Case Study: Innovative Strength Technologies for Paper and Board on the Basis of Modified Renewable Raw Materials

Transcription

1 Journal of Korea TAPPI Vol. 49. No. 3, 2017, 71-78p ISSN (Print): Printed in Korea Case Study: Innovative Strength Technologies for Paper and Board on the Basis of Modified Renewable Raw Materials Jan-L. Hemmes, Jinho Lee 1 and Ron Lai 2 Received December 16, 2016; Received in revised form February 20, 2017; Accepted June 20, 2017 ABSTRACT Today and in the foreseeable future the paper and board industry has increased difficulties to access high quality fiber raw materials economically. At the same time the conventional technologies to impart strength by using high refining and high levels of starch for increasing strength are often in conflict with the productivity targets. In addition the need for environmental sustainability favors lower unit weight with high protection functionality for fiber based materials competing in the future markets. Kemira has developed Eco- Fill and FennoBond as new and unique strength technologies with distinct value as a response to these challenges for various paper, board and tissue applications. The EcoFill technology is based on modified cellulosic materials with controlled solubility. It has already found its way into paper and board applications. The EcoFill technology is based on ECA, a modified cellulosic materials with controlled solubility. Strength is imparted to the treated furnish through the increase of hydrogen bonding. Strength properties can be enhanced by selective treatment of the weaker and lower binding components in the paper web. EcoFill is a unique technology used for filler or fiber treatment and is especially powerful when high strength or large substitution with cheaper raw material is required. Using the EcoFill technology for filler treatment enabled the customer to increase the filler content by 5% or more without major compromises for strength quality. SEM inspection of the microtome sections of the filled papers (Fig. 1) show the good uniformity and even filler distribution in the sheet. Although substantially more filler can be seen on the surface, the technology binds the filler well, so no increased dusting in printing and converting is observed. Other proven benefits of these strength technologies include quality upgrades, improved productivity and energy savings. The second part of the presentation will discuss how the gained expertise together with the innovative use of chemistry in the future will make the use of natural products like Starch and Cellulose more cost effective and more valuable for the paper and board industry. Keywords: Ecofill technology, fennobond, ECA (engineered cellulose additives), CCA (charge control additives), ecofill brite, ecofill lite Kemira Germany, Global Marketing Strength Additives, D Frankfurt, Germany 1 Manager, Application and Marketing Pulp & Paper, Kemira Korea, Seoul, Republic of Korea 2 Global Business Development Manager, Pulp & Paper, Kemira Sweden, Kungälv, Sweden Corresponding Author: J. of Korea TAPPI Vol.49 No.3 May-Jun

2 Case Study: Innovative Strength Technologies for Paper and Board on the Basis of Modified Renewable Raw Materials 1. Introduction Today and in the foreseeable future the paper and board industry has increased difficulties to access high quality fiber raw materials economically. Dry strength of paper and board is a very important functional requirement for many end uses and has traditionally been adjusted by the paper producer through the use of Kraft fibers, suitable optimization of refining and utilization of natural or synthetic binders. As a result of limited availability of high quality virgin and recycled fibers and the growth of packaging and tissue we expect the growth of the dry strength chemicals market to be higher than the annual average growth of the paper industry and estimate it to average out at 3.5% until The highest growth market will remain to be APAC in Fig. 2. Technologies to impart strength by using refining and high levels of starch or synthetic polymers are often in conflict with the productivity targets. In addition the need for environmental sustainability of packaging materials favors lower unit weight with high protection functionality which can be translated into an even higher demand of strength for fiber based materials to be successful in future markets. Untreated-Baseline, 80 g/m 2 EcoFill TM -Baseline + 4% Filler Fig. 1. SEM cross sections of offset papers at different filler levels (EDX results for Ca in red). Fig. 2. Development of global strength market (APAC: Asia Pacific, SA: South Africa, EMEA: Europe, Middle East, and Africa, CAGR: compound annual growth rate). 72 펄프 종이기술 49(3) 2017

3 Jan-L. Hemmes Jinho Lee Ron Lai During the recent years Kemira has put much R&D effort to develop technologies that meet the technical, economical and sustainability requirements of modern paper and board production lines. We have also used more biomaterials as a basis for our paper chemistry with a focus on areas like dry strength, sizing and coating binders with a high specific use of functional chemistry. In this contribution we will focus on Kemira`s EcoFill Technology, and on the economic value it brings to the paper from the combined view on raw materials, process chemistry and end use properties. Industrial cases will demonstrate how we realize this value for a specific paper. A short outlook on future technologies will round up. 2. Cellulose Based Strength Technologies and Ecofill Technology There is a lot of development efforts ongoing in the area of cellulose based products since MFC and NCC has been researched in the 80ies of the last Century. Though their basic properties are well described by science, main efforts are currently being put on the cost and energy effective manufacturing in industrial scale (Fig. 3). We will return to this topic at the end of the article in a bit more detail - meanwhile concentrate on a product which we at Kemira call ECA. ECA stands for Engineered Cellulose Additive. These products are high molecular weight soluble polymers made from Cellulose by chemical modification and have an anionic charge density which is an order of magnitude higher as wood fibers and an order of magnitude lower as CMC. ECA can be described as a cellulose based compound in between that of a MFC and CMC designed to give efficient improvement in strength while giving good dewatering properties when used in combination of fixatives. Due to the high molecular weight we produce and sell it in powder form, ready for onsite dispersion similar like a dry PAM polymer. The ECA product is used in Kemira`s EcoFill technology. EcoFill is a ready-to-use two-component concept combining Engineered Cellulosic Additive (ECA) and Charge Control Additive (CCA) to treat either the filler slurry or fibers. It provides strength to paper and board by binding ECA to the fiber or filler. The charge control additive use in EcoFill are different based on the requirement as the EcoFill chemistry must be compatible with the furnish. The application way of EcoFill should be added. For EcoFill Brite, the fresh filler is diverted from Fig. 3. Cellulose chemistry: products charge, size and manufacturing process. J. of Korea TAPPI Vol.49 No.3 May-Jun

4 Case Study: Innovative Strength Technologies for Paper and Board on the Basis of Modified Renewable Raw Materials the normal filler flow, treated with ECA and CCA and dosed at the same point back to the furnish as previously. The treatment is continuous. For Eco- Fill Lite, the ECA and the CCA are normally added to the thick stock. For even higher addition of fillers or substitution of high strength Kraft furnish with lower quality grades, EcoFill Brite enables significant cost reduction and improve sustainability without compromising production efficiency. With EcoFill ECA we have created a reliable and robust strength system that can be mixed with the filler as part of the Kemira EcoFill Brite concept. EcoFill application technology ensures the filler is very well anchored to the fiber surfaces. It also ensures uniform paper quality and excellent machine run ability. EcoFill is suitable for fillers like e.g. GCC, PCC and GCC/PCC blends. As a part of our application technology we utilize a proprietary high filler mixing rig for filler treatment together with an ECA make-down unit and a simple dosing pump for the CCA. This is required to achieve the proper charge neutralization, avoid flocculation and achieve even distribution of individual filler particles in the paper. The above Fig. 4 uses high resolution SEM photographs to help illustrate and explain the EcoFill Brite mechanism and impact on papermaking. The 500 SEM photo shows the filler is well distributed in the paper matrix. Good distribution of filler is achieved due to the combined action of diluting and mixing the filler through our EcoFill mixing rig and then injecting this into the furnish. The 2,000 SEM photo shows the well-fixed filler particles attached to the fiber surface. This is achieved by a combination of using the ECA to bind the filler to fibers and controlling the charge of the filler slurry in an optimum range with the CCA in our mixing unit, to give the best optical properties and strength performance. In a similar manner we can also treat weak fibers with the strength concept. EcoFill Lite is a robust technology for packaging grades withstanding high closure of the wet end system and high conductivity levels. It is usually applied in combination with a charge control additive. Depending on the case and furnish composition the concept can be used to achieve strength increases of over 10% up to 25% when added to the thick stock of the paper machine or to the weak fiber stream. 3. Ecofill Technology Industrial Cases 3.1 Case 1: White top liner A North American producer of white top liner Filler distribution 500 SEM photo Filler fixation 2,000 SEM photo Fig. 4. Cellulose chemistry: products charge and size and manufacturing. 74 펄프 종이기술 49(3) 2017

5 Jan-L. Hemmes Jinho Lee Ron Lai qualities with a 2 ply machine wanted to save on virgin Kraft fiber in the bleached Kraft fiber containing top ply. Printability had to be maintained at increased ash levels, mainly surface strength was considered to be critical. EcoFill Brite was added at 5.5 kg/t to the filler pigment PCC and after the optimization work filler levels could be increased by 5% (9% to 14-16%). The SEM pictures of the liner shows how the filler pretreatment (Fig. 5 red areas) with EcoFill results in better optics and good printability even at 9% reduced grammage of the top ply. Surface strength of the top liner at the higher ash levels was even increased. No pigment or fiber dusting could be found in the press room. The overall economic benefit for the customer in this case was calculated to be well over 1 million. 3.2 Case 2: EcoFill Brite for UWF with high filler An Asian producer of uncoated free sheet for offset and laser print applications introduced the EcoFill Brite technology to become more economic, eliminate dusting and keep the runability of the paper machine. Grammage area was gsm produced on a gap former machine at around 1,100 m/min. Fiber base is tropical hardwood and some softwood Kraft. Using the EcoFill technology for filler treatment enabled the customer to increase the filler content by 5% without major compromises for quality. SEM inspection of the microtome sections of the filled papers (below Fig. 6) show the good uniformity and even filler distribution in the sheet. Although substantially more filler can be seen on the surface the technology binds the 205 gsm reference with 6-8% filler 205 gsm with Ecofill Brite and 14% filler Fig. 5. SEM cross sections of WTL at different filler levels (EDX results for Ca in red). Untreated-Baseline 80 gsm UFS Grade Ecofill TM -Baseline + 4% Filler 80 gsm UFS Grade Fig. 6. SEM cross sections of offset papers at different filler levels (EDX results for Ca in red). J. of Korea TAPPI Vol.49 No.3 May-Jun

6 Case Study: Innovative Strength Technologies for Paper and Board on the Basis of Modified Renewable Raw Materials filler well, so no increased dusting in printing and converting is observed. At this 5% higher ash level the estimated net savings are around 1.5 M. In the meantime the customer has been changing from GCC to PCC filler and has added additional filler so that a range of 21-28% filler over the range of produced grammages and grades can be achieved. The estimated total savings increases to 1.7 M annually. 3.3 Case 3: Quality upgrade of sack paper The third case describes our experience in upgrading of a European sack paper. The customer wanted to produce a Kraft based high performance grade with better strength properties and maintained porosity. Addition of the EcoFill Lite dual system in the thick stock led to an increase in tensile energy absorption (TAE) values of 20%. Porosity targets could be maintained. The contribution from these additional high performance grades improved the viability of the mill adding over 1 million in added value. 3.4 Case 4: Quality upgrade of Testliner and Medium The last case refers to Testliner and Medium corrugating board materials production. A quality upgrade was desired by the customer and running of overweight with the negative consequences for raw material cost and productivity had to be avoided. By implementation of the EcoFill Lite concept mechanical specifications could be met for all grades and also production records were achieved during two consecutive month after the change had been implemented. 3.5 Outlook on industrial applications of macro fibrillated cellulose (MFC) and nano crystalline cellulose (NCC) In the last part of the paper we will discuss how in the future paper expertise together with the innovative use of chemistry will make the use of renewable products from cellulose more cost effective and more valuable for the paper and board industry. A lot of information is already known about the unique properties of micro fibrils and nano crystalline cellulose in paper applications, however, there are also major drawbacks related to this technology -namely manufacturing costs and dewatering properties. Ionic dry strength polymers Fig. 7. Quality up-grade on Sack Paper. 76 펄프 종이기술 49(3) 2017

7 Jan-L. Hemmes Jinho Lee Ron Lai Fig. 8. Quality upgrade on Testliner and Medium. have synergistic effects with MFC, reducing the amounts needed and improving the dewatering of those systems. In addition Kemira has developed an additive for on-site production of wood based MFC which is added during the fibrillation step and improves the rheology and energy consumption in the homogenizer. The benefit of such a concept has been tested for multilayer board and confirmed in pilot trials using high amounts of CTMP to replace Kraft fibers. In the Fig. 9, it can be seen how internal bond can be maintained with a combination of MFC, cationic starch and a dry strength polymer (FB=Fennobond, Kemira s strength chemical trade name) without compromising on press dryness. 4. Conclusions The effects of dry strength chemicals are complex but can be used to make big differences on the functionality and quality of the end product and also on the productivity of a paper, board or tissue machine. The investment in these technologies should receive the best possible return. Requirements are different from grade to grade as is Fig. 9. Middle ply of multilayer board light weightening by replacing kraft with CTMP. J. of Korea TAPPI Vol.49 No.3 May-Jun

8 Case Study: Innovative Strength Technologies for Paper and Board on the Basis of Modified Renewable Raw Materials the environment of the production line - it is thus important to select the fittest technology to do the specific job from a range of technologies and best application practices available. Kemira has developed EcoFill as new and unique strength technology with distinct value for various paper, board and tissue applications. Application technology is a key for new technologies to fully unfold the potential benefits for the customers. Kemira's value calculator is an integral part of our process to select products and optimize value by comprehensive technical and economical surveys. EcoFill is a unique technology used for filler or fiber treatment and is especially powerful when high strength or large substitution with cheaper raw material is required. Overall, the benefits of Kemira's strength technologies include quality upgrades, improved productivity and energy savings. In the future new technologies based on cellulose as renewable source are under development. Chemistry has the answers to make MFC, NCC and new derivatives available for the paper maker at acceptable cost and with optimized performance on strength and dewatering. Literature Cited 1. Lindström, T., et al., On the nature of joint strength in paper, a review of dry and wet strength resins used in paper manufacturing, STFI-PF report 32, Watanabe, M., Gondo, T., and Kitao, O., Advanced wetend systems with carboxymethylcellulose, Tappi J. 3(5):15-19 (2005). 3. Kajanto, I. and Kosonen, M., Journal of Science & Technology for Forest Products and Processes: Vol. 2, No. 6, Klemm, D., Keamer, F., Moritz, S., Lindrtrom, T., Ankerfors, M., Gray, D., and Dorris, A., Nanocellulose: A new family of nature-based materials, Angewandte chemie International Edition 50(24): (2011). 78 펄프 종이기술 49(3) 2017