Sustainable Nonwoven Materials by Foam Forming Using Cellulosic Fibres and Recycled Materials Aachen Dresden International Textile Conference Aachen, 27.-28.11.2013 Pirjo Heikkilä, Petri Jetsu, Karita Kinnunen, Marjo Määttänen, Kyösti Valta & Ali Harlin VTT Technical Research Centre of Finland
2 Contents Background Our approach Foam forming method Textiles from recycled cardboard Conclusions
3 Background Textile processing path is complex including water and energy intense steps and use of various chemicals Sustainability issues with textile processes Some chemicals harmful for people and environment Water purification needs and waste waters Large energy use e.g. due to drying
4 Background World textile fibre consumption (70 million tons/year, 2010) Synthetics ~60% Cotton ~33% Man-made cellulosics ~4% Others (natural fibres other than cotton ~3%) Sustainability issues with certain fibres Synthetics oil based raw material Cotton environmental issues: water use and chemicals Viscose use of CS 2 in process
5 Our approach Sustainability issues of nonwoven materials can be considered in processing as well as in raw material choice. Our process: 1. Foam forming instead of wet-laying less water, less energy, excellent formation 2. Use of cellulose carbamate instead of viscose process no need for carbon disulfide (toxicity & environmental risks) 3. Use of recycled cardboard as raw material for cellulosic use of recycled instead of virgin/genuine cellulose
6 Foam forming in general Foam as transport media instead of water: fibres and additives mixed with foam Foam consists of water, foaming agent and air (typical air content 50-70%) Air bubbles prevent flocculation of fibres In paper processing significant resource savings (raw material, drying energy and chemical costs) with foam forming technology.
7 Foam forming as textile processing method Advantages over traditional forming and other textile methods: Possibility to adjust porosity and bulkiness in forming. Less water compared to wetlaying less energy in drying and transport. Possibility to use longer fibres compared to wetlaying and airlaying. High forming consistency compared to wetlaying. Good formation, more homogeneous compared to other nonwovens and textiles. Better productivity compared to most other textile processes.
8 Foam forming / laying research environments Handsheet formers Small-circulation device KISU SUORA-research environment Sample size 250*380 & 500*500 mm. Laboratory pressing & drying Web width 120 mm. Laboratory pressing & drying Web width 250 mm. Reeled sample & offline cylinder drying ~1000 m/min (foam) 2000 m/min (water) Web speed - 300 m/min (foam) 300 m/min (water) Amount of >Few grams > 5 kg > 300 kg fibers Layered From one upto five 3-layers (foam) Single layer (foam) products Single layer (water & water) 3 layers (water) Forming 1-sided dewatering 1-sided dewatering Fourdrinier / hybrid / gap geometry
9 Foam laid products from commercial fibres 100 % Viscose (9 mm) Viscose (9 mm)-bicomponent 60 g/m 2 (PES/PE, 5 mm) 1:1 mixture 60 g/m 2 Viscose (9 mm) - pine kraft 1:1 mixture 60 g/m 2
10 Textiles from recycled cardboard Recycled cardboard (or paper) Purification Carbamatization Dissolution Cellulose carbamate solution Wet-spinning Cellulose fibres Foam forming Nonwoven web
11 Purification steps of recycled fibres Fines removal DDJ For RCF Board Cooking and O-delign. Cold caustic extraction CCE Bleaching DEpDP Enzyme Treatment EG Acid Washing A Ash removal P: 2 % => 0.6 % B: 7.9 % => 1.4% Lignin removal B: 16.2% => 5% Hemicelluloses removal P: 21 % => 9 % B: 21 % => 8% Brightness and purity Reactivity and viscosity adjustment Metal removal
12 Cellulose carbamate process Ref RCF paper RCF board DP initial DP CCA CCA (%) final Ball visco. (s) N (%) Ref Domsjö 780 300 6.1 40 1.2 RCF Paper 600 290 5.6 19 2.2 RCF Board 290 250 6.3 22 1.5
13 Cellulose carbamate process (in viscose process line) CCA dissolving CCA stabile at dry state Solution 4-10% in NaOH 8% solution chilled to +5 C for long time storage
14 Wet-spinning and properties of fibres Stretch ratio % Titre dtex Tenacity cn/dtex Elongation % Modulus cn/dtex Ref Domsjö 100 2.0 2.1 15.2 74.5 RCF Paper 120 1.9 2.1 16.2 72.5 RCF Board 120 2.2 2.0 15.4
04/12/2013 Foam laying of wet-spun fibres CCA fibres were cut to 13 mm or 25 mm length and bundles opened using laboratory scale carding device. The quality of the sheets formation depended on how well the carding was done. 15
16 Techno-economic feasibility of dissolving pulp process [ /adt] 500 400 300 200 100 0-100 Ref SW DP Ref HW DP RCF Board RCF Paper Waste 2 2 2 2 Utilities 5 5 3 12 Chemicals 32 24 25 49 Wood and RCF 341 289 223 260 By-products -80-66 6 5 Tot. 300 254 259 328 The total costs of RCF board over 15 % lower than the reference SW and same as reference HW. Reference pulp mill Nordic prehydrolysis kraft pulp mill producing 2000 adt/day of pulp. The fibre raw material cost was dominating factor for all cases covering 80% of total costs. Especially the price of RCF fibres has been fluctuating. Revenues from by-products were deducted from the costs only with reference mills. Techno-economic feasibility study is based on the mass and energy balances of process as well variable production cost estimates.
17 Summary and conclusions Foam laying is viable method for more sustainable, and presumably also economically feasible, nonwoven production. Use of recycled raw material interesting option also from economical point of view. Cellulose carbamate technology can replace viscose technology also mechanical properties similar than those of commercial fibres. The production of the staple grade fibres from recycled paper and board using carbamate technique was proven to work with rather good economic - variable costs of dissolving pulp produced from board was 15% lower than reference softwood pulp.
18 Thank you for your attention! Questions? Senior scientist Pirjo Heikkilä, Dr. Tech. VTT Technical research centre of Finland +358 40 689 1443 pirjo.heikkila@vtt.fi Acknoledgement Tampere University of Technology Wet-spinning
19 VTT creates business from technology