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ISSUE 04-05 / 2001 |
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| Labeling | BACK to contents |
SUITABLY
ATTIRED FOR THE OCCASION 2
Focus on Labelling Techniques
for PET Containers
Continuing our three part series
on labelling of PET bottles Dr. Joachim von Meyer of KHS reviews the option
of paper labels using hot-melt or cold adhesive.
Foil or paper, roll-feed or pre-cut sheet-feed, hot-melt or cold-melt? There
are plenty of options, and as in so may other aspects of the beverage business
there is no ready-made solution. Roll-feed labelling was discussed in some
detail in our first article. We now address the various aspects of sheet-feed
paper labelling
Paper or Foil?
What are the general arguments in favour of paper labels? Possibly the major
consideration when answering this question from an international standpoint
is the fact that paper is available worldwide and is quickly obtained. This
is not always the case with foil labels. Another advantage of paper labels
is that paper does not present a problem with static electricity – something
that can occur with foil labels. Unlike foil labels, paper labels are also
an inexpensive solution, particularly when using small quantities. This situation,
however, can be quickly reversed when processing large batches. Foil labels
also have the very clear advantage of being insensitive to moisture, unlike
paper labels. Again, unlike the not so stable paper labels, foil labels are
much more capable of coping with possible bottle expansion when bottles are
filled with carbonated beverages. Both materials have their advantage and
disadvantages, which we can only indicate here. The final decision has to
be made based on the widest possible range of requirements.
Good Price-Performance Ratio
As mentioned in part 1 of this series sheet-feed of pre-cut labels can be
used for paper labels just as well as the roll-feed method. Inexpensive labelling
equipment is a primary factor in favour of sheet-feed processing. Both the
hot-melt as well as cold adhesive labelling techniques can be used to apply
paper labels.
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| This new Innoket Roland HS hot-melt labeller is designed for a wide variety of non-returnable PET containers. |
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| The Innoket Roland for cold adhesive labelling |
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| The Innoket KL 2000: up to 70,000 containers per hour |
Hot-melt Labelling
The principle of hot-melt, sheet-feed labelling is basically similar to that of cold adhesive labelling. The main difference lies in the fact that the labels are pre-cut and fed from a magazine instead of a roll.
The labelling process in brief: Dabs of hot-melt are applied directly to the containers. The containers are then rotated past the label magazine where the glue picks up a label directly from the magazine. The rotary motion wraps the label tightly around the bottle, after which the overlapping ends are precisely stuck together by a strip of glue.
It is possible to apply other labels
by integrating an additional wet-glue labelling station into the line.
The Adjustable Label Magazine
Increased flexibility of the hot-melt labelling technique is offered by a
newly developed adjustable label magazine. It is no longer necessary to change
label magazines when processing various bottle sizes. Apart from having fewer
format parts, this system means shorter changeover times.
Returnable PET Containers
The hot-melt method of paper label application is principally suitable for
non-returnable PET containers. This is because initial glue application is
applied directly to the containers. Too much effort is required to remove
labels and hot-melt residue from returnable PET containers. Cold adhesive
labelling is a real alternative in this case.
Shoulder, front, and back labels can be effortlessly processed by the cold adhesive technique. It is also possible to overlap the ends of front and back labels so that they appear to be wrap-around labels. The main advantage is that labels applied using the cold adhesive method can be easily removed with conventional bottle washers. Installation of an additional delabeller is therefore not necessary for returnable PET.
Cold labelling technique
Similar to the hot-melt process, the bottles for cold adhesive labelling are conveyed by a feed scroll and star-wheel, feeding them onto the carrousel and to the labelling station. The label materials are removed from the label magazine by a glue segment to which a glue drum has already applied glue. The glue segment is run past a gripper drum. The gripper drum pulls the label off the glue segment by means of special grippers and transfers with its glued side to the container. The cold adhesive technique involves applying labels with glue covering the entire label surface, which ensures maximum labelling reliability. Another advantage of cold adhesive labelling is that one labelling station is capable of applying several labels.
For All Capacity Ranges
Labelling of PET containers with sheet-fed paper labels using hot-melt as well as cold adhesive techniques begins in the low capacity range and goes right through to the high capacity range. KHS have machines to meet all of these requirements. The hot-melt range of Innoket Roland HS labellers is capable of applying labels at between 4,000 and 45,000 containers per hour. The Innoket KL 2000 is capable of handling up to 70,000 containers per hour.
In the third and final article Dr. von Meyer takes a close look at adhesive labelling.| 143 |
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