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Radiation Curing
Coatings and Printing Inks
Patrick Glöckner et al.
1 Introduction
1.1 Definition
1.2 Main differences compared to conventional coatings
1.3 Advantages and disadvantages
1.4 EB versus UV curing
1.5 Historical development
1.6 Market figures and main applications
2 Basics of radiation curing technology
2.1 UV curing technology
2.1.1 Free radical UV curing
2.1.1.1 UV exposure and initiation
2.1.1.2 Propagation – curing mechanism
2.1.1.3 Chain termination
2.1.1.4 Unique features
2.1.2 Cationic UV curing
2.1.2.1 Initiation – UV exposure
2.1.2.2 Propagation – curing mechanism
2.1.2.3 Unique features
2.1.3 UV curing by photolatent bases
2.2 Electron-beam technology (EB curing)
2.2.1 Principle
2.2.2 Unique features
2.2.3 Electron-beam for cationic curing
2.3 Summary and comparison of the different radiation curing technologies ...
3 Raw materials
3.1 Components of radiation curable coatings and printing inks
3.2 Photoinitiators and photosensitizers in UV curing
3.2.1 Generalities
3.2.2 Free radical photoinitiators
3.2.2.1 Type I photoinitiators
3.2.2.2 Type II photoinitiators
3.2.2.3 Photosensitizers
3.2.2.4 Visible UV curing
3.2.3 Cationic photoinitiators
3.2.4 Photoinitiators for clearcoats
3.2.5 Photoinitiators and photosensitizers for pigmented coatings
3.2.6 New developments
3.3 Monomers and oligomers
3.3.1 General structure-properties relationships
3.3.1.1 Functional groups and functionality
3.3.1.2 Influence of monomers and oligomers on the viscosity of
the formulation
3.3.1.3 Influence of monomers and oligomers on the reactivity
of the formulation
3.3.1.4 Influence of monomers and oligomers on the chemical and mechanical
properties of films
3.3.2 Oligomers for curing by free-radical polymerizationVincentz Network, Hannover, Germany – www.european-coatings.com – books@european-coatings.com
3.3.2.1 Epoxy acrylates
3.3.2.2 Urethane acrylates
3.3.2.3 Polyether acrylates
3.3.2.6 Acrylated oligoacrylates
3.3.2.7 Silicone acrylates
3.3.2.8 Self-initiating acrylate resins
3.3.2.9 Thiol-ene systems
3.3.2.10 Unsaturated polyesters
3.3.2.11 Saturated resins
3.3.3 Monomers for curing by free-radical polymerization
3.3.3.1 Monofunctional monomers
3.3.3.2 Difunctional monomers
3.3.3.3 Polyfunctional monomers
3.3.3.4 Inert solvents
3.3.4 Resins for curing by cationic polymerization
3.3.4.1 Epoxides
3.3.4.2 Vinyl ethers
3.3.4.3 Oxetanes
3.3.4.4 Polyols
3.3.4.5 Acrylates
3.4 Special radiation curable systems
3.4.1 Water-based radiation curable coatings
3.4.2 Radiation curable powder coatings
3.4.3 Dual cure technology
3.5 Additives
3.5.1 Pigment wetting and dispersing additives
3.5.2 Rheological additives
3.5.3 Substrate wetting additives
3.5.4 Defoamers and deaerators
3.5.5 Antioxidants and formulation stabilizers
3.5.6 Surface control additives: flow, leveling, slip, scratch resistance
3.5.6.1 Flow and leveling additives
3.5.7 Matting agents
3.5.8 Additives to improve adhesion
3.6 Colorants
3.6.1 General introduction
3.6.2 Organic pigments in UV curable coatings
3.6.3 White pigments in UV curable coatings
3.6.4 Black pigments in UV curable coatings
3.6.5 Effect pigments in UV curable coatings
3.6.6 Fillers
4 Radiation sources
4.1 UV radiation technology
4.1.1 Light sources
4.1.1.1 Mercury medium pressure lamps
4.1.1.2 Doped mercury medium pressure lamps
4.1.1.3 Mercury low pressure lamps
4.1.1.4 LED arrays
4.1.1.5 Plasma curing
4.1.2 UV curing equipment
4.1.2.1 Power systems of mercury lamps
4.1.2.2 Reflectors
4.1.2.3 Inertization
4.1.2.4 Equipment for curing on 3-dimensional substratesVincentz Network, Hannover, Germany – www.european-coatings.com – books@european-coatings.com
4.1.2.5 Security
5 Areas of application
5.1 Wood coatings
5.1.1 Conventional UV curing wood coatings based on acrylates or
unsaturated polyesters
5.1.2 Water-borne UV wood coatings
5.1.3 UV powder coatings
5.2 Overprint varnishes
5.3 Pigmented printing inks
5.3.1 Screen printing
5.3.2 Litho-offset
5.3.3 Flexographic printing
5.3.4 Letterpress
5.3.5 Industrial inkjet printing
5.4 Other industrial and automotive coatings
5.4.1 Automotive coatings
5.4.2 Coil coatings
5.5 Adhesives
5.6 Electronics and telecommunication
5.7 Others
5.7.1 Radiation curable silicone release coatings
5.7.2 Radiation curing scratch-resistant coatings
5.7.3 Radiation curing paints for professional painters
5.8 Outlook
6 Special test methods
6.1 Characterization of raw materials and uncured formulations
6.1.1 Chemical functionality
6.1.1.1 Acid number
6.1.1.2 Hydroxyl number (OH-number)
6.1.1.3 Iodine number
6.1.1.4 Epoxy value/epoxy equivalent weight
6.1.2 Rheological tests for coatings and printing inks
6.1.2.1 Theoretical principles
6.1.2.2 Testing of flow behaviour
6.2 Testing of the curing process and the cured film
6.2.1 Simple methods for testing cure
6.2.1.1 Fingernail scratch test
6.2.1.2 Thumb twist test
6.2.1.3 Powder test
6.2.1.4 Adhesive tape test for through-cure
6.2.1.5 Solvent test (MEK or acetone test)
6.2.2 Checking of cure by instrumental methods
6.2.2.1 UV/visible spectroscopy
6.2.2.2 Photo differential scanning calorimetry
6.2.2.3 Fourier transform infrared (FTIR) spectroscopy
6.2.2.4 NIR spectroscopy
6.2.2.5 Volume shrinkage
6.2.3 Determination of migratable componentsVincentz Network, Hannover, Germany – www.european-coatings.com – books@european-coatings.com
7 Environmental and occupational protection
8 Trouble shooting
8.1 Properties of the liquid coating/ink
8.2 Curing behaviour and mechanical properties of the cured coating/ink......
8.3 Appearance of the cured coating/ink
8.4 Sensorial properties of the cured coating/ink
Authors
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