3
* Simple proven process* Quick make-ready* low speed sensitivity* low impression sensitivity* variable ink film (better fidelity)
* consistent long runs
* Cylinders expensive* Cylinders take time to make
PLUS
MINUSENGRAVED CYLINDER
IMPRESSION ROLL
DOCTORBLADE
WEB
INK
Rotogravure
4
WEBBLANKETCYLINDER
PLATECYLINDERDAMPING
TRAIN
INK TRAIN
IMPRESSIONCYLINDER
INK DUCT * Proven process
* Highest quality process print
* High manning* High skill level needed* Color control issues* Not in line with die cutting etc.
PLUS
MINUS
Lithography
5
MINUS
* Low cost presses* In line capability* Quick make-ready* Less manning/skill level* Consistent color
* Process print quality* Variable industry capability
PLUS
WEB
PLATE
IMPRESSION ROLL
ENCLOSED INK
CHAMBER
ANILOX
Flexography
6
2. Composition and Chemistry
- Oil base
- Solvent Base
- Water Base
- Radiation Cure
1.Physical Form
- Liquid
- Paste
Ink Types
7
WATER(65%)
Wet Ink2#/Ream
Dry Ink.7#/Ream
1.3#/Ream
.1#/Ream
.2#/ReamSOLUTIONRESIN (10%)
EMULSIONRESIN (10%)
ADDITIVES (5%)
PIGMENT (10%) .2#/Ream
.2#/Ream
TYPICAL PROPERTIESViscosity 50-100 centipoiseSolids 35%Tack Very lowDrying Absorption/evaporationTrap Wet on dryCure ImmediateVOC < 1% by wt.Odor Very lowCost OK
•FLEXO
•GRAVURE
Ink Formulation – Water Base
8
SOLVENT(65%)
80% ALCOHOL
20% ACETATEWet Ink2#/Ream
Dry Ink.7#/Ream
POLYAMIDERESIN (10%)
NITROCELLULOSERESIN (10%)
ADDITIVES (5%)
PIGMENT (10%)
1.3#/Ream
.1#/Ream
.2#/Ream
.2#/Ream
.2#/Ream
TYPICAL PROPERTIESViscosity 50-100 cpsSolids 35%Tack Very lowDrying Absorption/evaporationTrap Wet on dryCure ImmediateVOC 65% by wtOdor LowCost OK
•FLEXO
•GRAVURE
Ink Formulation – Solvent Base
9
ADDITIVES (5%)
SOLVENT(30%)
ACRYLATE MONOMER
Wet Ink2#/Ream
Dry Ink
ACRYLATEPREPOLYMER (55%)
PIGMENT (10%)
.6#/Ream
1.1#/Ream
.2#/Ream
.1#/Ream
TYPICAL PROPERTIES
Viscosity 10-200 poiseSolids 97%Tack Moderate to very highDrying Free radical cureTrap Wet on Wet, or Wet on DryCure ImmediateVOC <3% Odor ModerateCost High
•FLEXO
• LITHO
ADDITIVES (5%)
Ink Formulation - UV
10
Viscosity 100-200 poiseSolids 90%Tack Very highDrying Absorption/ oxidationTrap Wet on WetCure OvernightVOC 10% Odor ModerateCost OK
PIGMENT (10%)
QUICKSET RESIN 75%
DRIERS/WAX 5%
DISTILLATE 10%
.2#/Ream
1.5#/Ream
.1#/Ream
.2#/Ream
Dry Ink1.8#Ream
• LITHO
Ink Formulation – Oil Ink
12
steel blanket cylinder
substrate
ink
High viscosity ink and planographic image carrier1. Low dot gain2. Uneven solid areas (limited impression)3. Weak metallic inks (limited ink film)
Litho Inks – Oil Base or UV
13
steel plate cylinder
substrate
plate ink
Low visc ink and raised, resilient image carrier1. Dot gain very impression dependent2. Smooth solid areas, even on rough stock 3. Strong metallic inks
Flexo Inks: Solvent, Water, UV
14
Low viscosity ink and recessed cells image carrier1. Low dot gain2. Uneven solid areas (limited impression)3. Very sensitive to rough stock (skip outs)
steel base
substrate
ink
Roto Inks: Solvent or Water Base
15
ENGRAVED CYLINDER
IMPRESSION ROLL
ROTO
PLATE
CYLINDER
ENCLOSED INK
CHAMBER
ANILOX
CI DRUM
FLEXO
* less make-ready* less speed sensitivity* less impression sensitivity* variable ink film (better fidelity)* consistent long runs
* lower cost (plates)* quicker response* growing industry focus
Comparing Roto and Flexo
16
WEBFLEXO
PLATE
IMPRESSION ROLL
ENCLOSED INK
CHAMBER
ANILOX
WEBBLANKETCYLINDER
PLATECYLINDERDAMPING
TRAIN
INK TRAIN
IMPRESSIONCYLINDER
LITHO
Comparing Roto and Flexo
18
THEORY OF LITHOGRAPHY
NON IMAGE AREA IS WATERLOVING (HYDROPHYLLIC)
IMAGE AREA IS WATERREPELLANT (HYDROPHOBIC)
LITHOGRAPHIC PLATE
19
LITHOGRAPHIC PRINCIPLE
LITHOGRAPHIC PLATE
ImageNon-image
Image
Water rejecting Water rejecting
Water receptiveHydrophobic Hydrophobic
Hydrophylic
Ink receptiveInk receptive
Ink rejectingOleophylic
Oleophylic
Oleophobic
23
OFFSET LITHO PRESS CONFIGURATION
BlanketCylinder
Plate Cylinder
DampeningRollers
Fountain Solution
ImpressionRoller
Sheet orWeb
Ink Distribution Rollers(oscillating)
OFFSET PROOFING
Blanket roller picks up ink from plate Transfers it to substrate
Plate Substrate
Plate is inked up by a hand roller
Difficult to accurately control ink film thicknessfrom hand roller to plate. This will cause somevariation when transfering to substrate.
PRUFBAU INKING MECHANISM
Distribution roller Blanket roller
Blanket roller
Back roller oscillating to distribute ink evenly
32
CONVENTIONAL (DUCTOR) DAMPENING SYSTEM
Fountain roll
Ductor
VibratorForm roll
Form roll
Platecylinder
Fountain solution
33
CONTINUOUS-FEED (DALHLGREN) DAMPENING SYSTEM
Platecylinder
Fountain solution
Metering roll
Chrome transfer roll
Slip nip
Oscillator roll
First ink form roll
Second ink form roll
34
BRUSH DAMPENING SYSTEM
Fountain solution
Meteringroll
Brush roll
Chrome vibrator roll
Ink form rollers
Platecylinder
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