Photostabilization of polymers
OwnerDavid J. Carlsson, Tony Suprunchuk +1inventors
InventorsDavid J. Carlsson, Tony Suprunchuk, David M. Wiles
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Abstract
Articles formed from polymers which are susceptible to degradative attack by ultraviolet radiation are stabilized by the application of a thin continuous layer of an energy transfer agent, which agent does not significantly absorb radiation in the ultraviolet region of the spectrum. The energy transfer agent is a substituted phenol, and the agent is used in amounts of at most 0.4%, by weight, based on the demonstrate prolonged resistance to ultraviolet degradation.
Claims21
Thin films, fibers, and filaments of polymeric material having high surface area in relation to volume stabilized against the degradative effects of actinic radiation, comprising said polymeric material containing an energy transfer agent which is incorporated into a thin surface layer having a thickness of not more than 1 micron, said energy transfer agent being a substituted phenol of the formula:
- ##STR2## wherein n is 0 or an integer from 1 to 6, and Z is a group --R or --OR wherein R is a hydrocarbyl group, or a derivative of such a substituted phenol in which the benzene ring is substituted by one or more hydroxyl, nitro, halogen, --R or --OR substituents wherein R is a hydrocarbyl group, the amount of energy transfer agent in the layer being at most 0.4% by weight based on the weight of the polymeric material, said energy transfer agent being differentiated from an ultraviolet absorber by a screening test which comprises (i) depositing the energy transfer agent onto a first thin film of a polymeric material in a stabilizing amount, said material having a high inherent transmission of incident ultra-violet radiation in the absence of any ultra-violet stabilizer, (ii) positioning a second film of said polymeric material containing no stabilizer so as to receive only radiation which has passed through said first film;
- (iii) irradiating said first film which has said agent deposited thereon with ultra-violet light, and (iv) determining the extent of degradation of said second film, said second film being degraded almost as rapidly when an energy transfer agent has been deposited on said first film as when irradiated in the absence of said film, this not being the case when said first film is stabilized with an ultra-violet absorber.
An article stabilized against the degradative effects of actinic radiation, which comprises a polymeric substrate having a maximum thickness of about 50 microns and having incorporated into substantially only a continuous thin surface layer thereof an energy transfer agent which is a substituted phenol of the formula:
- ##STR3## wherein n is 0 or an integer from 1 to 6, and Z is a group --R or --OR wherein R is a hydrocarbyl group, or a derivative of such a substituted phenol in which the benzene ring is substituted by one or more hydroxyl, nitro, halogen, --R or --OR substituents wherein R is a hydrocarbyl group, said layer being not more than 1 micron thick, the amount of energy transfer agent in the layer being at most 0.4% by weight based on the weight of the polymeric substrate, said energy transfer agent being differentiated from an ultra-violet absorber by a screening test which comprises (i) depositing the energy transfer agent onto a first thin film of a polymeric material in a stabilizing amount, said material having a high inherent transmission of incident ultra-violet radiation in the absence of any ultra-violet stabilizer, (ii) positioning a second film of said polymeric material containing no stabilizer so as to receive only radiation which has passed through said first film;
- (iii) irradiating said first film which has said agent deposited thereon with ultra-violet light, and (iv) determining the extent of degradation of said second film, said second film being degraded almost as rapidly when an energy transfer agent has been deposited on said first film as when irradiated in the absence of said first film, this not being the case when said first film is stabilized with an ultra-violet absorber.
Dependencies are inferred from the claim text.