The ups and downs of specialty chemicals: tracking trends in the wet end.

What's hot and what's not? That is always the question. A recent Solutions! article concerning wet end chemicals made the point that chemicals can be specialty or commodity. Regardless of this designation, every chemical is special to someone depending on its use and performance. This article identifies some specialty chemicals whose use is increasing and some whose use is decreasing with an explanation for the trend. Any discussion of this type has a risk that some people will agree and others will disagree about the comments on the chemicals mentioned. Readers should therefore approach this article with the intention of gaining information rather than arguing that a particular viewpoint is correct.

Some chemicals whose use seems to be increasing include deaerators, high charge starches, ASA size, coagulants, and microparticulates. Use of defoamers, AKD size, rosin, and high molecular weight retention aids appears to be declining.

DEAERATORS AND DEFOAMERS

Deaerators prevent accumulation of entrained air while defoamers treat an entrained air problem that already exists. The former is preventive. The latter fights a fire. Entrained air traps dirt. It leads to deposits, interferes with efficient chemical adsorption, causes pinholes, and results in poor formation and porosity. The deaeration technology to prevent these potential upsets has wide use in Europe but is less common in the United States. On-line measurement systems are useful to close loop control using deaeration or defoamer chemicals. Since an ounce of prevention is usually worth more than a pound of cure, deaerator use will continue to increase while defoamer use will decline.

HIGH CHARGE STARCHES

As wet end systems have closed up and furnishes have become more contaminated with anionic charge, a need has developed to neutralize the negative charge while maintaining the effectiveness of a chemical being used. Starch suppliers have developed technologies that incorporate significantly higher cationic charge with the starch. This approach overcomes the furnish and soluble charge in a way that permits full adsorption of the starch and imparts its strength enhancement or internal size retention. This technology will continue to gain importance especially as systems close up and furnishes become more contaminated

ASA AND AKD/ROSIN SIZE

Alkaline papermaking has generally supplanted acid papermaking as a primary process technology. ASA and AKD internal sizes have therefore increased in use at the expense of rosin sizes. ASA use is growing faster than AKD use. ASA imparts better on-machine size compared with AKD. Technology today allows it to run deposit free. In addition, it does not negatively affect sheet coefficient of friction. As furnishes become more contaminated, the higher sizing efficiency of ASA is also preferential over using increasingly more AKD to achieve the same result.

COAGULANTS

Use of coagulants or low molecular weight, high charge density polymers is increasing. In the 1970s and 1980s, the coated paper segment discovered that these polymers were very effective in neutralizing coated broke charge and tying up latex that could lead to white pitch. Over the last 20 to 30 years, this concept has extended to all forms of paper where a high charge demand requires neutralization, where contaminants require attention, or both. As suppliers develop increasingly more specific polymers that work for specific customer needs, this technology will continue to grow well into the future.

MICROPARTICULATES AND HIGH MOLECULAR WEIGHT RETENTION AIDS

Microparticulate technology will continue to replace high molecular weight retention polymers as the retention package of choice. The high weight polymers can over-flocculate the fiber and lead to poor formation and porosity. The microparticulates are generally better for the entire package of retention, drainage, and formation. Suppliers are developing new microparticulates as the customer base expands. For these reasons, older retention packages will continue to decline.

The picture presented here is only a brief snapshot. Processes are changing. Technology that is current today may be passe tomorrow. Our journey continues.

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