| 主权项 |
1. A method for providing a flexographic printing member, comprising:
imaging a laser-engraveable layer of a flexographic printing precursor using near-infrared radiation to provide a flexographic printing member with a relief image in the resulting laser-engraved layer, the flexographic printing precursor comprising a laser-engraveable layer being prepared from a laser-engraveable composition comprising one or more EPDM elastomeric rubbers in an amount of at least 30 weight % and up to and including 80 weight %, based on the total laser-engraveable composition weight, the laser-engraveable composition being essentially free of CLCB EPDM elastomeric rubbers, the laser-engraveable composition further comprising at least 2 phr and up to and including 90 phr of a near-infrared radiation absorber, and at least 3 phr and up to and including 20 phr of a vulcanizing composition that comprises a mixture of at least first and second peroxides, the vulcanizing composition being essentially free of sulfur vulcanizing compounds, wherein: the first peroxide has a t90 value of at least 1 minute and up to and including 6 minutes as measured at 160° C., the second peroxide has a t90 value of at least 16 minutes and up to and including 40 minutes as measured at 160° C., the molar ratio of the first peroxide to the second peroxide is at least 1:20 and to and including 1:2.67, the laser-engraveable composition exhibits a t90 that is greater than 1.7 seconds, the laser-engraveable layer has a Δ torque (MΔ=MH−ML) of at least 13 and up to and including 22, and the weight ratio of the near-infrared radiation absorber to the vulcanizing composition in the laser-engraveable composition is from 1:5 to and including 5:1. |
