New Poly-Urea Capsules for Carbonless Copy Paper, 1999 Papermakers Conference Proceedings

Robert M. Trozenski

The use of carbonless copying paper provides significant advantages as compared to one-time carbon paper. Most business form sets are made out of carbonless copying paper. A multiple form set of a reactive carbonless copy paper consists of three different types of paper sheets: the coated back (CB), the coated front and back (CFB), and the coated front (CF). A unique carbonless copy paper known as self-contained (SC) is also produced. The annual production of carbonless copy paper in 1997 was approximately 2.7 million metric tons. The world market for carbonless paper consists of mature markets in Europe, United States, and Japan, which exhibit a slowly decreasing demand. Additionally, markets in Asia Pacific and South America exhibit high growth rates. BAYER has developed an interfacial polyaddition process for the production of microcapsules, which are necessary for the manufacturing of carbonless copy paper. Through ongoing research and development efforts, an improved process using tailor-made isocyanates and a new crosslinking system was introduced, producing microcapsules with thin poly-urea capsule walls. Traditionally, microcapsule walls were thicker and therefore required the use of considerably more raw materials. The thinner wall of the new process microcapsules exhibits excellent physical integrity and allows for a significant reduction in raw material use. Consistent production of custom-made, high quality microcapsules is achieved through the use of a proprietary, continuous emulsification system, followed by flexible curing (continuous or batch). The proprietary system produces microcapsule slurry at solids content greater than 50%. Also, a high capacity microcapsule production facility requires minimal space.