E01

Direct Engraving The “Real” Digital Technology

Markus Feil, BASF Printing Systems

Principle of Laser Imaging Process

Principle of Laser Imaging Process

Laser

polymer plate

Principle of Laser Imaging Process Laser generates high intensity light beam Plate material absorbs light Light energy is converted into heat Thermal decomposition and evaporation of plate/mask material LAMS-layer 3 - 4 microns

Relief layer 500-700 microns

Principle of Laser Imaging Process Mask ablation 3-4 microns

Material ablation 700 microns

Laser Imager

Plate Processing Prepress

Back exposure Exposure (film / laser)

Direct engraving

Washing Drying Finishing

Ready for press

Today

Tomorrow

Differences in digital plate making Seamless sleeves

Digital sleeves

Digital plates

LEP (on sleeve)

Layout / Artwork

Layout / Artwork

Layout / Artwork

Layout / Artwork

Application of adhesive

Cutting of plate

Pre-exposure

LEP imaging

Pre-exposure

Plate imaging

Cleaning

Drying of adhesive in oven

Pre-mounting

UVA Exposing

Cutting of plate

Sleeve imaging

Flat wash-out

Pre-exposure

UVA Exposing

Flat drying

Stripping and mounting

Round wash-out

Flat finishing

Round drying

Vulcanising

Flat postexposing

Round finishing

Grinding

Round postexposing

Cleaning

Mounting

Coating of black layer

Butt joining

Imaging

Printing

Cleaning

Cleaning time: max. 60 sec. Cleaning temperature: RT - 30°C Cleaning agent: Printclean® After cleaning rinse with water Dry shortly with pressurized air No swelling compared to solvent washout

Disadvantages: conventional and CTP plates ß Drying time mainly determines the total processing time ß Handling and recovery of solvents necessary ß Many individual processing steps on different equipment ß Source of error: (film manufacturing), exposure and developing ß High labor cost Goal: Simplification of printing plate manufacturing How? Direct Engraving

Advantages of direct laser engraving Less processing steps:

Even faster getting-to-print: with sleeve technology Direct data transfer to plate:

cost saving ecologically beneficial process stability Gain in time

production reliability reproducibility flexibility

Why photopolymer? Rubber

Silicone rubber

Photoploymer

Why photopolymer? m 300 m/min, without dynamic - 4 pt text

Photopolymer

Elastomer 1

Rubber - Nd-YAG

Elastomer 2

Example Linework

Example Text

Why CO2 Laser? A [%] 100

Excimer Nd:YAG l = 308 nm l = 1064 nm

C02 - Laser l = 10,64 µm

80 60 40 20 0 0,1

0,5

1

10 l[µm]

Characteristics of light absorption of photopolymer

Screen ruling / resolution (

resolution screen ruling

)2 + 1 = grey levels

Laser

Resolution:

110 lpi

120 lpi

150 lpi

Nd: YAG

2540 dpi

534 GL

449 GL

287 GL

CO2

1270 dpi 1524 dpi 1778 dpi 1270 / 1778 dpi

134 GL 192 GL 262 GL 197 GL

113 GL 162 GL 220 GL 152 GL

72 GL 104 GL 141 GL 97 GL

Analog vs digital engraving

Digital multibeam engraving:

Analogue multibeam engraving:

‡ Steplike dot shape

‡ Smooth, controllable dot shape

‡ Laser output 0 % or x %

‡ Laser output modulated

‡ 2-dimensional

‡ 3-dimensional ‡ option: undercut

The benefits of analog engraving

Flat shoulder

Steep shoulder Very steep shoulder

Example Highlights

Printing sample Screen

42 L/cm

Resolution

1778 dpi

Substrate

PE

Ink

Solvent based

Laser

STK, BDE 4131

Samples

100 µm

Samples

Factors influencing engraving process Goal: process efficiency (speed, resolution etc.)

Process parameters

Laser and optics

material properties

• adv. feed rate

• wavelength

• optical properties

• extraction

• output power

• thermophysical

• beam diameter

• beam quality

Laser and system construction

properties

Material selection + formulation

Current Technology Technology

Details

Size of laser system Laser source Laser performance Spotsize Engraving time 1 m_ Rotations Advanced feed

4 500 x 1300 x 1600 mm (L x B x H) CO2 (Multi-beam-technology) 150 W / 250 W 35 µm 1.5 h (1 270 dpi) min. 300 rpm, max. 600 rpm Depending on resolution < 20 µm

Resolution Data format Grey levels

1270 dpi - 1778 TIFF Resolution: 1270 dpi 1524 dpi 1778 dpi 1270 / 1778 dpi

dpi

110 134 192 262 197

lpi GL GL GL GL

120 113 162 220 152

lpi GL GL GL GL

Key questions of LEP process: ßdebris removal and filtering ßLaser resolution and reproducibility ßMulti beam medium power Laser system preferable instead of single beam high power Laser system

Development of suitable Laser system optimised for the LEP plate plays key role for success of LEP technology

Key Question: Debris removal Evaporated material has to be extracted from laser system

•

polymer particles

•

low molecular weight fragments

•

gases/fumes

BASF Responsible Care® Development of suitable filter/exhaust system

Current situation / comparison Critical areas Seamless sleeves

Improvements

Many production steps high costs long lead times limited demand logistcis of sleeves

Endless/seamless no mounting (printer) higher print quality

digiflex

Conventional processing higher capital costs limited capacity

Higher print quality better reproducable less variables

LEP

Laser systems yet to be optimised Plate systems yet to be developed

no variables 100% reproducable short lead times excellent print quality

digisleeve

Advantages

Reproducable tonal values Internal makeready

Reproducable dot gain Extremley high contrast Fine gradations

Steeper shoulders, brilliant anchoring

Enhanced printing quality Cost saving compared with conventional flexography

Also suitable for letterpress Conventional

Laser engraved

48 l/cm; tonal value 10 %

48 l/cm; tonal value 10 %

Conclusion LEP ß

Plate materials suitable for all ink systems have been developed, further optimization in progress

ß

Focus on - debris removal and filtering - laser resolution and reproducibility - imaging speed

ß

Direct laser engraving will be the future technology for Flexo plate making and BASF’s R&D focus

We hope to meet you at DRUPA 2004 to introduce you the newest developments of Direct Engraving. Thank you for your attention! Markus Feil, BASF Printing Systems