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Q: Why is pigment dispersion such a common problem in UV inks?
Stable pigment dispersion is a common challenge in UV inkjet, screen printing, flexographic, and offset ink formulations. Poor pigment wetting can result in uneven color strength, reduced print definition, sedimentation, viscosity changes, and inconsistent film performance after curing.
The issue is not determined by the pigment alone. Resin chemistry, pigment surface characteristics, dispersants, monomers, additives, viscosity, and curing conditions can all influence how well pigment particles are wetted and stabilized.
Q: What role does UV resin play in pigment dispersion?
UV resin is an important component of the liquid phase and cured film. A resin with suitable pigment wettability can help the formulation wet and distribute pigment particles more effectively. At the same time, the resin needs to provide appropriate viscosity, curing response, adhesion, flexibility, and film formation.
This means pigment wetting should be evaluated as part of the complete UV ink formulation rather than as an isolated resin property.
Q: Which UV resins can be considered when pigment wetting is a priority?
Two Lencolo UV ink resin grades are specifically positioned around pigment wetting.
L-6121 is a low-viscosity UV polyester resin with good pigment wettability. It can be considered when an ink developer needs to improve pigment wetting while maintaining a relatively low-viscosity resin system for printing applications.
L-6211 is a low-viscosity, two-functional UV polyurethane resin that also provides good pigment wettability. Its polyurethane chemistry gives formulators another option when pigment dispersion needs to be considered together with flexibility and film toughness.
The two grades therefore provide different resin chemistries for comparative formulation work rather than representing a single universal solution.
Q: Is good pigment wetting enough to create a successful UV ink?
Not necessarily. A UV ink must satisfy several requirements simultaneously. After pigment dispersion, formulators may still need to optimize curing speed, flexibility, adhesion, viscosity, surface appearance, and substrate compatibility.
For example, L-6105 is a low-viscosity UV polyurethane resin positioned for high elasticity. It can be considered when the cured ink needs greater flexibility. L-6111, a low-viscosity UV epoxy acrylate resin, is positioned for fast curing and may be relevant to high-speed printing where rapid film formation is important.
Q: How does the substrate affect resin selection?
Substrate compatibility can be just as important as pigment wetting. UV inks may be applied to glass, metal, plastic, PET films, paper, and other substrates, and each can impose different adhesion and flexibility requirements.
For glass and hardware applications, L-8400A/8400B are UV resin options associated with adhesion to these substrates. L-6030/6040, based on UV pure acrylic resin, can be considered where adhesion is an important requirement in UV ink formulations. For PET and flexible film applications, L-8412A is a UV polyurethane resin positioned for high flexibility on PET.
Q: Can changing the resin alone solve pigment dispersion problems?
It may help, but changing the resin is not always sufficient. Pigment type, pigment concentration, surface treatment, dispersant selection, resin-pigment compatibility, monomer selection, viscosity, dispersion equipment, and processing conditions can all affect the final dispersion stability.
For this reason, L-6121 and L-6211 should be treated as candidate materials for formulation testing rather than guaranteed solutions for every pigment system.
Q: What is a practical way to develop a UV ink with better pigment dispersion?
A useful approach is to define the pigment, substrate, printing process, target viscosity, curing system, and required mechanical properties first. Several resin candidates can then be compared under controlled formulation conditions.
For example, L-6121 and L-6211 can be evaluated for pigment wetting and dispersion stability, while L-6105, L-6111, L-8400A/8400B, L-6030/6040, or L-8412A can be considered according to flexibility, curing speed, or substrate requirements.
The main principle is to treat pigment wetting, resin compatibility, viscosity, curing, and substrate adhesion as connected variables. This system-level approach can provide a more reliable route to developing stable UV inks for inkjet, screen printing, flexographic, and offset applications.
https://www.lencolo37.com/
Guangdong Lencolo New Material Co., Ltd.
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