Medical Printing Inks

Printing Inks and Ink Delivery System

Though the ink delivey system in regular Pad Printing can use open or closed ink containers, the rotational printing process uses only open ink containers. The selection of an open or closed ink container further affects which solvents and inks can be used. For example, there is more evaporation of solvent out of the ink in an open container. The ink reservoir is accompanied by a blade, called a “doctor blade”, which passes over the plate after ink application to squeegee it clear of excess ink.

Inks & Thinners for Pad Printing

Pad Printing ink formulations have two key properties: High Opacity and High Viscosity. An experienced print operator chooses the proper ink, including any needed:

• Solvents or Additives (based on air temperatures and humidity)
• Cycling speed of the press being used, and
• Specific materials and parameters unique to each project.

VISCOSITY OR TACK - The ink cannot transfer properly from plate to pad, and from pad to product, unless it is tacky enough to “stick” and transfer completely when the surfaces roll together. In order to keep the entire print process running at an efficient speed, ink tackiness must be achieved very quickly once the ink is applied to the plate.

SOLVENTS - Thinning solvents may be added to the printing inks in order to control the precise timing of the shift from fluid to viscous texture.

SURFACE HARDNESS - Hardeners can be added to the ink if the final product’s surface requires strong resistance to abrasion or solvent contact.

CURING - The natural curing time of ink on a finished productcan take a day or two at room temperature, or the product can be heated to cure more quickly.