Sustainable Nonwoven Materials by Foam Forming Using Cellulosic Fibres and Recycled Materials

Aachen Dresden International Textile ConferenceAachen, 27.-28.11.2013Pirjo Heikkilä, Petri Jetsu, Karita Kinnunen, MarjoMäättänen, Kyösti Valta & Ali HarlinVTT Technical Research Centre of Finland

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Contents

Background Our approach Foam forming method Textiles from recycled cardboard Conclusions

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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 environmentWater purification needs

and waste waters Large energy use e.g.

due to drying

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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 CS2 in process

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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

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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.

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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.

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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

Web speed - 300 m/min (foam)300 m/min (water)

~1000 m/min (foam)2000 m/min (water)

Amount of fibers

>Few grams > 5 kg > 300 kg

Layered products

From one upto five 3-layers (foam)Single layer (water & water)

Single layer (foam)3 layers (water)

Forming geometry

1-sided dewatering 1-sided dewatering Fourdrinier / hybrid / gap

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Foam laid products from commercial fibres

100 % Viscose (9 mm)60 g/m2

Viscose (9 mm)-bicomponent(PES/PE, 5 mm) 1:1 mixture

60 g/m2

Viscose (9 mm) -pine kraft 1:1 mixture

60 g/m2

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Textiles from recycled cardboard

Recycled cardboard (or paper)

PurificationCarbamatizationDissolution

Cellulose carbamate solution

Wet-spinning

Cellulose fibres

Foam forming

Nonwoven web

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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 removalP: 2 % => 0.6 %B: 7.9 % => 1.4%

Lignin removalB: 16.2% => 5%

Hemicelluloses removalP: 21 % => 9 %B: 21 % => 8%

Brightness and purity

Reactivity and viscosity adjustment

Metal removal

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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 1.2RCF Paper 600 290 5.6 19 2.2RCF Board 290 250 6.3 22 1.5

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Cellulose carbamate process (in viscose process line)

CCA dissolving

CCA stabile at dry stateSolution 4-10% in NaOH 8% solution chilled to +5°C for

long time storage

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Wet-spinning and properties of fibres

Stretch ratio%

Titre dtex

TenacitycN/dtex

Elongation%

ModuluscN/dtex

Ref Domsjö 100 2.0 2.1 15.2 74.5RCF Paper 120 1.9 2.1 16.2 72.5RCF Board 120 2.2 2.0 15.4

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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.

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Techno-economic feasibility of dissolving pulp process

-1000

100200300400500

RefSWDP

RefHWDP

RCFBoard

RCFPaper

Waste 2 2 2 2Utilities 5 5 3 12Chemicals 32 24 25 49Wood and RCF 341 289 223 260By-products -80 -66 6 5Tot. 300 254 259 328

[€/a

dt]

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.

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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.

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Senior scientist Pirjo Heikkilä, Dr. Tech. VTT Technical research centre of Finland

+358 40 689 1443pirjo.heikkila@vtt.fi

Thank you for your attention!Questions? Acknoledgement

Tampere University of Technology

Wet-spinning

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