Mark J. Kirwan Paper and Paperboard Packaging Technology
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ENVIRONMENTAL AND WASTE MANAGEMENT ISSUES
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•
fine particles of activated carbon absorb dioxins and furans, heavy metals
and other organic compounds
•
sprays of limewater mixtures neutralise acidic gases such as sulphur dioxide
(SO
2
) and hydrogen chloride (HCl)
•
bag filters remove dust particles down to 10 microns size
•
high chimney stack of 100m.
Emissions are monitored by appropriate authorities. In Europe, a European Directive,
1989, lays down minimum standards; national standards may be tighter.
For a detailed account of independent monitoring in London, consult reference
(Onyx, 2000). This report is the result of independent monitoring of air quality in
the vicinity of an EFW incinerator. Amongst the conclusions it was stated that the
incinerator did not appear to have a significant impact on air quality and that the
results were within national and European guidelines.
Incineration is widely practised in countries such as Germany, France,
Sweden, Denmark and Switzerland, where environmental issues have a high
profile. Many of the incinerators today produce heat for local communities, in
addition to electricity.
The UK Government view is that incineration can provide environmental benefits,
especially if markets for recycled material are uncertain and if it would signifi-
cantly reduce transport use. It accepts that as the EU landfill directive is imple-
mented, waste may be diverted from landfill at a rate faster than the markets for
recyclate can sustain and hence, alongside a move to a higher level of recycling,
a move to a higher level of incineration with energy recovery is necessary over the
next 10–15 years in order to develop a more sustainable waste management
system (‘Less Waste more value’, 1998).
It is claimed that incineration with energy recovery is the preferred option com-
pared with recycling when environmental aspects are taken into consideration.
This claim is based on the relative analysis of CO
2
emissions (New Scientist,
1997).
An innovation in the use of polyethylene (PE) recovered from liquid-packaging
cartons and plastic laminated wrappings has been reported where the PE is gasi-
fied after separation and used as a fossil-fuel replacement in a CHP system (Stora
Enso, 2002b).
2.5.3.4 Landfill
Disposal to landfill of waste, including paper and paperboard waste, is perceived
as the least environmentally sound option. There are several objections:
•
waste of agricultural land – this is not the case where waste is disposed of in
disused quarries but such sites are not usually located near the source of the
waste
•
emissions and waste of energy in the use of road or rail transport
•
dangers such as contamination of ground water by leaching, scavenging and
health hazards
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PAPER AND PAPERBOARD PACKAGING TECHNOLOGY
•
release of methane which is a much more harmful ‘greenhouse’ gas
•
shortage of space in convenient locations.
In many locations, however, it is a low-priced option and the government has to
use other means in order to divert waste from landfill. In Europe, a Landfill Directive
99/31/EC has set targets for the reduction of biodegradable waste.
2.6 Life cycle assessment
Life cycle assessment (LCA) is an audit (list or inventory) of the resources used by
a product in its manufacture and an assessment of the environmental consequences
(impact). LCA can also be applied to a process. The first stage is to define the
scope of the study. This sets the boundaries across which material resources and
energy pass into the cycle and from which the products and waste emissions to air,
water and solid waste leave the cycle. The study can include extraction of raw
material, manufacture, transportation, use up to the point of ultimate disposal or
recovery – hence the description ‘cradle to grave’ and even ‘cradle to cradle’.
The audit is factual and specific but must be carried out in conformance with
ISO (International Organization for Standardisation) standards. The second phase
is the assessment of environmental impact. Whilst the criteria used in the audit is
objective, assessing effect is more difficult as the threshold level for an effect may
be different in one location compared with another for a variety of reasons. An
example already noted was the case of receiving waters which can be as different
as a shallow river compared with a tidal estuary.
The ISO standards for LCA have been drawn up after international liaison
coordinated by Society of Environmental Toxicology and Chemistry (SETAC)
and the European Commission.
The following Standards have been issued:
ISO 14040:1997 LCA Principles and framework
ISO 14041:1998 LCA Goal and scope definition and inventory analysis
ISO 14042:2000 LCA Life cycle impact assessment
ISO 14043:2000 LCA Life cycle interpretation
ISO/TS 14048:2000 LCA Data documentation format
ISO/TR 14049:2000 LCA Examples of application of ISO 14041 to goal and
scope definition and inventory analysis.
Life cycle assessment is useful in quantitatively highlighting points in a life
cycle where environmental impact is high, and for evaluating the effects of life cycle
changes, by, for example, substituting one process with an alternative process. A case
study indicating several life cycle changes has been published, ‘Towards sustainable
development in industry – an example of successful environmental measures
within the packaging chain’. It is the result of cooperation between Tetra Pak,
Stora Enso and the Swedish Forest Industry Federation. It includes paperboard
minimisation and changes in printing, plastic extrusion coating, distribution, recovery
ENVIRONMENTAL AND WASTE MANAGEMENT ISSUES
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and recycling, all of which have reduced environmental impact in the life cycle
of a one-litre milk carton (SFI, 2002).
2.7 Conclusion
Basically, we are where we are today with respect to all paper and paperboard
issues for reasons other than those based on environmental considerations. Paper
recovery and recycling was established at least 100 years ago for sound technical/
commercial reasons. In 2002, recovered paper and paperboard provided around
45% of the world’s demand for fibre. The amount of fibre recovery and recycling
is rising for several reasons:
•
fibre demand is rising as the production of paper and paperboard increases
•
higher proportions are being recovered for societal and waste management
reasons.
Benefits can be stated for each of the three main fibre sources:
1. Chemically separated fibre – flexible fibre giving products with high strength;
when bleached is chemically pure cellulose, making the fibre odour and taint
neutral and the best choice for the packaging of flavour and aroma sensitive
products; process chemicals are recovered and reused; and the energy used in
manufacture is renewable as it is derived from the non-fibrous components of
wood.
2. Mechanically separated fibre – stiff fibre giving high bulk, i.e. high thickness
for a given weight of fibre (g/m
2
), which results in products with high stiffness
compared with products incorporating other fibres; high yield from wood; may
be given chemical treatment to lighten colour; and is sufficiently odour and
taint neutral for the packaging of many flavour and aroma sensitive products.
3. Recovered fibre – recovered fibre is functionally adequate and cost effective
in many applications. The quality depends on the paper or paperboard from
which the fibres were recovered. The use of recovered fibre in making recycled
paper and paperboard would rate highly for societal and economic reasons but
the environmental benefits are not proven. The main environmental benefit
claimed is that recycling in this way ‘saves trees’ and a general feeling is that
because waste is being reused the activity ‘must be an environmental benefit’.
Another benefit claimed is that recovered fibre retains the original solar energy
and the energy expended in the manufacture and use of the virgin fibre. Further
energy is, however, consumed in collecting and delivering fibre to the mills and
more energy proportionately is required to make recycled products. There are
more fibre losses in paper and paperboard manufacture using recycled fibre, and
as equivalent recycled products incorporate a higher weight of fibre, more water,
proportionally, must be evaporated during manufacture. As all these energy needs
are met by fossil fuel, the associated emissions are also proportionally greater.
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PAPER AND PAPERBOARD PACKAGING TECHNOLOGY
These points are made not in order to be controversial but solely to counter the
view that somehow it is better for the environment to use recovered fibre. Logistically,
we need recovered fibre for recycling. It would be difficult to replace recovered
fibre with virgin fibre over a short period, and the economic constraints of the
market together with society’s waste management needs will ensure an expansion
in the recovery and use of waste paper. This is important as sustainability depends
on economic and social needs as well as environmental implications.
The respective benefits of the different types, and combinations, of fibre
become more specific when particular papers and paperboards are considered for
specific applications. All fibres are not universally interchangeable. It is, therefore,
not practical to insist on a mandatory minimum level, or declaration, of recovered
fibre content.
Industry requires virgin fibres to meet the functional needs of many applica-
tions. It also needs virgin fibre to maintain the quality of recovered fibre and the
total quantity of fibre required by the industry overall. Virgin fibre is also required
to replace (‘top up’) recycled fibre which is lost in reprocessing. Fibres cannot be
recycled indefinitely, and reprocessing reduces fibre length to the point when it
eventually accumulates as sludge.
Hence for all practical purposes it is correct to say that virgin and recycled
fibres are both necessary.
Sustainability, as we have seen, depends on social and economic aspects as
well as environmental criteria. Many commentators have said that the environmental
debate has moved on from single issues, such as the virgin/recovered fibre debate,
to a more holistic environmental consideration of whole systems, which comprises:
•
procurement of raw materials
•
using energy to make paper/paperboard
•
converting the material into packaging
•
meeting regulations at all stages applying to air and water emissions and
solid waste
•
meet needs of the product to be packed during packing, distribution, point of
sale or delivery to customer and use by the ultimate consumer
•
end-of-life management of the packaging where the options are for either to
reuse, recycle, incinerate with energy recovery or dispose to landfill.
The whole system must be sustainable in environmental, economic and societal
terms and should include processes to ensure continuous improvement. The issues
discussed provide evidence that this is the approach currently used in the manufac-
ture and use of paper and paperboard based packaging.
The wood supply for the paper industry is sustainable. Independent forest certi-
fication is established in many regions including North America and Europe. Over
50% of the energy used in paper and paperboard manufacture is renewable. Mills
not having biomass available as part of their process and mills and factories where
electricity is imported are in the same situation as society at large as regards the
resources used. At the present time, the greater proportion of that energy depends
ENVIRONMENTAL AND WASTE MANAGEMENT ISSUES
81
on fossil fuels but the proportion of renewable energy is increasing. The mills have
increased their efficiency in energy usage (CHP) and have reduced emissions by
switching from coal and oil to natural gas. Reductions have been made in water
consumption, and the quality of water returned to nature has been improved. The
amounts of paper and paperboard recovered and the proportion of recovered fibre
used in the manufacture of paper and paperboard have increased.
By their activities in all these areas and by having independent assessments to
internationally accepted environmental and quality management standards, the
companies involved in the manufacture and use of paper and paperboard packaging
continue to demonstrate their commitment to sustainable development and con-
tinuing improvement.
Finally, an important feature of the paper and paperboard industry which
underpins its claim to sustainability is the part it plays in the carbon cycle.
The carbon cycle links the atmosphere, the seas and the earth in a fundamental
way (Fig. 2.6). All life depends on carbon in one form or another. Paper and
paperboard are involved because:
•
CO
2
in the atmosphere is absorbed and transformed into cellulose fibre in
trees
•
trees cumulatively form forests
•
forests are essential to climate, biodiversity, etc., they store solar energy and CO
2
•
the principle raw material for paper and paperboard is wood
•
non-cellulose wood components provide just over 50% of the energy used to
manufacture paper and paperboard and this releases CO
2
back into the
atmosphere
Carbon dioxide
Energy recovery plant
Used paper board
Sustainable forest
management
Wood chips
and thinnings
Timber
Production
Recovered paper
and board
Virgin fibres
Residues and
non-recyclable paper
and board products
Paper and
board products
Pulp, paper
and board mill
Figure 2.6 The paper and paperboards carbon cycle. (Reproduced, with permission, copyright,
Confederation of European Paper Industries.)
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PAPER AND PAPERBOARD PACKAGING TECHNOLOGY
•
some paper and paperboard in long life usages such as books, together with
timber, act as carbon sinks which remove CO
2
from the atmosphere
•
when paper and paperboard are incinerated after use with energy recovery
and even when it biodegrades in landfill, it releases CO
2
back into the
atmosphere.
The overall effect is that the paper industry invests in forests. This results in an
accumulation of new wood as a result of incremental growth exceeding the wood
harvested by a good margin. Furthermore, the amount of the CO
2
used to produce
the wood harvested exceeds the amount given back by the use of biofuel in the
manufacture of paper and paperboard and at its end of life when it is incinerated
with energy recovery or biodegraded.
Hence the paper and paperboard industry effectively promotes forest development
and removes CO
2
from the atmosphere, features which support the, desirable, aim
of sustainable development.
References
AF&PA (2001) American Forest and Paper Association, visit http://www.afandpa.org.
Akerman, F. (1997) Why Do We Recycle? Tufts University, Massachussetts.
Battershell, C. (2003) British Petroleum, to conference in Brussels 16–17 June 2003 ‘The Hydrogen
Economy – A Bridge to Sustainable Energy’.
CEPI (2002) Environmental Report 2002 – Working Towards More Sustainability.
EEA (1995) Europe’s Environment, The Dobris Assessment. European Environment Agency, p. 494,
visit http://www.eea.eu.int.
EEA (2003) European Environment Agency Third Report (source: NNECE/FAO), visit http://
www.eea.eu.int.
FAO (2001) Global Forest Resources Assessment 2000. Executive summary, visit http://www.fao.org/
forestry/index.jsp.
FAO (2003) Assistant Director-General, Forestry Department, M. Hosny El-Lakany, Rome, 27 July,
visit http://www.fac.org/forestry/index.jsp.
Holmen, A.B. (2002) Environmental Report 2002.
ICFPA (2002) International Council of Forest and Paper Associations, Sustainability Report, August.
Lomborg, B. (2002a) The Skeptical Environmentalist, Measuring the Real State of the World,
Cambridge Press, p.130 (based on US Energy Information Agency, EIA and World Resources
Institute, WRI, sources).
Lomborg, B. (2002b) The Skeptical Environmentalist, Measuring the Real State of the World,
Cambridge Press, p. 128 (based on EIA, International Energy Outlook 1997, p.37).
Lomborg, B. (2002c) The Skeptical Environmentalist, Measuring the Real State of the World, Cambridge
Press, p. 135 (based on EIA, WI (Worldwatch Institute) and BP (British Petroleum) sources).
Lomborg, B. (2002d) The Skeptical Environmentalist, Measuring the Real State of the World,
Cambridge Press, p. 131 (based on EIA, Annual Energy Outlook 2001, p. 75).
Lomborg (2002e) The Skeptical Environmentalist, Measuring the Real State of the World, Cambridge
Press, p. 130 (based on WRI (World Resources Institute), World Resources 1996–97 and Botkin, D.B.
and Keller, E.A., 1998, Environmental Science: Earth as a Living Planet).
M-real (2002) M-real Environmental Report 2002.
New Scientist (1997) Pearce, F., vol. 165, no. 2109, pp. 30–34.
Onyx (2000) Report on Air Quality in the Vicinity of the South East London Combined Heat & Power
Facility, visit www.onyxgroup.co.uk/pdfs/selchpairreport.pdf.
ENVIRONMENTAL AND WASTE MANAGEMENT ISSUES
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Perkins, A. (1993) ‘Do Board Mills Produce Harmful Emissions?’, Iggesund/Packaging News
Environmental Seminar, London, October.
PT (2001) Paper Technology, Thermophilic Membrane Bioreactors in Paper Mills, vol. 42, no. 1, February,
pp. 32–40.
PT (2003) Paper Technology, Chemical Additives and Pigments, vol. 24, no. 5, June, pp. 5–7.
Remrod, J. (1991) Forest of Opportunity, 1991 (based on FAO data).
Robson, N.C. (1997) More and Better Packaging – A Solution to World Food Waste, Asian Packaging,
no. 306, August, pp. 26–28.
SFI (2002) Swedish Forest Industries Federation, ‘Towards sustainable development in industry –
An example of successful environmental measures within the packaging chain’, 20 August, visit
http://www.forestindustries.se/pdf/sustainable_development.pdf.
Stora Enso (2002a) Environment Resources 2002, p. 22.
Stora Enso (2002b) Energy-less is more 2002, p. 4.
Tickell, C. (1996) ‘Greenery & Governance’, Burntwood Memorial Lecture for the Institution of
Environmental Sciences, November.
UK Biomass (2003) visit http://www.britishbiogen.co.uk/bioenergy/electricity/elecmap.htm.
UNEP (2000) Global Environmental Outlook 2000, United Nations Environmental Programme.
UNEP (2002) Global Environmental Outlook-3, United Nations Environmental Programme.
UN (2003) World Population Prospects: The 2002 Revision and Urbanization Prospects, Population
Division of the Department of Economic and Social Affairs of the United Nations Secretariat, see
http://esa.un.org/unpp, 7 September.
UNEP (1995) Global Biodiversity Assessment V.H. Heywood (ed.), United Nations Environmental Pro-
gramme, p. 12.
WI (1998) Worldwatch Institute press release 04/04/1998, visit www.worldwatch.org/alerts/.
3 Paper-based flexible packaging
Mark J. Kirwan
3.1 Introduction
Flexible packaging is the fastest growing type of packaging.
Paper-based flexible packaging comprises sachets, pouches, bags made on form,
fill, seal equipment and overwrapping materials. It is also used as lidding and to
provide product protection and as tamper evidence when used as a membrane
(diaphragm) in rigid plastic, metal and glass containers. Paper-based flexible
materials are also used for bag-in-box lining material, multiwall and single-
wall bags.
Paper-based flexible packaging is usually printed and is lighter in weight than the
other forms of packaging. Here are some facts about paper-based flexible packaging
in the USA:
•
flexible packaging is the second largest type of packaging in the USA (17%)
•
most flexible packaging is used in retail (54%)
•
largest application is for food in the retail and institutional markets
•
medical and pharmaceutical packaging usage is 8%
•
usage for industrial, consumer products and institutional non-food is sig-
nificant (FPA, 2003).
The position in Europe is similar with flexible packaging, accounting for nearly
one third of total annual expenditure on consumer packaging. The packaging of
food products accounts for 75–80% of this flexible packaging (AMCOR, 2003).
Flexible packaging based on paper uses composite structures in which the
properties of the paper are combined with those of other materials, such as
plastics, aluminium foil, wax and other materials by means of coating, lamination
and impregnation. Depending on the combination of materials used, paper-based
flexible packaging can provide the following properties:
•
barrier to moisture and moisture vapour
•
barrier to gases, such as oxygen, carbon dioxide and nitrogen, making flexible
packaging suitable for vacuum and gas-flushed packaging and for the
protection of products sensitive to flavour and aroma loss or contamination
•
resistant to products, including those containing fat
•
barrier to light
•
sealable by heat sealing and use of cold-seal coatings
•
medical packaging applications place special requirements on paper-based
packaging, such as: to be sterilisable by gas, irradiation and steam, to provide
Paper and Paperboard Packaging Technology
Edited by Mark J. Kirwan
Copyright © 2005 by Blackwell Publishing Ltd
PAPER-BASED FLEXIBLE PACKAGING
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satisfactory pack seals, using both heat and cold sealing, which peel without
generating loose fibres, and to be permeable to a sterilising gas but imper-
meable to the entry into the pack of microbiological contamination
•
strength for packing, distribution and use
•
printable by several printing processes.
Flexible packaging is usually supplied on reels for forming, filling and sealing by
the end-user (packer), although some pouches/sachets and die-cut lids are supplied
to packer/fillers, especially for small-quantity orders.
Flexible packaging is used for the packing of:
•
solids in the form of free-flowing products such as powders, granules and
agglomerates
•
solids in the form of blocks, slices, bars and tablets
•
individual items and groups of items
•
liquids and pastes
•
multipacks
•
medical devices, kits and consumables such as dressings and surgical gloves.
Sachets and pouches may be single-portion, or single-dose, packs and they can
also be multiportion packs, for example for coffee, with a recloseable feature.
These packs may be sealed under vacuum or may be gas flushed.
The main materials, or substrates, used in flexible packaging until the middle of
the twentieth century comprised paper, aluminium foil and regenerated cellulose
film (RCF). Paraffin wax-coated paper was widely used as a barrier to moisture,
moisture vapour and volatiles, and it has product-release properties. Subsequently,
the uses and properties of waxes were enhanced with microcrystalline waxes and
plastic additives which provided better heat sealing, barrier properties and made
them more versatile for use as a laminating adhesive, for example paper to paperboard,
paper to aluminium foil and RCF to plastic films.
From the 1950s onwards, plastics began to play a larger role in packaging. The
change was particularly significant in flexible packaging. Plastics became available
as films, emulsion coatings and in extrusion coatings and laminations. Plastics were
also used as adhesives and heat-seal coatings. New conversion equipment, ancillary
materials and higher-performance adhesives became available, and printing processes
and inks were modified to suit their use with plastics. The development of plastics
themselves and new techniques in blown film, cast film, biaxial orientation,
co-extrusion, lamination and coating significantly increased the use of plastic
flexible packaging such that by 2004 approximately 70% of flexible packaging
was solely plastic in composition.
The availability of plastics has, however, widened the opportunities for paper-
based flexible packaging. The use of wax has diminished though its use in several
types of application is still an option, and other non-food packaging materials,
such as bitumenised kraft papers (kraft union), whilst still available in some markets,
have been replaced by polyethylene film.
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PAPER AND PAPERBOARD PACKAGING TECHNOLOGY
However, paper and aluminium foil are still widely used in flexible packaging.
Papers are used in the form of laminates and as a substrate for coating and
impregnating.
Paper is used in flexible packaging because:
•
paper is a strong material available in reel form in a range of widths and
substances (grammages or basis weights), which meets the needs of printing,
conversion and packaging machinery and also, thereafter, in distribution and
consumer use
•
paper is a suitable substrate for providing functional packaging properties.
This may be achieved in paper manufacture, for example greaseproof or
glassine paper, or by addition of other materials by subsequent conversion in
the form of a coating, lamination or impregnation
•
paper imparts stiffness in the packed sachet or pouch
•
paper can be printed by all the main, commercially available, inks and printing
processes
•
there is a wide choice of the print quality which can be achieved depending
on the colour, surface finish, smoothness and gloss of the paper surface and
whether the surface has a mineral pigmented coating
•
the surface promotes adhesion in a range of conversion processes including
those using water and solvent-based adhesives, wax and curing (cross linking)
100% solid adhesives as well as plastic extrusion coatings and laminations
•
fibre choice, stock preparation and papermaking can be varied to achieve
specific product characteristics, for example porosity and heat sealing in an
infusible tissue for a tea bag, grease resistance in a greaseproof, glassine or
size press treated for grease resistance, mould resistance, etc.
•
paper-based medical packaging meets specific requirements for sterilisation,
sealability, peelability, porosity and microbiological barrier
•
paper is cost-effective when used in flexible packaging, it is environmentally
benign and naturally sustainable.
Aluminium foil is used in flexible packaging as a barrier to moisture, moisture
vapour and common gases, and it is also a light barrier. Some applications for
aluminium foil have been replaced by metallised paper, metallised film and ethylene
vinyl alcohol (EVOH).
Regenerated cellulose film is usually discussed within plastic packaging but as
it has its origin in bleached chemical woodpulp some mention is justified here. It is
a clear transparent film. In its various specifications with respect to coating and
additives, it has a wide range of applications because of its barrier properties and
composition together with its suitability for lamination to paper, aluminium foil
and plastic films. All the properties listed above can, however, be matched in most
respects with lower cost plastic films, particularly oriented polypropylene film,
and this has led to a significant fall in usage. Today its marketing is based on the
fact that it is derived from a renewable resource, i.e. forestry, and that it has excellent
stiffness in packaging machineability and point-of-purchase (POP) display. RCF