Patent ID: 6124370
Filing Date: 2000-09-26
Classification: C08J

Abstract:
A foamed article made by a dual cure process (1) comprising the steps of:1A. Compounding and simultaneously or subsequently shaping a composition consisting essentially of at least one olefinic polymer, selected from the group consisting of homogeneously branched linear or substantially linear ethylene copolymers, ethylene/vinyl acetate (EVA), ethylene/methacrylate, ethylene/acrylic acid (EAA), and diene containing polymers, bearing pendent crosslinking functionality with at least one foaming agent and, optionally, at least one other component selected from the group consisting of curing agent, filler, foaming agent activator, free radical crosslinking coagent, sulfur crosslinking promotor, pigment, foam nucleator, antioxidant, process aid, ultraviolet light absorber, and flame retardant, to form a shaped, substantially uncrosslinked, foamed article precursor;1B. Performing a first stage cure on the precursor of Step 1A in such a manner that most of the pendent, moisture-activated crosslinking functionality remains unreacted;1C. Simultaneously with or subsequently to the first stage cure of Step 1B, foaming the precursor of Step 1A to form a shaped, partially cured, foamed article; and1D. Performing a second stage, post-foaming moisture-activated cure of the pendent crosslinking functionality of the shaped, partially cured, foamed article of Step 1C, to obtain a shaped foamed article having a gel level of at least 90% determined according to ASTM D-2765-84;dual cure process (2) comprising the steps of:2A. Compounding under nongrafting conditions (i) at least one olefinic polymer, (ii) at least one moisture-activated, crosslinking functionality capable of being grafted to the olefinic polymer to form an olefinic polymer with pendent, moisture-activated crosslinking functionality, (iii) at least one free radical initiator, (iv) at least one foaming agent, and optionally (v) at least one curing agent to form a substantially homogeneous, uncrosslinked foamed article precursor;2B. Shaping the precursor of Step 2A under grafting conditions such that the free radical initiator is activated and a shaped, substantially uncrosslinked olefinic polymer with pendent, moisture-activated crosslinking functionality is formed;2C. Simultaneously with Step 2B, performing a first stage cure of the olefinic polymer with pendent, moisture-activated crosslinking functionality in such a manner that most of the pendent, moisture-activated crosslinking functionality remains unreacted;2D. Simultaneously with the first stage cure of Step 2C, foaming the precursor of Step A to form a partially cured, foamed article; and2E. Performing a second stage, post-foaming moisture-activated cure of the pendent crosslinking functionality of the partially cured, foamed article of Step 2D, to obtain a shaped foamed article having a gel level of at least 90% determined according to ASTM D-2765-84; ordual cure process (3) comprising the steps of:3A. Compounding under nongrafting conditions (i) at least one olefinic polymer, (ii) at least one moisture-activated, crosslinking functionality capable of being grafted to the olefinic polymer to form an olefinic polymer with pendent, moisture-activated crosslinking functionality, (iii) at least one free radical initiator, (iv) at least one foaming agent, and optionally (v) at least one curing agent to form a substantially homogeneous, uncrosslinked foamed article precursor;3B. Shaping the precursor of Step 3A under grafting conditions such that the free radical initiator is activated and a shaped, substantially uncrosslinked olefinic polymer with pendent, moisture-activated crosslinking functionality is formed;3C. Simultaneously with or subsequent to Step 3B, performing a first stage cure of the olefinic polymer with pendent, moisture-activated crosslinking functionality in such a manner that most of the pendent, moisture-activated crosslinking functionality remains unreacted;3D. Simultaneously with or subsequently to the first stage cure of Step 3C, foaming the precursor of Step 3A to form a partially cured, foamed article; and3E. Performing a second stage, post-foaming moisture-activated cure of the pendent crosslinking functionality of the partially cured, foamed article of Step 3D, to obtain a shaped foamed article having a gel level of at least 90% determined according to ASTM D-2765-84,wherein the at least one olefinic polymer of dual cure process (3) includes at least one ethylene/propylene/diene terpolymer rubber.