Paper Applications for Selvol Polyvinyl Alcohol
SEKISUI Specialty Chemicals offers a complete line of polyvinyl alcohol (PVOH) resins for paper applications. Our manufacturing facilities in Calvert City, Kentucky; Pasadena, Texas; and Tarragona, Spain, employ advanced computer-controlled production technology to provide the highest-quality PVOH. All plants are ISO 9002 certified.
As part of our commitment to the paper industry, SEKISUI Specialty Chemicals maintains a fully staffed paper applications laboratory in Houston, Texas. We have equipped the lab with state-of-the-art analytical instruments to support applications and customers in the paper market.
Paper Machine Applications at the Wet End
Manufacturers use PVOH to control the deposition of stickies associated with the use of secondary fiber. PVOH encapsulates the stickies and forms a multilayer shield that effectively covers the surface, rendering it nontacky. U.S. Patent 4,886,575 (assigned to Betz Laboratories, Inc.) may cover this technology’s features.
PVOH may also be effective in controlling pitch deposition in Kraft, acid sulfite and ground wood papermaking systems. U.S. Patent 4,871,424 (assigned to Betz Laboratories, Inc.) may cover this technology’s features.
* These applications may be subject to certain U.S. patents and equivalents issued in other countries. No license is granted with the purchase of Selvol™ Polyvinyl Alcohol. Please contact your SEKISUI Specialty Chemicals sales representative for additional information.
Paper Machine Applications at the Size Press
PVOH finds use at the size press as a clear size to grant surface strength and barrier properties. In this capacity, manufacturers often use it to upgrade the performance of starch. PVOH performs well at this because it’s much stronger and much more resistant to oils, greases, waxes and organic solvents than other surface sizing agents.
Pigmented Surface Sizing
Because of its superior strength, manufacturers can formulate PVOH at much lower levels than other binders. This optimizes the pigment system’s brightness and opacity effects.
Ink Jet Papers
PVOH is the preferred binder for ink jet size press coating formulations using silica pigments. Its superior binding strength controls the dusting that may occur with starch. PVOH is a hydrophilic polymer that acts alongside the silica pigment to quickly absorb the water-based ink into the coating layer, thus reducing wicking, mottling and bleeding.
Optical Brightener Carrier
Compared with starch, PVOH delivers 2.0-2.5 more UV brightness units, or conversely, lower levels of expensive fluorescent dye at equal brightness. This greater efficiency may allow the reduction or elimination of fluorescent dyes at the wet end.
Oil and Grease Resistance
PVOH exhibits excellent barrier properties to oils, greases, waxes and solvents. Manufacturers use it alone or with starch to meet Vanceometer, Turpentine, K&N ink holdout and other specifications. PVOH is also a very effective fluorochemical carrier. Fluorochemical-PVOH blends achieve high 3M Kit Ratings at a much lower cost than with fluorochemicals alone.
Surface applications of PVOH and alkyl ketene dimer (AKD) blends show outstanding improvements in Cobb and Hercules sizing (HST) values on both acid and alkaline papers, with little to no size value loss upon aging. Unlike starch, a PVOH surface application doesn’t degrade the internal sizing effect of a wet-end additive like AKD and ASA.
PVOH’s higher strength provides an effective means of achieving plybond adhesion on multiply paperboard.
Paper Machine Applications at the Coater
Because of its superior strength, coatings with PVOH can achieve a significant reduction in total binder level. This may create substantial cost savings while providing a significant improvement in brightness, gloss and opacity. Its water retention properties also allow manufacturers to formulate coatings with little to no hydrocolloid. Unlike some natural cobinders, PVOH doesn’t require a base like ammonia to be solubilized.
Ink Jet Dyes
PVOH is the ideal binder for ink jet coatings with silica pigments. Compared to typical latex binders, it provides superior binding strength and improved ink jet print quality. PVOH is a hydrophilic polymer. It acts alongside the silica pigment to quickly absorb the water-based ink into the coating layer, thus reducing wicking, mottling and bleeding.
Optical Brightener Carrier
Manufacturers recognize that PVOH is the best carrier for fluorescent dyes. The addition of 0.5-2.0 parts (dry) PVOH per 100 parts pigment can boost brightness by an additional 4-plus units. Such improvements are significant for high 80s/low 90s brightness papers. PVOH also provides superior binding strength and good water retention properties, which helps reduce latex and hydrocolloid levels.
Manufacturers can use Selvol™ Polyvinyl Alcohol 203S, a fine-grind version of Selvol™ Polyvinyl Alcohol 203 (99% of particles pass through an 80-mesh screen), as a noncook carrier by adding it directly to a pigment dispersion or a pigmented formulation while under high shear agitation for a minimum of 15 minutes.
U.S. Patent 5,057,570 (assigned to SEKISUI Specialty Chemicals) describes using Selvol Polyvinyl Alcohol 203S in coating color formulations as a “non-cook” product, as either a pigment binder or an optical brightener carrier.
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