Tissue and Towel Adhesives Adhesives are a critical component of any paper towel or bath tissue manufacturing operation. Water-based adhesives designed for paper towel and bath tissue manufacturing are used for core winding, ply bonding, core start up, and tail-tie applications. These adhesives are unique in that they need to have excellent tack when wet to increase efficiency but dry to a tack free film to prevent the roll from having a sticky or dirty effect. In addition, the adhesives used for tissue and towel manufacture need to be easily separated from the pulp fibers during recycling. These factors play a crucial role in the adhesive formulators choice of resin for water-based tissue and towel adhesives.
POLYOX™ Water Soluble Resins POLYOX™ Water Soluble Resins are large molecular weight poly ethylene oxide polymers that are ideally suited for use in water-based tissue and towel adhesives. Aqueous solutions of POLYOX™ have a high degree of wet tack and dry to form tack free residues that leave tissue and towel rolls feeling soft and clean. In addition, dried POLYOX™ films remain water soluble and are easily dissolved in the process water during paper recycling. This leads to paper towels and bath tissue that is much easier to recycle. Common grades of POLYOX™ used for tissue and toweling adhesives are listed below.
POLYOX™ for Tissue and Towel Adhesives
Achieving Proper Dissolution of POLYOX™ Although POLYOX™ resins are fully water soluble, care should be taken to make sure they are dissolved completely. The key to dissolution is good initial dispersion. If POLYOX™ resins are not properly dispersed prior to wetting the particles will agglomerate and form gels that will not dissolve. High shear mixing must be avoided to prevent POLYOX™ from being degraded. There are three recommended techniques for good dispersion and dissolution.
Direct addition of POLYOX™ resins is recommended for small, lab scale and less than drum quantities. This method depends mainly on the rate at which the POLYOX™ is added to the water. If it is added to slow, the viscosity of the solution builds too rapidly and if it is added to fast the particles will clump and not dissolve. Using a stirring mechanism that creates a large vortex with only a moderate amount of shear is recommended and makes direct addition to water much easier.
Direct Addition to Water
POLYOX™ is insoluble in water that is near it's boiling point. This inverse solubility allows for another method of dispersion and dissolution. To use the hot water method all of the water necessary for the solution should be heated to near boiling (97°C). A vortex should be created by mixing the water at 500- 600 rpm. The POLYOX™ is then added and allowed to disperse in the hot water. After about one minute, the stir rate should be reduced to 50-60 rpm and the heat source removed until the solution cools and the POLYOX™ is dissolved. This method is recommended for small to medium size batch production.
Hot Water Method
POLYOX™ is insoluble in alcohols and glycols and can be easily dispersed in this medium prior to hydration with water. One of the most reliable methods for large scale batch production is to add the non-solvent (alcohol or glycol) to a stirred vessel. The POLYOX™ is then dispersed in the non-solvent followed by the addition of the requisite amount of water. Stirring is then continued until a homogeneous solution is achieved.
Dispersion in Water-Miscible Non-Solvents