Toschi presents the new TAD Vision TM tissue system

Ing. Stefano Zangolini, Toschi Spa

In these last few years, the consumer tissue market has increased its demand for better quality products far beyond any previous expectations. This phenomenon, which has already been taking place in the USA and Canada for several years, is now occurring in the European market too, suggesting that it will follow the North American trend. Concurrently, quality improvement has continued in the Away-From-Home market too, driving tissue producers to struggle for greater softness, bulk, strength and absorbency for their products. Crescent Former (CFR) technology was a recent (and simpler) answer to meet market demands. The bulky and soft tissue (compared to previous products) produced by CFR machines invaded nearly all the markets to the extent that today most of the tissue machines recently installed use this technology. Meanwhile, large tissue producers and multinational companies were benefiting from another technology: the Through Air Drying (TAD) processes developed independently by Procter & Gamble and Kimberly Clark.

THE TAD PROCESS. TAD tissue products have been on the market for over thirty years now, starting with Procter & Gamble's entry in the late 1960's and continuing through today. Due to their enhanced absorbency and softness, these products have been targeted at the premium retail consumer level. As the market evolved, they have been particularly preferred as premium two-ply towels and single-ply tissues. This technology uses a hot air flow blown through the tissue before the Yankee dryer. Web dewatering is very mechanically gentle, without high impact pressing. This process yields bulkier, softer and more absorbent products and has been jealously guarded by major players until it was available to a larger number of tissue producers upon patent expiry. Today, due to the high investment costs, only few tissue producers have TAD units in operation, most of them located in highly developed countries. These are large units with outputs ranging from 55,000 to 70,000 tpy with a corresponding demand for large markets to absorb their daily production. Strategic decisions about plant location are also strongly effected by the high impact of transportation of such high bulk products. Considering that in the USA, the maximum transportation distance from the mill is normally considered 1,000 - 1,500 km before costs erode away any profit, it is easily understandable that such large production quantities cannot be absorbed by all markets. This situation made the development and design of a compact, efficient and relatively low cost TAD system necessary. A system capable of satisfying the highest demand in terms of quality standards while, at the same time, allowing installation in smaller markets (even in grow- in countries) and, more importantly, lowering the entry level into this technology and making it available to a larger number of players.

KNOW-HOW, MILL SET-UP AND PRODUCTION TROUBLESHOOTING. Another limiting factor to the wide-spread of TAD technology worldwide is the fact that it is not easy to operate these units efficiently only the largest producers could sustain a long learning period on the first TAD unit. Until today, TAD tissue machine suppliers where not able to provide production instructions and guidelines. Every TAD tissue producer has spent a long time setting and fine tuning his units, developing solutions and modifications to optimize efficiency and smooth production. The limit to TAD technology diffusion could be overcome through the joint effort of a tissue producer with tissue machine manufacturer.

TOSCHI AND PROCTER & GAMBLE: THE TAD VISION TM TISSUE SYSTEM.

Recently, Procter & Gamble and Toschi have developed a compact TAD system which allows very quick and simple installation and has a suitable size for placement in markets smaller than those of North America or those of the main Western European countries. The licensing agreement signed between the two companies makes it possible to manufacture and supply complete TAD mills based on P&G technology, featuring their famous outflow pre-dryers, all over the world. The TADVISION TM system has been conceived as an easy and effective answer to most problems and can be supplied in "turn-key" fashion which includes all papermaking equipment, saving customers time in project management. An integral part of the Proposed package is comprised of P&G's operational know-how, including operating guidelines and practical training of the mill's staff during system start-up. This constitutes a substantial added value to any supply package, capable by itself of reducing the learning curve for newcomers into TAD tissue production to a minimum. There is also another very appreciable feature, given by the possibility of benefiting from the strong effort in terms of Research & Development constantly carried out by P&G. Once any development on their machines is made available to the other producers under a license, it will be applicable to the TAD VISION TM system.

PRODUCT COMPARISON. Those readers who have consulted every issue of the Perini Journal will note that other tissue machine suppliers have already shown the main advantages of TAD tissue products versus conventional products such as those obtained with Crescent Former technology. However, it is useful to review here some data relevant to toilet tissues and towels. The product benefits are clear. Table 1 summarizes the attributes achievable by a product obtained with TAD technology versus products made utilizing conventional, wet pressing technology. It should be stated that these properties cannot be achieved with certain TAD processes due to their configuration. As can be seen, these products have 60% of the dry density compared to conventional products. This permits the producer to utilize less fiber per roll of product and still develop the same roll diameter. Taken to its extreme, this reasoning would allow using only 60% of the fiber while maintaining the same roll diameter, but this can compromise other properties, such as softness and strength, so the producer must decide which properties are the most important in his product. The 60% increased absorbency is a direct result of the lower density, as there is more void volume in the structure, which results in more liquid being held per gram of fiber. The 60% increase in wet to dry density results in the product being able to hold the liquid, even when wet, rather than letting the fiber structure collapse. The increased softness is a result of the product's being more cloth-like in surface feel, as well as drape. This allows obtaining the softness of premium two-ply products with a single-ply sheet, that is lower in basis weight than the two plies. The customer has to decide the best balance of the benefits for his market. This can go all the way from minimizing fiber required in away-from-home products to producing an improved product at a lower cost per roll. TAD products in North America are now approaching the 25% market share of all retail and away-from-home production, and comments from both North American and European producers suggest that the market share will increase in the next foreseeable future.

TOILET TISSUE. Focusing on toilet tissue properties, graphs 1 and 2 clearly indicate that TAD toilet tissue has nearly twice the bulk and softness compared to conventional products. The benefit is that a one-ply tissue performing like a two-ply conventional one can he obtained with 75% to 85% of the two-ply weight, increasing rolls of product per ton. Even if the TAD machine runs at a lower speed compared to a conventional one, we must consider the importance of producing single-ply reels. We don't need to operate the machine at 1600 - 1800 m/min and produce two or three plies to make the same amount of finished product. Savings in terms of efficiency are immediately clear, as are savings in output, expected to be in the range of 40% more.

TOWEL. Graphs 3 and 4 point out the main figures to analyze a tissue towel product. According to P&G testing standards, two-ply absorbency ranges from 20 to 22 g water/g fiber, compared to 9-12 g water/g fiber of conventional products. What was indicated for the toilet tissues in terms of bulk is applicable to towel products too and, thanks to the lower fiber density and the higher bulk, it is possible to obtain similar or better product characteristics at a lower basis weight.

OTHER PRODUCTS. Today the market also offers other products in addition to toilet tissues and towels. P&G is selling its Puffs TAD facial tissue and in the USA they are launching a radically new product for TAD: the Bounty napkins.

These products, together with indications from tissue producers of new developments, show that the expansion of TAD is only at the beginning.

OPERATIONAL COST BENEFIT. A key driver for TAD technology is the cost benefit for producing premium products. Table 2 shows a comparison of estimated manufacturing costs for conventional and TAD tissues. The average production cost is between 5% to 20% higher than what is reachable with conventional CFR systems at the same capacity (we assumed as reference a 700 USD/ton cost for virgin pulp as raw material). Thanks to the higher properties of the finished TAD products and to the substantial savings in terms of fibers, it is possible to obtain up to 20-25% more rolls out of a ton of product, while maintaining the final roll diameter. The result is a substantial reduction in cost per roll -- up to 22% less in the case of single-ply products compared to two-ply conventional products having the same characteristics.

The high quality of the TAD product allows placing it at the premium level, increasing profit per ton even more.

TAD TECHNOLOGIES. As we indicated above, the two main TAD tissue producers (Procter & Gamble and Kimberly Clark) developed their own TAD design in the late 60's. Even though both of them use hot air to pre-dry the tissue web, these two technologies are quite different in principle. As indicated in previous issues of the Perini Journal, Procter & Gamble utilizes the outflow technology while Kimberly-Clark uses the inflow system. There are several pros and cons to these two configurations, regarding both product quality as well as machine operation.

Since Procter & Gamble was the first company to move into the TAD field, they had the possibility to "choose" the simpler design: the outflow technology, which creates fewer operational and maintenance problems.

THE ADVANTAGES ARE SUMMARIZED HERE BELOW:

-The TAD drum is much simpler in construction. The air enters the drum from a bottom supply hood and is exhausted from a top exhaust hood as shown in Fig. 1. Due to this arrangement, the TAD drum is simpler in design and does not need any internals to convey the airflow from the shell to the journal (when side exhaust is performed in inflow design). Furthermore, there are no internal roll elements that require adjustment, so the system is much easier to operate.

-Since the air is going from the inside outwards, there is minimal fiber build-up inside the drum.

-For the same reason there is no problem in producing wet- strength tissues since the design minimizes resin problems in the TAD section.

-The particular configuration of the tissue machine doesn't require any adjustment of the seal rolls, which are stationary. This characteristic translates into a more efficient sealing effect thus increasing machine efficiency and reducing production costs.

-The simple design of the structure allows an easy extraction of the TAD drums for maintenance purposes, reducing downtime.

-The cross-machine speed profile is much easier to adjust, compared to inflow design systems.

-There is no contact between the seal roll and the tissue web. In the inflow design, where this contact occurs, the process has a limit in the dry content of the tissue web after the first pre-dryer: if it is too low the tissue sticks to the roll destroying the web and causing paper breaks.

ON THE OTHER HAND, THE ADVANTAGES OF THE MORE COMMONLY AVAILABLE INFLOW SYSTEMS ARE:

-Higher hot air flow rates are possible, due to the support provided by the drum. (however, this requires higher fan horsepower, which increases exponentially with flow rates).

-Due to its characteristics, it is possible to install a single large TAD drum with no significant limitation in size. This avoids the need of installing the two or three smaller pre-dryers required in the outflow system.

PROCESS COMPARISON. The differences are not only those listed above. The Procter & Gamble technology is based on a transfer consistency at the Yankee dryer between 60% and 70% (dry content) and therefore the complete chemistry of the process is different. This technology was patented by Procter & Gamble and is part of the TADVISION TM license to transmit this knowledge. As already stated, the main impact on the products is the higher softness and bulk of the "outflow-produced" tissues. In the analyses of market available products (that we are carrying out and that will be part of future technical releases) we have found a higher absorbency capacity of the "outflow-produced" tissues as well as a faster absorbency rate. As a conclusion, we believe that the P&G based outflow design is easier to operate, more efficient and simpler in machine design, while the commonly available inflow design based units are slightly more difficult to set up and commission. Not to mention the different impact of these two technologies on the quality of the finished product.

TAD VISION TM:

THE SOLUTION. As we can see, there were good reasons for the TAD technology to remain a "secret" among few players:

-High investment costs

-Long learning curve

-Little offer of different solutions from machine suppliers

-Large production requiring large and developed markets

-No guidelines and training programs given by machine suppliers

The answer to all these points is given by TAD VISION TM: a complete and "turn-key" package that today, after the signing of a license agreement, Toschi and Procter & Gamble can provide to tissue producers worldwide. The scope of the supply is based on a complete package including the stock preparation plant, tissue machine with relative accessories as well as all the mill's typical facilities such as the electrical system, steam boiler, etc. The purpose of such a complete offer is to protect tissue producers from all the problems arising from the management of such a project and the interface with different sub-suppliers. The design of the plant has been carried out with the clear intent of supplying a compact, high quality system capable of uniting high performance with a low investment cost. The sizes chosen by Toschi and Procter & Gamble are summarized in Table 3 and are intended to satisfy a wide demand in terms of flexibility and machine output. But the presence of Procter & Gamble with its guidance and experience is of essential importance also for a substantial reduction of the learning curve for new TAD tissue producers. Thanks to dedicated training programs and in-house assistance during start-up, it will be possible to have smooth and trouble-free plant commissioning.

CONCLUSIONS. All the major tissue producers in the world are already utilizing TAD production. Most of them are investing only in TAD technology for their new plants.

The advantages of TAD tissue products are multiple:

-TAD products are bulkier and softer and satisfy most markets present trend for higher quality tissues for both branded and private label products (for the consumer market) as well as in the Away-From-Home sector.

-It is possible to use less total fiber per roll, while providing the same or better performance.

-The cost per roll is less than that of conventional CFR products while TAD product benefit of a higher selling price.

At the same time most of the factors that limited TAD technology from spreading in the markets are now overcome by the new TAD VISION TM system which is a positive answer to all the previous limitations.

TOSCHI S.P.A.

Toschi S.p.A. is based just outside of Lucca, Italy and began producing and selling papermaking machines under its trademark some fifty years ago. Recently, following the strong partnerships developed between the Mennucci family, holders of the majority shares, and Italian tissue entrepreneur Fabio Perini, owner of 49% of the company, Toschi made its first steps in the field of wide tissue PMs and recently received an order for a 4.54-m wide Ahead model 11.45 unit. At the same time, the company is continuing its activity as world leader in the supply of small and medium size "turn-key" systems both for tissue and paper production and supplies systems and machinery to papermaking manufacturers all over the world. Toschi's Tissue Division supplies tissue systems from 45 to 130 tpd, running from 800 to 7900 m/mm. A totally new approach has been used to redesign Crescent Former machines. The result is the Ahead series: a range of tissue machines from 70 to 130 tpd. These units feature several unique developments designed to improve operational efficiency and reduce downtime. And the Modulo, now proposed in a single size of 45 tpd and operating at 800 m/min, continues its success with the recent start-up of the second unit. Thanks to its motivated team, the Paper and Board Division, Toschi supplies systems for the production of linerboard, fluting, printing/writing grades, etc. The production programs include systems with widths of up 3.5 m, operating speeds of up to 800 m/min and productions of up to 400 tpd. Toschi's leading product is the fabricated steel dryer, a product that combines high technological features with elevated drying performances. The Stock Preparation Division supplies a wide range of machines and solutions for stock preparation lines for both tissue and paper production using also waste paper and with productions up to 400 tpd. Complete customer assistance services is the company's goal. And a full range of services, such as dedicated and detailed engineering, erection supervision, plant commissioning and operating assistance, is supplied by Toschi.s