OptiSizer Curtain
Improving strength and surface properties
The new, innovative surface sizing method applies the starch as a curtain of size. When the application method is combined with hard-covered nip rolls, which ensure a good penetration of starch, the results in coated cartonboards production are significant: stiffness, quality and production values can be increased, and energy and raw material consumption reduced.
High production capacity and stiffness
Less drying and improved runnability
High surface quality and flat topography
Energy and raw material savings
New application method
A new size application method where size is applied as a curtain flow on hard-covered rolls makes it possible to produce high quality coated cartonboards with enhanced properties. The new curtain sizing process has already been demonstrated repeatedly at Valmet’s Paper Technology Center pilot trials. High increase in board stiffness values have been reached with curtain starch application.
The application beam forms a curtain of starch on roll with high solids and viscosity, which gives totally new operating window for sizing compared to pond, film or spray application as seen in Figure 1.
As high starch solid contents (20-30%) can be used with curtain application giving the opportunities to improve runnability of size press (less wetting of sheet) and to increase savings in drying energy. Reduction of wetting and increased pressure in the nip also reduce or eliminate the unwanted roughening effect of sizing. Consequently, very good surface smoothness and topography are achieved, which might lead into a possibility to reduce the amount of coating color.
Cartonboards with enhanced properties
The new opportunities in size composition with curtain application make it possible to produce coated cartonboards with enhanced properties. The optimized balance between size coverage and size penetration can be adjusted by nip load in curtain sizing. For example, low pressure in sizing can be used to maximize board stiffness, and high pressure can be used, if the target is to increase ply bond or internal bond, see Figure 2.
Want to talk to our sizing experts?
If you wish to get further information like technical specifications, need a quotation, or wish to discuss different solutions, fill in the contact form and our experts will contact you shortly.
Contact our expertsNew materials in size
Curtain sizing will give opportunities to mix new materials in size with no risk of plugging rods. Such opportunities include, for example, adding highly refined fibers, micro or even nano-scale fibrillated cellulose to sizing process. Of course, chemicals and pigments, which are already being used in sizing can be also applied with curtain sizing process, like, GCC, clay, hydrophobic sizing agents, color dyes or barrier chemic, etc.
Combining sizing with long nip metal belt calendering
When the new sizing process is combined with metal belt calendering (OptiCalender Metal Belt) with a long nip, the stiffening effect is further improved. At the same time, the topography and smoothness of the sheet are improved significantly. The effect of metal belt calendering is based on high amount of heat transferred from thermo roll and metal belt to the board web. This combined process of curtain sizing and metal belt calendering has a potential for a completely new performance level of coated boards, see Figure 3.
Want to know more about metal belt calendering?
Read more about Valmet's unique metal belt calendering
ExploreHow to plan a successful rebuild?
Rebuilding a paper or board machine can improve the competitiveness of your business and your processes. Download our e-book to learn more.
Download e-bookPlanning a grade conversion?
The world is changing fast; the consumption of papers is decreasing and boards increasing. Update your paper machine with Valmet to produce more profitable products.
Discover moreExplore our latest board and paper press releases
- Oct 3, 2024Valmet to supply an OptiConcept M board making line to Anhui Linping Circular Development in China
- Sep 26, 2024Metsä Board Simpele improves working conditions and safety with Valmet Fold-up Wall
- Sep 5, 2024Valmet to start change negotiations in Finland in its Paper business line’s Board and Paper Mills business unit
- Aug 16, 2024Valmet and Spinnova Plc sign a partnership agreement regarding process equipment for textile fibre production
- Aug 1, 2024Valmet closes the agreement to acquire majority shares in FactoryPal, a subsidiary of Körber
- Jul 8, 2024Valmet to supply operator training simulator to Graphic Packaging International in Waco, Texas, United States
- Jul 2, 2024Valmet to supply a high-capacity winder to Wuzhou Special Paper in China
- Jun 26, 2024Valmet to supply both a papermaking line and a paper machine rebuild to a customer in Asia-Pacific
- Jun 25, 2024Valmet to deliver a tissue machine to Andhra Paper in India
- Jun 19, 2024Valmet receives the second order of converting lines to Metsä Tissue in Mariestad, Sweden