Process for making flexographic printing plate
View Patent ↗A process for making a flexographic printing plate is provided, the process including a step of forming an image mask on a flexographic printing starting plate by discharging an oil-based ink by an ink-jet method, the flexographic printing starting plate having a support and a photosensitive resin layer provided thereon; a step of subjecting the photosensitive resin layer to overall exposure via the image mask; and a step of developing the photosensitive resin layer thus exposed.
1. A process for making a flexographic printing plate, the process comprising:
a step of forming an image mask on a flexographic printing starting plate by discharging an oil-based ink by an electrostatic ink-jet method, the flexographic printing starting plate having a support and a photosensitive resin layer provided thereon; wherein the oil-based ink discharged is overprinted a plurality of times; wherein the oil-based ink comprises a coloring agent that absorbs or reflects light to which it is exposed; and wherein the oil-based ink is a dispersion in which charged particles of a dye or a pigment are dispersed in an insulative organic solvent,
a step of subjecting the photosensitive resin layer to overall exposure via the image mask, wherein the photosensitive resin layer used has a surface resistivity of 1×10 10 Ω/□ or more; and
a step of developing the photosensitive resin layer thus exposed.
2. The plate-making process according to claim 1 , wherein the pigment is a high resistivity carbon black.
3. The plate-making process according to claim 1 , wherein the insulative organic solvent is selected from the group consisting of straight-chain or branched aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, and halogen-substituted derivatives of these hydrocarbons.
4. The plate-making process according to claim 1 , wherein the oil-based ink has a viscosity of 0.5 to 5 mPa·sec.
5. The plate-making process according to claim 1 , wherein the process further comprises a back flash exposure step.
6. The plate-making process according to claim 1 , wherein the process further comprises a post exposure step subsequent to the development step.
7. The plate-making process according to claim 1 , wherein the support is a polyester.
8. The plate-making process according to claim 1 , wherein the photosensitive resin layer comprises a microgel binder.
9. A process for making a flexographic printing plate according to claim 1 , wherein the charged particles are particles of a pigment.
10. A process for making a flexographic printing plate according to claim 9 , wherein a charge control agent is used to charge the particles of the pigment.
11. A process for making a flexographic printing plate according to claim 10 , wherein the amount of charge is in the range of 5 to 200 μC/g.