- This topic is empty.
-
Posts
-
Q: Why does my UV ink have unstable color, viscosity, or sedimentation even after adding a dispersing agent?
A: Pigment dispersion in UV ink is rarely determined by the dispersing agent alone. Poor pigment wetting, insufficient particle breakdown, excessive pigment loading, unsuitable resin viscosity, incompatible monomers, or inadequate stabilization can all contribute to agglomeration and sedimentation.
The first step is to identify where the problem actually occurs. Is the pigment difficult to wet? Is the dispersion process insufficient? Does viscosity increase during storage? Or does the problem appear only after adding other formulation components? This helps avoid simply increasing dispersant dosage without addressing the underlying cause.
Q: Does the type of pigment affect resin selection?
A: Definitely. Organic pigments, inorganic pigments, carbon black, and specialty powders have different surface characteristics, particle sizes, and oil absorption. As a result, they can behave very differently in the same UV ink formulation.
The resin needs to provide suitable interaction with the pigment while also meeting the requirements of the printing process and cured film. A resin with good pigment wettability can help achieve more uniform color development, but dispersion stability still depends on the complete formulation.
Q: Which UV resins can be considered when pigment wettability is important?
A: Lencolo L-6121 is a low-viscosity UV polyester resin positioned for good pigment wettability and can be considered for UV ink formulations where pigment distribution and manageable viscosity are important.
Another option is Lencolo L-6211, a low-viscosity, two-functional UV polyurethane resin also positioned for good pigment wettability. Its polyurethane chemistry provides an alternative when flexibility, toughness, and substrate compatibility also need to be considered.
The choice between polyester and polyurethane should be based on the overall formulation target rather than pigment wetting alone.
Q: Does using a low-viscosity resin automatically improve pigment dispersion?
A: Not necessarily. Lower viscosity may help processing, but pigment concentration, resin structure, monomer compatibility, dispersant dosage, and grinding conditions also affect dispersion.
For example, Lencolo L-6105 is a low-viscosity UV polyurethane resin positioned for high elasticity, while Lencolo L-6111 is a low-viscosity UV epoxy acrylic resin positioned for fast curing. These materials address different formulation requirements and should not be treated as universal dispersion solutions.
Q: When should I add a dedicated dispersing or wetting additive?
A: If the resin alone cannot provide sufficient pigment wetting or stabilization, a dedicated additive may be necessary, particularly with difficult pigments or high pigment loading.
Lencolo 1108 and Lencolo 1109 are positioned as wetting dispersants for matte powder. Their actual suitability depends on the powder, resin system, concentration, and dosage, so laboratory screening is recommended rather than assuming that a higher dosage will always produce better dispersion.
Q: Can good pigment dispersion still result in poor printing performance?
A: Yes. Dispersion is only one part of UV ink performance. The ink also needs suitable adhesion, flexibility, rheology, curing, and substrate compatibility.
For glass and hardware applications, Lencolo L-8400A/8400B is positioned for good adhesion. L-6030/6040 UV pure acrylic resins can also be considered when adhesion is important. For flexible PET substrates, Lencolo L-8412A is positioned for high flexibility.
These requirements should be evaluated together with pigment dispersion rather than separately.
Q: How should I test a new UV ink dispersion system?
A: A useful test should cover the entire process, from dispersion to storage and final curing. Check viscosity before and after dispersion, color strength, gloss, transparency, sedimentation, agglomeration, foam, adhesion, flexibility, and curing performance.
The printing method also matters. Inkjet formulations require particular attention to viscosity and jetting stability, while screen, flexographic, and offset inks may place greater emphasis on rheology, transfer, print definition, and film formation.
Q: What is the main principle for improving pigment dispersion in UV inks?
A: Treat dispersion as a formulation compatibility problem, not simply an additive-selection problem. Pigment characteristics, UV resin chemistry, monomers, dispersants, viscosity, grinding conditions, substrate, printing process, and curing conditions all interact.
Lencolo provides UV resin and functional additive options for different formulation requirements, but the final combination should always be confirmed through application-specific testing.
https://www.lencolo37.com/
Guangdong Lencolo New Material Co., Ltd.
- You must be logged in to reply to this topic.