Reactive fluoropolymer and laser-engraveable compositions and preparatory methods
View Patent ↗A composition comprises a fluoropolymer such as an elastomeric fluoropolymer and at least 1 weight % of a fluoro-functionalized near-infrared radiation absorber. This composition can be formed into laser-engraveable layers for various elements that can be laser-engraved to provide relief images. The resulting laser-engraved elements can take various forms including flexographic printing members, and can be used to apply various inks to receiver materials in an imagewise fashion.
1. A flexographic printing precursor comprising a thermally crosslinked laser-engraveable layer comprising a crosslinked elastomeric fluoropolymer and a fluoro-functionalized near-infrared radiation absorber, the crosslinked fluoropolymer having a glass transition temperature of less than and including 0° C., the crosslinked laser-engraveable layer being formed from a reactive fluoropolymer composition comprising a reactive fluoropolymer, the fluoro-functionalized near-infrared radiation absorber, and a compound that causes crosslinking of the reactive fluoropolymer during thermal curing,
wherein the reactive fluoropolymer is selected from the group consisting of: poly(tetrafluoroethylene oxide-co-difluoromethylene oxide) α, ω-diol bis(2,3-dihydroxypropyl ether), poly(tetrafluoroethylene oxide-co-difluoromethylene oxide) α, ω-diol, ethoxylated poly(tetrafluoroethylene oxide-co-difluoromethylene oxide) α, ω-diol, and a multifunctional (meth)acrylate end-functionalized derivative of one of such compounds.
2. The flexographic printing precursor of claim 1 , wherein the fluoro-functionalized near-infrared radiation absorber is a fluoro-functionalized carbon black, fluoro-functionalized carbon nanotube, fluoro-functionalized graphene, or fluoro-functionalized dye, or a mixture or combination of any of these materials.
3. The flexographic printing precursor of claim 1 , wherein the fluoro-functionalized near-infrared radiation absorber is a fluoro-functionalized carbon black that is present in an amount of at least 1 weight % and up to and including 35 weight %, based on the total dry reactive fluoropolymer composition weight.
4. The flexographic printing precursor of claim 1 , further comprising one or more materials selected from the group consisting of hollow, solid, or porous particles, surfactants, plasticizers, lubricants, non-fluorinated resins, and microspheres, in the crosslinked laser-engraveable layer.
5. The flexographic printing precursor of claim 1 , wherein the reactive fluoropolymer has a number average molecular weight of at least 1000 g/mol.
6. The flexographic printing precursor of claim 1 , further comprising a substrate on which the thermally crosslinked laser-engraveable layer is disposed.
7. The flexographic printing precursor of claim 5 , further comprising an elastomeric rubber compressible layer between the substrate and the thermally crosslinked laser-engraveable layer.
8. The flexographic printing precursor of claim 5 , further comprising a conductive layer between the substrate and the thermally crosslinked laser-engraveable layer.
9. The flexographic printing precursor of claim 5 , wherein the substrate comprises a polyimide, polyester, or a fabric web adhered to a polyester film.
10. The flexographic printing precursor of claim 9 , further comprising an elastomeric rubber compressible layer between the substrate and the thermally crosslinked laser-engraveable layer.
11. The flexographic printing precursor of claim 1 , wherein the crosslinked fluoropolymer is present in an amount of at least 30 weight % and up to and including 99 weight %, based on the total weight of the thermally crosslinked laser-engraveable layer.
12. The flexographic printing precursor of claim 1 , wherein the crosslinked fluoropolymer has a glass transition temperature of at least −100° C. and up to and including 0° C.
13. The flexographic printing precursor of claim 1 , wherein the weight ratio of the crosslinked fluoropolymer to the fluoro-functionalized near-infrared radiation absorber being from 19:1 to and including 4:1.