Dispersants help inks: opening a new chapter in color and printing performance
Dispersants help inks: opening a new chapter in color and printing performance
I. Mechanism of action of dispersants
Dispersants mainly play a role in dispersing, stabilizing, wetting and solubilizing in inks. Their core function is to reduce the surface tension between pigment particles and prevent pigment agglomeration, thereby achieving uniform dispersion. Specific mechanisms of action include:
Electrostatic stabilization mechanism: Dispersant molecules adsorb on the surface of pigment particles to form a charged double-layer structure, which prevents particle aggregation through charge repulsion.
Steric hindrance mechanism: The long chain structure of the dispersant forms a spatial barrier on the surface of the pigment, hindering direct contact between particles.
Solvation: Dispersants interact with solvent molecules to enhance the wettability of the solvent to the pigment and promote the dispersion of the pigment in the medium.
II. Specific application of dispersants in inks
Pigment dispersion and stabilization
Improving dispersion efficiency: By optimizing the molecular structure of the dispersant (such as introducing anchoring groups and solvation chains), the dispersion speed and uniformity of the pigment in the binder can be significantly improved.
Preventing sedimentation and flocculation: During storage and use, dispersants can effectively inhibit the sedimentation and reaggregation of pigment particles, ensuring the long-term stability of the ink system.
Ink performance regulation
Viscosity regulation: The amount of dispersant added can affect the rheological properties of the ink, and the appropriate printing viscosity can be obtained by controlling the amount of dispersant.
Gloss optimization: Evenly dispersed pigment particles can form a flat ink surface and improve the gloss of printed products.
Transparency improvement: In transparent inks, dispersants can reduce the scattering of light by pigment particles and enhance the transparency of inks.
Printing adaptability improvement
Enhanced fluidity: Dispersants can reduce the yield value and thixotropy of inks and improve the transfer performance of inks on printing equipment.
Drying performance regulation: By selecting dispersants of different polarities, the drying speed of the ink can be adjusted to adapt to different printing speeds and substrate requirements.
3. The influence of dispersants on ink performance
Positive impact
Improved coloring power: Evenly dispersed pigment particles can give full play to their coloring ability and reduce the amount of pigment used.
Enhance weather resistance: A stable dispersion system can prevent pigment particles from aggregating or changing color under conditions such as light and heat.
Improve printing quality: Uniform pigment dispersion can reduce defects such as spots and color differences in printed products.
Potential negative effects
Increased viscosity: Excessive dispersant may cause the viscosity of the ink to increase, affecting printing adaptability.
Reduced water resistance: Some dispersants may introduce hydrophilic groups, reducing the water resistance of the ink.
Migration and blooming: Under certain conditions, the dispersant may migrate from the ink to the surface, causing blooming.
IV. Principles of dispersant selection
Pigment matching
Different pigments (such as organic pigments and inorganic pigments) have different surface properties, and dispersants with corresponding anchoring groups need to be selected.
Binder compatibility
The dispersant should have good compatibility with the ink's binder (such as resin, solvent) to avoid phase separation.
Application performance requirements
According to the printing method (such as offset printing, gravure printing, flexographic printing) and the type of substrate (such as paper, plastic), select a dispersant with appropriate dispersibility and printing adaptability.
Environmental protection and regulations
Preferably select dispersants that meet environmental standards (such as low VOC, APEO-free) to meet relevant regulatory requirements.
V. Challenges and solutions in dispersant applications
Dispersion stability issues
Challenges: Pigment particles may reaggregate during storage or use.
Solutions: Use dispersants with multiple stabilization mechanisms, or combine physical dispersion methods (such as grinding, ultrasonic treatment).
Dispersant migration
Challenges: Dispersants may migrate to the surface of the ink, affecting the printing quality.
Solutions: Select dispersants with larger molecular weight and lower mobility, or fix dispersants through cross-linking reactions.
Interaction between dispersants and resins
Challenges: Dispersants may chemically react with ink resins, affecting ink performance.
Solutions: Perform compatibility tests and select dispersants that have no adverse interactions with resins.
VI. Development trends of dispersants
Green and environmental protection
Develop low-VOC, APEO-free, biodegradable dispersants to meet environmental regulations.
High performance
Develop dispersants with ultra-high dispersion efficiency and multifunctionality (such as integrated dispersion and thickening).
Intelligence
Develop responsive dispersants that can automatically adjust dispersion performance according to environmental conditions (such as temperature and pH value).
Application of nanotechnology
Use nanodispersants to achieve nanoscale dispersion of pigment particles and further improve ink performance.
VII. Conclusion
Dispersants play a vital role in inks. By optimizing pigment dispersion, regulating ink performance and improving printing adaptability, they significantly improve the quality and application effect of inks. With the increasingly stringent environmental regulations and the continuous development of printing technology, the research and application of dispersants will continue to progress in the direction of green environmental protection, high performance and intelligence.