Abstract A cross-linked olefin polymer is produced by applying high energy ionizing radiation to a mixture of the olefin polymer and a cross-link promoter such as trimethylolpropane triacrylate in an amount such that the mixture absorbs a radiation dose of between about 0.1 and about 1 megarad. The cross-link promoter serves to enhance the cross-linkability of the olefin polymer such that a high degree of cross-link is achieved with a small radiation dose. The mixture can also contain a foaming agent which can be made to expand and thereby produce a cellular product. Products fashioned of the cross-linked polymer have improved dimensional stability and are more resistant to thermal shrinkage and distortion. The cross-linked olefin polymer can be fashioned into a variety of products having utility in many fields including the packaging and construction industries.
A METHOD OF PRODUCING CROSS-LINKED POLYETHYLENE COMPRISING APPLYING HIGH ENERGY IONIZING RADIATION TO A MIXTURE OF POLYETHYLENE, A FOAMING AGENT, AND A CROSS-LINK PROMOTER SELECTED FROM THE GROUP CONSISTING OF TRIMETHYLOLPROPANE TRIACRYLATE, TRIMETHYLOLPROPANE TRIMETHACRYLATE, PENTAERYTHRITOL TETRAACRYLATE, AND PENTAERYTHRITOL TETRAMETHACRYLATE IN AN AMOUNT SUCH THAT THE MIXTURE ABSORBS A RADIATION DOSE OF BETWEEN ABOUT 0.1 AND ABOUT 1 MEGARAD, SAID CROSS-LINK PROMOTOER BEING PRESENT IN SAID ADMIXTURE IN AN AMOUNT UP TO ABOUT 10 WEIGHT PERCENT BASED UPON THE WEIGHT OF SAID MIXTURE.
Claim 2
Independent Claim
82 words
A METHOD OF PRODUCING CROSS-LINKED POLYETHYLENE COMPRISING APPLYING HIGH ENERGY IONIZING RADIATION TO A MIXTURE OF POLYETHYLENE, A FOAMING AGENT, AND A CROSS-LINK PROMOTER SELECTED FROM THE GROUP CONSISTING OF TRIMETHYLOLPROPANE TRIACRYLATE, TRIMETHYLOLPROPANE TRIMETHACRYLATE, PENTAERYTHRITOL TETRAACRYLATE, AND PENTAERYTHRITOL TETRAMETHACRYLATE IN AN AMOUNT SUCH THAT THE MIXTURE ABSORBS A RADIATION DOSE OF BETWEEN ABOUT 0.1 AND ABOUT 1 MEGARAD, SAID CROSS-LINK PROMOTOER BEING PRESENT IN SAID ADMIXTURE IN AN AMOUNT UP TO ABOUT 10 WEIGHT PERCENT BASED UPON THE WEIGHT OF SAID MIXTURE.
Claim 3
Dependent Claim
25 words
A method according to claim 1 wherein said foaming agent is of a type which decomposes and evolves a gas by the application of heat.
Claim 4
Dependent Claim
32 words
A method according to claim 2 which includes the step of applying heat to the resulting cross-linked polyethylene to cause said foaming agent to decompose and thereby produce a cellular polyethylene product.