Claims
- 1. A blend of monomer photopolymerizable by ultraviolet radiation at a first frequency selected from the group consisting of acrylic acid, methacrylic acid, and esters of acrylic or methacrylic acid; an amount of photoinitiator effective to polymerize said monomer at said first frequency and 0.1 to 5 percent by weight of a precursor of an ultraviolet absorber compound selected from compounds of this formula: ##STR4## where Pr is selected from saturated acyl or acryloyl and R.sup.1 is an alkenyl group of 2-5 carbon atoms.
- 2. A blend according to claim 1 in which R.sup.1 is vinyl.
- 3. A blend according to claim 2 in which Pr is acetyl.
- 4. A blend according to claim 1 in which the monomer is methyl methacrylate.
- 5. A blend according to claim 2 in which the photoinitiator is an onium salt or a mixture of diphenyl carbonyl and triethylamine.
- 6. A method of stabilizing a polymer degradable by ultraviolet radiation and formed of a monomer polymerizable by ultraviolet radiation selected from the group consisting of acrylic acid, methacrylic acid, or esters of acrylic acid or methacrylic acid, comprising the steps of:
- adding to said monomer an effective amount of a protoinitiator and 0.1 to 5 percent by weight of a precursor compound to form a blend, said precursor compound being selected from a compound of the formula: ##STR5## where Pr is a protective group which shows little absorption of ultraviolet energy at a first wavelength from 340 to 400 nm but is degradable by shorter wavelength ultraviolet radiation from 270 to 380 nm to convert the OPr group to a hydroxyl group, said Pr group being selected from saturated acyl or acryloyl and R.sup.1 is alkenyl of 2-5 carbon atoms,
- irradiating the blend with ultraviolet radiation at said first wavelength to polymerize the monomer to form said polymer without removing the protective group from the precursor compound; and
- irradiating the blend with ultraviolet radiation at said second wavelength to convert the OPr group to a hydroxyl group whereby said hydroxyl form of the compound is capable of absorbing ultraviolet radiation at said first frequency and can protect the polymer from degradation.
- 7. A method according to claim 6 in which R.sup.1 is vinyl.
- 8. A method according to claim 7 in which Pr is acetyl.
- 9. A method according to claim 8 in which the monomer is methyl methacrylate.
- 10. A method according to claim 6 in which the photoinitiator is an onium salt or a mixture of diphenyl carbonyl and triethylamine.
Parent Case Info
This is a continuation of application Ser. No. 742,413 field Jun. 7, 1985, now abandoned.
ORIGIN OF THE INVENTION
This invention was made in performance of work under Contract No. DE-AC03-83FS11944 from the U.S. Department of Energy.
US Referenced Citations (7)
Continuations (1)
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Number |
Date |
Country |
Parent |
742413 |
Jun 1985 |
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