Note: Descriptions are shown in the official language in which they were submitted.
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A METHOD OF PRODUCING AN ADHESIVE SURFACE PROTECTIVE
SHEET THAT INCLUDES A GRIPPING TAB
FIELD OF INVENTION
The present invention relates to a method of producing an adhesive surface
protective
layer that includes a gripping tab and of fastening the protective layer to a
product. and
also to an arrangement for carrying out the method, and to a product produced
in
accordance with the method.
BACKGROUND OF THE INVENTION
Wound dressings and so-called surgical plasters are often provided with an
outer
adhesive layer that enables the dressing to be fastened to the skin of a user.
The adhesive
coating of such dressings is protected by a protective layer, for instance a
layer of so-
called release paper, partly to facilitate handling of the dressing prior to
use and partly to
prevent dust and other contaminants fastening to the adhesive coating and
partly to
prevent the adhesive from drying-out. These release layers can be easily
peeled away
from the adhesive coating without impairing its adhesive properties and, for
this reason,
are produced from material that has poor adhesion to the adhesive or from a
material that
has been treated with a release agent, such as silicone-coated paper or
silicone-coated
plastic foil. The release layer is comprised of two mutually overlapping parts
which can
each be removed from the dressing prior to its application. In order to
facilitate removal
of that pan of the mutually overlapping portions of the release layer which
lies nearest to
?~ the adhesive coating. it is often folded so as to provide a Gripping tab
that can be gripped
by the user when the outermost part of said two overlapping parts of the
gripping foil has
been removed.
Wound dressings. or plasters. are produced in different sizes. This means that
release
foils of different sizes must be kept in store for and in the dressing
manufacturing
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process. An object of the present invention is to eliminate or at least
substantially reduce
the need to store release foils of several different sizes.
When mounting mutually overlapping foil parts, it is difficult to fasten the
outermost
release foil to the adhesive coating along the overlapping edge of the other
foil,
particularly in the case of dressings that have a three-dimensional surface
profile, e.g.
dressings that include a central wound pad. Consequently. there is a danger
that the
properties of the adhesive coating will be impaired in this region of the
dressing. Another
object of the invention is to eliminate or at least greatly reduce this
danger.
A third object of the invention is to increase the flexibility of release foil
and other types
of protective layers for products that include an outer adhesive coating and
also to
simplify application of such foils and products.
It will be understood that by adhesive coating is meant all types of adhesive
surfaces that
need to be protected by removable protective layers, and then particularly all
adhesive
surfaces used with wound dressings, for instance acrylate glue and soft,
sticky
elastomers.
SUMMARY OF THE INVENTION
These objects are achieved in accordance with the invention with a method of
manufacturing adhesive surface protective layers that include a gripping tab,
said method
being characterised by mounting at least one strip of material to the
protective layer,
fastening each strip to said protective layer along an elongate join. and
providing a
2~ weakening line in each elongate join.
In a preferred embodiment, two or more strips are fastened to the protective
layer and the
elongate join and its associated weakening line are produced by ultrasound
welding.
In one variant. the elongate join in each strip is produced by gluing, and the
associated
weakening line is produced by punching.
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The invention also relates to a method applied in the continuous manufacture
of products
that include an outer adhesive layer for providing said adhesive layer with a
protective
layer that includes a gripping tab, wherein the product blanks are formed on a
travelling
web of material, characterised by mounting to at least one strip of material a
protective
layer that has the same width as the travelling product-blank web, fastening
each strip to
the protective layer along an elongate join and providing a weakening line in
said join,
and thereafter mounting the protective layer with its associated strips and
cutting the
finished products from the travelling product-blank web.
The invention also relates to an arrangement for manufacturing adhesive
surface
protective layers that include a gripping tab, said arrangement being
characterised by
means for mounting at least one elongate strip of material on the protective
layer, means
for fastening each strip to the protective layer along an elongate join, and
means for
providing a weakening line in each join.
The invention also relates to an arrangement for producing products that
include an
adhesive layer protective layer which has a gripping tab with a starting point
from a
travelling web of product blanks that include an outer adhesive layer, said
arrangement
being characterised in that it includes a protective layer web which has the
same width as
the product-blank web and which is reeled-up on a storage reel, at least one
web of strip-
like material reeled-up on a storage reel, a rotatable roller which extends
transversely to
the direction of movement of said product-blank web across the full width of
said web,
wherein the protective-layer web and each web of strip-like material move
around said
roller with the web or webs of strip-like material situated between the roller
and the
protective-layer web. and wherein said arrangement further includes means for
pressing
the protective-layer web into abutment with the adhesive layer on the product-
blank web.
means for fastening each web of strip material to the protective layer along a
longitudinally extending join prior to bringing said protective layer into
abutment with
the product-blank web, means for producing a weakening line in each
longitudinally
extending join. and means for cutting finished products from the product-blank
web.
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In one preferred embodiment of said arrangement, the means for fastening each
web of
strip material to the protective layer and for producing a weakening line in
the established
join comprise the ultrasound horn of an ultrasound welding unit and an anvil
surface
provided on the roller, said anvil surface having the form of a bead that
extends parallel
with the direction in which the product-blank web moves around the periphery
of said
roll. Preferably, at least two devices for fastening a web of strip material
to the protective
layer are disposed along the length of the roll, said fastener devices being
moveable in
the length direction of the roller and said roller including along its length
a plurality of
anvil surfaces with which the fastener devices can electively coact.
The invention also relates to a product that includes an outer adhesive
surface and a
peelable protective layer fastened to said surface and including a gripping
tab, wherein
said product is characterised in that an elongate strip of material extends
over the
protective layer from one end of the product to its opposite end; in that the
strip is
fastened to the protective layer by a join that extends between said ends of
said product in
spaced relationship with both long edges of the strip; and in that a weakening
line extends
in the join from one end to the other end thereof.
According to a preferred embodiment, the weakening line is continuous and
extends
depth-wise through the strip.
The weakening line is intermittent in one variant of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described with reference to the accompanying
drawings, in
which
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Fig. 1 is a schematic, perspective view of one embodiment of an inventive an
arrangement for producing a protective layer that includes a gripping tab and
for
fastening said layer to an outer adhesive layer on a web of material;
Fig. 2 is a schematic, perspective view of a dressing provided with a
protective layer in
accordance with the invention;
Fig. 3 is a cross-sectional view of that part of the dressing in Figure 2
which includes said
gripping tab; and
Fig. 4 is a schematic view similar to the view of Figure 3 and shows a known
dressing
which has been provided with mutually overlapping release foils in a known
manner.
DESCRIPTION OF EMBODIMENTS
Figure 1 is a schematic illustration of an arrangement 1 for producing and
fastening a
protective layer that includes a gripping tab to an underlying, travelling web
of material 2
which has an upwardly facing adhesive layer 3. The web 2 is moved in the
direction of
the arrow A in some suitable manner, e.g. with the aid of a belt conveyor or
some like
means.
The arrangement 1 includes a web 4 of protective layer material rolled-up on a
storage
reel s, and one or more webs 6 of strip material rolled-up on storage reels 7.
The
protective-layer web 4 and the webs 6 of strip material run around a part of
the periphery
of a rotatable roller 8 with the webs 6 lying inwardly of the web 4 relative
to the roller
and with said webs 6 mutually separated in the axial direction of the roller.
The
protective-layer web 4 has the same width as the travelling web 2 and extends
parallel to
said web. In the case of the illustrated embodiment, two webs 6 of strip
material are
disposed in spaced relationship with the longitudinal edges of the web 4. The
roller 8
carries a circumferentially extending bead 9 at the location of each web 6 of
strip
material, said bead being spaced from the longitudinal edges of its associated
web 6. An
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ultrasound horn 10 included in an ultrasound welding unit (not shown) is
arranged
opposite each bead 9, and the web 4 of protective layer material and the webs
6 of strip
material run between the horn 10 and the beads 9. The roller 8 is mounted at a
distance
from the travelling web 2 such that the protective layer 4 will come into
abutment with
the upper adhesive surface 3 of the travelling web subsequent to the
protective layer 4
having passed the horn 10.
The arrangement 1 operates in the following way.
The web 4 of protective layer material is fed from the storage reel ~ in an
appropriate
fashion and applied to the travelling web 2 with the aid of the roller 8. the
peripheral
speed of which coincides with the running speed of the web 2. The web 4 can be
advanced either by driving the roller 8 or the storage reel ~ or by driving
both roller and
reel. A pair of rolls can be placed downstream of the roller 8 in the
direction of web
movement and adapted to effect the advancement of both the travelling web 2
and the
web 4 of protective layer material. In this case, it may be suitable to space
the roller 8 at a
greater distance from the web 2 and to allow the downstream pair of rolls to
press the
web 4 against the adhesive layer 3 on the upper surface of the web 2. The webs
6 of strip
material are fed from the storage reels 7 in a similar manner. Feeding of the
web 4 of
protective layer material and the web 6 of strip material is suitably designed
to ensure
that these webs will be stretched slightly as they are advanced.
The beads 9 function as anvil surfaces for the ultrasound horn 10 and are
effective in
welding the web 6 of strip material to the web 4 of protective layer material
as the webs
pass the horn 10, therewith producing a longitudinally extending or elongate
weld join
1 I. The beads are also constructed to produce a weakening line in the centre
of the join
l1.
After the web ~4 of protective layer material has been applied to the
travelling web 2, the
finished products I?, i3 are cut or punched from said web with the aid of
appropriate
punching or cutting devices 14, 1 ~ .
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Figures 2 and 3 illustrate an example of a finished product 12 cut from the
web 2. The
various layers in the product have been identified with the same reference
signs as those
used to identify the webs in Figure 1. The product 12 thus comprises a part
which has
been cut from the web 2, and a protective layer 4 which has a strip 6 fastened
thereto by a
join 11 and which is located on the adhesive layer 3 on the part cut from said
web 2.
Those parts 16, 17 of the strip 6 situated on respective sides of the join 11
form gripping
tabs. As described earlier, the ultrasound- welding operation is effected so
as to obtain a
weakening line 18 that extends along the centre of the join. When a user grips
the
gripping tabs 16, 17 in order to remove one or both protective layers. only a
small force is
required to peel away the protective layer 4 along the weakening line I8. Once
having
removed the protective layer 4, the adhesive surface of the product 12 can be
applied to
the place intended.
The product illustrated in Figures 2 and 3 may, for instance, be a wound
dressing that in
addition to the adhesive layer 3 includes a layer 19 of absorbent foam
material, e.g.
polyurethane foam, and a layer 20 of liquid-impermeable but vapour-permeable
material,
such as polyurethane film, for instance. The layer 3 may consist of a layer of
soft, sticky
elastomeric material, for instance silicone gel. and the protective layer 4
and the tabs 16,
I7 may consist of polypropylene film. The tabs 16, 17 need not be comprised of
the same
material as the protective layer 4, although they shall, of course, be made of
a weldable
material so that a weakening line 18 can be obtained in the ultrasound welding
process.
The weakening line 18 will preferably have a depth that is at least greater
than half the
thickness of the tabs and the weakening will preferably extend through the tab
material 6
and into the protective layer 4 so that the protective layer 4 can be easily
removed from
the adhesive layer 3. Naturally, the weakening line may extend through both
the strip 6
and the protective layer 4, although this alternative is not preferred for
those reasons
made apparent in the following text.
Figure 4 is a schematic illustration of a known dressing that includes
mutually
overlapping release foils ?I, 2'_'. The overlap part of the bottom release
foil '_'1 has a
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folded edge so as to form a gripping tab. In the case of a dressing of this
kind, there is a
serious risk that a gap 23 will form between the overlapping release foil 22
and the
release foil 21. This gap can cause the adhesive to dry out in the region of
said gap and
therewith impair the properties of the adhesive. This risk is particularly
great in dressings
that have a three-dimensional surface profile, for instance a dressing that
includes a
central wound pad.
One advantage afforded by the invention. is that the risk of such gaps
occurring is non-
existent, especially when the weakening line terminates short of the side of
the protective
layer 4 that lies proximal to the adhesive 3 and thereby presents a totally
intact surface to
the adhesive. The weakening lines may alternatively consist of perforations
since any
impairment to the adhesion of the adhesive in the perforations will be local,
so that no
continuous region of poor adhesion will occur.
It has been found that in the case of a protective layer that consists of
polypropylene film
having a thickness of 100 p,m and a strip comprising polypropylene film having
a
thickness of 100 ~.m can be provided with a tight and easily opened weakening
line with
the aid of a bead that has a semi-circular cross-section and a radius of 0.5
mm as an anvil
surface for coaction with the horn of an ultrasound unit of the type 20kHZ DCP
2200
from Dukane, USA.
The described arrangement is constructed to produce from the travelling
product-blank
web 2 products that have a width corresponding to half the width of the web 2.
When
wishing to divide the product-blank web 2 into products whose widths are
smaller than
half the length of said web, this can be achieved very easily by fastening the
requisite
number of strips 6 on the web 4 of protective layer material. In this regard,
it will be
necessary. of course, to adapt the number of beads 9 on the ultrasound horn 10
and the
positions of said beads to those dimensions that the various products shall
have in the
cross-direction of the product-blank web. In order to facilitate modification
of the
arrangement 1 with respect to changes in product dimensions, the ultrasound
unit and the
storage reels 7 carrying the strip material may be supported for movement
along the
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roller 8 with the aid of some suitable mechanism. In order to obviate the need
to change
the roller 8 each time the arrangement shall be re-set, the roller 8 may be
provided along
its length with a plurality of beads 9 which are situated to correspond to the
various
widths of all products that are included in the assortment produced by cutting
said
products from a travelling product-blank web. This will enable the arrangement
1 to be
quickly adjusted, by moving the ultrasound welding units and the storage reels
7
transversely to a position opposite those beads that are applicable to the
products that
shall be cut from the product-blank web 2. Naturally, an ultrasound unit may
be arranged
opposite each such bead while activating solely those units that shall coact
with the
selected beads.
In one illustrated embodiment of the method, the grip-tab strips are fastened
in
conjunction with mounting the protective layer 4 to the travelling product-
blank web 2.
However, it may be suitable to manufacture a protective layer that includes
gripping tabs
before mounting said protective layer 4, for instance when the grip-tab strips
extend
transversely to the direction of movement of the protective layer and
therewith applied by
an intermittent process. The weakening lines may, of course, not be through-
penetrating
in such a process.
Ultrasound welding is applied in the described embodiment to produce a join
and a
weakening line in the centre of said join in one and the same operation.
Alternatively, the
attachment can be achieved with a heat welding process or gluing process and
the
weakening lines can be produced with conventional methods, such as punching or
the
like. As will be understood, attachment of the strips and production of the
weakening
lines may be effected in different stages. When gluing is used, the joins are
preferably
made after the weakening lines have been produced. When gluing is used,
protective
layers and strips need not consist of heat weldable material and all materials
that are now
used as release materials may be used instead.
A further advantage afforded by the described method is that protective layer
material
and strip material need only be stored in one single width which greatly
facilitates storage
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and handling of these materials in respect of adjusting the process line to
the manufacture
of new products.
Although the method has been described solely with respect to the manufacture
of
products of uniform thickness, it will be understood that the method is not
restricted to
such manufacture and that products having a three-dimensional surface profile,
e.g.
wound dressings with a centrally arranged wound pad carried by and surrounded
by thin
material can be provided with a protective layer that includes gripping tabs
in the
aforedescribed manner. The described method is primarily intended for the
manufacture
of wound dressings. However, it will be understood that all products that
include
adhesive layers which need to be protected may be provided with a protective
layer that
includes gripping tabs in accordance with the invention.
The described embodiment may, of course, be modified within the scope of the
invention. For instance, the adhesive may be an acrylate glue and plastic
material other
than polypropylene may be used as release film, e.g. polyethylene. The
invention is
therefore limited solely by the contents of the accompanying Claims.
