Note: Descriptions are shown in the official language in which they were submitted.
CA 0223~861 1998-0~-26
Background and SummarY
Jensen U.S. patent 5,133,821 and Samuelsen U.S. patent
4,867,748 disclose dressings having adhesive layers of
hydroc:olloid-containing materials with upper surfaces protected by
covering layers, preferably of elastomeric film, and undersurfaces
protected by removable release sheets. The Samuelsen patent
suggest that such a contoured dressing may be made by a pressing
and molding operation using blanks in which the three layers are
pre-laminated together and, following the molding step, the blanks
are then die cut in a conventional manner. The Jensen patent
discloses a continuous method in which contoured dressings are
produc~ed by advancing webs of material through three successive
operating stations.
In the first operating station of the Jensen patent, a strip
of adhesive material containing hydrocolloids, and supported upon
a release web, is contoured between a pair of rollers. According
to the patent, the upper contouring roller may be coated with a
release agent to prevent it from sticking to the adhesive material
but, in a preferred embodiment, a web of silicone-coated release
paper is interposed between the contouring roller and the adhesive
material. The release paper is sacrificial and is removed from the
adhesive layer in a delaminating step following the contouring
step. Thereafter, the adhesive surface of each partially-formed
dressing is covered by a so-called adhesive carrier layer in a
seconcl laminating station, the adhesive carrier layer thereby
taking the place of the removed paper layer used in the contouring
step. Finally, the second Laminate advances from the laminating
station to a cutting station where the finished dressings are cut
into final shape between a pair of cutting rollers.
The Jensen patent does not elaborate on why it is important
that t:he contouring, laminating and cutting steps be carried out in
three successive stations and, in particular, why it is critical
that contouring be completed before the adhesive carrier layer is
applied to the exposed surface of the adhesive layer. Experience
CA 0223~861 1998-0~-26
has shown that the sequence is indeed important and that if the
adhesive carrier layer (i.e., the backing layer) is a thin
elastomeric film, it is not suitable for use as the release web in
the contouring station for purposes of preventing the contouring
roller from adhering to the adhesive layer. Hence, in a continuous
proce~;s for making hydrocolloid dressings, the prior art has
emphasized the necessity of having successive stations for
contouring, laminating, and cutting, with the complexities in
equipment and timed operation that such a system inherently
require.
Other references revealing the state of the art are U.S.
patent:s to Gross 4,340,557, Morgan 4,867,821, Lauritzen 4,622,089,
Eastin 5,201,976, Tsukamoto et al 5,006,189, Willhite et al
4,823,783, Beisang et al 4,780,168, Trenka 5,074,944, Wright
3,824,761 and Volke 4,963,858.
~ main aspect of this invention therefore lies in the
discovery, that, contrary to the teachings of the prior art, it is
indeecl possible to make contoured hydrocolloid wound dressings in
an operation in which at least the contouring and cutting steps are
combined, and preferably the laminating, contouring and cutting
steps are combined, with such steps being performed simultaneously
to produce a highly effective product in which a stretchable
backing layer covers the contoured adhesive surface of the dressing
without wrinkles and deformations. A further aspect of the
invent:ion lies in the discovery that such steps may be combined at
a single operating station t:o produce a product free of wrinkles
and deformations if the backing layer is restrained against
stretc:hing along the general plane of the product being formed, or
the simultaneous processing steps are carried out in a manner to
avoid such stretching, as the hydrocolloid-containing adhesive
material is displaced to form the contoured product.
Avoidance of stretching of the backing material in the plane
of the dressing allows the contouring step to be combined with the
cutting step and, preferably~, with the laminating step, all at a
CA 0223~861 1998-0~-26
single operating station. The steps taken to avoid such stretching
of the backing layer during processing depend on factors such as
the st:retchability, recovera.bility and thickness of the backing
material selected, the flowability and adhesiveness of the
hydrocolloid-containing material, and the temperature at which the
operation is performed. In general, it has been found that the
backing layer must be able to resist stretching along the plane of
the dressing (as exemplified by the plane of the flat release sheet
or web) in response to shear forces exerted by the hydrocolloid-
containing adhesive material. as that material is forced to flow
outwardly and/or inwardly under compression. Where the backing
material is highly stretchable and would be incapable of resisting
such ~;tretching action in response to the outward/inward flow of
the adhesive material in a contouring operation, it has been found
that stretching of the backing layer may be prevented by removably
attach,ing to it a flexible and substantially non-stretchable
reinforcing layer. Ideally, if the stretchable backing layer is a
film, then the reinforcing l.ayer may also provide the surface on
which the film was originally cast.
Another aspect of the invention lies in the further discovery
that t.he three operations -- laminating, contouring and cutting --
may be performed simultaneously by the same contouring, laminating
and c~utting dies. Preferably, such dies are in the form of
rollers, although it is possible that the contouring and cutting
operat:ions may be performed simultaneously at one station by a pair
of reciprocating platens and the laminating operation performed
either at the same station or immediately adjacent to it.
Other features, advantages, and objects of the invention will
become apparent from the specification and drawings.
Drawinqs
Eigure 1 is a diagramatic and schematic view depicting a
preferred embodiment of the process of this invention.
E'igure 2 is a perspective view of a contoured dressing made by
the process of Figure 1.
CA 0223~861 1998-0~-26
F igure 3 is a fragmentary sectional view depicting the action
that occurs between the upper and lower
contouring/laminating/cutting rollers used in the process of this
invent: ion .
Figure 4 is a still further enlarged sectional view of the are
encirc led in phantom in Figure 3.
F igure 5 is an enlarged fragmentary sectional view of a
contoured dress ing made in accordance with the invention .
Figure 6 is a diagramatic and schematic view depicting a
seconcl embodiment of the process of this invention.
I~igure 7 is an enlarged sectional view illustrating the
contouring mold and anvil platen of the second embodiment in open
condil:ion .
Figure 8 is a view sim Llar to Figure 7 but showing the mold
and p:Laten in closed condition.
Detailed De~cription of Preferred Embodiment~
l~eferring to the embodiment depicted in Figures 1, 3 and 4, a
continuous strip 10 of soft, pliant, hydrocolloid-containing
adhes:ive material is discharged from extruder 11 and enters the nip
between upper and lower rollers 12 and 13. The rollers are power
driven with the lower roller 13 serving as a rotating anvil having
a substantially smooth outer surface 13a. The upper roller 12
funct:ions as a contoured laminating, contouring and cutting die and
has a developed surface def ining recesses 12a with relatively deep
centr<l 1 portions 12b and relatively shallow peripheral portions
12c. Cutting blades 12d surround the peripheral portions, with the
length of the blades being sufficient to contact anvil roller 13 to
perform a cutting operation as depicted in Figure 3. In the
diagr.~matic and schematic view of Figure 2, the upper roller 12 is
shown to have three such recesses 12a; however, it is to be
under ;tood that a different number may be provided and that the
shape; of the recesses (or, if desired, protrusions) may be varied
depending on the particular contour of the dressing to be produced.
~ Figure 1 depicts a contoured dressing 14 as it is released
CA 0223~861 1998-0~-26
from the laminating/contouring/cutting station. A portion of such
a dressing is illustrated in section in Figure 5 where it will be
seen that the dressing has a hydrocolloid adhesive layer 15 derived
from the extruded adhesive strip 10. The adhesive layer 15 has a
relatively thick central body portion 15a and a thin peripheral
flange portion 15b. A stretchable backing layer 16 of film or
fabric covers the contoured surface of adhesive layer 15, and a
removable reinforcing layer 17 of flexible but relatively stiff and
non-stretchable material covers the backing layer 16. The
underside of the dressing 14 is protected by a removable release
sheet 18 of siliconized paper or other suitable material.
While dressing 24 has been described in completed form in
connection with Figure 5, a final step must be undertaken either by
the manufacturer or user before the dressing is ready for use. The
removable reinforcing layer 17 must be peeled away from the backing
layer 16 as indicated in broken lines in Figure 5. Figure 2
illustrates the dressing 14 with the reinforcing layer 17 removed,
revealing the stretchable upper backing layer 16 and the edges of
the adhesive layer 15 and release paper layer 18. It is to be
understood that at the time the dressing is to be used, the planar
release layer 18 is peeled away from the underside of the adhesive
layer to expose the adhesive layer for contact with the skin over
and about an attachment site.
The term "dressing" is here used to refer to hydrocolloid-
containing wound dressings as well as dressings more commonly
referred to as hydrocolloid adhesive wafers or faceplates for
ostomy appliances. Reference may be had to patent 4,867,748 for
examp,les of the general use of this term.
Adhesive material 15 may be of any of a variety of
hydrc,colloid-containing adhesive compositions well known in the
art. In general, such material comprises a tacky semi-solid binder
in which particles of one or more hydrocolloids are dispersed.
Althc,ugh polyisobutylene is preferred as the binder, other viscous
semi-solid adhesive materials may be used such as, for example,
CA 0223~861 1998-0~-26
styrene block polymer rubbers, silicone rubber, acrylonitrile
rubber, polyurethane rubber and natural rubber (caoutchouc). The
hydrocolloid content is commonly a blend of hydrocolloids such as
carboxymethyl cellulose, pectin, guar gum and/or gelatin, but other
hydrocolloids such as karaya, polyvinyl alcohol, carbowax and
carboxypolymethylene have been disclosed in the literature and may
be used. For further information concerning such hydrocolloid-
containing adhesive compositions, and citations of other background
materials relating thereto, reference may be had to co-owned U.S.
patent 4,738,157.
A suitable material for backing layer 16 is a think film of a
nylon/polyether block polymer elastomer (PEBAX resin from ATO,
Philadelphia, Pennsylvania) but polyurethane or other polymers
having similar properties ma~ be used. An elastomeric film having
a thickness within the range of about 0.5 to 1.5 mils is believed
particularly suitable. Films of silicone rubber and latex rubber
may a:Lso be effective. Further, the backing layer may be an
elastomeric or stretchable fabric, such as a non-woven fabric.
Stretchable non-woven microporous fabrics composed of polyethylene
fibers are known and may be used, for example, the microporous
fabric marketed under the designation MF5260 by Freudenberg
Nonwovens LP, Halifax, England and other stretchable fabrics having
similar properties are believed suitable.
~ 'hile films that are highly stretchable are often elastomeric
in character, the problems to which this invention is addressed
arise largely because of the stretchability of the backing layer 16
rather than the extent of its recovery after stretching forces are
remove!d. Therefore, the term "stretchable" is preferably and more
accura,tely used here to describe the physical characteristic of the
backing film or fabric, and it is the prevention or restraint of
such stretching of the backing layer 16 by the non-stretchable and
remova,ble reinforcing layer 17 that is particularly important in
this process.
I'he purpose of reinforcLng layer 17 is to restrain stretching
CA 0223~861 1998-0~-26
of the backing layer 16 in planar directions in response to the
flow of adhesive material (in the directions of arrows 26 and 27)
during the contouring operat.ion. If displacement of the adhesive
material under pressure during contouring is accompanied by
stretching of backing layer 16, then objectionable wrinkling and
deformation of the backing layer is likely to occur and be present
in the resulting dressings. It is at the interface between backing
layer 16 and pliant adhesive layer 15 that the forces tending to
stretch the backing layer are transmitted so that if such forces
are insufficient to cause st.retching of the backing layer in the
absence of the reinforcing layer, then such reinforcement becomes
unnecessary. Thus, reinforcing layer 17 may be omitted if the
backing layer 16, although necessarily formed of stretchable
materi.al, does not stretch .in planar directions (in response to
displacement of adhesive material during contouring) either because
of the composition or thickne.ss of the backing layer or because the
forces at the interface are insufficient to result in stretching of
the backing layer by reason of factors such as the composition,
temperature and/or flow characteristics of the adhesive material.
Use of reinforcing layer 17 is therefore optional in those
instances where it is not required for purposes of preventing
stretching of the backing layer 16 during a combined
laminating/contouring/cutting operation as generally depicted in
Figures 1 and 3. When used, reinforcing layer 17 must be flexible
but nevertheless relatively stiff, especially when compared with
the film or fabric backing layer 16. Layer 17 may be capable of
being deformed or embossed, but an essential characteristic is that
it must be substantially non-stretchable. A strong paper is
believed particularly suitable, but other materials, such as
flexible but substantially non-stretchable polymeric films, may
also be used. Where the stretchable layer 16 takes the form of an
elastomeric film, the reinforcing layer 17 is most advantageously
formecl of sheet material on which the film has been deposited by
conventional extruding or solvent-casting techniques. In such a
CA 0223~861 1998-0~-26
--8--
case, a polyolefin-coated paper (for example, a polyolefin-coated
paper from Schoeller Technical Papers, Pulaski, New York) is
especially suitable for use as reinforcing layer 17.
A substantially continuous supply of a reinforcing web 17 is
providLed from a supply roll lnot shown) and is directed over guide
roll 20 to extruder 21 (Figure 1). The stretchable backing
material 16 in the form of a thin layer is discharged by the
extrucler onto layer 17, and the two continue together as a combined
backing web 22 about guide roller 23 to the
laminating/contouring/cutting station where the combined web enters
the nip between upper and lower rollers 12 and 13 along the upper
surfac:e of the extruded strip 10 of adhesive material. At the same
time, a web of release sheet: material 24 from a supply roll (not
shown) enters the nip beneath the extruded strip 10. The extruded
strip and the two webs merge together to form a laminate which is
simult:aneously contoured ~and cut) between the rollers as
determined by the surface of contouring roller 12.
r)uring such operation, the viscous hydrocolloid-containing
adhesive material should be maintained at a temperature that
promot:es the flow of such material under pressure. Such a result
may be achieved by heating rollers 12 and 13. The temperature may
vary depending on the composition of the adhesive material involved
but, in general, temperatures within the range of about 120 to
220~F. are believed suitable. As an alternative to heating the
rollers, or in addition thereto, the strip 10 of adhesive material
may be!passed through a preheating zone in advance of roller 12 and
13, a:Lthough such preheating may be unnecessary if the distance
between the rollers and the extruder is relatively short.
~ t lower temperatures within the range indicated, a rebound
effect: may be observed, as described below, and that effect tends
to become diminished as temperatures are increased. In Figure 3,
it will be noted that the leading portion of cutting edge 12d of
the upper roller 12 has already contacted the surface of the lower
anvil roller 13, serving as a dam to limit forward displacement of
CA 0223~861 1998-0~-26
the adhesive material of extruded strip 10 in the direction of
arrow 26 in Figure 4. Substantial backflow occurs in the direction
of arrows 27, causing the hydrocolloid-containing adhesive material
to expand or flow into the recess 12b of the contouring roller 12.
Since the soft and heated adhesive material is not only deformable
but compressible to at least a limited extent, release of
compressive force as the materials pass through the nip tends to be
accompanied by a slight expansion in the thickness of the dressing
beyon~ the dimensions established by the spacing between the
rollers.
',ubstantial flow of adhesive material occurs as indicated by
~rrows 26 and 27 in Figures 3 and 4, and such flow imparts
considerable force on the backing film or fabric 16. The
reinforcing layer 17, when needed and used, resists such forces
that would otherwise stretch, distort and displace the thin backing
layer 16. If movement of the backing layer relative to the
reinforcing layer were free to occur, noticeable deformation and
distortion would result and, especially if the backing layer were
elastomeric as well as stretchable, wrinkling of the backing layer
would also take place as the stretched elastomer at least partially
recovers or retracts following the laminating/contouring/cutting
steps. Unacceptable warping and distortion of the dressing in
other respects could also result. However, the frictional forces,
or forces of adhesion, between the stretchable backing layer 16 and
the reinforcing layer 17 exceed the forces exerted on the backing
layer by the adhesive material as it is displaced in the directions
of arrows 26 and 27, and the strength of the reinforcing layer 17
(aided by the support for that layer provided by the contoured
roller) resists tearing of the reinforcing layer, during a
contouring operation. Conse.quently, the reinforcing layer serves
to prevent significant stret.ching of the backing layer 16 and the
aforementioned problems of deformation, distortion and wrinkling
are thereby avoided.
In the embodiment of F:igures 6-8, the process is similar to
CA 0223~861 1998-0~-26
--10--
the one already described except that a vertically movable
contou.ring/cutting die and an anvil platen rather than rollers are
provid.ed at the contouring and cutting station. Also, lamination
does not occur simultaneously at the contouring/cutting station but
immedi.ately in advance of that station.
Specifically, a movable upper platen or die 30 carried by
reciprocating mechanism 31 is located above stationary lower platen
32. l'he upper platen is recessed at 33 to serve as a contouring
die an.d is provided with cutt:ing edges 34. Lower platen 32 serves
as a supporting anvil. As in the previous embodiment, both the
upper and lower elements 30 and 43 are heated, or other means
provicled to insure that the adhesive material is properly heated at
the contouring/cutting station.
';pecifically, a movable upper platen or die 30 carried by
reciprocating mechanism 31 is located above stationary lower platen
32. l'he upper platen is recessed at 33 to serve as a contouring
die and is provided with cutting edges 34. Lower platen 32 serves
as a supporting anvil. As in the previous embodiment, both the
upper and lower elements 30 and 32 are heated, or other means
provicled to insure that the adhesive material is properly heated at
the contouring/cutting station.
P, strip of extruded hydrocolloid-containing adhesive material
10 is discharged from extruder 11 and enters the nip between upper
and lower power-driven laminating rollers 35 and 36. Lamination of
the ad.hesive material 10 with.the combined backing web 22 (composed
of stretchable backing laye:r 16 and non-stretchable reinforcing
layer 17) and with release web 24, occurs between rollers 35 and 36
immedi.ately in advance of t:he contouring/cutting station. (As
previously noted, the use of reinforcing layer 17 is optional in
those instances where the backing layer 16, although stretchable,
is not so highly stretchable that reinforcement to prevent
stretc:hing during contouring is necessary.) Figure 6 and 7 depict
the laminate as it enters the contouring/cutting station with die
30 in its raised or open position, and Figure 8 is a fragmentary
CA 0223~861 1998-0~-26
view showing die 30 in its :Lowered position. The flow of heated
adhesive material is again indicated by arrows 26 and 27 and is
similar to that occurring in the process of the first embodiment.
~ Jnlike the continuous operation of the first embodiment
however, the advancement of a laminate at the contouring/cutting
station must be intermittent because of the reciprocating operation
of the upper die 30. Since the operation of the extruder 22 is
continuous rather than intermittent, a conventional web
accumulation bank 40, diagrammatically shown in Figure 6, should be
interposed between the roller 35, 36 and the contouring/cutting
station to take up slack that:would otherwise develop in the web by
reason of the non-continuous or interrupted movement of the
laminate into and through the contouring/cutting station.
The arrangement of Figures 6-8, in which a lamination step
occur-; in advance of the contouring/cutting station, may also be
utili.zed in a system that includes contouring and cutting rollers
of the first embodiment in place of the platens of the second
embod:iment, but in such a c.ase it is believed desirable for the
adhes:ive strip and the release web to be brought together at the
advance lamination station and later joined or laminated to the
stretchable backing at the c:ontouring/cutting station.
In all embodiments of the invention, contouring and cutting
occurs simultaneously at the same station, whether by rollers 12,
13 or by platens 30, 32. In addition to the operating efficiencies
and r~educed spatial requirements so achieved, proper registry or
concentricity of contouring and cutting ~or each dressing is
assured, thereby avoiding or greatly reducing wastage of expensive
mater.ials (especially hydroc:olloid-containing adhesive materials)
that .is known to occur when such steps are performed successively
at different stations and some proportion of the dressings so
produced must be discarded because proper registry is lacking.
While in the foregoing, we have disclosed embodiments of the
inven-tion in considerable detail for purposes of illustration, it
will be understood by those skilled in the art that many of these
CA 0223586l l998-05-26
--12--
details may be varied without departing from the spirit and scope
of the invention.
