BACKGROUND OF THE INVENTION
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The present invention relates to label converting and application, and more particularly
to an apparatus and method for converting label base stock to a roll of releasably backed labels.
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Self-adhesive or pressure-sensitive labels are used in a wide variety of applications for
labeling bottles, jars, and other containers and articles. The label application equipment operates at
high speeds resulting in thousands of labeled articles per hour. The label manufacture and application
typically fall into two broad techniques, depending on whether the label stock is converted into labels
during manufacture of the labels (and therefore well prior to application) or as part of the application
process.
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In the first technique, the labels are individually formed on a continuous web (also
known as a release liner) prior to their use in the application equipment. In this case, the release liner
is pulled through the machine, and the labels are transferred from the release liner to the articles to
be labeled. The application equipment draws the release liner about a peel edge adjacent the article
to be labeled. Because the label is stiffer than the release liner, the label continues in a straight line
past the peel edge and onto the article. This first technique involves sophisticated label manufacture,
but straightforward label application. Consequently, the application equipment and processes are
relatively simple, inexpensive, and reliable.
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In the second technique, the labels are cut from a continuous web of label stock at or
adjacent the application equipment. In this case, the face web is severed into discrete labels. The cut
labels are applied to the articles as quickly as they are cut. The second technique involves
straightforward label manufacture but sophisticated label application. Consequently, the application
equipment is less simple, more expensive, and less reliable.
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In this second technique, the labels can be cut either before or after the face web is
separated from the liner. "Butt cut" is a term describing a label cut that severs the web transversely
from edge to edge to form individual labels from the face web without the disadvantage of creating
a waste label skeleton or matrix associated with "die cuts," which are discussed below. If cutting
occurs before the face web is separated from the release web, a butt cut knife blade cuts deeply
enough to sever both the face web and pressure sensitive adhesive layer on its back -- without
penetrating the release liner. This requires precision cutting that is difficult to maintain in actual use
conditions. If the cut is too deep, then the backing liner may be weakened to the point that the
backing liner breaks as it is pulled through automated label application machinery. This causes
expensive downtime and wasted material. If the butt cut is not deep enough, then the label will not
cleanly separate during application. Further, the operator must randomly inspect the labels after the
cuts have been made to determine whether the cut is deep enough.
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Alternatively, the face web may be cut when it is not attached to the release liner --
either because the equipment separates the face web from the release liner or because the label stock
is "linerless" (meaning that it never included a liner). An example of this approach is illustrated in
International Patent Application No. WO 90/05089 entitled "Improvements Relating to the
Application of Labels to Articles" published 17 May 1990, which describes a label applicator that
makes and applies butt cut labels without the use of a backing liner. The vacuum chamber provides
the suction to hold the butt cut label until the conveyor belt transfers it to the applicator station,
where a roller and belt apply the label to the article. (International Application at pages 9-11.)
Because the butt cut label lacks a backing liner, this apparatus requires an elaborate means --
comprising parallel conveying belts supported by guide rollers and channels with a vacuum chamber
between the guide rollers -- to hold the butt cut label during application. (International Application,
Fig. 2.)
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In contrast to a butt cut, a "die cut" is a label cut made by a patterned cutting blade
that severs the web to form a label having a desired configuration, leaving a skeleton or matrix waste
of face web material. If the base stock does not include a backing liner, then the die cut skeletal
waste of the face web provides the means for pulling the face web through the automated labeling
equipment. See, for example, Canadian Patent 1,248,412 entitled "Self Adhesive Labels and the
Manufacture Thereof'' issued 10 January 1989 (page 16 and Fig. 7).
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The previously cited International Patent Application No. WO 90/05089 at page 2 also
discloses the application of die cut labels to articles. A cutting drum and anvil cooperate to die cut
labels from a continuously fed base stock having a pressure sensitive adhesive coating on one side.
Each label, after being cut from the web, is held to the anvil by a vacuum until the label reaches the
application station, where the label is released and applied to the article. The face web is pulled
through the labeling machine by the skeletal face web waste formed by the die cut.
SUMMARY OF THE INVENTION
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The aforementioned problems are overcome in the present invention wherein an
apparatus converts base stock to releasably-lined labels by separating the face web and the backing
liner, cutting a label from the face web, and pressing the cut label back onto the backing liner to form
the releasably-lined label.
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As disclosed, a butt cut is made to form the label. Alternatively, the labels may be die
cut, in which case the waste matrix must be collected.
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In one embodiment of the invention, a labeling applicator is located downstream of
the label cutting and pressing operations. The liner-backed labels are pulled through the labeling
applicator by the backing liner.
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The label apparatus and method of the invention have several advantages. First,
because the face web and backing liner are separated prior to the cut, the label cut is made through
the face web without the possibility of cutting the backing liner. The cutting blade can sever the
pressure sensitive adhesive-coating and the face web to engage the anvil roller to form a clean,
complete, and reliable label cut. Further, since the backing liner is removed prior to the cutting
operation, there is no need to inspect the subsequent cut to assure that the face sheet and pressure
sensitive adhesive coating have been completely severed -- or that the backing liner has not been cut
or weakened. Second, because the backing liner is not cut or weakened during the conversion of base
stock to back-lined labels, the invention reduces the downtime and waste caused when the backing
liner of prior art labels break as the back-lined labels are pulled through label applicators. Third, the
label applicator equipment can be located immediately downstream of the cutting operation so that
the pressure sensitive adhesive will not bleed across the cut to cause more difficult label separation
during application. Fourth, the invention eliminates the need to use sensor marks on butt cut labels;
sensor marks are required to use prior art butt cut labels with many conventional application
equipment. Fifth, base stock manufacturers can continuously convert the base stock to rolls of liner-backed
labels that can be stored until use by the customer, who can feed the converted roll directly
to conventional label application equipment without further processing.
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These and other objects, advantages, and features ofthe invention will be more readily
understood and appreciated by reference to the detailed description of the preferred embodiment and
the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
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- Fig 1 is a cross-section side view of prior art label base stock;
- Fig. 2 is a diagrammatic view illustrating the apparatus for cutting and applying labels
according to the invention; and
- Fig. 3 is an enlarged diagrammatic view illustrating the laser cutting device cutting
means.
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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
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As shown in Fig. 1, conventional label base stock 10 includes a face web 12 (also
known as "label web" or "base web") and a backing liner 16. The face web 12 has a pressure
sensitive adhesive layer 14 adhered to its rear surface. The backing liner 16 has a release agent
coating 18, such as a silicone release material, on its front side adjacent to the pressure sensitive
adhesive layer 14 of face web 12.
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The backing liner 16 can serve two functions. First, the backing liner prevents the
pressure sensitive adhesive layer 14 from adhering to the front side ofthe face web 12 when the label
base stock material is in a roll. However, this first function can be met without the backing liner if
a release agent is applied to the front side of the face web, as is known in the art. Further, in
applications where the backing liner serves only this first function, the backing liner can be peeled off
and discarded prior to processing the face web.
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The second function of the backing liner is to provide a means by which the label base
stock 10 can be pulled through automated labeling equipment. In this second function, the backing
liner is essential to enable the use of many existing types of automated label applicators -- especially
when the base stock has been converted to butt cut labels.
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Referring to the drawings, Fig. 2 shows the labeling apparatus ofthe present invention.
The base stock 10 travels to separating means 23, which separates the base stock into its face web
12 and backing liner 16 components. The face web travels to cutting means 29, which cuts labels 34
from face web 12. The labels 34 and the backing liner 16 are united at pressing means 37 to form
releasably-lined labels 42. The releasably-lined labels 42 are optionally imprinted and applied to an
article. After the backing liner 16 is separated from the releasably-lined labels 42, the backing liner
travels to pulling means 51 and is taken up by rewind mandril 28.
1. Structure of the Labeling Apparatus
A. Base Stock
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As shown in Fig. 2, unwind mandril 20 provides a rotatable mounting for the base
stock feed roll (not shown) containing base stock 10. A roll of base stock is used to provide an
essentially continuous supply of base stock.
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As shown in Fig. 1, base stock 10 comprises face web 12 having adhesive layer 14
adhered to its rear surface and a backing liner 16 releasably attached to the face web 12 by the
adhesive layer 14. Base stock constructions are well known in the art.
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The face web 12 is made of a flexible material such as paper or plastic. The rear
surface of face web 12 is coated with an adhesive layer 14, preferably a pressure sensitive adhesive.
As is known in the art, the pressure sensitive adhesive is selected according to the intended end use
of the label by considering, for example, the length of time the label is intended to be affixed to an
article and the temperature or other environmental conditions to which the label will be exposed.
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The backing liner 16 includes a flexible base material such as paper or plastic and a
coating layer 18 of release agent or material covering its front surface. The release material 18 may
be a silicone coating or other material (e.g., PTFE varnish) or other substances that allow the backing
liner 16 to release from the face web 12.
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The base web 10 is fed from the unwind mandril 20 over guide roller 22, which is
positioned to manage the base stock 10 as it unwinds from the feed roll. Other web handling
equipment may be utilized to facilitate the web management, as is known in the art. See, for example,
International Patent Application No. WO 90/05089 entitled "Improvements Relating to the
Application of Labels to Articles" published 17 May 1990 and Canadian Patent 1,248,412 entitled
"Self Adhesive Labels and the Manufacture Thereof'' issued 10 January 1989, both of which are
incorporated herein by reference.
B. Separating Means
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Separating means 23 for separating the backing liner 16 from the face web 12 is
located downstream from the unwind mandril 20. The separating means 23 can include, for example,
idler roller 24 and vacuum anvil roller 26, which act in cooperation to separate the backing liner from
the face web, as is explained more fully in the operation section below.
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The backing liner 16 is fed from guide roller 22 over idler roller 24 so that the front,
release-agent coated side of backing liner 16 engages the surface of idler roller 24. The idler roller
24 is positioned downstream relative to guide roller 22 so that the backing liner 16 forms an angle
relative to the face web 12 at the guide roller 22.
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The face web 12 is fed from the guide roller 22 to vacuum anvil roller 26. The
vacuum anvil roller is positioned downstream relative to idler roller 22 so that the face web 12 forms
an angle relative to the backing liner 16 at guide roller 22. The vacuum anvil roller creates a suction
at its surface to hold face web 12 on the surface as the roller rotates. Vacuum cylinders or rollers are
known in the art; see, for example, the previously cited Canadian Patent No. 1,248,412 at page 16.
Face web 12 is fed so that its front or face side is against the surface of vacuum anvil roller 26 and
its opposite rear side with adhesive coating 14 faces outwardly relative to vacuum roller 26.
C. Cutting Means
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Cutting means 29 for cutting label 34 from face web 12 is downstream from separating
means 23. Cutting means 29 can include, for example, a rotary cutter 30 cooperating with vacuum
anvil roller 26 to form cuts 35 in face web 12 and thus create labels 34. Rotary cutter 30 includes at
least one cutting blade 32, and preferably a plurality of cutting blades. Cutting blades 32 can be either
a butt cut blade or a die cut blade, forming butt cut labels and die cut labels, respectively. If cutting
blade 32 is a die cut blade, then label 34 will embody the pattern of the die cut blade; and skeleton
or matrix waste 36 is formed (indicated by broken lines), as is known in the art. If cutting blade 32
is a butt cut blade, the face web 12 is transversely severed so that there is no skeleton or matrix waste
formed.
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Cutting means 29 can also include, for example, a laser cutting device 31 (Fig. 3) that
emits cutting beam 33. Laser cutting devices are known to those of skill in the art. The laser 31 can
be programmed to form either die or butt cuts. The anvil roller 26 can be formed of a suitable
nonmetallic material as the backing surface for the laser cut formed by laser cutting device 31, as is
also known in the art.
D. Pressing means
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Pressing means 37 is downstream from the cutting means 29. Pressing means 37 can
include, for example, pressure nip or traction nip roller 38, which cooperates with vacuum anvil roller
26 to form nip 40. Label 34 is fed from cutting roller 30 to nip 40 with the adhesively-coated rear
surface of label 34 facing traction nip roller 38. Backing liner 16 is fed from idler roller 24 to nip 40
with the release-agent coated front surface of backing liner 16 facing vacuum anvil roller 26. Nip
40 is sufficiently narrow to squeeze or press label 34 and backing liner 16 together to form releasably-lined
label 42. The vacuum suction provided by vacuum roller 26 ceases in the region of the nip, as
is known in the art. (See, for example, the previously-cited Canadian Patent 1,248,412 at page 16
and Fig. 7.) Waste matrix 36 (formed if a die cut is used) is rewound by waste-uptake mandril 44.
E. Imprinting Means
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Releasably-lined label 42 is fed from nip 40 across peel plate 46. Peel plates and their
equivalents are known in the art. Imprinting means 48 is mounted relative to and in cooperation with
peel plate 46 to print a design or other label information on the front surface of label 34. The
imprinting means can include, for example, a thermal transfer printer, direct thermal printer, hot stamp
printer a laser printer, or other similar or equivalent printing devices.
F Label-Affixing Means
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Label-affixing means 54 for affixing label 34 to an article 56 is downstream from the
imprinting means 48 or the pressing means 37. Label-affixing means 54 are known in the art, and
include, for example, automated label-applicators capable of affixing pressure sensitive adhesive labels
to articles 56 traveling along conveyor belt 58. Label-affixing means 54 can include or act in
cooperation with peel plate 46 to separate label 34 from backing liner 16, as is known in the art. The
backing liner 16 wraps around the terminal end 50 of peel plate 46.
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Label-affixing means 54 can be located immediately downstream from the pressing
means 37. "Immediately downstream" as used herein includes a length of time sufficiently short to
minimize the bleeding of the adhesive 14 across cut 35. The bleeding or migration of adhesive
increases with time after the cutting of the adhesive. Such bleeding or migration can cause
operational problems during subsequent separation of the labels 34 from the backing liner 16.
G. Pulling Means
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Pulling means 51 for pulling backing liner 16 is located downstream from the pressing
means 37 (and downstream from the optional imprinting means 48 and the label-affixing means 54).
Pulling means are known in the art, and include, for example, traction nip roller 38 cooperating with
rewind nip roller 52. Backing liner 16 is pulled between the nip formed by traction nip roller 38 and
rewind nip roller 52, at least one of which is powered to provide the pulling force. Backing liner 16
is taken-up or rewound by driven rewind mandril 28 to form a roll of spent backing liner.
II. Operation of the Labeling Apparatus
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Base stock 10 travels from the unwind mandril over guide roller 22. Face web 12
peels or separates from backing liner 16. Face web and backing liner 16 are each pulled at an angle
relative to each other. The face web 12 readily peels from the backing liner 16 because there is a
much stronger bond between the pressure sensitive adhesive layer 14 and the face web 12 than
between adhesive layer 14 and the backing liner 16.
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After separation from the backing liner, the face web 12 travels to the vacuum anvil
roller 26. The suction ot the vacuum roller holds the face web on the anvil surface. The cutting
blades 32 of rotary cutter 30 sever face web 12 by piercing first its adhesively-coated rear side. The
blades continue inwardly toward the front side of face web 12 to engage the surface of the anvil roller
26. Thus, the blades form label 34 by making a clean, complete, and reliable cut. Label 34 then
travels on the surface of the vacuum anvil roller to nip 40. If the cutting means forms die cut labels,
then the skeleton or matrix waste is taken up by waste-uptake mandril 44. If laser cutting device 31
is used, the laser beam 33 performs the same function as cutting blades 32, also cutting from the
adhesively-coated rear side toward the front side of face web 12 to engage the surface of anvil roller
26.
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After separation from the face web, the backing liner 16 travels around idler roller 24
to engage label 34 at nip 40. Traction nip roller 38 and vacuum roller 26 cooperate to press label 34
to the backing liner to form releasably-lined labels 42. At this point, if a roll of releasably-lined
labels is desired, then the releasably-lined labels can be fed to pulling means 51 and rewind mandril
28.
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Alternatively, if an imprinted-labeled article is desired, the releasably-lined labels 42
can travel through imprinting means 48 and label-affixing means 54. The backing liner 16 wraps
around the terminal 50 of peel plate 46 prior to entering the pulling means 51. The rewind mandril
28 takes up the spent backing liner.
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The above descriptions are those of preferred embodiments ofthe invention. Various
alterations and changes can be made without departing from the spirit and broader aspects of the
invention as defined in the claims, which are to be interpreted in accordance with the principles of
patent law, including the doctrine of equivalents.