Patent EP0463759A2 successfully refreshed from Google Patents.
EP0463759A2
Expired / Lapsed
EP
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Production of thermoplastics foams
Assignee: Rapra Technology Ltd
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Filing: 1991-06-10
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Granted: —
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Expires: 2011-06-10
Abstract
Abstract A method and apparatus for the production of foamed thermoplastics using nitrogen gas as the foaming agent, wherein the nitrogen gas is mixed with a polymer melt in a mixing apparatus of the type comprising a hollow cylindrical stator (14), (not necessarily static), and a cylindrical rotor (10) journalled for rotation within the stator (14), the facing cylindrical-surfaces of the rotor and stator carrying respective pluralities of circumferentially extending rows of cavities (18, 20); between which material to be mixed is passed in travelling through the mixer. Nitrogen gas is introduced into the polymer melt via a gas injector disposed at the upstream end of the mixer.
Inventors
- 👤 George Martin Gale
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 15:49
CPC Classifications
B; B29; B29C; B29C44/00; B29C44/34; B29C44/3442; B29C44/3446; B29C44/3402; B29C48/00; B29C48/25; B29C48/285; B29C48/29; B29C48/295; B29C48/36; B29C48/365; B29C48/37; B29C48/375; B29C48/385; B29C48/395; B29C48/40; B29C48/465; B29C48/467; B29C48/468; B29C48/47; B29C48/03; B29C48/07; B29K; B29K2105/00; B29K2105/0005
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
81 words
A method for the production of foamed thermoplastics using nitrogen gas as the foaming agent, wherein the nitrogen gas is mixed with a polymer melt in a mixing apparatus of the type comprising a hollow cylindrical stator, (not necessarily static), and a cylindrical rotor journalled for rotation within the stator, the facing cylindrical surfaces of the rotor and stator carrying respective pluralities of circumferentially extending rows of cavities, between which material to be mixed is passed in travelling through the mixer.
Claim 2
Dependent Claim
37 words
A method as claimed in claim 1, wherein the nitrogen gas is introduced to the mixer within one of the stator cavities adjacent the upstream end of the mixer, considered in the direction of material passage therethrough.
Claim 3
Dependent Claim
39 words
A method as claimed in claim 1, wherein the nitrogen gas is introduced to the mixer at a location opposite a rotor cavity and adjacent the upstream end of the mixer, considered in the direction of material passage therethrough.
Claim 4
Independent Claim
118 words
An apparatus for the production of foamed thermoplastics using nitrogen gas as the foaming agent, the apparatus characterised by a mixer (30) of the type comprising a hollow cylindrical stator (14) (not necessarily static), a cylindrical rotor (10) journalled for rotation within the stator (14), the facing cylindrical surfaces of the rotor and stator carrying respective pluralities of circumferentially extending rows of cavities (18, 20), between which material to be mixed is passed in travelling through the mixer, an extruder (32) for supplying polymer melt to the input end of the mixer (30), and a gas inlet (38) disposed adjacent or upstream of the inlet end of the mixer (30) for enabling nitrogen gas to be introduced thereto.
Claim 5
Dependent Claim
61 words
Apparatus as claimed in claim 4, wherein the miner (30) is a cavity transfer mixer in which the cavities are disposed with (a) the cavities (20) in adjacent rows on the stator circumferentially offset, (b) the cavities (18) in adjacent rows on the rotor circumferentially offset, and (c) the rows of cavities (20, 18) on the stator and rotor axially offset.
Claim 6
Dependent Claim
38 words
Apparatus as claimed in claim 4 or 5, wherein there is provided a cooling means (40) at the outlet end of the mixer (30) for cooling the polymer/nitrogen mixture prior to this being passed through a die (42).
Claim 7
Dependent Claim
36 words
Apparatus as claimed in claim 4, 5 or 6, wherein the extruder (32) has a screw which is attached directly to the rotor (10) of the mixer (30) so that the rotor and screw rotate together.
Claim 8
Dependent Claim
46 words
Apparatus as claimed in claim 4, 5 or 6, wherein the rotor (10) of the mixer (30) is driven by a separate drive means (46) so as to enable it to be driven at a faster or lower speed than the screw of the extruder (32).
Claim 9
Dependent Claim
42 words
Apparatus as claimed in any of claims 4 to 8 wherein the gas inlet comprises a gas injector (80) disposed within one of the stator cavities (18) adjacent the upstream end of the mixer, considered in the direction of material passage therethrough.
Claim 10
Dependent Claim
43 words
Apparatus as claimed in any of claims 4 to 8 wherein the gas inlet comprises a gas injector disposed at a location opposite a rotor cavity (18) and adjacent the upstream end of the mixer, considered in the direction of material passage therethrough.
Claim 11
Dependent Claim
24 words
Apparatus as claimed in claim 8, including a gear pump (48) for transferring the polymer melt from the extruder (32) to the mixer (30).
Claim 12
Dependent Claim
18 words
Apparatus as claimed in claim 11, wherein the nitroen inlet is disposed upstream of the gear pump (48).
References Cited (Backward Citations)
No citation records indexed.
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