Selvol and Water: A Love-Hate Relationship
Because Selvol polyvinyl alcohol is a water-soluble polymer, it is sometimes perceived as having little or no water resistance. However, Selvol polymers can provide both water retention or water resistance depending on the grade selected. Our polymer range includes both hydrophilic and hydrophobic polyvinyl alcohol.
As a hydrophilic polymer, Selvol exhibits excellent water retention properties. Low viscosity grades like Selvol 103, 107, 502, 203 and 205 are preferred for these types of applications since they provide optimum coating rheology. The figure below compares Selvol Polyvinyl Alcohol 203 with other hydrocolloids using the dynamic ABO AKADEMI methodology. As you can see, Selvol performed very well in this comparison. In addition, Selvol provides much higher binder strength and the ability to boost optical brightener performance.
On the other hand, proper Selvol grade selection and the use of crosslinkers opens up an entire range of insolubilities. The water resistance of a specific grade of Selvol Polyvinyl Alcohol is primarily determined by its hydrolysis. Super hydrolyzed grades like Selvol Polyvinyl Alcohols 125 and 165 yield maximum water resistance as seen in the figure below.
Surface applications of polyvinyl alcohol and alkyl ketene dimer (AKD) blends demonstrate outstanding improvements in Cobb and Hercules Sizing (HST) values on both acid and alkaline papers, with little or no loss in size values upon aging. Unlike starch, a surface application of polyvinyl alcohol does not degrade the internal sizing effect of a wet end additive like AKD or ASA.
Selvol hydrophobicity is further exhibited by its excellent resistance to oils, greases, waxes and solvents. It can be used alone or with starch to meet Vanceometer, Turpentine, K&N ink holdout and other specifications. Selvol is also a very effective carrier for fluorochemicals. Blends of Selvol polyvinyl alcohol and fluorochemicals achieve high 3M Kit Ratings at a much lower cost than with the use of a fluorochemical by itself.
Sekisui Specialty Chemical, producer of Selvol, manufactures the largest range of polyvinyl alcohol polymers and copolyers worldwide, serving a variety of industries and applications. For more information on Selvol in paper and paperboard applications, please see our brochure.
To find out which grade will best enhance your products or processes, contact a Selvol paper specialist at our Houston Technology Center.
Or request a sample today!