Method for irradiating organic polymers
First Claim
1. A method for irradiating a high molecular weight organic polymer in flowable solid form which is capable of undergoing chain scission when subjected to radiation with high energy electrons so as to utilize more efficiently said radiation to a impinge the polymer with a distinct radiation pattern to provide continuity in molecular weight distribution comprising the steps of:
- (a) forming a bed of an organic polymer in flowable solid form, said bed having a substantially uniform depth which exceeds the penetration potential of the electrons and a width greater than the pattern of the radiation beam;
(b) passing said bed of organic polymer through a radiation zone providing a radiation beam narrower than the width of said bed of organic polymer;
(c) irradiating said bed of organic polymer so that the radiation impinges only in a distinct pattern which is less than the total width of said bed of organic polymer at an intensity sufficient to cause controlled chain scission of said polymer but not of sufficient intensity to penetrate the entire depth of the organic polymer to provide irradiated and non-irradiated polymer;
(d) removing said irradiated and non-irradiated organic polymer from said radiation zone;
(e) mixing the irradiated and non-irradiated polymer; and
(f) recovering an organic polymer having a continuous distribution of a decreased molecular weight with an increased melt flow rate.
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Abstract
A method for irradiating and modifying high molecular weight organic polymers with high energy radiation so that the radiation impinges only in a distinct pattern which is less than the width of the polymer so as to cause controlled chain scission and continuity in molecular weight distribution. The method improves the flow rate and millability of the polymers.
56 Citations
18 Claims
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1. A method for irradiating a high molecular weight organic polymer in flowable solid form which is capable of undergoing chain scission when subjected to radiation with high energy electrons so as to utilize more efficiently said radiation to a impinge the polymer with a distinct radiation pattern to provide continuity in molecular weight distribution comprising the steps of:
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(a) forming a bed of an organic polymer in flowable solid form, said bed having a substantially uniform depth which exceeds the penetration potential of the electrons and a width greater than the pattern of the radiation beam; (b) passing said bed of organic polymer through a radiation zone providing a radiation beam narrower than the width of said bed of organic polymer; (c) irradiating said bed of organic polymer so that the radiation impinges only in a distinct pattern which is less than the total width of said bed of organic polymer at an intensity sufficient to cause controlled chain scission of said polymer but not of sufficient intensity to penetrate the entire depth of the organic polymer to provide irradiated and non-irradiated polymer; (d) removing said irradiated and non-irradiated organic polymer from said radiation zone; (e) mixing the irradiated and non-irradiated polymer; and (f) recovering an organic polymer having a continuous distribution of a decreased molecular weight with an increased melt flow rate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A method for irradiating a high molecular weight propylene polymer in flowable solid form which is capable of undergoing chain scission when subjected to radiation with high energy electrons so as to utilize more efficiently said radiation to impinge the polymer with a distinct radiation pattern to provide continuity in molecular weight distribution comprising the steps of:
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(a) forming a bed of said propylene polymer in flowable solid form, said bed having a substantially uniform depth which exceeds the penetration potential of the beamed electrons and a width greater than the pattern of the radiation beam; (b) passing said bed of said propylene polymer through a radiation zone said radiation zone having a radiation pattern narrower than the total width of said bed; (c) irradiating said propylene polymer so that the radiation impinges only in a pattern which is less than the total width of said bed at an intensity sufficient to cause controlled chain scission of said polymer but not of sufficient intensity to penetrate the entire depth of the propylene polymer to provide irradiated and non-irradiated polymer. (d) removing said irradiated and non-irradiated organic polymer from said radiation zone; (e) mixing the irradiated and non-irradiated polymer; and (f) recovering propylene polymer having a decreased molecular weight with an increased melt flow rate value. - View Dependent Claims (18)
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Specification