Method and apparatus for attaching labels to containers

In a method for attaching labels to containers, the labels are removed from a stack by rolling contact with an adhesive surface coated with a cold glue. Prior to termination of the removing step, a localized hot glue coating is in addition applied to the foremost label in the stack. After the label has thus been coated with cold glue and hot glue, it is peeled of the adhesive surface and pressed into contact of its glue-coated backside with a container. The provision that the hot glue coating is applied to the label while it is still held in the magazine ensures that the shape and position of the hot glue coating is fully independent of the speed of the labelling operation.

DESCRIPTION 
The invention relates to a method for attaching labels to containers 
according to the generic clause of claim 1, and to an apparatus for 
performing the method according to the generic clause of claim 7. 
Already known are methods and apparatus of this type, in which the hot glue 
is applied to the previously cold glue-coated labels after release from 
the adhesive surface, either by means of spray nozzles disposed at fixed 
positions adjacent the periphery of a gripper cylinder (DE-OS 30 41 057), 
or by means of an applicator roller rotatably mounted adjacent the 
periphery of a gripper cylinder (DE-OS 26 42 046). The removal of the 
labels and their cold-glue coating process permits an accurate and 
unhampered removal of even intricately shaped labels with a high output. 
The additional dot- or strip-shaped hot glue application results in that 
the labels reliably adhere to materials, such as metal or plastics, which 
are insufficiently suitable for applications using cold (or "wet") glue. 
The labels may therefore be used as a warranty seal. On the other hand, in 
both of the cited cases the hot glue is applied to the labels while they 
are in motion, resulting in difficulties regarding the accurate location 
and area definition of the hot glue application. This makes itself 
particularly felt in the case of high outputs and corresponding conveying 
speeds. 
There is already also known a method and apparatus for its performance of a 
completely different type, in which the removals of the labels from a 
staionary magazine is not accomplished by means of adhesive surfaces 
having a large area coated with cold or wet glue, but rather directly by 
the container to be labelled, which to this purpose is provided with a 
narrow hot flue strip extending along a generatrix (DE-GM 87 03 630). For 
bonding the overlap of the leading and trailing ends of the label on the 
container, the trailing end of the foremost label in the magazine is in 
each case provided with a row of hot glue dots by means of a series of 
stationary applicator nozzles. This known method is only suitable for 
applying simple wrapper labels to cylindrical containers, and that only 
with a relatively low output. The method does not permit the application 
of more intricately shaped labels to containers of non-cylindrical shape, 
particularly with the purpose to act as a warranty seal. 
It is an object of the invention to improve a method and apparatus of the 
type defined above so as to reduce the dependency of the accuracy of the 
hot glue application on the speed and output of the labelling operation. 
This object is attained according to the invention by the characteristics 
of claim 1 as regards the method, and by the characteristics of claim 7 as 
regards the apparatus. 
According to the method of the invention, and in the apparatus according to 
the invention, the hot glue is applied while the respective label is still 
completely or partially retained on the stack or in the magazine, 
respectively, when the cold-glue coating operation has not yet begun or is 
just in progress. In this manner, all the problems resulting from the hot 
glue applications to moving labels are immediately avoided. The shape and 
position of the hot glue application can be accurately determined and 
maintained constant. Even the operation with varying output performance, 
as customary in the case of modern labelling machinery, does not result in 
any variation of the hot glue application. Due to the separation of areas 
coated with cold glue and hot glue, mutual impairment of the adhesive 
strengths and malfunctions in the release of the labels from the adhesive 
surfaces are fully avoided. 
Advantageous improvements of the method according to the invention are set 
forth in claims 2 to 6, and of the apparatus according to the invention, 
in claims 8 to 10. 
The method according to the invention and the apparatus according to the 
invention ensure a constant quality of the hot glue application under all 
operational conditions. The apparatus according to the invention may 
moreover be of a relatively simple construction, since the control of the 
hot glue applicator is independent of the moving speed of the adhesive 
surfaces or the gripper cylinder, respectively; it is therefore not 
required to provide variable derivative action timing for the activation 
of the applicator. Moreover there occurs no "trailing" of the hot glue 
coating which might otherwise be caused by a displacement of the 
applicator device and the label surface relative to one another.

The apparatus of FIGS. 1 and 2 is integrated in an only partially shown 
labelling machine and serves for attaching anchor-shaped labels 2 to 
bottles 11 having a metal closure cap, e.g. a screw cap, so that label 2 
acts as a warranty seal. 
The apparatus comprises a rotor 8 mounted for continuous rotation about a 
vertical axis 12 and having eight shafts 13 rotatably mounted adjacent its 
periphery in parallel to axis 12. The lower ends of shafts 13 are 
operatively connected to a not shown cam transmission housed within rotor 
8 and acting to impart oscillating movements to shafts 13 in response to 
the rotation of rotor 8. The upper ends of shafts 13 are mounted in a 
removable cover plate 20. Secured to each shaft 13 is a respective remover 
element 3 formed with a part-cylindrical adhesive surface 4 at a position 
excentrically offset from the axis of the respective shaft 13. 
Provided adjacent the periphery of rotor 8 is a cold or wet glue applicator 
device 6 comprising a glue roller 14 mounted for continuous rotation in 
the direction of the arrow shown, a glue nozzle 15 and an adjustable 
doctor blade 16. On passing glue roller 14, remover elements 3 are 
controlled in such a manner that their finely grooved adhesive surfaces 4 
come into substantially slip-free contact with the circumferential surface 
of glue roller 14 to thereby receive a uniform coating of the cold glue 
supplied by nozzle 15 and metered by doctor blade 16. 
Also disposed at a fixed position adjacent the periphery of rotor 8 is a 
magazine 1, composed of a plurality of parallel guide rods, and adapted to 
contain a stack of labels 2 in such a manner that the foremost label 2 in 
the stack exposed at the removal opening of magazine 1 extends at a 
tangent to rotor 8. The ends of the guide rods defining the removal 
opening are provided with small projections (not shown) acting to retain 
labels 2 in magazine 1 as the stack is subjected at its rear end to the 
action of a likewise not shown pusher member. On passing magazine 1, 
remover elements 3 are controlled in such a manner that their adhesive 
surfaces 4, previously coated with a strip-shaped cold glue pattern, come 
into substantially slip-free contact with the foremost label 2 in the 
stack to thereby gradually remove it from the label stack and thus from 
magazine 1, by the adhesive action of their glue coating. 
Finally, a gripper cylinder 5 equipped with cam-controlled gripping fingers 
17 and resilient pressure pads 18 is mounted adjacent the periphery of 
rotor 8 for continuous rotation in the direction of the arrow shown. On 
passing gripper cylinder 5, remover elements 3 are controlled in such a 
manner that the leading ends of labels 2 are gripped by gripping fingers 
17 and the labels are subsequently peeled off adhesive surfaces 4 in a 
careful manner. During these operations, part of the cold glue on adhesive 
surfaces 4 is transferred to the backside of the respective labels 2 so as 
to form a strip-shaped cold glue pattern 19 thereon as indicated by 
horizontal lines in FIG. 3. 
As illustrated in FIGS. 2 and 3, adhesive surfaces 4 are provided with 
cutouts at locations corresponding to those of the guide rods of magazine 
1 and gripping fingers 17 of gripper cylinder 5, these cutouts resulting 
in the formation of respective glue-free areas on the backsides of labels 
2. In addition, the upper narrow portion of each remover element 3 
corresponding to the strip-shaped top portion 2b of the labels 2 is 
somewhat shortened relative thereto, or the upper portion of adhesive 
surface 4 is completely omitted. The upper free end portion of the 
strip-shaped neck portion 2b of each label does thus not come into contact 
with remover element 3 on removal from the label stack, so that it remains 
free of cold glue. 
Disposed above cover plate 20 in the normal operation of the apparatus is a 
plate-shaped bridge 9 having one of its ends pivotally connected to a 
vertical support bar 21 and releasably and rotatably support at its 
intermediate portion on center axis 12 of rotor 8 by means of a plug and 
socket connection. In the case of malfunction, or for a conversion of the 
apparatus requiring replacement of shafts 13 with remover elements 3 after 
cover plate 20 has been taken off, bridge 9 can be pivoted upwards to a 
substantially vertical position as indicated by the arrow in FIG. 2. 
Secured to the other end portion of bridge 9 adjacent magazine 1 is a hot 
glue applicator device 7 comprising a glue nozzle 10 accurately directed 
onto the upper end portion of the strip-shaped neck portion 2b of the 
foremost label 2 in magazine 1. A heatable hose 22 is provided in the 
usual manner for connecting applicator device 7 to a glue supply assembly 
23 comprising a heatable supply reservoir, a pressure pump, control 
components and the like and operable to supply liquid hot glue to 
applicator device 7. The latter further includes a solenoid valve 24 
acting to admit the pressurized hot glue to glue nozzle 10 in successive 
pulses, so that the latter applies an annular bead-shaped hot glue coating 
25 to the upper end portion of neck portion 2b of successive labels 2. At 
the location of hot glue coating 25 the label is free of cold glue. 
Solenoid valve 24 of applicator device 7 is connected to and controlled by 
a sensor 26 acting to detect control pins 27 provided on the periphery of 
rotor 8 in association with each shaft 13. Sensor 26 is located so as to 
cause glue nozzle 10 to be activated for a short interval whenever one of 
adhesive surfaces 4 comes into contact with the trailing end of the 
foremost label 2 in magazine 1 (cf. FIG. 1). The application of glue 
coating 25 is terminated when the bar-shaped center portion of adhesive 
surface 4 comes into contact with neck portion 2b of label 2 and starts to 
remove it from magazine 1. The hot glue coating 25 is thus applied to an 
absolutely stable or stationary portion of label 2, independent of the 
operating speed of the labelling machine. 
Advantageously solenoid valve 24 is additionally controlled by a (not 
shown) bottle detector acting to prevent the removal of a label in the 
absence of a respective bottle. In this case, the hot glue application 
process is activated only when a bottle is available for a respective 
label, in other words, it is avoided that a label which is not as yet to 
be removed receives more than one hot glue coatings. The removal of labels 
may be prevented either by intermittent retraction of magazine 1 away from 
rotor 8, or by suitably controlling the movements of remover elements 3. 
The labels 2 retained on the periphery of gripper cylinder 5 by its 
gripping fingers 17 thus have their outwards facing backsides provided 
with an annular hot glue coating 25 at their uppermost end portions, and a 
cold glue coating 19 in the form of horizontal stripes at their central 
and lower portions as illustrated in FIG. 3. For reducing the consumption 
of cold glue, coating 19 may be formed with additional void areas. The hot 
glue coating may also be of different shape, for instance in the form of a 
dot. 
After the labels 2 have thus been coated with cold glue by adhesive 
surfaces 4, and with hot glue by means of glue nozzle 10, removed from the 
stack in magazine 1, and subsequently peeled off adhesive surfaces 4 in 
the manner described above, gripper cylinder 5 acts to apply them to 
bottles 11 carried on a bottle table 28 rotating in the direction of the 
arrow shown in FIG. 1, and to bring them into intimate contact with the 
body, neck and closure element of the bottles with the aid of resilient 
pressure pads 18 and an arrangement of blow nozzles (not shown). 
Thereafter, cold glue coating 19 ensures good adherence to the glass, and 
hot glue coating 25, to the metal of the bottle closure element. The label 
is finally pressed into conformity with the contours of bottle 11 by means 
of brush and/or sponge rollers (not shown). After the hot glue has been 
permitted to cool down, and the cold glue to dry, the opening of the 
bottle closure element inavoidably results in the strip-shaped neck 
portion 2b of label 2 being torn, so that the desired warranty seal effect 
is obtained in this manner.