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Coated Paper & Board
Production & Trade Tables
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After a tough couple of years, it seems things at last are looking up for coated grades. 2002 saw a small increase in output (see Table 1), although production was still below 2000 levels. The market is expected to continue to grow slowly in 2003 (PPI, January 2003) and a limited amount of new capacity is due come on stream in the next 12 months - for instance, in Europe, Stora Enso's rebuilds of PM 5 at Corbehem, France (which produces LWC paper for rotogravure printing) and of PM 2 at Kotka, Finland (coated magazine paper); and in Asia, Shandon Quanlin's 200,000 tonne/yr WFC (woodfree coated) paper mill in Gaotang, Shandong province, China.
"Key current market drivers for coated papers are gloss, opacity, and cost efficiency," says RohmNova. The chemicals company believes one way that paper producers can deliver these properties is through the use of hollow-sphere synthetic pigments in their coating formulations. To this end, RohmNova has introduced NovaPlex G1000, which, it says, is a cost effective, high solids multi-modal synthetic pigment for coated paper and paperboard that improves gloss, ink gloss and coverage.
| Metso Paper’s new OptiSpray on-line spray coating process, MD Lang Papier, Albbruck |
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Continued investment
Suppliers are also continuing to invest in research, new plants and new technology: good news for the industry.
One example of technological innovation comes from Metso Paper, which recently installed its first OptiSpray on-line spray-coating process on PM 5 at MD Lang Papier's Albbruck mill, Germany. In this new system, the coating color is atomized under high pressure and applied simultaneously to both sides of the web while it is not in contact with any part of the machine. The paper is then dried by means of high-performance TurnDry air dryers.
Printing results from the first reels produced after PM 5 restarted in January 2003 are said by Metso to be very promising. MD Lang Papier hopes to exploit the advantages of the new spraying technology in order to produce the same high-quality paper grades already being supplied by PMs 6 and 7 at Albbruck, as well as to open up new markets.
OptiSpray is one of a family of coating technologies supplied by Metso Paper that also includes: OptiCoat Duo, OptiBlade, OptiCoat Jet, OptiSizer and AutoBlade and ValCoat applicator roll coating heads. The company has been awarded contracts for a number of coater installations in 2003 and 2004, including several in the rapidly expanding Chinese market (see Table 2). Metso is also celebrating a world record for Coater 3 on PM 8 at UPM-Kymmene's Kymi Paper mill, Kuusankoski, Finland. The off-machine OptiCoater equipped with two OptiCoat Jet (free jet) coating stations, high-speed unwind and OptiReel Plus reel is said to have achieved a maximum speed of 2,204 m/min, a flying splice at 2,004 m/min, and a running speed of 1,785 m/min.
On the R&D side, RohmNova enhanced the capabilities of its pilot coater in two ways during 2002:
• A de-aerator was installed to optimize the performance of the Jet-Fountain applicator
• A new short-dwell coater was installed and has successfully supported a number of customer evaluations. To date, the coater has been successfully run at speeds of more than 1,220 m/min.
The company says it plans additional investments for the pilot coater facility in 2003, including further enhancement of the drying section.
CalciTech is another supplier investing in new solutions for coated paper producers. This recently formed company aims to take market share from ground calcium carbonate (GCC) and Kaolin with a range of Synthetic Calcium Carbonate (SCC) coating pigments.
The new products are manufactured by a process that involves the selective dissolution of calcium from industrial waste and its subsequent precipitation from solution with waste CO2 into pure calcium carbonate.
The first two products in the CalciTech range were unveiled in February 2003. Calci LS is engineered to maximize light scattering and is targeted to partially replace and extend Titanium Dioxide (TiO2), Aluminium TriHydrate (ATH) and Precipitated Silica (PS), as well as fully substitute calcined clay in fine paper and SCA+ applications on a cost effective basis.
The second product, Calci SG, is designed to provide a super gloss coating for premium grade printing and writing papers including LWC and coated folding boxboard. In the latter application, Calci SG allows for a reduction in calendering nips to improve bulk at no loss in gloss, says CalciTech.
Tests on paper coated with CalciTech SCC carried out by the Centre Technique du Papier (CTP) in Grenoble, France (the French pulp and paper research institute) show that it demonstrates improved brightness, opacity and gloss compared with GCC 90-coated paper, both before and after calendering.
"This gain in gloss before calendering can bring something new to the paper industry," says Francois Roux, CalciTech's product development manager.
Initial quantities remain very limited and are distributed to a selected number of launch customers, since CalciTech's commercial test plant in Leuna, Germany, can produce only 800 tonnes/yr SCC. Large volume supply will become available following the commissioning of the company's first full commercial scale plant at the Leuna complex in 2004. Total capital investment in the plant will be Euro 12 million ($13 million). The production facilities are projected for a capacity of 40,000 tonnes/yr in the first stage.
CalciTech has also entered into negotiations with Carbide Industries of Louisville, KY to source carbide lime. Successful negotiations will result in the construction of a US production plant for the manufacture of the entire range of CalciTech SCC products.
Kemira Chemicals is another supplier investing in its production facilities. The company is spending Euro 5 million in an expansion of the Siilinjärvi pigment plant in Finland. The new calcium sulphate pigment production line will raise the plant's total production capacity to 100,000 tonnes/yr. The production line, whose technology has been developed by Kemira itself, will be operational by late 2003.
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| CalciTech's commercial test plant for production of Synthetic Calcium Carbonate, Leuna, Germany |
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The company's calcium sulphate pigment, marketed under the brand name CoCoat, is used for coating printing paper to improve the brightness, opacity and printability of paper. Calcium sulphate also facilitates the production of lighter paper, as it has a lower density than other pigments. Kemira says the pigment has created a lot of interest among papermakers looking for niche products in areas such as direct mail marketing.
Sizing it up
Kemira has also been active in its attempts to strengthen its sizing agents business over the last 12 months. A new ASA production unit was started up in October 2002 in Krems, Austria, doubling the site's capacity and making Kemira the largest producer of ASA sizing agents in Europe. The ASA content of the product produced at Krems is kept at a minimum 95%, and the process residue levels are very low, giving a brighter product and less strain on the water cycle. Kemira also designs and manufactures the emulsifying equipment, adding to the reliability of the product, it says.
The company's work on a new surface size line has borne fruit in the form of Hydrores SF 4. Applied with starch, the new surface size offers excellent printability and prevents ketone migration when high quality office paper is produced with AKD as internal size. Test results from a pilot paper machine show that Hydrores SF 4 significantly improves hydrophobic properties of office paper when AKD is used as the internal sizing agent, says Kemira. Benefits include improved ink-jet printing properties such as optical density and wicking (roughness), as well as less ketone migration. The product will be launched later this year.
Kemira is also targeting the North American sizing market, following its 2002 acquisition of Vinings Industries. Kemira says transfer of sizing technology from its European bases has progressed according to plan, and it has established customer contacts in all the main sizing technologies.
| GL&V's HydraSizer, as seen at Solvay Paperboard |
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Another new development in the sizing market is the Hydra-Sizer from GL&V, a technology for applying uncooked starch or other additives on the wet end of the paper machine. This technology can be used to apply regular unmodified starches, which cook in the dryer section. The application is very uniform and has high retention says GL&V. The starch application can be controlled to apply starch to the surface of the sheet only, or to distribute starch throughout the thickness of the sheet.
Solvay Paperboard, in Syracuse, NY has purchased a total of three Hydra-Sizers, the first of which has been running on its PM 2 since August 2001. This machine makes recycled linerboard in the 171-337 g/m2 range. The Hydra-Sizer was installed on the base fourdrinier to apply corn starch, which increased the strength properties of the sheet. The compressive strength properties were significantly improved, allowing the mill to reduce refining, and increase off-machine production, says GL&V. This unit is the first Hydra-Sizer installation in the US.
Solvay has since purchased two more Hydra-Sizers. The second installation started up in August 2002 on the mill's new PM 3, making recycled corrugating medium. This installation allowed the mill to achieve target strength characteristics using a blend of OCC and mixed office waste furnish. The third Hydra-Sizer is now undergoing optimization trials on the mill's PM 1, which produces lightweight linerboard.
Improving runnability and printability
"Improving the high-speed flow behavior of paper coatings is critical to blade coater runnability," says RohmNova. The company is introducing a new concept in understanding and measuring the runnability of coating colors. Coating flows close to a solid boundary, such as a blade, are different from those in the bulk, says the supplier. Wall slip can occur through an 'apparent slip', which is manifested by formation of a thin layer of liquid phase - the 'slip layer' - that has a viscosity lower than that of the color adjacent to a boundary wall. The slip layer consists of the particle-free suspending medium. In blade coating applications, occurrence of a slip layer at the blade tip boundary has been hypothesized to relate to runnability and wet bleeding. Occurrence of slip close to the blade nip reduces friction and blade streaks. High slip velocities are therefore desirable for good blade coater runnability, explains RohmNova.
Coating colors may have the same high-shear viscosity and water retention but give different slip velocity. Slip reduces with high solids and high viscosity thickeners. High solids colors can be made to behave like lower solids coatings, which have good blade runnability, by incorporation of a lubricant. From the three different families of lubricants, calcium stearate, polyethylene emulsions, and organic glycerides, calcium stearate has been found to especially induce slip. RohmNova says that among various calcium stearates, its product, Sunkote 455, has been found to be the most effective for creating slip, even in coatings with 100% narrow-particle-size calcium carbonate. "This lubricant can be efficiently used to assist supercalendering, but also improve coater runnability by providing slip," says RohmNova.
Improved printability is increasingly important for coated board mills, as a trend toward higher impact graphics is underway in all segments, points out Eka Chemicals. The printed image and glueability of the package is critical for carrier board producers to expand into folding carton applications for computer software and frozen foods, it says.
Ammonium zirconium carbonates, such as Eka's product, AZCOTE, are becoming widely used in synthetic binder coatings for coated paper and board. Potassium zirconium carbonates deliver the benefits of zirconium chemistry without ammonia. Both reportedly offer better ink hold out and printability, and do so at a lower overall coating cost, the supplier says.
Zirconium carbonates react rapidly to provide a ready to use coated sheet at the end of the paper machine. Alternative chemistries react more slowly; they require a delay or cure time before the paper may be printed or converted into a package, says Eka.
Another advantage claimed for zirconium carbonates is that coated paper and paperboard produced with appropriate zirconium chemistry may be tested for relevant end use properties immediately, greatly reducing instances of paper being returned by dissatisfied customers.
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