethylene, copolymer of propylene, and copolymer of ethylene, wherein the polymer has a melting point that is greater than the melting point of the thermoplastic polymer.
25. A dispensing apparatus which comprises a pressurised dispensing container having a valve body provided with two annular valve seals through which a valve member is axially slidable, said seals being disposed at inlet and outlet apertures of a valve chamber so that the valve functions as a metering valve, wherein at least one of the annular valve seals is formed from a blend comprising:
a thermoplastic elastomer including at least 80% a propylene component with isotactic crystallinity in which all or substantially all of the substituent groups lie on the same side of the carbon chain; and
a polymer selected from one or more of polypropylene, polyethylene, copolymer of propylene, and copolymer of ethylene, wherein the polymer has a melting point that is greater than the melting point of the thermoplastic polymer.
26. A dispensing apparatus as claimed in claim 24 , comprising a pressurised dispensing container operatively connected to the valve body and containing the fluid to be dispensed and a hydrofluorocarbon propellant comprising propellant type 134a or 227.
27. A dispensing apparatus as claimed in claim 24 , wherein the fluid to be dispensed comprises a liquid or particulate product as a solution or suspension in a carrier liquid comprising alcohol.
28. A dispensing apparatus as claimed in claim 27 , wherein the alcohol comprises ethanol.
29. The seal of claim 14 wherein the filler is selected from calcined clays, nano particle clays, talcs and amino-silane-coated clays.