September 2008
By Christopher D. Smith, Global Marketing Manager, Graphic Papers SBU, Nalco Company
There is serious concern among papermakers currently not only about the costs of manufacture of their highest brightness and whiteness grades, but more importantly whether or not the raw materials will be available to make these important grades of paper.
Inflationary forces have been recognized in nearly all of the raw materials used in papermaking, including wood and pulp prices at near record highs and an unprecedented rise in both commodity and specialty chemical costs. Many factors have conspired to create this perfect storm of demand outstripping supply, including the rapid globalization of feedstock supply and the rise and continued growth of emerging economies such as China and India, and by no means is one single factor to blame.
One example of the extraordinary impact that globalization has had is the recent impact on fluorescent whitening agents (FWAs) or optical brightening agents (OBAs). A key raw material for FWAs, diamino stilbenic acid (DAS), was already in short supply last year when additional plant capacity was taken off line, which has resulted in almost a 250% global cost increase in this raw material this year. Furthermore, the Chinese government has banned non-military production of para-nitrotoluene (PNT), which is a direct pre-curser to diamino stilbenic acid (DAS). To make matters even worse, in anticipation of the Olympics, certain production facilities near Beijing were idled, with most chemical plants constrained to 50% capacity production and truck traffic of hazardous material had already been officially reduced and was due to be even further curtailed during the games.
Although a regionally-based disruption like this would normally not have a large and sustained global impact, recent globalization efforts have resulted in many chemical manufacturers off-shoring significant portions of their production capacity in an effort to obtain comparative production advantages and be nearer to emerging markets. This has had a significant impact on the supply of FWAs and many other specialty chemicals and has necessitated significant off-contract price increases up to and exceeding 50%. In even more severe cases certain materials including FWAs are in such short supply that deliveries could not be met or customers unwilling to take price increases have lost supplies to other competitors willing to accept cash-on-delivery terms, spot pricing or other changes in terms.
The average consumer does not have visibility with respect to these structural changes in the raw materials used for the production of paper. However, the consumer has demonstrated in numerous market studies that all things being equal that they will always prefer a whiter, brighter (actually bluer) paper over another that is not equally as white and bright. How much more consumers will pay for whiter paper continues to be a debate, but with such significant production capacity available globally, there will always be a producer willing to obtain share by providing the very highest whiteness papers at the lowest achievable cost.
As a result of these conditions, the global papermaker is looking for ways today, more than ever, to cost efficiently and effectively reach their highest whiteness and brightness targets. There are many ways to accomplish this, including increasing pulp bleaching, alternating furnish composition and recipes, changing dye packages, and optimizing specialty chemical efficacies.
Making the most of FWAs
One of the most straightforward ways to optimize specialty chemical efficacies is to optimize the usage of FWAs within the papermaking process. In many cases, the papermaker can increase their ratio of di-sulfonated to tetra-sulphonated FWAs in the wet end, especially in the very highest whiteness papers. If incremental di-sulfonated FWAs are available from the FWA supplier, this is a rather simple way to go and it has been proven to be a more cost-effective way than by using more tetra-sulfonated FWAs. In fact, by simply switching to a di-sulfonated FWA in the wet end, better light-fastness, improved ash and total retention, and lower system charge should all be observed.
Another item to look at is where and how the FWAs are added to the process. Proper mixing must be ensured to reduce the possibility of the FWAs prematurely interacting with other additives, and the additive location must be such that the FWAs in the wet end have enough and not too much time to be in the process. The ratio of wet end and size press FWAs can also be optimized in terms of additive location, as the size press FWA addition will always be more effective but a balance must be made between potential for “greening” or streaking.
One must also be observant of other additives that may quench FWAs added to the wet end. Certain organic coagulants have a higher affinity for quenching FWAs, as do certain cationic starches. Most specialty chemical suppliers will be able to tell you whether or not their specific coagulant will quench FWAs and if they have an alternative that will not have as high of a quenching effect.
Finally, considering another approach and utilizing a novel brightness enhancer such as EXTRA WHITETM Brightness Technology makes sense. This novel patent pending technology is in use in nearly 30 paper machines globally now on the highest brightness and whiteness grades produced globally. The technology has been proven to reduce thermal reversion and activate FWAs. The technology is added to the size press and has demonstrated FWA reductions of up to 50% in the size press and nearly 40% in the wet end and equal brightness and whiteness.
learning by example
The following examples illustrate the commercial impact that Extra White brightness technology has had on the production of high whiteness and brightness paper.
An uncoated freesheet manufacturer wanted to more consistently and cost-effectively produce their highest brightness (98 Tappi Brightness) grades. Pre-trial the mill was using 36 lbs/ton of hexasulfonated OBA at the size press, 5 lbs per ton in the machine chest and 8 lbs/ton of disulfonated OBA in the surge chest with an average incoming pulp brightness of 90.1 to produce 96.5 brightness paper. Upon introduction of 2.5 lbs/ton of Extra White brightness technology to the size press run tank, the following effect was observed:
• Production of in-specification 98 brightness production
• An 0.8 point increase in TAPPI brightness
• An immediate reduction of size-press OBA demand of 11 lbs/ton
• A historically low OBA demand for 98 Brightness production that was 40% lower in the size press and wet end than all historical norms for the grade production.
An uncoated freesheet producer manufacturing copy and offset paper at a rate of 189,000 tons/yr and at 2,800 F/min was having difficulties cost-effectively producing their standard paper grades. Producing higher brightness grades was only possible with extended bleaching and a high amount of OBAs. These actions also had a significant impact on operational efficiency as wet end stability and fiber integrity were negatively impacted. Costs of OBAs were rising with supply in question and the negative operational and cost impacts were causing the machine to lose global competitiveness.
Nalco was asked to provide a solution with its Extra White brightness technology and upon addition of 2 lbs/ton to the inlet of the transfer pump to the size press an immediate reduction of 30% of size press OBAs was recognized and wet end demand was further reduced by 20%.
There are numerous ways available to improve the efficacy of specialty chemicals to allow cost-effective production of high brightness grades to satisfy the market demand for such grades. With the collective talents and experiences of both papermakers and specialty chemical suppliers, it is possible to get there quickly by choosing the most efficient and effective path.
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