Tissue softness improvement through greener chemicals

Focusing just on bulk and surface softness may not be enough for tissuemakers today. Major tissue producers, such as Georgia Pacific (Koch group), Kimberly-Clark, SCA, Metsä and even some store brands are following the philosophy of the broader soft touch - each in its own way.

Ercole Pieroni, Eka Chemicals European Tissue Team

Tissue chemistry is playing a greater role in delivering a broader range of “soft”. New greener debonders and softeners are working in concert with mechanical enhancements, processing virgin and recycled fibers into a range of tissue and toweling products. These chemistries have shown compatibility with all process chemicals added in tissue and towel grades production.


TODAY’S BEST DEBONDING CHEMISTRIES EXHIBIT GOOD SUBSTANTIVITY TO FIBERS, AND ARE ABLE TO DECREASE THE BONDED AREA BETWEEN FIBERS, thus creating a bulkier and softer sheet. The almost unavoidable downside is a loss in strength, as illustrated in the diagram (fig.1). In literature, it is quite hard to find articles spelling out new formulations in tissue, because secrets are closely guarded. Regardless of the particular chemistries, helping the tissuemaker gain the right balance requires modifications in formulations, which are easy to apply, and utilize synergistic chemistries at lower dosages. In the 1980s the tissue industry turned to debonding the fibers having the non-specific unique formulations developed for this market. These products contained both cationic and non-ionic surfactants. Paper scientists realized later that non-ionic surfactants did most of the debonding work on fibers and that cationic surfactants only facilitated retention onto the anionic fibers. The result of this dedicated research was a gradual decrease of cationic surfactants in tissue formulations up to the 90’s when cationic surfactants were reduced to less than 7% of the softener formulations. This was good for economy, wetting rate and reduced toxicity in light of a greener product. On an increasing basis since the early 90’s, environmentally friendly, safe debonders and tissue softeners have moved to the forefront. Even with the reduction of cationic surfactants to 5% (the minimum necessary for retention to the fibers), there is not yet a substitute chemistry which truly meets a higher environmental threshold.


GREENER DEBONDERS (TISSUE PAPER PRODUCTION). Although the cationic surfactants could be readily biodegradable, and in some cases also listed for food contact, they are always toxic to aquatic organisms. Since most debonding is obtainable by the non-ionics, formulations with natural fats, non-ionic surfactants and anionic surfactants (with the elimination of cationic surfactants) could be the answer. Easily emulsified in water, anionic formulations have proven good retention to fibers, combined with using well-known low-toxicity cationic polymers. Furthermore, this type of formulation has at least the same debonding efficiency, and very low impact on wetting properties. Softeners can be similar to or the same as debonders or other formulations for purposes like silicone micro emulsions, which are sprayed on the paper alone or together with cationic surfactant formulations. The small effect on strength sometimes seen after spraying debonder type formulations onto the paper can be attributed to spray through product that has ended up in the white water and acts as a small dose of debonder. The effect most often seen is a decrease in friction on the paper surface, which creates a nice surface softness of the paper without the loss of strength typical of debonder use.


SOFTENERS ACT AS RELEASE AGENTS ON THE COATING OF THE YANKEE CYLINDER and are also sprayed on the contacting side of the Yankee (operator side). Because of this, it is very important to have a Yankee chemical coating that can handle this decrease in adhesion to be able to have a good creping so the softness gained is not lost with coarse creping. Because all debonders act as release agents on the Yankee cylinder, the technique for sprayed coating chemicals needed to be carefully adjusted to compensate for and obtain the optimization of cost/performances by both dedicated application technologies. Yankee Cylinder coating chemicals, which handle the release effect from a greener softener, is then the possible answer. The right greener debonder chemical, applied at the minimum dosage, can actually boost surface softness as well. The combination of applications know-how and new proprietary formulations have demonstrated greater efficiency for a range of grades, allowing tissue producers to maintain a competitive edge.


LOTIONING ADDITIVES ADD VALUE (TISSUE PAPER CONVERTING). For more than a decade there has been an increasing interest in adding diverse oils and fats referred to as lotions or emollients in converting. Some consumers are paying more for the absence of skin irritation and perceived value for hygiene. Some brand names are considered market leaders in many countries, delivering a “high-lotion” effect, employing chamomile-like and other extracts. Because the product is soft to the touch and is portrayed as having a “soothing” feeling, the broader definition of soft certainly applies here. Others are employing low dosages of silicon oil, added to achieve an inviting hand feel in very much the same way as a softening spray, so less than 1 kg/ton. Other emollients include white Vaseline®, vegetable oils and fats like coconut oil or shea butter, fatty alcohols like cetyl alcohol (C16) and a range of surfactants. In these formulations, cosmetic ingredients like perfumes or Aloe Vera can be added either as such or in microencapsulated form. The lotions can be added to the paper web in a variety of ways.


GREENER TISSUE SOFTNESS IS A REALISTIC MARKETING APPROACH IN SUSTAINABILITY ISSUES. A challenging issue for tissuemakers is to provide the “soft touch” that the consumer wants and needs, and a “soft” environmental image at the same time. Sometimes “soft” achievement in the marketplace is not actually related to tissuemaking, but to broader issues. SCA’s World Wildlife Fund’s “green mark” in 2007 is a good example of this point.


THIS PARTICULAR RECOGNITION FOCUSES ON RECYCLED CONTENT, wood sourcing and pollution control - but not on green tissue chemistry. In another ranking, Metsä has achieved the Nordic Environmental Label (Swan Label), which measures environmental impact during the entire life cycle of products, including raw materials, chemicals and production processes. It should be noted that Georgia Pacific and SCA also have been granted the Swan label. Kimberly-Clark, having some of the top consumer tissue brands in Europe, demonstrates a strong commitment to the broad soft touch issues, and has made a significant contribution to sustainability issues.


REDUCTION OF WATER CONTAMINATION BY USING GREENER SOFT APPROACHES can also positively impact tissue functionality and improve the image of tissue producers, becoming a good tool in the hands of marketing. Running tissue-making more efficiently, especially when energy and environmental necessites are involved, gains significantly from a more efficient use of cleaner and greener chemistry. Polluting less and less is the answer to future requests in soft tissue by lower dosages of effective eco-friendly chemistries, designed to work in concert, able to minimize environmental impact and contribute to a “soft” footprint.


For further information, contact: ercole.pieroni@eka.com or arne.andersson@eka.com


Softness: A “TAD” Better


The TAD process has proven itself for softness gains, since it creates a bulky and less bonded sheet. Other ways to improve bulk include the use of a shoe press on the Yankee for increased bulk (lower bonding) at the same dry content, or introducing dry fibers into the pulp shortly before sheet forming. Multi-layering technologies also make it possible to use short fibers for softness and get the maximum strength from long fibers in different constructions.

There are also mechanical possibilities in converting, like different embossing or calandering techniques.

The paper chemistry research has developed:


• Debonders are added to the wet end of the paper machine with increased softness and decreased strength as results.

• Softeners are products sprayed on the wet paper before the Yankee cylinder affecting the surface characteristics of the paper with minimal loss in strength.

• Lotions are products sprayed, printed or even extruded onto the dry paper to affect surface characteristics. With very high dosages there can even be enough material to transfer the product onto the surface where it is used. This operation is normally done in tissue paper converting. For high-end brands, tissue must feel soft, smell soft, be gentle on skin, and leave a very small environmental footprint. The European markets demand much more than bulk and surface softness.

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