ADHESIVE TAPE AND METHOD FOR PRODUCING IT

BANDE ADHESIVE ET SON PROCEDE DE PRODUCTION

English Abstract

The invention relates to a method for producing an adhesive tape for
redetachable closure or fixing, comprising a strip-like carrier
(1), which is being coated with a self-adhesive agent (2), at least on the
active area which during use of the adhesive tape is brought into
contact with a counter surface (7), and also relates to the adhesive tape as
such. For improving production of the adhesive tape, several
methods are suggested, according to one of which in a first step the active
area is coated with a self adhesive agent (2) forming a continuous
layer, and in a second step, in order to reduce the effective entire adhesive
area, a non-adhering or less-adhering separating pattern (4) is
printed on the self adhesive layer.

French Abstract

Cette invention concerne un procédé de production d'une bande adhésive pour fixation ou fermeture redétachable ou réouvrable, ainsi que la bande adhésive elle-même. La bande adhésive comprend un support (1) du type bande qui est recouvert d'un agent auto-adhésif (2) au moins sur la surface active qui, lorsqu'on utilise la bande adhésive, est mise en contact avec une surface opposée (7). Pour améliorer la production de la bande adhésive, on peut utiliser plusieurs procédés; selon l'un d'entre eux, on recouvre dans une première étape la surface active avec un agent auto-adhésif (2) pour former une couche continue, puis dans une deuxième étape on imprime sur ladite couche auto-adhésive un motif qui n'adhère pas ou qui adhère moins afin de réduire la surface adhésive efficace totale.

Claims

7
WE CLAIM:
1. An adhesive tape comprising:
a carrier, said carrier being coated with a self-adhesive agent, at least
on an active area of said carrier which during use is brought into contact
with
a counter surface, wherein said active area consists of a non-adhering or less
adhering separating pattern and an adhesive pattern of self-adhesive agent
printed into blank spaces of said separating pattern;
said carrier comprising a finger lift strap adjacent to said active area;
and,
a second section of said carrier longitudinally adjacent to said active
area, said second section comprising a continuous adhesive layer, said
adhesive layer being active.
2. An adhesive tape as claimed in Claim 1 further comprising:
a second section of said carrier longitudinally adjacent to said active
area, said second section comprising a continuous adhesive layer, said
adhesive layer being active.
3. An adhesive tape as claimed in Claim 1 wherein said carrier is a carrier
strip.
4. A method for producing an adhesive tape according to Claim 1 for
redetachable closure or fixing comprising:
providing a carrier;
coating said carrier with a self-adhesive agent at least on an active
area of said carrier by forming a continuous layer of said self-adhesive
agent;
coating said carrier with a non-adhering or less adhering separating
pattern in order to reduce the effective adhesive area on said carrier; and,
providing a finger lift strap arranged in a section adjacent to said active
area.

8
5. The method of Claim 4 further comprising:
printing said separating pattern on said active area; and,
printing said adhesive agent in blank spaces of said non-adhering or
less adhering separating pattern.
6. The method of Claim 4 further comprising:
activating said non adhering or less adhering substance by optical,
physical or chemical means.
7. The method of any one of Claims 4 to 6 wherein said carrier is a
carrier strip.

Description

CA 02224562 1997-12-11
WO 96/41604 PCT/US96/09711
1
Adhesive tape and method for producing it
The invention relates to a method for producing an adhesive tape for
redetachable
closure or fixing, comprising a strip-like carrier, said earner being coated
with a self
adhesive agent, at least on the active area which during use of said adhesive
tape is
brought into contact with a counter surface.
Also, the invention relates to an adhesive tape for redetachable closure or
fixing,
comprising a strip-like carrier, said carrier being coated with self adhesive
agent, at
least on the active area which during use is brought into contact with a
counter
surface.
In many applications such adhesive tapes should solve two opposing objects:
They
should have sufficient high adhesion which is ensured already by light
pressing of the
adhesive tape against an uneven surface, and it should be possible to
repeatedly peel
them of from said surface for opening without destroying said counter surface.
The
last mentioned object is particuly difficult to solve if the counter surface
against
which the adhesive tape is pressed with its redetachable area consists of a
thin plastic
foil, a sensitive fabric or the like. This problem arises particularly with
disposable
diapers which are covered on the after donning the diaper outer side with a
water
proof plastic foil which for cost reasons alone but also for improving wearing
comfort should be made as thin as possibly. An adhesive tab used for such a
disposable diaper must repeatedly be opened for inspection of the diaper and
for
correction of the diaper fit. The high adhesive force welcome to ensure a save
diaper
closure, however, easily causes destruction of said thin cover foil of the
diaper when
peeling off the adhesive tape.
An extensive discussion of these problems can be found for example in Canadian
o
patent 1 239 752. Suggestions for solving these problems can be found e.g. in
EP 0
269.713 E1, EP 0 321 234 B1, US-patent 4,067,337, US-patent 4,210,144 or PCT-
application PCT/LTS92/08950 (WO 93/07845). EP 0 269 713 B 1 discloses
particularly in figure 6 an adhesive tape designed for closing containers,
which in its
detachable area is provided with an adhesive pattern consisting merely of thin
lines.
SUBSTITUTE SHEET (RULE 26)

CA 02224562 2000-10-17
2
The section of the adhesive tape designed to be as firmly fixed to the counter
surface
as possible comprises, on its surface, a continuous layer of adhesive agent,
while the
opposing end of the adhesive tape is free of glue thereby forming a strap
which can be
grasped by a person in order to lift the section covered with a light adhesive
pattern
only from the counter surface.
DE 4 202 704 C2 also seems to be pertinent. Disclosed is a fixing tab for a
diaper
with a flat carrier being coated on one side with discrete adhesive segments
made of
self adhesive agent, at least on the section being designed to be sticked
during use to
the second diaper part, whereby said self adhesive agent has such adhesive
forces that
the fixing tab formed by coating with the self adhesive agent comprises a peel
resistance of a defined value against the outer foil of the diaper and can be
detached
several times from the outer foil and reattached without damaging the foil.
The adhesive tape described in the first paragraph of this specification is
disclosed in
US-patent 4,067,337. Referring to the embodiments disclosed therein, reduction
of the
effective adhesive area is accomplished with a grid- or sieve-like super-
imposed layer
that is placed like a stencil on the continuous layer of adhesive agent, the
effective
area thereof being reduced to the openings in the stencil. As described in US-
patent
3,666,609, particularly a plastic net can be used.
Production of the aforesaid adhesive tape is comparatively complicated and
therefore
expensive. It is therefore an object of an aspect of the invention to develop
an
adhesive tape that can be produced at lower costs, which shows adhesive forces
sufficient high also in case the adhesive tape is pressed only slightly
against an
uneven counter surface, and which, however, can be peeled off several times of
a
sensitive counter surface, particularly a thin plastic foil, without damaging
the latter.
The adhesive tape produced in the inventive manner shows a very good
adhesiveness,
however, can be lifted easily from the counter surface. During lifting the
imprinted
separating pattern hinders building up of high forces applied to the counter
surface, so
that in the course of repeated lifting of the adhesive tape no damage of the
counter

CA 02224562 2001-10-09
3
surface could be observed, e.g. of a counter surface consisting of the thin
plastic foil.
The surface pattern, e.g. checkered pattern, of the adhesive tape, consisting
of
adhesive squares or areas and imprinted, non-adhesive areas, will be slightly
stretched
when lifting off the adhesive tape; the surface of the counter part, e.g. a
thin plastic
foil, during the lifting procedure is only stretched between two non-adhesive
points of
the pattern in the peeling direction, whereby the forces imposed on the
counter surface
are spread evenly in all directions and therefore stress the, e.g. thin foil
forming the
counter surface only within its elasticity, i.e. without damaging it.
The separating pattern can be comprised of discrete points or areas and/or
extended
areas. In this context such a geometry of a separating pattern has advantages
in which
the adhesive layer is interrupted by sections of the separating pattern in the
area of the
preferred peel line. The preferred peel line can extend exactly transversally
to the
adhesive tape, it is preferably arranged, however, under a peel angle of e.g.
30°.
The separating pattern can be produced using roller printing or by means of a
silk
screen and is preferably made from paint, ink, powder or silicon oil.
The carrier can be made of foil, paper, woven or non-woven fabric, in case of
a foil
the foil preferably consists of polyethylene, polypropylene, polyvinylchloride
or
polyester. Also a fleece or non-woven fabric made of polypropylene or
polyester can
be used.
In accordance with one embodiment of the present invention, there is provided
an
adhesive tape comprising:
a carrier, the carrier being coated with a self adhesive agent, at least on an
active area of the carrier which during use is brought into contact with a
counter
surface, wherein the active area consists of a non-adhering or less adhering
separating
pattern and an adhesive pattern of self adhesive agent printed into blank
spaces of the
separating pattern;
the carrier comprising a finger lift strap adjacent to the active area; and,

CA 02224562 2001-10-09
3a
a second section of the carrier longitudinally adjacent to the active area,
the
second section comprising a continuous adhesive layer, the adhesive layer
being
acts ve.
The adhesive tape can comprise a second section, adjacent to the active area,
which
second section comprises a continuous layer of an adhesive agent which is
overall
active, too. Such a second longitudinal section serves as a means to fix the
adhesive
tape permanently to a basic surface. The continuous layer of adhesive agent
can be the
same as the adhesive layer of the first longitudinal section; taking into
account special
restrictions, however, it can be different.
Furthermore, the carrier can comprise a lift strap arranged in a section
adjacent to its
active area. The section forming the lift strap can consist of an area free of
adhesive

CA 02224562 1997-12-11
WO 96/41604 PCT/US96/09711
4
agent or of a section that was coated with adhesive agent and covered with a
protective foil or separating foil thereafter.
According to an alternative embodiment the active area of the adhesive agent
can
comprise a continuous layer of adhesive agent which in turn comprises a print
coverage thereon covering said first layer completely in order to adjust a
reduced
adhesive retention force, said print coverage made of a material like paint,
ink,
powder, silicon oil or the like. By suitable selection of different parameters
like the
agent or material forming the reducing layer, the thickness of the reducing
layer and
its moisture content, the aggressive adhesive retention force of the adhesive
layer can
be reduced to a favourable value.
To enhance conceivable applications of the inventive adhesive tape it can be
useful to
have the carrier coated with an adhesive layer also on its lower surface. The
adhesive
layer on the lower surface can be an ordinary, overall active layer of
adhesive agent
or glue, or can be a special adhesive layer comprising the features of claim 3
or claim
4.
The drawing shows several embodiments of the invention as an example. In the
drawings show:
Figure 1 - an adhesive tape in perspective view;
Figure 2 - a section of the adhesive tape shown in figure 1 in enlarged scale
compared to figure 1 at the beginning of lifting off the tape
from a foil forming the counter surface;
Figure 3 - the advanced lifting procedure in a depiction according to figure
2;
Figure 4 - six different separating patterns;
Figure 5 - in top view an alternative embodiment of an adhesive tape;
Figure 6 - in a schematic drawing production of an adhesive tape according to
'~
figure 5;
S~1BSTITUTE SHEET (RULE 26)

CA 02224562 1997-12-11
WO 96/41604 PCT/US96/09711
Figure 7 - a symbolic depiction of the peeling forces induced into a counter
surface by said adhesive tape;
Figure 8 - the shear forces generated between adhesive tape and counter
surface
according to figure 7 and
Figure 9 - the peel angle as well as the peel line.
The adhesive tape shown in figure 1 consists of a strip-like carrier l, being
coated on
its top surface with a continuous layer of adhesive agent 2. In a first
longitudinal
section 3 a separating pattern 4 is imprinted on this adhesive layer 2 in
order to
reduce the active adhesive area, whereby said separating pattern comprises
discrete
non-adhesive areas which are symmetric and evenly arranged.
In a second longitudinal section 5 adjacent to said separating pattern 4 the
adhesive
layer 2 is not coated; the active adhesive area is therefore formed by the
surface of
the second longitudinal section 5, which is used for permanently fixing the
adhesive
tape to a basic surface.
Figure 1 furthermore shows that carrier I comprises a glue-free section
forming a
finger lift strap 6 being arranged opposite said second longitudinal section
5.
Figures 2 and 3 show a detail of longitudinal section 3 coated with said
separating
pattern 4 stickingly fixed to a counter surface 7 in form of a plastic foil.
Upon lifting
the active area of the adhesive tape formed by the first longitudinal section
3 from
said plastic foil 7, the uncovered adhesive areas 2a between the imprinted
separating
areas cause stretching of the related areas of plastic foil 7 each only for a
short period
of time, so that damage of plastic foil 7 is avoided. Upon separation of
adhesive area
2a from plastic foil 7, the areas of plastic foil 7 being stressed by adhesive
areas of
the adhesive tape can relieve.
.. Figure 4 shows six different embodiments for separating pattern 4. Two of
these
examples show separating pattern 4 comprising extended areas 8, while the
remaining four examples comprise discrete areas 9 in form of crosses or
asterisks.
Figure 5 shows an embodiment of the adhesive tape being modified compared to
figure 1. The first longitudinal section 3 forming the active area of the
adhesive tape
SUBSTITU T E SHEET (RULE 26)

CA 02224562 2000-10-17
6
comprises an imprinted non- or less-adhering separating pattern 10 and an
adhesive
pattern I 1 of self adhesive agent printed into the blank spaces of said
separating
pattern. The separating pattern 10 is grid- or sieve-like, while the adhesive
pattern 11
is comprised of discrete glue segments. Figure 6 shows in a symbolic manner
production of the active arcs 3: The carrier 1 is firstly conveyed in
direction of the
arrow through a printing station 12 for the separating pattern, which imprints
separating pattern 10 on the active area 3, and is thereafter conveyed to
printing
station 13 for the adhesive pattern, printing the adhesive agent in the blank
spaces
{sieve spaces) of separating pattern 10. In principle, such a printing
procedure can be
carried out in reversed order, too.
Figure 7 symbolizes the peel force induced by adhesive tape 14 into counter
surface
7, which force between the two dotted lines amounts to about a third of
lifting force
F and outside this central region amounts to about a sixth of lifting force F.
Figure 8 symbolizes the shear force between adhesive tape 14 and counter
surface 7.
Figure 9 shows an adhesive tape 14, which is lifted of a counter surface 7
along an
advancing peel line 15, which encloses a peel angle a with a line extending
transversally of lifting tab 14. According to the imrention the separating
pattern 4 or
10, respectively, should be arranged or designed in a manner so that peel lure
15
consistently crosses sections of separating pattern 4 or 10, respectively, so
that in the
region of peel line 15 no continuously extending area of adhesive agent or
glue
exists.

Representative Drawing