Mark J. Kirwan Paper and Paperboard Packaging Technology
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RIGID BOXES
257
Surrounding the main wrapping lines are special purpose machines for miscel-
laneous operations, such as hinging, stitching, labelling, sealing, hot-melt fixing,
corner cutting and many more.
An alternative method of box covering is known as envelope or loose wrapping.
This uses a cover paper which is not preshaped but is folded and pleated around
the box with only the edge of the paper being secured to the board by adhesive.
9.7.1 4-Drawer box
The construction of a 4-drawer rigid box demonstrates the range of operations
which may be necessary in order to meet a specific design for a luxury or novelty
pack. The example is taken, with permission, from ‘The Packaging Designer’s
Book of Patterns’ (Lászlo Roth and George L. Wybenga, 1991).
Wrapper
Wrapper
Quad Quad
Spotter Spotter
Gluer Gluer
Figure 9.7 Machine layout for producing rigid box and lid.
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Step 1: The first set of operations, Figure 9.8, result in the preparation of an
outer sleeve and four inner sleeves, which form the drawer guides. Adhesive
tape is used to make the various joins.
Figure 9.8 Preparation of outer and inner sleeves. (Reproduced, with permission, from John Wiley &
Sons, Inc.)
RIGID BOXES
259
Step 2: Then the face of the drawer guides and the outer sleeve are covered with
decorative materials, Figure 9.9.
Step 3: The drawers are cut, scored and corner-stayed. Finally, the drawer pulls
are applied, and the assembly checked for a snug fit. The complete assembly
is shown in Figure 9.10.
Figure 9.9 Covering of outer sleeve and face of drawer guides. (Reproduced, with permission, from
John Wiley & Sons, Inc.)
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PAPER AND PAPERBOARD PACKAGING TECHNOLOGY
9.8 Conclusion
Use of the rigid box continues to compete and find a multitude of uses in the pack-
aging world of today. Its raison d’être remains the need to engender the feeling of
quality whilst providing physical protection for its contents. Design versatility, the
use of accessories and widely varying print finishes provide a unique packaging
proposition that continues to delight its users and consumers.
Figure 9.10 Production of drawers and final assembly. (Reproduced, with permission, from John
Wiley & Sons, Inc.)
RIGID BOXES
261
References
BS, 1986, British Standard 1133 Subsection 7.3
Lászlo Roth, George L. Wyybenga, 1991, The Packaging Designer’s Book of Patterns, 1st edition,
John Wiley & Sons, Inc. pp. 342–344
Websites
www.nationalpaperbox.org.
www.boxpackaging.org.uk.
www.londonfancybox.co.uk.
10 Folding cartons
Mark J. Kirwan
10.1 Introduction
Cartons are small to medium sized boxes made from paperboard (‘cardboard’).
They comprise a significant proportion of the packaging found in the retail sector,
i.e. in supermarkets and shops of all kinds, in mail order, in vending machines, in the
service sector (hospitals, schools, catering, etc.) and in the dispensing of medicines.
Cartons meet packaging needs cost-effectively by providing product protection
and information, visual impact and convenience appropriate for the product
concerned and its method of distribution and consumer use.
Folding cartons are delivered to the packer in a flat form. This may be either as
a flat printed and profiled blank, or as a side seam glued carton which is folded flat.
The carton packer erects, fills and closes the carton either manually, mechanically
or by a combination of manual and mechanical means. The flatness of the folding
carton prior to the packaging operation is a major space-saving benefit in distribu-
tion and storage before use and distinguishes folding cartons from rigid cartons,
which are ‘set-up’, ready for use at the point of manufacture.
Cartons increased in popularity with the pattern in retailing, whereby the
shopkeeper trading locally, apportioning the product on demand from bulk, was
replaced by manufacturers marketing brands and trading nationally and internation-
ally. This was facilitated by the development of machinery to apportion the product
and to erect, fill and close cartons.
Folding cartons are made from paperboard, often referred to as ‘cardboard’
or ‘cartonboard’. There are several different types of paperboard differing in the
types of pulp used in their construction. The main types of pulp, as has already
been discussed in Chapter 1, are chemical bleached, chemical unbleached,
mechanical and recycled. Paperboard is usually multilayered and may comprise
layers of more than one type of pulp. Surfaces are usually, but not always,
coated with a mineral-pigmented coating to enhance appearance and printability.
The properties of paperboard can be extended by the use of other materials,
plastic extrusion coatings and other functional coatings and treatments.
Paperboard is characterised by its thickness and weight per unit area. Packaging
trade and national and international standards organisations give different
guidances as regards the thickness range for defining paperboard. The upper limit
for practical purposes would, however, be 1000µm. The lower limit has been
defined as 250 and 225µm but there are cartons in use at 200µm and even lower.
The units of measurement are microns (0.001mm), or thousandths of an inch
(0.001 in.). Weight per unit area is measured in either grammes per square metre
(g/m
2
) or pounds per 1000square feet.
Paper and Paperboard Packaging Technology
Edited by Mark J. Kirwan
Copyright © 2005 by Blackwell Publishing Ltd
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The carton manufacturer sells cartons by number of cartons, 1 million or whatever,
and hence is interested in buying by the area, rather than the weight required to
make a given number of cartons, taking account of set-up and in-process waste.
In practice, this is facilitated by modern paperboard manufacturing, which is
computer-controlled on the paperboard machine within tight weight per unit area,
i.e. yield, tolerances and in finishing by accurate sheet counting, in the case of sheeted
orders, and length in the case of reels of a given width.
As has also been discussed in Chapter 1, the compression strength of paperboard
is highly dependent on stiffness that correlates with thickness to a much higher
degree than weight per unit area.
Packaging technologists, packaging buyers and brand managers in end-using
companies often ask what type of paperboard they should use for a particular type
of product.
The answer, however, depends on a number of factors and the starting point is
to examine all the packaging needs. The use of a check list is advised to ensure
that all relevant factors are considered. This review will provide guidance on the
required appearance, for example surface, etc., and performance, for example strength
and product protection characteristics, required to achieve the desired appearance,
printability, conversion and usage. These needs in turn depend on:
•
Product – type, weight, volume, shape or consistency, i.e. powder, granule,
etc., and whether it is pre-packed in a pouch, jar, etc., or whether it is packed
in direct contact with, or in close proximity to, the paperboard. Any special func-
tional or legal requirements relating to the protection of the product in packing,
storage, transit, merchandising and consumer use must be identified.
•
Presentation – surface and structural carton design, standard of printing and
overall visual impact. It maybe that the reverse side of the paperboard is seen or
printed. Presentation is closely related to the positioning of the product
in its particular market. Each product market will have characteristics.
All products, for example breakfast cereals, chocolate confectionery, ethical
prescription-only medicines, proprietary over-the-counter medicines, tobacco,
etc., are presented in characteristic ways.
There are also international differences in the ways products are presented.
The ways products are presented also depend on the point of sale or use, i.e.
whether in self-service display, vending, mail order or catering, etc. and
whether the product is bought by one person as a gift for another. Additionally,
within specific product markets, there will be luxury, or top-of-the range
products, average, middle-of-the-range, medium-priced products and
budget, value-for-money products, at the lower-priced end of the range.
Packaging, including the choice of paperboard, will reflect this segmentation
and product positioning.
•
Packing, distribution and use – details of the number of cartons to be packed in
a given time and whether production is variable through the year are needed at
the outset to indicate the extent of mechanically assisted cartonning required.
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Distribution and storage factors include consideration of the transit packaging
and whether any special environments are involved, such as deep freeze or
chilled distribution. Consumer use could include how the pack is used and
whether this imposes specific needs such as the reheatable requirements of a
convenience food product or the way the carton is handled in use, for example
compression needs of a cigarette carton.
In practice, many of the requirements imposed by these needs interact. The
carton structural design contributes to the carton compression strength, and the
surface strength relates to printability and glueablity, etc.
Folding cartons are usually printed on the outside surface with text, illustrations
and decorative designs. Varnishing is used to enhance appearance and to protect print.
Graphical design reinforces brand values, particularly in self-service merchan-
dising. Cartons are sometimes printed on the reverse side, for example cartons for
chocolate confectionery. Printing provides information on the product and how to use
it safely. Hot-foil stamping and embossing are also used to create visual impact.
Folding cartons are produced in a wide range of structural shapes having a
choice of closure design, including reclosure features where necessary, together
with ‘add-on’ features, such as handles, windows and internal platforms.
The structural design of most folding cartons is based on a rectangular or
square cross section. The type of product to be packed, the method of filling and
the way the pack will be distributed, displayed (merchandised) and used
will influence the dimensions and design in general. Rectangular shapes are easy
to handle mechanically, especially when packed in large volumes at high speeds,
easily merchandised, and conveniently handled and stored by the consumer. Other
shapes are, however, possible and are used to meet specific needs, for example
round, elliptical, triangular, pyramidal, domed, wallet shaped, etc.
All this is possible in manufacture because of the fundamental paperboard
properties whereby it is an inherently strong material which is printable, creasable
and glueable.
The overall result is that folding cartons are used to package a wide range
of products from foodstuffs – such as cereals, frozen, chilled foods and ice cream,
confectionery, bakery products, tea, coffee and other dry foods – to non-food products,
such as pharmaceuticals, medical and healthcare products, perfumes, cosmetics,
toiletries, photographic products, clothing, cigarettes, toys, games, laundry, paper
goods, household, electrical, engineering, sport and leisure, gardening and DIY
products, etc. Around 55% of all cartons are used in the packaging of food products
(Pro Carton, 1999).
10.2 Paperboard used to make folding cartons
The main types of paperboard, i.e. solid bleached board (SBB or SBS), solid
unbleached board (SUB or SUS), folding box board (FBB or GC1 or GC2) and
white lined chipboard (WLC, GT or Newsboard), have been described in Chapter 1.
FOLDING CARTONS
265
The outer surface is usually coated with a mineral-pigmented coating based on
china clay and/or calcium carbonate to enhance the appearance (colour, smoothness,
surface structure and gloss level) and printability. The reverse side may also have
a mineral-pigmented coating for appearance and printability.
The performance of paperboard and cartons can be extended by the use of
additional materials and by using processes such as lamination, plastic-extrusion
coating, impregnation and functional-surface coating. Such treatments are used
to ensure that cartons meet the needs of product protection throughout the distribu-
tion and storage chain up to, and including, the ultimate consumer.
Performance laminations of paperboard are possible with greaseproof and
glassine paper, polyvinylidene dichloride (PVdC or Saran
®
)-coated paper and
aluminium foil. These surfaces provide grease/fat resistance. Wax used as adhesive
for a greaseproof or glassine lamination enhances the barrier of these laminates to
moisture and moisture vapour. For product release, greaseproof paper or glassine
coated with a silicone-release coating is used. Aluminium foil provides a number
of functional benefits, such as barrier to moisture and moisture vapour, grease/fat
barrier, odour barrier, product release and heat resistance. PVdC provides heat
sealability and a barrier to moisture and moisture vapour, grease/fat, flavours and
odours; it is not, however, used widely in carton constructions. It is used as a coating
on oriented polypropylene (OPP) film which is used as a barrier overwrap for
chocolate confectionery, tea and cigarette cartons.
Coated paper with good printability can be laminated with paperboard using
microcrystalline wax blends as the adhesive to provide a paperboard with moisture
vapour resistance.
Paperboard can be plastic extrusion coated to achieve a range of barrier, heat
sealing and heat resistant properties with polyethylene (PE), polypropylene (PP),
polyethylene terephthalate (PET or PETE), polymethylpentene (PMP) and iono-
mer (Surlyn
™
).
Paperboard may be coated with silicone, wax or a heat seal varnish. It can be
impregnated with wax during paperboard production. Water-based coatings can
provide heat sealing and grease resistance. Wax is a good barrier to volatile
contamination from outside and for the retention of flavour and aroma within
packaging.
10.3 Carton design
10.3.1 Surface design
This involves all the aspects of a carton which relate to its overall visual impact.
The basis is the colour of the surface of the paperboard, its smoothness and surface
finish. The colour is usually white, though other colours are possible by the use of
coloured mineral pigmented coatings. High whiteness enhances print contrast. Surface
finish can be either high gloss, satin or matte. There are variations in appearance
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between paperboards, and the existence of the ultra high-gloss cast-coated products,
also available in different colours, extends the gloss range further. A matte finish
may increase print contrast and make text easier to read whereas gloss and sparkle
can attract attention. It is also possible to apply an overall embossed design to the
paperboard surface, for example linen effect. All other variations in surface
appearance are achieved by conversion, printing and varnishing.
There are many possible types of lamination which are used to create a visual
effect. Plastic film, for example cellulose acetate, polypropylene, etc. may be
applied to enhance gloss and a luxury appearance. Aluminium foil or metallised
polyester plastic film is used to produce an overall metallic effect. Papers, such as
a high specification coated paper or coloured glassine, for example chocolate coloured,
may also be laminated to a paperboard base. In the latter example, there is also a
performance element relating to product protection.
Whilst plastic extrusion coating is primarily used as a functional addition to
paperboard, it can also have a visual effect. This is usually to impart gloss.
Printing offers a very extensive range of possibilities for creating visual
impact. It is used for brand names, text, illustrations and diagrams. This range can
include tactile text and decoration. Printing can provide solid colour or patterned
decoration.
Varnishing is done over print to improve rub resistance, and it can also be used
to create a visual effect. This effect can result in a gloss, satin or matte surface, and
may either be all over the surface or limited to specific parts of the design. Pearlescent
varnishes can also be applied to create a special effect.
Localised effects can be produced by hot-foil stamping or embossing or by a
combination of both. The hot-foil effect is achieved with an aluminium (coloured)
foil applied to a heat-resistant film and a heated die profiled to the required design.
Embossing can also be used to create an overall decorative effect.
10.3.2 Structural design
Structural design is based on the creative and functional needs of the pack. A carton
has to perform efficiently in the packaging operation and thereafter to protect the
product throughout its life during distribution to the point of sale or dispensing and
to its use by the ultimate consumer. This represents the functional requirement.
The function may need to include convenient features, such as opening and reclosure
features, carrying handles, windows, internal platforms to locate and display the
product, etc.
Structural design must also take into account the dimensions, volume and, if
a solid, the shape of the product. The design is usually in three dimensions though
there are examples of two-dimensional paperboard packaging, for example blister
cards and wallet-style packs for retort pouches.
In addition to the development of a functional design, paperboard gives the
designer the scope for creating more imaginative designs whilst not compromising