Controllably degradable polymer compositions

Claim 1

Plastic composition which is controllably degradable by photooxidation which comprises a vinyl polymer, at least one first complex comprising a non-ionic organosoluble antioxidant complex of iron with a chain-breaking, peroxide-decomposing, metal ion deactivating or ultraviolet light stabilizing compound selected from the group consisting of a dithiocarbamate, dithiophosphate, xanthate, cyclic phosphate, oxime, benzthiazole and benzimidazole, and such that the iron complex is a photoactivator and is present in a concentration of about 0.0005 to 0.5% by weight, and at least one second complex comprising a non-ionic organosoluble ultraviolet light stabilizing complex of nickel or cobalt with a chain-breaking, peroxide-decomposing, metal ion deactivating or ultraviolet light stabilizing compound selected from the group consisting of a dithiocarbamate, dithiophosphate, xanthate, cyclic phosphate, oxime, benzthiazole and benzimidazole, and such that the nickel or cobalt complex is a photostabilizer and is present in a concentration of about 0.01 to 0.5% by weight, the concentrations of the iron complex and nickel or cobalt complex being independently varied relative to each other yet coordinated to produce a controllably desired ultraviolet photodegradation embrittlement time for the composition, which embrittlement time is capable of being retarded or delayed by controlling the length of the induction period defining the interval between the start of exposure to photodegrading ultraviolet light and the point at which ultraviolet photodegradation by photooxidation begins in dependence upon the controllable amount of the nickel or cobalt complex in relation to the amount of the iron complex, and which composition upon reaching the end of the induction period and the point at which ultraviolet photodegradation by photooxidation begins is capable of undergoing photodegradation at a correspondingly comparatively rapid photooxidation rate to ultimate embrittlement in dependence upon the controllable amount of the iron complex in relation to the amount of the nickel or cobalt complex, said composition being such that at a concentration ratio by weight of about 1:1 of the nickel or cobalt complex to the iron complex the embrittlement time thereof is at least about 125 hours after exposure to photodegrading ultraviolet light.