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1 Paper and paperboard â raw materials, processing and properties
Daven Chamberlain1 and Mark J. Kirwan2
1Paper Technology, Bury, Lancashire, UK
2Paper and Paperboard Specialist, Fellow of the Packaging Society, London, UK
1.1 Introduction â quantities, pack types and uses
Paper and paperboard are manufactured worldwide. The world output for the years quoted is shown in Table 1.1. The trend has been upward for many years; indeed, worldwide production has more than doubled in just three decades. Both materials are produced in all regions of the world. The proportions produced per region in 2010 are shown in Table 1.2.
Paper and paperboard have many applications. These include newsprint, books, tissues, stationery, photography, money, stamps, general printing, etc. The remainder comprises packaging and many industrial applications, such as plasterboard base and printed Âimpregnated papers for furniture. In 2010, paper and paperboard produced for packaging applications accounted for 51% of total paper and paperboard production (BIR, 2011).
A single set of figures for world production of paper and paperboard hides a very Âsignificant change that has taken place in the last decade. A large amount of investment has poured into Asia, resulting in the creation of many new mills with large and fast machines. Consequently, the proportion of world production originating from Asia has increased by 10% since 2003; Europe and North America have been the casualties, and both regions have experienced significant numbers of mill closures during this period.
As a result of the widespread uses of paper and paperboard, the apparent consumption of paper and paperboard per capita can be used as an economic barometer, i.e. indication, of the standard of economic life. The apparent consumption per capita in the various regions of the world in 2010 is shown in Table 1.3.
The manufacture of paper and paperboard is therefore of worldwide significance and that significance is increasing. A large proportion of paper and paperboard is used for packaging purposes. About 30% of the total output is used for corrugated and solid fibreboard, and the overall packaging usage is significant. Amongst the membership of CEPI (Confederation of European Paper Industries), 43% of all paper and paperboard output during 2011 was used in packaging, (CEPI, 2011).
Not only is paper and paperboard packaging a significant part of the total paper and paperboard market, it also provides a significant proportion of world packaging Âconsumption. Up to 40% of all packaging is based on paper and paperboard, making it the largest Âpackaging material used, by weight. Paper and paperboard packaging is found wherever goods are produced, distributed, marketed and used.
Table 1.1 World production of paper and paperboard
Source: BIR (2010).
|
| 1980 | 171 |
| 1990 | 238 |
| 2000 | 324 |
| 2005 | 367 |
| 2006 | 382 |
| 2007 | 394 |
| 2008 | 391 |
| 2009 | 371 |
| 2010 | 394 |
Table 1.2 World production % of paper and paperboard by region for 2010
Source: BIR (2010).
|
| Europe | 27.1 |
| Latin America | 5.2 |
| North America | 22.5 |
| Africa | 1.1 |
| Asia | 43.1 |
| Australasia | 1.0 |
Table 1.3 Apparent per capita consumption of all types of paper and paperboard in 2010
Source: BIR (2010).
|
| North America | 234.8 |
| Europe | 142.0 |
| Australasia | 135.0 |
| Latin America | 45.5 |
| Asia | 40.0 |
| Africa | 7.8 |
Many of the features of paper and paperboard used for packaging, such as raw material sourcing, principles of manufacture, environmental and waste management issues, are Âidentical to those applying to all the main types of paper and paperboard. It is therefore important to view the packaging applications of paper and paperboard within the context of the worldwide paper and paperboard industry.
According to Robert Opie (2002), paper was used for wrapping reams of printing paper by a papermaker around 1550; the earliest printed paper labels were used to identify bales of cloth in the sixteenth century; printed paper labels for medicines were in use by 1700 and paper labels for bottles of wine exist from the mid-1700s. One of the earliest references to the use of paper for packaging is in a patent taken out by Charles Hildeyerd on 16 February 1665 for âThe way and art of making blew paper used by sugar-bakers and othersâ (Hills, 1988). For an extensive summary of packaging from the 1400s using paper bags, labels, wrappers and cartons, see Davis (1967).
The use of paper and paperboard packaging accelerated during the latter part of the Ânineteenth century to meet the developing needs of manufacturing industry. The Âmanufacture of paper had progressed from a laborious manual operation, one sheet at a time, to Âcontinuous high-speed production with wood pulp replacing rags as the main raw material. There were also developments in the techniques for printing and converting these materials into Âpackaging containers and components and in mechanising the packaging operation.
Today, examples of the use of paper and paperboard packaging are found in many places, such as supermarkets, traditional street markets, shops and departmental stores, as well as for mail order, fast food, dispensing machines, pharmacies, and in hospital, catering, Âmilitary, educational, sport and leisure situations. For example, uses can be found for the packaging of:
- dry food products â for example cereals, biscuits, bread and baked products, tea, coffee, sugar, flour and dry food mixes
- frozen foods, chilled foods and ice cream
- liquid foods and beverages â milk, wines and spirits
- chocolate and sugar confectionery
- fast foods
- fresh produce â fruits, vegetables, meat and fish
- personal care and hygiene â perfumes, cosmetics and toiletries
- pharmaceuticals and health care
- sport and leisure
- engineering, electrical and DIY
- agriculture, horticulture and gardening
- military stores.
Papers and paperboards are sheet materials comprising an overlapping network of Âcellulose fibres that self-bond to form a compact mat. They are printable and have physical properties which enable them to be made into various types of flexible, semi-rigid and rigid packaging.
There are many different types of paper and paperboard. Appearance, strength and many other properties can be varied depending on the type(s) and amount of fibre used, and how the fibres are processed in fibre separation (pulping), fibre treatment and in paper and Âpaperboard manufacture.
In addition to the type of paper or paperboard, the material is also characterised by its weight per unit area and thickness. Indeed, the papermaking industry has many specific terms, and a good example is the terminology used to describe weight per unit area and thickness.
Weight per unit area may be described as âgrammageâ because it is measured in grammes per square metre (g mâ2). Other area/weight-related terms are âbasis weightâ and âsubstanceâ, which are usually based on the weight in pounds of a stated number of sheets of specified dimensions, also known as a âreamâ, for example 500 sheets of 24 in. Ă 36 in., which equates to total ream area of 3000ft2. The American organisation TAPPI (Technical Association of the Pulp & Paper Industry, 2002â2003) issues a standard that describes basis weight in great detail; Âcurrently there are 14 different areas used for measurement, depending upon the grade being measured. It is therefore important when discussing weight per unit area, as with all Âproperties, to be clear as to the methods and units of measurement.
Thickness, also described as âcaliperâ, is measured either in microns (”m), 0.001 mm or in thou. (0.001 in.), also referred to as points.
Appearance is characterised by the colour and surface characteristics, such as whether it is smooth or rough and has a high gloss, satin or matte finish.
Paperboard is thicker than paper and has a higher weight per unit area, although the Âdividing line between the two is somewhat blurred. Paper over 225 g mâ2 is defined by ISO (International Organization for Standardization) as paperboard, board or cardboard. Some products are, however, known as paperboard even though they are manufactured at lower grammages; for example, many producers and merchants now class products of 180â190 g mâ2 upwards as paperboard, because improvements in manufacturing techniques mean these lightweight materials can now be produced with similar strength properties to older Âheavyweight grades.
The main types of paper and paperboard-based packaging are:
- bags, wrappings and infusible tissues, for example tea and coffee bags, sachets, pouches, overwraps, sugar and flour bags, and carrier bags
- multiwall paper sacks
- folding cartons and rigid boxes
- corrugated and solid fibreboard boxes (transit or shipping cases)
- paper-based tubes, tubs and composite containers
- fibre drums
- liquid packaging
- moulded pulp containers
- labels
- sealing tapes
- cushioning materials
- cap liners (sealing wads) and diaphragms (membranes).
Paper and paperboard-based packaging is widely used because it meets the criteria for successful packing, namely to:
- contain the product
- protect goods from mechanical damage
- preserve products from deterioration
- inform the customer/consumer
- provide visual impact through graphical and structural designs.
These needs are met at all three levels of packaging, namely:
- primary â product in single units at the point of sale or use, for example cartons
- secondary â collections of primary packs grouped for storage and distribution, Âwholesaling and âcash and carryâ, for example transit trays and cases
- tertiary â unit loads for distribution in bulk, for example heavy-duty fibreboard Âpackaging.
Paper and paperboard, in many packaging forms, meet these needs because they have appearance and performance properties which enable them to be made into a wide range of packaging structures cost-effectively. They are printable, varnishable and can be laminated to other materials. They have physical properties which enable them to be made into Âflexible, semi-rigid and rigid packages by cutting, creasing, folding, forming, winding, gluing, etc.
Paper and paperboard packaging is used over a wide temperature range, from frozen-food storage to the temperatures of boiling water and heating in microwave and Âconventional ovens.
Whilst it is approved for direct contact with many food products, packaging made solely from paper and paperboard is permeable to water, water vapour, aqueous solutions and emulsions, organic solvents, fatty substances (except grease-resistant papers), gases such as oxygen, carbon dioxide and nitrogen, aggressive chemicals, and volatile vapours and Âaromas. Whilst paper and paperboard can be sealed with several types of adhesive, with certain special exceptions, such as tea-bag grades, it is not itself heat sealable.
Paper and paperboard can ...
