Ink "kitchen" & Color Management:
- INK Maker GT18
- control and measuring equipment - spectrodensitometer
- colour quality
- INK formulation – archive of ink recipes
Composition of solvent-based inks:
- solvent-based printing ink for flexographic printing and rotogravure technology is a mixture of pigments (or dyes) which ensure the required color, binders which mixed with pigments create an ink with the required resistance properties, solvents which ensure the suitable viscosity and affect properties of drying of inks, as well as additives.
- pigments – add color and decide about lightfastness, resistance to chemical and organic substances
- binders – resins which ensure performance characteristics of inks, i.e. their usefulness for e.g. external or inter-layer printing. They moisten pigments and add shine. Applied types of binders: NC; PU; PVB.
- solvents - dissolve resins, affect the ink drying rate, affect ink viscosity. Their disadvantage is that they can aggressively affect printing plates.
- waxes - improving the abrasion and scratch resistance, impact the degree of sliding;
- adhesion promoters;
- plasticizers – impact flexibility of ink coating;
- defoamers - prevent foaming of inks.
Composition of flexographic UV inks:
Initially, UV inks – binders and photoinitiators – are liquid. As a result of UV radiation, photoinitiators create free radicals which affect the binder. Polymerization takes place as a consequence of which a permanent non-sticky layer of ink appears.
Advantages of UV ink systems:
- No solvents - no emissions, no pollution
- 100% preservation - high speed of printing, possible fast processing
- inks do not dry on the printing elements of printing plates – “clean” print of fine lines and “lights” of raster elements
- non-absorbent surfaces can be easily printed on
- no head appears on the ink cup
- high quality of print, great chemical resistance
- no need to apply a retardant, thinner or viscosity control when printing a certain volume
- changes of ink tones during printing of a certain volume are minimum
- a greater scope of reproduction of the tone value and higher print ruling
- inks remain “fresh” in ink cups and it is not necessary to wash ink and printing units every day
- leftover ink from the machine is a fully valuable product
- lower ink consumption and smaller storage surface area
- UV ink system in combination with the CTP system makes Flexo UV competitive concerning production quality and costs in comparison to gravure (smaller and average volumes)
Disadvantages of UV ink systems:
- it is necessary to use inks with low migration to direct food packaging
- in the case of food packaging, only surfaces with a higher barrier can be printed on, which has a layer of polyester or aluminum
Cold seal is a special adhesive based on natural latex rubber. A dried layer of cold seal adhesive has such properties that it does not adhere to itself affected by a specific pressure force.
- used to pack heat sensitive products in the case of which heat sealing could be problematic (melting of the packaged product), e.g. chocolate, ice-cream, chocolate wafers. Application allows packaging at a high speed.
Examples: Chocolate bars and wafers, chocolate ice cream.
Cold seal packaging can be also manufactured as laminates – the top film has a special anti-adhesive layer which prevents the cold seal from adhering.