A cost-effective retention system based on polyethylene oxide for pitch control and improved machine operating efficiency with DIP in furnish

Abstract

The practice of pitch dispersant without retention aid drastically increased resinous substance at the headbox. The paper made under such condition performed badly in pressrooms on Man Rowland Offset with common impression cylinder (CIC) configuration. The CIC roll was heavily covered with fibre fragment which contained 50-70% wood extractives. The polyethylene oxide (PEO) retention program was applied in combination with Enhancer A for pitch control. The paper quality in view of linting and sticky deposition on offset presses was remarkably improved. Several new enhancers were evaluated on the dynamic jar in order for further improvement of first pass retention. The machine trial on one selected enhancer proved to be very encouraging. However, the introduction of deinked pulp (DIP) later in 1995 complicated the papermaking chemistry due to the carryover of contaminants. The initial PEO retention program was suffered, resulting in the build-up of fibre fines and stickies in the recirculating white water. The sticky deposition on the forming wire and pressing felts contributed to crumbing problem and poor stock dewatering, and consequently resulting in wet end breaks. A new retention program based on bentonite/enhancer/PEO was commenced in June 1996. This is considered a breakthrough, giving a significant improvement in machine operating efficiency.