Method and apparatus for printing a fibrous web

A printing roll for marking a fibrous web with a print, said printing roll comprising:

• a first colorant transfer zone on a generally cylindrical peripheral surface of said printing roll, said first colorant transfer zone having a maximum axial dimension less than the length of said printing roll and defining a shaped cavity, whereby rolling contact between said printing roll and said fibrous web causing said first colorant transfer zone when coated with colorant to create a mark on said fibrous web according to a principal pattern determined by the shape of said cavity;
• and
• an array of recesses in a spaced apart relationship on said generally cylindrical peripheral surface, said array of recesses defining a second colorant transfer zone substantially surrounding said first colorant transfer zone and being capable of printing a background pattern on said fibrous web upon which said principal pattern is visually eminent, said first colorant transfer zone having a higher colorant holding capacity per unit area of said generally cylindrical peripheral surface than said second colorant transfer zone, whereby said zones print on said fibrous web contrasting marks forming said principal and background patterns, said array of recesses constituting means for collecting dirt particles adhering to said printing roll and being trained over said generally cylindrical peripheral surface when said generally cylindrical peripheral surface is subjected to a scraping action for removing excess colorant therefrom;
• and wherein said recesses define therebetween circumferentially discontinuous land areas, whereby every possible imaginary circumferential line contained in a plane perpendicular to a rotational axis of said printing roll and passing through a land area intercepts at least one recess of said array.

A method for preventing build-up of dirt particles under a doctor blade scraping excess colorant from a printing roll which is in rolling contact with a fibrous web for printing on said fibrous web a principal pattern corresponding to a shaped cavity formed on a generally peripheral surface of said printing roll and defining a first colorant transfer zone having a maximum axial dimension less than the length of said printing roll, said method comprising the step of providing on said generally cylindrical peripheral surface an array of recesses in a spaced apart relationship substantially surrounding said first colorant transfer zone, said array of recesses constituting means for collecting dirt particles adhering to said printing roll which are being trained over said generally cylindrical surface when said printing roll is subjected to a scraping action by said doctor blade for removing excess colorant therefrom, said array of recesses defining a second colorant transfer zone printing a background pattern on said fibrous web upon which said principal pattern is visually eminent, said first colorant transfer zone having a higher colorant holding capacity per unit area of said generally cylindrical peripheral surface than said second colorant transfer zone, whereby said zones print on said fibrous web contrasting marks forming said principal and background patterns;

• and wherein said recesses define therebetween circumferentially discontinuous land areas, whereby every possible imaginary circumferential line contained in a plane perpendicular to a rotational axis of said printing roll and passing through a land area intercepts at least one recess of said array.