Note: Descriptions are shown in the official language in which they were submitted.
CA 02596163 2007-08-07
1
T-TABBED DOUBLE-SIDED TAPE AND METHOD OF PREPARATION
Field of the Invention
The present invention relates to double-sided tape and an improved method of
applying it. In particular the invention relates to an improved tabbed tape
and method
of removing the liner from double-sided tape.
Background of the Invention
As is well known double-sided tape must be provided with a liner that prevents
the two adhesive surfaces of the tape from bonding to adjacent objects and/or
each
other. When double-sided tape is used to bond two surfaces together, usually
the first
adhesive layer is applied to the first surface. The tape liner is present and
protects the
second adhesive layer, until the second surface is required to be bonded. This
is
accomplished by first removing the liner from the second adhesive layer of the
tape
and then bonding the second adhesive layer of the tape to the second surface.
Removing the liner from the second adhesive layer of the tape requires
breaking the bond between the protective liner and the tape at one end or the
other.
Usually a fingernail or sharp object is used to separate the liner. This
operation
necessarily causes damage to the expensive adhesive surface, impeding the
proper
bonding of the tape to the second surface. Moreover, this operation causes
stress to
be applied to the end of the tape, which often results in the tape being
lifted off the first
surface at this stress point. Various methods have been attempted to minimize
or
eliminate the damage to the adhesive surface and the lift-off effect at the
stress point.
One method uses an extended tab, which protrudes beyond the end of the
tape. This is done by cutting some of the adhesive portion of the tape away
and
leaving a portion of the liner extending beyond the tape, which can be easily
grasped
for removal. This method is wasteful, in that a portion of the expensive
adhesive is
thrown away. The method also introduces the problem of impacting the integrity
of the
liner. When the adhesive portion of the tape is cut there is the possibility
of also cutting
CA 02596163 2007-08-07
2
the liner, especially when the cutting method used is die stamping. Another
limitation
of this method is that only one tab at the end of the tape is provided. This
is especially
limited in the case where the length of the tape is large, such as, for
example, when
wound into rolls.
Another method is to pre-start the liner, which is costly and ineffective. It
is
desirable to provide a more efficient and cost-effective way to remove liner
from
double-sided tape, without the damaging effects on the tape or the liner.
Summary of the Invention
The present invention comprises a method to remove easily and without
damage the liner from double-sided tape before the tape is bonded to a
surface. The
invention also relates to double-sided tape with a special T-shaped tab, which
facilitates in the removal of the liner.
The method for applying a release liner to an exposed surface of an adhesive
tape has the steps of: a) anchoring a portion of the release liner along a
portion of the
exposed surface of the tape; b) establishing a slack in an un-anchored portion
of the
release liner; and c) re-anchoring a portion of the release liner to a portion
of the
adhesive tape, the re-anchoring occurring at a distance along the release
liner from
the un-anchored slack forming a loop of the release liner along the length of
the
adhesive tape.
Another method for applying a release liner to an exposed side of double-sided
adhesive tape has the steps of : a) unrolling a roll of double-sided adhesive
tape; b)
unrolling a roll of release liner across a lifting plate; c) anchoring a
portion of said
release liner to a portion of said double-sided tape beyond an end of said
lifting plate;
d) lifting said lifting plate; e) dropping said lifting plate to create a
slack in the un-
anchored portion of said release liner; f) re-anchoring a portion of said
release liner on
the opposite side of said slack to a portion of said double-sided adhesive
tape such
that said slack forms a loop between said release liner and said double-sided
adhesive
tape; and g) rolling a roll of double-sided adhesive tape with release liner
attached.
CA 02596163 2007-08-07
3
With respect to the latter method, in some cases, the double-sided adhesive
tape of said unrolling step has a carrier liner in removable registration atop
one of the
adhesive sides.
In some cases, the lifting step further comprises lifting a lifting arm
connected to
said lifting plate.
In some cases, the dropping step further comprises dropping a lifting arm
connected to said lifting plate. Further, some dropping steps are accomplished
by
connecting the lifting arm to said lifting plate with a wire.
One way to perform the lifting step is to lift the lifting arm using a cam
profile
attached to a cam wheel. The cam wheel, in some cases, is rotated by a drive
wheel,
which may or may not involve a pulley system. A spindle may be connected to
the
drive wheel.
A system for applying a release liner to an exposed side of double-sided
adhesive tape may comprise: a lifting plate; a roll of double-sided adhesive
tape; a roll
of release liner, said roll of release liner adapted to unroll atop said
lifting plate; a
means to lift and drop said lifting plate to create a slack in said release
liner; a means
to adhere said release liner to said double-sided adhesive tape such that said
slack
forms a loop between said release liner and said double-sided adhesive tape;
and a
means to roll said double-sided adhesive tape with said release liner
attached.
In such a system, the double-sided adhesive tape has a carrier liner in
removable registration atop one of the adhesive sides.
The system can also comprise a lifting arm connected to said lifting plate
adapted to lift and drop said lifting plate, especially where the lifting arm
is connected
to said lifting plate with a wire.
In some variations, a cam profile attached to a cam wheel lifts and drops the
lifting arm, especially where a drive wheel rotates the cam wheel. More
especially, a
pulley system can be used by the drive wheel to drive the cam wheel.
CA 02596163 2007-08-07
4
In some embodiments, a means for releasing compressed air can bond said
release liner to said double-sided adhesive tape. Some of these embodiments
will use
a trigger knob mounted on said cam wheel, said trigger knob adapted to control
the
release of said compressed air.
A guide roller may be used to guide said double-sided adhesive tape and said
release liner to said rolling means.
An improved double-sided adhesive tape taught in more detail below comprises
an elongate carrier strip, with a length and width defining a pair of opposing
planar
faces that are separated by a thickness that is substantially smaller than
either the
length or width, a layer of pressure-sensitive adhesive applied to each of the
opposing
faces along the length, and a release liner strip in removable registration
atop one of
the adhesive layers, the improvement comprising a loop formed between said
release
liner strip and the adhesive layer upon which it is in registration, said loop
defined by
bending a length of the release liner out of registration with the adhesive
layer before
resuming the registration.
Further features of the invention will be described or will become apparent in
the course of the following detailed description
Brief Description of the Drawings
In order that the invention may be more clearly understood, embodiments
thereof will now be described in detail by way of example, with reference to
the
accompanying drawings, in which identical parts are identified with identical
reference
numerals and in which:
FIGURE 1 is a sectional view of a portion of a double-sided tape having the
improvement of a T-shaped tab in the release liner, with one side bonded to a
surface;
FIGURE 2 is a side view of a machine for manufacturing the improved double
sided tape;
FIGURE 3 is an isolated enlargement of a portion of the Fig. 2 machine; and
CA 02596163 2007-08-07
FIGURES 4a and 4b are isolated enlargements of a portion of the Fig. 2
machine, illustrating the formation of the tab along the release liner.
Description of Preferred Embodiments
Referring first to FIGURE 1, an improved double-sided tape 1 is shown. The
5 tape 1 is a carrier strip with a top side 2 and a bottom side 3, each of
which has had an
adhesive coating, particularly a pressure-sensitive adhesive (PSA) coating
applied to
them. Both the tape and the adhesive will be familiar to those of skill in the
art. For
example, the tape will typically be a polymeric film, especially a
polyethylene film. The
adhesive, especially the pressure-sensitive adhesive, will typically be an
acrylate
material. In many embodiments that will be familiar to those in the art, the
tape 1 is an
elongate web of the material having a defined width and a very long length,
the
thickness of the tape being substantially smaller than even the width. The PSA
is
applied using known techniques in a thin layer on each of the surfaces 2, 3.
In the depicted embodiment, the bottom side 3 of the tape 1 is shown after a
protective release liner has been removed to permit adhesion to a surface 4.
In a tape
1 of this type as known in the prior art, the release liner will have been
applied in a
continuous registration atop the surface 4. The release liner will typically
be of the
same composition as the tape, although it may be thinner, as it need not
display the
same strength and/or longevity as the tape. Because the release liner has been
coated with a specific coating, usually a silicone material, to which the PSA
does not
adhere as aggressively as to the surface of the tape 1, peeling of the release
liner off
of the tape leaves the PSA effectively intact on the tape. However, the
primary focus
of many prior attempts at facilitating peel of the release liner have been
directed at
weakening of the release liner itself, as with perforations, scorings, or the
like, or at
providing a release liner that is thin when compared to the tape. As these
strategies
are implemented prior to registration, to avoid damaging the tape, they
implicitly impair
the strength of the web of release liner during the registration process.
Also,
techniques that disrupt the continuity of the release liner on the tape pose
the potential
CA 02596163 2007-08-07
6
of exposing the PSA prematurely, allowing it to be contaminated by dirt, dust,
moisture
and the like.
However, and as readily viewed, albeit in a rather exaggerated manner, the
solution provided herein is to provide a tape in which a length of the release
liner 5 is
bent out of strict registration with the tape while it is being applied to the
tape. By
doing this, a loop of the release liner material is formed that extends away
from the
tape. The loop, which rejoins the tape in registration at a position very
close to the
point from which it departs from registration with the tape, provides a tab 6
with a
general "T" shape in which the tape represents the cross member of the "T" and
the
loop represents the upright member.
When top side 2 of tape 1 is required to be bonded to a second surface, the
liner 5 is removed to expose the adhesive coating of top side 2. This is
accomplished
by a simple lifting motion of tab 6, which releases the liner at edges 7,
thereafter
promoting the easy removal of the entire liner.
The integral construction of the tab 6 with liner 5 has the advantage that a
single pulling motion of the tab 6 commences the removal of liner 5 from tape
1 in both
directions. Optionally, the tab 6 can be cut at its apex to allow dispensing
of the liner 5
in two stages.
As can be seen from Figure 1 the tab 6 is located at a distance from edge 7 of
tape 1. The advantage of locating the tab 6 away from edge 7 is that during
the
operation of removing liner 5 the disengagement of liner 5 from the top
adhesive side
2 takes place in a direction toward the edge 7. This eliminates the "lift-off'
effect that
would occur at stress point 8 if the lifting of the liner 5 took place in the
opposite
direction and provides superior bonding between the two surfaces.
In addition to eliminating the damage to the adhesive surface and the lift-off
effect of conventional double-sided tape release liners, the T-tabbed tape
also has the
advantage of providing an easy and time-efficient way of removing the release
liner as
compared to prior art release liners. Additionally, as tab 6 is constructed of
the same
CA 02596163 2007-08-07
7
thin material as liner 5, it can easily be folded down such that the tape 1
can be wound
into rolls or, if required, pre-cut strips of T-tabbed tape can be stacked one
on top of
another.
Another advantage of the tab over prior art, such as the extended tab, for
example, is that several T-tabs can be provided, spaced within the length of
the
double-sided tape, as opposed to only one tab at the end of the tape.
Placement of the release liner 5 in this looped fashion atop the tape 1 allows
the web of tape to be wound upon itself in a roll, so that it may be dispensed
in a
manner similar to that used with conventional single-sided adhesive tape. In
rolling
the web up into a roll, each loop of the release liner folds downwardly onto
the
registered release liner. This folding of the loop also permits lengths of the
double-
sided adhesive tape 1 to be stacked atop each other, the release liner 5, and
particularly the loops formed therein, facilitating the separation of the
individual lengths
from each other.
In one embodiment, some or all of the loops may be cut, especially
transversely
and most especially at an apex of the loop. This allows the divided loop ends
to serve
as tabs which may be readily grasped and pulled to perform the peeling
operation.
While the illustrated embodiment shows a single loop formed in the release
liner
along its registration on the tape 1, it will be obvious that a plurality of
the loops may
be formed along a given length of the tape. The longitudinal spacing of the
loops
along the tape 1 would preferably be regular, and this will in many cases be
the natural
result of the manufacturing process. However, irregular spacing would
generally not
impede the utility of a tape having the irregularly-spaced loops.
In a preferred embodiment, tab 6 extends vertically to a desired length of
about
1" from the top side 2 of tape 1. This allows a sufficient amount of the liner
5 to be free
of adhesion with the PSA to permit a secure grip by a user.
CA 02596163 2007-08-07
8
A machine and method of assembling the tape construction described above.
These are illustrated in FIGURES 2 through 4b.
Beginning with Fig. 2, the device 100 consists of two feed rolls, one for the
protective liner 5 and one for the tape 1. The tape 1, earlier joined with the
carrier liner
(not shown) on the bottom side 3, has a top side 2 free to bind with the
protective liner
5. After the protective liner 5 is bonded to the tape 1 with the formation of
tab 6, the
material is collected into a final tape log 9 onto a winding roll 10.
From their respective feed rolls, the protective liner 5 is drawn over a metal
platen or lifting plate 11 and the tape 1 travels underneath, where both
layers then
make contact after the said lifting plate 11, proximate to a guide roller
described below.
The lifting plate 11 is rotatably fixed at one end to a support beam 12 and is
free at an
opposite end 13, where the protective liner 5 joins the adhesive 1. Thus, the
lifting
plate 11 rotates about its fixed support beam 12, raising and lowering its
free end 13.
The free end 13 of the lifting plate 11 also has a compressed air line
14mounted along
its length to urge the protective liner 5 against tape 1. The tape is then fed
under the
guide roller 15, as mentioned above.
As demonstrated in Figure 3, which isolates some of the elements from Fig. 2
to
focus better on their operation, the movement of the lifting plate 11 is
controlled by a
lifting arm 16. The lifting arm 16 is connected by a wire 17 to the lifting
plate 11. The
lifting arm 16 acts as a lever; its tail end being rotatably attached to
another fixed
support beam 12 and its head end having a cam follower 18. The said cam
follower 18
is controlled by a cam profile 19 on a cam wheel 20. The cam wheel 20 is
connected
by a pulley belt 21 to a drive wheel 22, which is coupled onto the said
winding roll 10.
The rotational motion of the winding roll 10 turns the coupled drive wheel 22
and
through the pulley belt 21, the cam wheel 20 is also turned. The pulley belt
21
connecting the drive wheel 22 to the cam wheel 20 is fitted by a tensioning
arm (not
shown) to allow different sizes of drive wheels to function within one
assembly. As the
cam wheel 20 rotates, the cam follower 18 interacts with the cam profile 19,
raising
CA 02596163 2007-08-07
9
and dropping the lifting arm 16. The movement of the lifting arm 16 controls
the hinged
lifting plate 11 through the connection of the wire 17.
The compressed air line 14 is mounted along the length of the free end 13 of
the lifting plate 11 to firmly adhere the protective liner 5 to the tape 1.
Furthermore, the
guide roller 15 is located directly after the lifting plate 11 to apply
pressure to the
formed material to ensure binding is secure. Connected to said compressed air
line 14
on said lifting plate 11, is a flexible air hose 23. A trigger knob 24 mounted
on said
cam wheel 20 controls the release of the compressed air line 14. The trigger
knob 24
makes contact with a valve switch 25 for the flexible air hose 23 to release
air at said
mounted air line 14. Immediately after the lifting plate 11 has fallen to its
lowered
position, the trigger knob 25 engages and opens the valve switch 25 on the
flexible air
hose 23, releasing air from the mounted line 14 onto the loop 26 and adhesive
1. The
liner 5, loop 26, and adhesive 1 then run through the guide roller 15 and are
wound up
in the final tape log 9
The tabs 6 are formed by the creation of slack in the protective liner 5 by
the
lifting plate 11. It is illustrated in Figure 4(a) that as the lifting arm 16
rises a distance d
it also raises the lifting plate 11 a distance d, and the liner 5 must travel
over the lifting
plate 11 and down to the adhesive 1 at a 900 angle. Then, as shown in Figure
4(b), as
the cam follower 18 disengages from the cam profile, the lifting arm rotates
about its
support beam 12, suddenly dropping the lifting plate 11. A loop 26 of
protective liner 5
is trapped from the slack formed by the distance the protective liner 5 had to
travel
from the free end 13 to the tape 1 when the lifting plate 11 was raised. It is
this loop
structure 26 that forms the tab 6 attribute within the tape log 9. The loop 26
is formed
from a fold in the trapped protective liner 5.
The height of the tab 6 from the top surface 2 of the tape 1 is determined by
the
position of the lifting arm 16 with respect to the cam wheel 20. The lifting
arm 16 is
flexibly mounted to allow rotation about its support beam such that the cam
follower 18
interacts with the cam profile 19 at a specific position and raises the cam
follower 18 to
a desired height. Therefore, the angle that the lifting arm 16 is mounted on
its support
CA 02596163 2007-08-07
beam 12 determines the point at which the cam follower 18 makes contact with
the
cam profile 19 and the height that the lifting arm 16 is raised. The distance
that the
lifting arm 16 is raised, d, is equal to the height the lifting plate 11 is
also raised, d, due
to the connecting wire 17. The height, h, of the loop 26 is consequently equal
to half
5 this distance, d. To ensure that the free end 13 of the lifting plate 11
will fall to its
lowest position to make contact with top side 2 of adhesive 1, the wire 17
connecting
the lifting arm 16 to the lifting plate 11 is adjusted as needed to correspond
with the
articulated mounting position of the lifting arm 16 on its fixed support beam
12. To
fabricate T-tabs 6 of different heights, the lifting arm 16 must be
repositioned on its
10 support beam 12 so its cam follower 18 interacts with the cam profile 20 at
a new
height.
As stated, an advantage of the tab 6 is the ability to provide a plurality
thereof
spaced within the final tape log 9. The spacing of the tabs 6 is determined by
controlling the angular speed of the cam wheel 20. This can be achieved
through
changing the diameter of the drive wheel 22, as the cam wheel 20 and drive
wheel 22
are connected via the said pulley belt 21. The feature of this connection is
the
relationship between the angular speeds and diameters of the cam wheel 20 and
drive
wheel 22. As the drive wheel 22 is coupled to the winding roll 10, it turns
with the same
constant angular speed. Therefore, as known to one skilled in the art, by
increasing
the diameter of the drive wheel 22 and keeping the diameter of the cam wheel
20
constant, it subsequently increases the angular speed of the cam wheel. When
the
speed of rotation of the cam wheel 20 increases, more interaction cycles
between the
cam follower and cam profile occur, which lifts the lifting plate more
frequently, and
creates more T-tabs within a roll spaced closely together.
Sufficient slack must be present in the liner feed roll 5 to prevent the loop
26
material from being drawn back and coming off of the adhesive 1. A belt
connection
(not shown) between the winding roll 10 to the protective liner 5 feed roll
keeps the
protective liner 5 roll moving at a faster speed then the adhesive 1 roll to
maintain
slack.
CA 02596163 2007-08-07
11
Other advantages, which are inherent to the structure, are obvious to one
skilled in the art. The embodiments are described herein illustratively and
are not
meant to limit the scope of the invention as claimed. Variations of the
foregoing
embodiments will be evident to a person of ordinary skill and are intended by
the
inventor to be encompassed by the following claims.
