Index
P
R
S
- scraper
- setoff
- shore hardness
- slip agent
- smearing
- snap-off
- squeegee
- squeegee angle
- squeegee stroke
- surface cure
- swelling
T
Glossary - P
press stability
Press stability means how stable the properties of the ink, especially viscosity, are maintained on the screen. The change of the density, the increase of the viscosity, clogging : these are the problems that should be avoided in the printing process. UV curable ink, which contains no solvent, is excellent in press stability, although smearing may happen in some cases.
printability
The properties which the ink should have in order to give the required finish. That includes the proper viscosity and thixotropy, the right properties of the dried ink film, right finish( glossy or matt) and right colors.
Glossary - R
Glossary - S
setoff
The phenomenon that happens when the printed matters are piled up: the ink of the lower material soils the back of the material that is piled on top of it.
shore hardness
This means the hardness of the rocks. It is also used to show the hardness of the squeegee rubber.
slip agent
The agent to improve abrasion resistance by adding slipping properties to the ink film. Slip agent is normally polyethylene wax or other kinds of wax. As the ink that contains slip agent is resistant to nail scratch, the superficial adhesion becomes good.
smearing
The problem that the ink on the back side (the side to be printed) of the screen protrudes beyond the image and smears the screen. That makes the image bold and may even destroy the image. This tends to happen to UV curable ink which is still wet on the screen.
snap-off
The phenomenon that the stencil moves off from the substrate immediately after touching the substrate. The proper clearance is necessary for smooth snap-off.
squeegee
The tool to squeege out the ink through the mesh by moving and putting the pressure on the ink. The rubber plate is sandwitched in between the holders.
surface cure
Oxygen in the air reacts to the radical in UV ink , consumes it and spoils its activity. The density of the radical is low on the surface of the ink due to this reaction, which slows polymerization. This causes insufficient curing which may lead to tack-lingering. However, this problem has been improved in current UV ink by better photo-polymerization resin and better photo-initiator.
Glossary - T
tack-regaining
The tackiness that appears on the surface of the printed ink after the ink is dried or cured. Tack-regaining causes blocking and often happens to UV ink. Anti-slip ink turns this "tack-regaining" to good account.
thick film screen
The screen on which photo-sensitive emulsion is coated thickly. This is normally around 100 meshes per inch with emulsion of 0.03-1mm(30-1000micrometer) thickness. This kind of screen makes the thick ink film.
thixotropy
The characteristic that fluidity increases by stirring and returns to the original state by stopping stirring. The ink with good reproducibility has proper thixotropy.
