EP0047171A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Process for irradiation of polyethylene
Assignee: DuPont Canada Inc
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Filing: 1981-09-01
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Granted: —
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Expires: 2001-09-01
Abstract
Abstract A process for the irradiation of homopolymers of ethylene and copolymers of ethylene and higher a-olefins is disclosed. The process comprises subjecting the polymer in the form of granules to an atmosphere of steam, irradiating the polymer in an inert atmosphere with electron or gamma irradiation and reducing the level of free radicals in the irradiated polyethylene by further subjecting the polymer to an atmosphere of steam. The preferred inert atmosphere is steam. The amount of irradiation used is less than 1.5 Mrad. The irradiated polymer, which exhibits improved processability and/or product properties when compared with non-irradiated polymer, may be used in a wide variety of end-uses e.g. fabrication into film, pipe and other articles, using extrusion, injection moulding and blow moulding techniques.
Inventors
- 👤 George White
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 15:02
CPC Classifications
C; C08; C08J; C08J3/00; C08J3/28; B; B29; B29B; B29B13/00; B29B13/08; B29B9/00; B29B9/16; B29C; B29C67/00; B29C67/24; B29C35/00; B29C35/02; B29C35/08; B29C35/0805; B29C2035/085; B29C35/0866; B29C2035/0877; B29K; B29K2023/00; B29K2023/04; B29K2023/06; B29K2105/00; B29K2105/0085; C08J2323/00; C08J2323/02; C08J2323/04
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
279 words
A process for the irradiation of a polyethylene selected from the group consisting of homopolymers of ethylene and copolymers of ethylene and higher a-olefins having 4-10 carbon atoms, and blends and mixtures thereof, comprising the steps of: (a) subjecting said polyethylene, in the form of granules, to an atmosphere of steam at a temperature of at least 80°C but less than the temperature of agglomeration of the granules for a minimum period of time inversely related to said temperature, said minimum period of time being in the range from 90 minutes when the temperature is 80°C to 20 minutes when the temperature is near that of agglomeration; (b) irradiating said polyethylene at a temperature less than the temperature of agglomeration of the granules with irradiation selected from the group consisting of electron and gamma irradiation, in an inert atmosphere, the amount of said irradiation being less than 1.5 Mrad; and (c) substantially reducing the level of free radicals in the irradiated polyethylene by subjecting said polyethylene to an atmosphere of steam at a temperature of at least 80°C but less than the temperature of agglomeration of the granules of irradiated polyethylene for a minimum period of time inversely related to said temperature, such that (i) when the irradiation is electron irradiation, the minimum period is in the range from 75 minutes when the temperature is 80°C to 30 minutes when the temperature is near that of agglomeration of the irradiated polymer, and (ii) when the irradiation is gamma irradiation, the minimum period is in the range from 20 minutes when the temperature is 80°C to 10 minutes when the temperature is near that of agglomeration of the irradiated polymer.
Claim 2
Dependent Claim
279 words
A process for the irradiation of a polyethylene selected from the group consisting of homopolymers of ethylene and copolymers of ethylene and higher a-olefins having 4-10 carbon atoms, and blends and mixtures thereof, comprising the steps of: (a) subjecting said polyethylene, in the form of granules, to an atmosphere of steam at a temperature of at least 80°C but less than the temperature of agglomeration of the granules for a minimum period of time inversely related to said temperature, said minimum period of time being in the range from 90 minutes when the temperature is 80°C to 20 minutes when the temperature is near that of agglomeration; (b) irradiating said polyethylene at a temperature less than the temperature of agglomeration of the granules with irradiation selected from the group consisting of electron and gamma irradiation, in an inert atmosphere, the amount of said irradiation being less than 1.5 Mrad; and (c) substantially reducing the level of free radicals in the irradiated polyethylene by subjecting said polyethylene to an atmosphere of steam at a temperature of at least 80°C but less than the temperature of agglomeration of the granules of irradiated polyethylene for a minimum period of time inversely related to said temperature, such that (i) when the irradiation is electron irradiation, the minimum period is in the range from 75 minutes when the temperature is 80°C to 30 minutes when the temperature is near that of agglomeration of the irradiated polymer, and (ii) when the irradiation is gamma irradiation, the minimum period is in the range from 20 minutes when the temperature is 80°C to 10 minutes when the temperature is near that of agglomeration of the irradiated polymer.
Claim 3
Dependent Claim
15 words
The process of Claim 1 in which, in step (b), the inert atmosphere is steam.
Claim 4
Dependent Claim
19 words
The process of Claim 1 or Claim 2 in which, in step (a), the temperature is at least 100°C.
Claim 5
Dependent Claim
19 words
The process of any one of Claims 1-3 in which, in step (c), the temperature is at least 100°C.
Claim 6
Dependent Claim
21 words
The process of any one of Claims 1-4 in which the amount of irradiation is in the range of 0.05-0.75 Mrad.
Claim 7
Dependent Claim
21 words
The process of any one of Claims 1-4 in which the amount of irradiation is in the range of 0.3-0.7 Mrad.
Claim 8
Dependent Claim
15 words
The process of any one of Claims 1-6 in which the irradiation is electron irradiation.
Claim 9
Dependent Claim
15 words
The process of any one of Claims 1-6 in which the irradiation is gamma irradiation.
Claim 10
Dependent Claim
17 words
The process of any one of Claims 1-8 in which the polyethylene is a homopolymer of ethylene.
Claim 11
Dependent Claim
25 words
The process of any one of Claims 1-8 in which the polyethylene is a copolymer of ethylene and a higher a-olefin having 4-8 carbon atoms.
Claim 12
Dependent Claim
12 words
The process of Claim 10 in which the higher a-olefin is butene-1.
References Cited (Backward Citations)
No citation records indexed.
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