Papermaking and Retention Aids

During the first steps of papermaking, pulp slurries are created, sent into a head box, and dispersed onto machine wires to begin the drying process and form a paper web. In this last step, approximately 60% of the water in the paper slurry must be removed, and retention aids play a significant role in determining paper quality and manufacturing efficiency. UCARFLOC™ is a line of high-viscosity polyethylene oxide retention aids developed for the papermaking industry that work at relatively low concentrations to provide the following benefits:
 

• Increased first-pass retention of pulp, fiber, and commonly used fillers like kaolin clay and TiO₂

• Creation of drainage effluent that is easier to filter and recycle

• Reduced energy consumption required for steam roller drying

• Better paper consistency and effective removal of pitch

These benefits stem from the fact that UCARFLOC™ retention aids are adept at flocculating fine particles in the pulp slurry. For more information on the mechanism in which polymers like UCARFLOC™ perform flocculation, check out this article.

How UCARFLOC™ Retention Aids Improve Modern Papermaking Processes

Generally, maximizing the retention of pulp, fines, and fillers is key to the initial papermaking process because it leads to increased paper web strength, prevents visual and physical defects, and creates process water that is easier to filter and reuse. In the past several years, paper mills have also adopted new trends that necessitate highly functional retention aids to offset challenges.
 

Papermaking Trend	Resulting Challenge	Functionality of UCARFLOC™	Benefit of UCARFLOC™
Higher cost of pulp and increased usage of fillers, recycled fiber, and high-yield pulp	More particulate must be retained from drainage	Flocculates high concentrations of fiber, fines, fillers, and pulp	Improves utilization of pulp, fillers, and fiber invested
Faster machine line speeds	Less time to retain particulate in drainage	Efficiently flocculates suspensions of paper particulate	Enables faster line speeds while maintaining paper quality
Increased water conservation by recycling effluent water	More pulp, fillers, fiber, and fines in recycled water	Highly effective at removing pulp, fiber, fillers, and fines from water	Reduces water costs and improves filtration processes

Below are data illustrating how well UCARFLOC™ increases first-pass retention of fillers like clay and titanium oxide. The paper furnishes used in this study contained 75% refined mechanical pulp and 25% semibleached kraft pulp. As a result of this increased retention, finished paper sheets had increased opacity and brightness, owing to the higher number of fines and TiO₂ retained. Other commonly used fillers, such as sodium aluminum silicate and calcined clay, have also been retained effectively using UCARFLOC™ retention aids and a combination of phenolic resin enhancers.
 

Effect of UCARFLOC™ on First-Pass Retention

Retention of Fillers using UCARFLOC™

Paper mills may also realize energy savings using UCARFLOC™ retention aids to efficiently eliminate water from the paper web upstream of drying using steam rollers. The following graph illustrates the direct result of UCARFLOC™ requiring less steam to dry paper fully later in the papermaking process.

UCARFLOC™ is also highly effective in removing pitch in drainage effluent. A study was made using wastewater samples from newsprint mills to determine the minimum concentration required to remove pitch. Using these samples, pitch was completely removed using a minuscule amount of UCARFLOC™ in a range between 5 and 10 ppm.

ppm UCARFLOC™	Pitch, sample A (g/L)	Pitch, sample B (g/L)
0 ppm (Untreated)	0.32	0.34
5 ppm	ND*	0.15
10 ppm	ND*	ND*
15 ppm	ND*	ND*

*ND = none detected (<0.02 g/L)

UCARFLOC™ Versus Other Retention Aids
Polyacrylamides (PAMs) or polyethylene imines (PEIs) are typically used as retention aids in papermaking. However, as these are cationic polymers, they face disadvantages when used to flocculate suspensions containing high concentrations of anionic particles. In comparison, UCARFLOC™ retention aids are nonionic polymers that remain effective in highly anionic suspensions and a wide variety of pH. Also, as mentioned previously, UCARFLOC™ is extremely effective at relatively low concentrations. The following chart compares the flocculating efficacy of UCARFLOC™ versus PAMs, demonstrating that UCARFLOC™ was better at retaining kaolin clay and reducing turbidity even at less than half the concentration of cationic PAM.

Summary

Rising costs of pulp have made it challenging for paper mills to stay cost-effective. Additionally, new trends tied to higher filler usage, faster operating speeds, and a water-reuse improvement introduce new complications to staying efficient. UCARFLOC™ polymers are perfectly designed to face these challenges by greatly increasing the retention of pulp, fillers, and fibers used in papermaking processes, allowing consistently manufactured higher-quality paper. As a result, drainage effluent is easier to recycle, and energy costs are reduced by requiring less steam to dry paper webs. UCARFLOC™ is more effective at providing these benefits at lower concentrations than other flocculants, such as polyacrylamides, thus also providing comparative cost savings. Click below to request a sample of UCARFLOC™ to start improving your papermaking process today.