Note: Descriptions are shown in the official language in which they were submitted.
PCT/~8 9 1 / 0 0 9 0 6
2~ ~ 92
- 1 - 21 ~ 199
METHOD OF AND APPARATUS FOR PRODUCING LABELS
The present invention relates to a method of and an
apparatus for producing a succession of self-adhesive labels
carried on a backing of release material.
It is known, for e~ample from EP-A-0275670, to produce
a succession of self-adhesive labels which are carried
directly on a backing of release material.
The present invention aims to provide an improved
method of and apparatus for producing labels.
Accordingly, the present invention provides a method of
producing a succession of self-adhesive labels carried on a
backing of release material, the method comprising the steps
of:- (a) providing a plurality of printed sheets; (b)
feeding the sheets in succession through an adhesive
spraying station at which adhesive is sprayed from a spray
nozzle onto an e~posed surface of each sheet; and (c)
adhering the adhesive-coated exposed surface of each of the
succession of sheets to a backing of release material,
characterised in that prior to feeding step (b) the sheets
are electrostatically charged thereby to enhance the coating
of adhesive onto the exposed surfaces.
The present invention also provides an apparatus for
producing a succssion of self-adhesive labels carried on a
backing of release material, the apparatus comprising an
adhesive spraying station comprising a spray nozzle for
spraying adhesive, means for feeding a succession of printed
sheets through the adhesive spraying station so that an
exposed surface of each sheet is coated with adhesive and
means for adhering the adhesive-coated surface of the sheets
to a backing for release material, characterised by means
for electrostatically charging the sheets before the sheets
are fed through the adhesive spraying station.
PCiTe~ malPApplticatfifoCne SUBSTITUTE SHEE~
WO91/18737 2 ~ 8 4 PCT/GB91/00906
Embodiments of the present invention will now be
described by way of e~ample only with reference to the
accompanying drawings, in which:-
Figure l is a diagrammatic elevation of an apparatus forproducing labels in accordance with a first embodiment of the
present invention;
Figure 2 is a diagrammatic plan view of the apparatus of
Figure l along line A-A;
Figure 3 shows a modification of the endless belt of the
apparatus of Figures l and 2; and
Figure 4 is a diagrammatic elevation of an apparatus for
producing labels in accordance with a second embodiment o. the
present invention.
Referring to Figures l and 2, an apparatus, designated
generally as 2, for producing a succession of self-adhesive
labels carried on a release bac~ing material includes a
magazine 4 for holding a stack of printed sheets 6. The
sheets 6 may be single layer or multi-layer sheets and are
printed by any suitable printing method, such as lithographic,
screen or laser printing. A sheet feeding mechanism 8 is
located above the stack of sheets 6 and is adapted to feed
from the magazine 4 a succession of sheets 6 from the top of
the stack. The sheet feeding mechanism 8 is represented as a
rotatable drive cylinder but may alternatively comprise any
suitable known sheet feeding mechanism. The sheets are fed in
succession past an electrostatic charqing device lO which is
adapted to apply an electrostatic charge of a given polarity
across the upper surface of the sheets 6. When the sheets 6
are made of paper, this charge is retained evenly over the
sheets 6. If desired, the electrostatic charginq device lO
may be omitted when the sheet feeding mechanism 8 is adapted
WO91/18737 2 ~ ~ g 6 7 ~ PCT/GB9l/00906
to feed sheets from the stac~ in such a way that the fed
sheets have an electrostatic charge. The sheets are fed by
the sheet feeding mechanism 8 onto a vacuum drive means
incorporating a vacuum conveyor 12 which comprises an endless
belt 14 mounted between a pair of drive rollers 16. The
surface of the endless belt 14 is provided with a series of
holes 18 and the space 20 between the opposed inner surfaces
of the endless belt 14 is connected to a source of suction.
As the sheets 6 are deposited onto the vacuum conveyor 12 the
bottom surface 22 of each sheet is suc~ed through the holes 18
against the upper surface 24 of the endless belt 14. This
ensures that each sheet 6 is firmly located on the vacuum
conveyor 12.
The vacuum conveyor 12 conveys the succession of sheets 6
through an adhesive spraying station 26 comprising a spray
nozzle 28 for spraying a coating of adhesive 30 onto the
exposed upper surface 32 of each sheet 6 passing through the
adhesive spraying station 26. In the preferred embodiment,
the spray nozzle 28 is adapted to spray electrostatically
charged droplets of adhesive onto the exposed surfaces 32.
This may be effected by feeding electrostatic charge from a
source of electric power to the spray nozzle 28, the charge
being of opposite polarity to that which is applied by the
electrostatic charging device 10. The adhesive may be a
water-or solvent-based pressure-sensitive adhesive or
alternatively a heat-sealable pressure-sensitive adhesive.
The succession of sheets 6 coated with adhesive 30 is
then fed by the vacuum conveyor 12 to a laminating station 34
comprising a pair of opposed rollers 36, 38 between which the
succession of sheets 6 is laminated to a bac~ing 40 of relezse
material, the laminating being achieved by adhering the
adhesive-coated surface 32 of each sheet 6 to the backing 40
of release material. The backing 40 of release material is
fed out from a reel 42 thereof and typically comprises a wa~-
W091/t8737 PCT/GB91/0~906
2~8~67~
-- 4 --
or silicone-coated paper. The adhesive coating 30 is urged
against the bac~ing ~0 of release material and then the
combined assembly passes over an idle roller 44 and is then
wound up on a ta~e-up reel 46 of the succession of
self-adhesive labels 6 on the backing 40 of release material.
In the illustrated arrangement, the sheets 6 are conveyed
through the adhesive spraying station 26 in spaced relation.
The spraying nozzle 28 may be operated either -continuously or
intermittently in synchronism with the disposition thereunder
of a sheet 6 to be sprayed with adhesive. A washing and
cleaning mechanism 48 is disposed in contact with the endless
belt 14 for cleaning excess adhesive 30 off the outer surface
of the endless belt 14.
If desired, the apparatus may also comprise a slitting
mechanism at, or downstream of, the laminating station 34 at
which the backing 40 of release material and the succession of
sheets 6 adhered thereto are longitudinally slit so as to
provide two adjacent reels 46 of the self-adhesive labels
carried on the bac~ing of release material. With this
arrangement, each printed sheet 6 would have a pair of
identical images printed thereof transversely adjacent to each
other.
As shown in Figure 3, the endless belt 14 may be modified
by the provision thereon of a succession of raised pads 58.
In use the sheet feeding mechanism 8 feeds the sheets 6 so
that each sheet lies on a respective pad 58 above the surface
60 of the endless belt 14. This assists the application of
adhesive to the sheets 6 and ensures that those parts of the
endless belt 14 which receive extraneous adhesive do not
actually contact the edges of the sheets 6.
A second embodiment of an apparatus for producing labels
in accordance with the present invention is shown in Figure
~0 91tl8737 PCr/GB91/00906
5 2~4~7~
4. This embodiment is a modification of that shown in Figures
1 and 2 and li~e parts are identified by like reference
numerals. In this embodiment, the vacuum conveyor 50
comprises a vacuum cylinder 52 which is hollow and the
cylindrical surface of which is provided with an array of
holes (not shown). The cylindrical void in the centre of the
vacuum cylinder is connected to a source of suction. The
sheets 6 are fed out from the stack thereof by the sheet
feeding mechanism 8. The bottom surface 22 of each sheet 6
engages the upper surface of the printing cylinder 52 which is
rotatably driven and conveys the sheet 6 through the adhesive
spraying station 26 to the laminating station 34. The
adhesive spraying station 26 is additionally provided with a
pair of shields 54, 56 which are located on upstream and
downstream sides, in relation to the direction of feeding of
the sheets 6, of the spray nozzle 28. The shields 54, 56 are
arranged so as to control the application of the spray of
adhesive ~0 to within defined boundaries. If desired, the
operation of the spray nozzle 28 is controlled so as to be
intermittently synchronized with the location of a sheet 6
between the shields 54, 56.
As with the first illustrated embodiment, the apparatus
may be modifed by the addition thereto of a slitter for
longitunally slitting the assembly of self-adhesive labels
carried on the release material. The apparatus may
additionally be provided with a downstream inspection station
at which the assembly of self-adhesive labels on the reel of
release bac~ing material can be inspected.
In each of the two illustrated embodiments, the
electrostatic charge initially on the sheets as they enter the
adhesive spraying station is either neutralised by the
application of the adhesive or dissipated at, or downstream
of, the adhesive spraying station as a result of contact of
the sheets with other parts of the apparatus. In the
resultant reel of self-adhesive labels, there is no
substan'ial electrostatic charge.
