High Speed Ink Liquid Interface Dynamics in Ultra Light Coated Virgin Hardwood Graphic Papers
Ultra-light coated virgin hardwood papers demand sub-50nm coat pore radii to balance high-speed inkjet solvent absorption against hardwood fiber swelling.
Mercurial Intrusion Porosimetry
Structural Measurement
Physical characterization techniques quantify the pore size distribution and total void volume within a solid substrate using high-pressure liquid displacement. Mercurial intrusion porosimetry measures these internal spaces by forcing a non-wetting liquid into the gaps of a paper or board sample. The pressure required to fill a pore is inversely proportional to its diameter.
Operational Physics
The sample is placed in a sealed chamber and submerged in liquid mercury. As pressure increases, the liquid enters smaller and smaller openings. Instruments record the volume of liquid absorbed at each pressure increment to calculate the exact dimensions of the voids.
This process continues until even the narrowest channels between fibers are filled. The resulting curve shows where the majority of the air space resides within the structure.
Ink Interaction
Understanding the void structure helps in predicting how liquids like inks and coatings will penetrate the surface. A sheet with a high volume of small pores will draw in ink through capillary action faster than one with few large gaps. This data is vital for optimizing the drying times and sharpness of printed images.
The technique is limited by the compressibility of the paper fibers, which can distort the measurements at extremely high pressures.