A copolymer includes (i) a plurality of ethylenic moieties A having a structure according to the formula:

##STR00001## wherein R.sup.2 and R.sup.3 independently represent hydrogen, a halogen, an optionally substituted linear, branched, or cyclic alk(en)yl group, or an optionally substituted aromatic or heteroaromatic; (ii) a plurality of acetal moieties B having a structure according to the formula:

##STR00002## wherein L.sup.1 represents a divalent linking group, x=0 or 1, and R.sup.1 represents an optionally substituted aromatic or heteroaromatic group including at least one hydroxyl group; and (iii) a plurality of acetal moieties C and/or moieties D which include a structural moiety including a chromophoric group having its main absorption in the infrared region.

A copolymer includes (i) a plurality of ethylenic moieties A having a structure according to the following formula:

##STR00001## wherein R2 and R3 independently represent hydrogen, a halogen or an optionally substituted linear, branched or cyclic alk(en)yl group, or an optionally substituted aromatic or heteroaromatic group, and (ii) a plurality of acetal moieties B having a structure according to the following formula:

##STR00002## wherein L represents a divalent linking group; x=0 or 1 and R1 represents an optionally substituted aromatic or heteroaromatic group including at least one hydroxyl group and optionally one or more additional substituent(s), and at least one electron withdrawing group in ortho or para position relative to the at least one hydroxyl group.

An ink-based digital printing system for variable data lithographic printing includes an imaging member having a surface configured to absorb dampening fluid. A dampening fluid patterning system jets dampening fluid onto the imaging member surface according to image data to form a dampening fluid pattern. The system includes a transfer member that receives the jetted dampening fluid pattern from the imaging member at a dampening fluid loading nip for subsequent inking of the dampening fluid pattern to form an ink pattern. The ink pattern is transferred to a substrate from the transfer member at an ink pattern transfer nip.

An imaging member includes a surface layer comprising a fluoroelastomer-perfluoropolyether composite formed from a reaction mixture comprising a fluoroelastomer and a perfluoropolyether compound. Methods of manufacturing the imaging member and processes for variable lithographic printing using the imaging member are also disclosed.

A copolymer includes (i) a plurality of ethylenic moieties A having a structure according to the following formula: ##STR00001##
wherein R.sup.2 and R.sup.3 independently represent hydrogen, a halogen, or an optionally substituted linear, branched, or cyclic alk(en)yl group, or an optionally substituted aromatic or heteroaromatic, and (ii) a plurality of acetal moieties B having a structure according to the following formula: ##STR00002##
wherein L represents a divalent linking group; x=0 or 1; and R.sup.1 represents an optionally substituted aromatic or heteroaromatic group including at least one hydroxyl group. Use of these polymers in the coating of lithographic printing plates provides a good abrasion resistance while the balance between the ink acceptance, arising from the ethylenic moieties, and the solubility in an alkaline developer, arising form the acetal moieties, can be controlled efficiently.

There is provided a photosensitive resin composition which enables production of a lithographic printing plate precursor having a non-image portion which has good solubility in an alkali aqueous solution and which enables production of a lithographic printing plate having excellent printing durability and excellent chemical resistance, a lithographic printing plate precursor obtained by using the photosensitive resin composition, and a method for producing a lithographic printing plate.

The photosensitive resin composition contains a polymer compound having a constitutional unit represented by the following Formula A-1 as a constitutional unit A and at least one constitutional unit among constitutional units represented by the following Formulas B-1 to B-6 as a constitutional unit B in the main chain, and an infrared absorbing material.

##STR00001##

A highlight microdot mask element includes: at least one imaged region having at least one imaged block and being optically transmissive; at least one opaque island formed by at least one non-imaged block, wherein an arrangement of the plurality of imaged regions and the at least one opaque island defines the highlight microdot print surface pattern; and an opaque void region surrounds the highlight microdot pattern. A flexographic plate highlight microdot printhead includes: at least one elevated region, each elevated region having at least one elevated block forming a print surface; at least one internal recess formed by at least one recessed block, wherein an arrangement of the plurality of elevated regions and the at least one recess define a the highlight microdot print surface pattern of a highlight microdot structure; and an recess void region surrounding the highlight microdot structure.

A positive-working lithographic printing plate precursor including a support and an image-recording layer formed on the support and consisting of a positive-working photosensitive resin composition, in which the positive-working photosensitive resin composition contains a compound having at least one electron-withdrawing group and at least one phenolic hydroxyl group in one molecule, an alkali-soluble resin, and an infrared absorber, and the electron-withdrawing group excludes a sulfonyl group; and a method of preparing a lithographic printing plate using the positive-working lithographic printing plate precursor.