Suppliers of coating and sizing solutions are not resting on their laurels. Since our last round up (PPI, May 2003), there has been a host of new developments, both in terms of chemicals and equipment. The increasing importance of the former means it is often the chemical (rather than equipment) suppliers who are driving the sector.
Coating and sizing chemicals
According to a paper presented by Bernd Balzereit of Omya at the ATIP convention in Grenoble last October, mineral consumption in the paper industry in Europe will rise from 12 million tonnes/yr in 2000 to 16.6 million tonnes/yr by 2010. Balzareit says that one of the key trends in the coated paper market in Europe is the substitution of GCC (ground calcium carbonate) for clay. This is driven by the never-ending quest for superior surface qualities of paper. To this end, Omya has developed GCC with a narrow particle size distribution, which, it says, gives improved coverage. Balzareit believes that the demand from papermakers for improved productivity at lower cost "Will intensify a vigorous search for synergies between pigments." And, he continues, "The opportunity for synergy exists not only between pigments of different types, but also within a family of pigments."
Another chemicals supplier, Kemira, is the only producer of calcium sulfate pigment in the world. The company started up a second calcium sulfate pigment production line at its Siilinj�rvi plant in Finland in September 2003. The plant is now able to produce 100,000 tonnes/yr dry pigment or 150,000 tonnes/yr in slurry form. Kemira's product, trade name CoCoat, is used for coating paper to improve brightness, opacity and printability. Kemira says CoCoat is most suitable for bright paper grades like LWC, MWC and MFC printing papers, coated fine papers and various types of paperboard. Calcium sulfate is lighter than conventional pigments, explains the supplier.
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On the sizing front, the company started up a new production unit for AKD size in Washougal, Washington State, US, in July 2003. Kemira says its new unit allows better flexibility to formulate sizing systems according to customer needs and means improved service for its North American customers, including a strong single source concept. In addition to the Washougal plant, Kemira has AKD-based size production units in Finland, Sweden, France, Austria, Spain and Brazil.
Kemira has also continued its R&D work on surface sizing over the last 12 months and developed a new polymer based formulation, marketed under the brand name Polygraphix. The product is the result of a technology transfer between research groups in Vaasa, Finland, Marrietta, Ga., US and Krems, Austria. Polygrafix is being well received on the market, says Kemira. A production unit was started up in Krems, Austria in July 2003.
Hercules Pulp and Paper Division says it has established a solid market presence with its Prequel ASA Internal Size and Emulsification Starch Technology range since last year's coating survey. The Prequel portfolio consists of a C16/C18 ASA blend, a straight C18 ASA and some ASA/AKD blends which are emulsified together enabling harder sizing at less deposition for hard sized paper and board. Prequel ASA technology is also widely emulsified in mill supplied starch.
Hercules says that the combination of Prequel ASA and Prequel Starch Technologies provides excellent results in challenging wet-end environments where mill starch is unavailable or limited in use. Prequel Starch delivers good ASA emulsion at one-sixteenth to one-quarter the amount of mill-cooked starch. A typical example is in recycled linerboard, says the supplier.
Hercules Pulp and Paper Division's latest development in the sizing sphere is Aquapel AKD Emulsion Technology. The supplier has also developed a series of Aquapel NP products, tailored specifically for the newsprint sector. These non-deposit high efficiency products are designed to provide improved print room performance.
Aquapel F AKD Size Technology is a high performance AKD emulsion with high charge cationic starch, enabling high performance at low addition.
In 2004, Hercules will introduce Aquapel M AKD Size Technology. This technology is food contact regulatory compliant for food contact board and paper. Aquapel M Technology enables hard sized board and paper grades for food contact, providing better efficiency and cost performance, says the supplier.
At the opposite end of the charge spectrum is Aquapel 7 Anionic AKD Emulsion Technology for wet end systems with cationic or near isolelectric point charge. Introduced in 2003, these products give benefits in near zero systems where a lot of cationic material is added to the wet end. In a high wet strength system, Aquapel 7 series can provide good sizing performance without upsetting retention characteristics due to overcharged fiber system. It also provides good performance where anionic retention systems are in place, adds Hercules.
Fluorolink perfluoropolyether (PFPE) from Solvay Solexis is a fluorinated surface treatment designed to provide needed oil and grease repellency for paper and board. Depending on the formulation selected, the product may be introduced at the wet end, the size press, or via coaters. Fluorolink products for the paper industry comply with FDA regulations 21 CFR 176.180 and 21 CFR 176.170 for paper and paperboard in direct contact with aqueous and fatty foods.
Marietta, Georgia-based Ulterion experienced a successful year in 2003, as the development of new products led to significantly increased sales, a larger customer base and the ability to expand its facilities. The company's portfolio includes a range of barrier coating products: Ulterion 535 SWH, Ulterion 536 OPV, Ulterion 537 SHW and Ulterion 538 OPV; release coatings products: Ulterion 892 and Ulterion 897; coating lubricants: Ulterion XF-280; and sizing agents: Ulterion 5000 MP and Ulterion 5010.
Eka Chemicals has most recently boosted its product range with the introduction of a family of patented, multi-functional rheology aid/lubricant products. These, it says, offer superior rheology and the potential for significant quality improvements, as this case history illustrates.
Case study: A North American fine paper mill was having problems with viscosity and blade scratches. At the optimum solids for good print quality, the viscosity of the coating was too high and when applied the coating would develop scratches. Normal procedure to combat the scratches was to lower the coating solids by two percent. Lowering the coating solids would solve the blade scratches; however lowering the solids introduced another defect visible as mottle. At lower solids when the sheet was printed, the print mottle was at an undesirable level. Eka's Bladecote XP 2109 then was introduced into the coating to lower the viscosity of the coating without reducing the solids of the coating. When the product was added to the coating formulation, the Brookfield viscosity of the coating was reduced by 60% and the High Shear viscosity was reduced by 15%, allowing the solids to be maintained at the normal level. Scratches were eliminated, and, additionally, since the coating solids were not lowered, sheet mottle was not present after printing.
The search for sizing efficiency
Today, papermakers are faced with many challenges that impact the ability to obtain high sizing efficiency says Bayer Chemicals. The company's Global Research and Development group has combined the understanding of internal and surface sizing chemistry to provide total sizing at the size press with its BAYSIZE TS sizing agents. These are new, proprietary, high-performance surface additives that are effective over a broad range of acid to alkaline papers, the supplier explains. BAYSIZE TS sizing agents are designed to offer optimum performance and versatility to the papermaker, as well as many cost reduction opportunities through increased size retention at the size press. As a result of reducing and/or eliminating the wet-end sizing additives, improved machine runnability and cleanliness may be realized. Bayer's new sizing agents are typically added to the surface via a size press and are compatible with a wide range of surface-applied additives. Other product benefits cited include:
- Versatility to allow for new grade opportunities
- Papermaking flexibility as a result of less complicated wet-end chemistry
- Improved printability.
Home and business users demand superior resolution and intense color from their inkjet printers. BAYSIZE TS is designed to create a paper surface that meets these higher standards. An example of quantitative improvement in inkjet text quality with the BAYSIZE TS sizing system compared to a competitor's conventional sizing system sheet is shown in Fig. 1 (below).
Coating equipment
Suppliers of equipment to manufacturers of coated paper have also been busy. Metso Paper's new ValCoat and ValSizer coating stations bring tailored solutions to coating process, to new machines and rebuilds, says the company's marketing manager, coaters and reels, Martti Tyrv�inen. "Simplified and ingenious technology and easy adjustability mean that this coating technology is designed for papermakers who want to master their medium size (maximum trim width approximately 6 m) technology with sophisticated coating application," he explains.
ValCoat is an applicator roll type coating station for applications of paper and board. "With ValCoat, the paper or board maker will achieve reliable and proven construction, user-friendly and easy maintenance and blade or rod metering for good quality results," says Tyrv�inen.
The ValCoat product family also includes ValSizer station, when sizing or film coating is needed and ValCoat Jet coating station, when free jet application is required. Tyrv�inen points out that Metso has sold more than 30 ValCoat and ValSizer coating stations for fine paper and coated board applications in the last three years. Some of the supplier's upcoming coater installations are listed in Table 1 (below), alongside selected installations from Voith Paper.
Voith says that paper industry caution with regard to investments in new costing units and coating machines during fiscal year 2002-2003 had an upside: the supplier used this period as an opportunity to complete its integration of Jagenberg, to further optimize successful and proven products, and to push ahead with the development of innovative, new processes.
The integration of Jagenberg has enabled the development of the new DynaCoat, which combines the advantages of the CombiBlade and Dynamic Coater, while incorporating new materials. Composite materials with strength properties exactly designed for the application ensure the straightness of the blade beam, which is vital for optimal coat profiles, says the supplier. Mechanical and thermal deformations can also be avoided without costly compensation systems, adds Voith. The first DynaCoat installation will be on PM 3 at Gold East Paper's Dagang mill, Jiangsu, China: a 10-m-wide fine paper machine running at 1,800 m/min. Start-up is scheduled for 2005.
On the film coating side, Voith's SpeedSizer AT has been chosen for PM 4, the new 300,000 tonne/yr LWC machine at LEIPA Schwedt mill, Germany, due to start up this summer. Voith's new composite material will be used for the nozzle beams of this film press. This, in conjunction with the automatic CD profile control, this will enable optimal CD coat profiles to be achieved, says Voith. Applicator rolls of large diameters, in conjunction with the sensitive nip load control, will minimize the misting that might occur at high speeds, the company adds.
The main focus of coating development work for Voith is its new Curtain Coating Technology: in a nozzle a free-falling curtain is formed and transferred to the web. The coat quantity is so low that an additional metering step by means of a blade or metering rod is no longer required. This DF ('direct fountain") Coater is ideal for papermakers in many respects, says Voith, since there is no more mechanical web stress, there are hardly any sheet breaks and no costs for metering elements and other wear parts, for example roll rubber covers. In addition, it is found that this process produces an ideal contour coat.
The supplier cites the example of German papermaker August Koehler, where, following the successful installations on CM 1 and CM 2 in Kehl, a third DF Coater has already been installed on CM 7 in Oberkirch, Germany. Curtain Technology is suitable for virtually all applications and can cover the widest application range of all well-known coating methods, says Voith.
BTG Ecl�pens has, in collaboration with paper producers, developed and expanded its range of coating blades and rods with a wide variety of blade tip materials to obtain optimal productivity and superior coating quality.
BTG's Duroblade-XXL, launched in 2003, has an extremely tough blade tip, enhanced with a shiny and very dense metal-based material, which, says the supplier, offers an exceptional surface smoothness, thereby giving fine paper and folding boxboard grades a pleasant visual appearance. BTG adds that the wear resistance of Duroblade-XXL exceeds that of any other hard-tip coating blade.
ACA Systems has launched a Dynamic Water Retention (DWR) module for its ACAV viscometers. This option is based on the commonly used static method.
With the new module, the base paper is weighed and then placed together with the filter on the lid of the DWR. The lid is closed and the pressure (1 - 2 bar), time, and static time are chosen using a PC in order to simulate the time between an application and a blade. 10-12 bar is used as a blade pressure. The instrument then automatically makes the measurement. Once it has been made, the lid is opened and the base paper is weighed.
According to the supplier, benefits of the method are threefold:
1. It is possible to measure characteristics of the coating color as well as the influence of the base paper on water retention.
2. The dynamic and static phase simulate the real circumstances of a coating machine.
3. The measurement time from one weighing to another only takes about three minutes.
Kadant says dramatically improving the filtration of the size press is one way that paper mills can resolve the question: how do you make a higher quality sheet on a more efficient machine without negatively affecting the environment or significantly changing the existing process?
Case study: A paper machine in the northeastern US manufacturing approximately 225 tonnes/day of coated printing and writing paper was experiencing problems with its sheet both on the paper machine and at the off machine coater. Many of these problems could be traced back to the pre-coat starch applied at the size press, and the amount of debris present in the starch loop. The machine utilized a puddle-type size press to apply a "pre-coat" of starch to prepare the sheet surface for a further functional coating. By design, the excess starch from the puddle re-circulated back to a machine run tank. This re-circulating starch solution continually picked up fiber and felt hair from the sheet, uncooked starch from the cooker, and other miscellaneous debris including large wads of paper during machine breaks.
The existing filter system running with 0.006 inch (150 µm) slotted wedge wire media was unable to maintain overall starch cleanliness over time. Two trials were run using a Kadant Pulse Purge filtration system: the first with 0.002 inch (50 µm) wedge wire media, the second with 0.001" media.
Results
By consistently filtering the precoat starch in the range of 25-50 µm, significant benefits were seen. When the trial unit was first put online, improvements were seen in overall runnability and quality. After the unit was taken offline, this same step change occurred in the negative direction. The following data summarize the tangible results of the two separate trials:
- Pre-coat size press solids rose from 9% to 12%
- Paper machine holes reduced by 11%
- Off-machine coater holes reduced by 11%
- Overall splice ratio reduced by 23.7%
- Pre-coat run tank sludge reduced by 68%
- Pre-coat sewer loss reduced by 260 gallons/day (985 l/day)
- Improvement in mill print tests
- Labor savings from decreased filter maintenance.
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| Start-up/Details |
Customer |
| Metso Paper - 2004 |
Trim at reel: 4,016 mm
Design speed: 600 m/min
Type: On-machine coater with one Valcoat coating
head for coating of SBB |
BM 1 - Iggesund Paperboard
Iggesund
Sweden |
Trim at reel: 7,800 mm
Design speed: 2,000 m/min
Type: On-machine coater with one OptiSizer coating head for coating of LWC |
PM 1 - Jiangxi Chenming Paper Co. Ltd
Nanchang, Jiangxi province
China |
Trim at reel: 5,900 mm
Design speed: 1,350 m/min
Type: On-machine OptiSizer for sizing and coating
of fine paper |
BM 1 - Stora Enso North America
Kimberly Mill, Kimberly, WI
US |
Trim at reel: 8,070 mm
Design speed: 900 m/min
Type: On-machine coater with five OptiCoat Jet coating
heads for coating and top coating of board |
BM 1 - Ning Shing Development Co.
Ningbo, Zheijiang province
China
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| Metso Paper - 2005 |
Untrimmed paper width: 5,650 mm
Design speed: 800 m/min
Type: On-machine coater with four ValCoat coating
heads for coating of folding boxboard |
BM 3 - Shandong Chenming
Shouguang, Shandong province
China |
| Voith Paper - 2004 |
Untrimmed paper width: 3,750 mm
Design speed: 1,000 m/min
Type: DF coater for production of woodfree coated
CCP and woodfree coated thermographic paper (30-70 g/m2) |
SM 7 - August Koehler,
Oberkirch
Germany |
| Voith Paper - 2005 |
Untrimmed paper width: 9,770 mm
Design speed: 2,000 m/min
Type: Dynacoat for production of woodfree coated paper (70-128 g/m2) |
PM 3 - Gold East Paper
Dagang, Jiangsu province
China |
| Voith Film coaters - 2004 |
Untrimmed paper width: 4,250 mm
Design speed: 600 m/min
Type: SpeedSizer for woodfree ink-jet paper and greaseproof paper (30-80 g/m2) |
PM 6 - Hostinne
Papcel, Litovel
Czech Republic |
Untrimmed paper width: 6,400 mm
Design speed: 1,300 mm
Type: SpeedSizer for testliner and corrugating medium (75-220 g/m2) |
CL 1 - Chueng Loong
Shanghai
China |
Untrimmed paper width: 8,100 mm
Design speed: 2,000 m/min
Type: SpeedSizer for LWC (39-60 g/m2) |
PM 4 - LEIPA Georg Leinfelder
Schwedt
Germany |
| Source: Metso Paper; Voith Paper. |
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