Dispersible Nonwovens for Flushable Wipes
Mango identifies top dipersible nonwovens in the wipes market.
With the third generation of INDA/EDANA’s Guidance Document for Assessing the Flushability of Nonwoven Consumer Products scheduled for release in late 2012, a review of the nonwoven substrates best able to meet these guidelines is appropriate.
The three substrates best positioned today to meet these guidelines can all be described as dispersible products. They are:
• Kimberly-Clark’s ion triggered airlaid
• Suominen’s Hydraspun (spunlaced wetlaid base web)
• Buckeye’s Airspun (non triggered airlaid)
All three are currently commercial and demonstrate potential to meet all of the current INDA/EDANA requirements for flushability. Each has strengths, weaknesses and opportunities for improvement. These will be discussed briefly.
There are only a few wipes market segments that either require flushability or will benefit from flushability. These are:
• Adult moist toilet tissue
• Toddler toilet care wipes
• Feminine hygiene wipes
• Adult incontinence wipes
• Bath/bathing wipes
The largest wipes market today for flushable wipes is adult moist toilet tissue, which would not exist without flushability. Notably missing is baby wipes, which years of market research indicate are rarely used in a manner benefited by flushability (changing the baby is not frequently near a toilet; typically, the wipe is wrapped in the soiled diaper).
The first of the flushable nonwovens well positioned for wipes is Kimberly-Clark’s ion triggered latex bonded airlaid. This product uses an acrylic binder that forms ionic bonds in the presence of certain water-soluble ions, which can be added to the wipe’s lotion; these bonds are reversible, disappearing if the level of these ions falls below a certain level (as in excess water in a toilet). The reduction of ion concentration “triggers” a significant reduction in wet strength, allowing the shear from normal “flushing” to cause the nonwoven to disintegrate or disperse. Early versions had issues with “hard” water; naturally occurring ions in the water kept the ionic bonds in place and prevented the product from dispersing. Current versions have eliminated this issue.
Kimberly-Clark is the market leader in North America with this ion triggered latex bonded airlaid. This nonwoven has the highest “in use” wet strength of any commercial dispersible nonwoven, with strengths equivalent to conventional nonwovens used in wipes. This provides potential use in future markets where flushability or even repulpability may be of use. Its negative attributes include the fact that it is only available to Kimberly-Clark; the cost of the binder is significantly higher than standard nonwoven binders; it is produced at only one site globally; and while dispersible, it is slower to disperse than other dispersible products on the market.
The second largest dispersible nonwoven by market share is Suominen’s Hydraspun. This product is composed of about 78% wood pulp, 20% Tencel and 2% bicomponent fiber, formed as a wetlaid web and then hydroentangled. The Tencel fiber is cut to a shorter length than is usual for spunlace fibers; this allows some entangling to provide wet strength without these entanglements becoming irreversible. The small amount of bonding fiber boosts wet strenth enough for use, but since so few of these fibers are used, they form very small, and relatively loosely bonded agglomerates of fibers. This combination of relatively short fiber hydrentangling, coupled with very low-level thermal bonding, provides enough in use strength for current flushable wipes with enough dispersibility for most waste treatment systems.
Suominen’s nonwoven is used currently by Procter & Gamble and Rockline in North America for adult moist toilet tissue, and is also used by Kimberly-Clark in Europe. Advantages include cost, limited exclusivity and multiple production sites (US and Sweden—the latter is the reason for Kimberly-Clark using this product in Europe, where importing its own airlaid from the US was just too expensive). The product also disperses quickly; but its wet strength in use is much lower than that of the ion triggered airlaid product from Kimberly-Clark. This product is acceptable for current flushable wipe products, but appears limited if markets requiring more strength develop.
Finally, in April 2011, Buckeye Technologies announced it had developed a new airlaid product called AIRspun Flushable, which according to the company’s CEO John Crowe, “was designed to meet the performance criteria of our customers including the flushability guidelines set forth by the nonwovens industries associations in North America and Europe.”
AIRspun Flushable is currently used in adult moist toilet tissue wipes converted by Nice-Pak Industries for Costco, as well as an adult incontinence wipe for CVS. While this product is essentially a latex bonded airlaid, it avoids infringing on Kimberly-Clark patents by not being “triggered.” The binder used, from Wacker, has limited water solubility. The wipe also contains some longer fibers to add strength; in its lotion, there is not enough water (1-3 times the wipe’s dry weight) to solubilize enough binder to reduce the strength in use signifcantly, but in a toilet with excess water (several thousand times the wipe’s dry weight) the binder solubilizes and the wipe disperses.
This type of product has the problem of dispersibility being inversely proportional to strength in use; if you make it stronger, it becomes less dispersible. It also needs some long fibers to boost in use strength; too many and it will fail some of the requirements of the INDA/EDANA Guidelines. On the positive side, the binder has broader availability than Kimberly-Clarks’. This product is relatively new and needs some fine tuning, but should be functional for the current flushable wipes markets. Its potential for other, higher strength requiring wipe markets is uncertain today.
In summary, today there are at least three good nonwoven substrate options for meeting the current (and projected) INDA/EDANA Guidance Document for Assessing the Flushability of Nonwoven Consumer Products. All three appear to perform satisfactorily in current nonwoven wipes markets requiring flushability.
Phil Mango is president of Phillip Mango Consulting. He has more than 30 years of experience in nonwovens, including positions with Air Products & Chemicals, Walkisoft USA and Concert Industries. In 1997, he co-founded Airformed Composites and designed, built and ran an airlaid line near Charleston, SC. Shortly after the sale of Airformed Composites to Concert Industries, Phil left to start his own consulting business with special emphasis on hygiene, wipes and packaging markets.
The ideas and opinions expressed in this article are those of the author and do not necessarily reflect views held by Nonwovens Industry.