Have you ever put together your own entertainment console or coffee table, gluing those little wooden pegs into pre-drilled holes? Or even built your own chairs or tables from scratch? You were probably using a wood glue that featured Selvol Polyvinyl Alcohol (PVOH) as a key ingredient.
High performance Selvol is used as a steric stabilizer for PVAc and VAE wood adhesives during the emulsion polymerization process. It is used in US wood adhesives types I, II, III and European types D1, D2, and D3. I can also be used as a formulation additive to impart additional adhesive strength. Partially hydrolyzed grades are recommended for penetration into the wood and development of fiber tear. Selvol PVOH imparts strength and heat resistance to the bond. Lower molecular-weight partially hydrolyzed Selvol penetrates the wood pores and dramatically boosts fiber tear, while higher molecular-weight allows the adhesive to sit on the surface of the wood improving adhesive holdout. A proper balance of penetration and holdout serves to distribute the strain over a wider area of the glue line that develops fiber tear. Selvol may be borated to enhance wet tack, water resistance and adhesion strength.
Partially hydrolyzed Selvol PVOH is used to boost the performance of wood assembly glues, usually in combination with a base emulsion, starch and clay. Selvol will bring strength, heat resistance and fiber tear to the formulation. The addition of partially hydrolyzed PVOH to polyvinyl acetate wood glues (white glues) permits the adhesive to wet the wood and penetrate the pores, thereby increasing the adhesion strength of these adhesives. Low molecular-weight grades, such as Selvol PVOH 205/E 205 will allow greater polyvinyl alcohol incorporation into the adhesive, while a grade such as Selvol 540 will allow high viscosity at lower polyvinyl alcohol levels. The Selvol may need to be borated to achieve the required level of wet tack and set speed.
Sekisui Specialty Chemical, producer of Selvol, manufactures the largest range of polyvinyl alcohol polymers and copolyers worldwide, serving a variety of industries and applications. To learn more about Selvol for wood adhesives or other adhesives and emulsions formulations, please view the respective brochures.