Pleated sterilization pouch

A pouch to hold sterile articles which is comprised of two sheets in face to face contact and sealed around the periphery except at an access opening. One of the sheets has one or more pleats which intersect the access opening in order to provide greater internal storage space. A flap on the unpleated sheet overhangs the edge of the pleated sheet, and is covered with a self-adhesive which extends partly into the pouch between the sheets at said access opening. This construction results in both sides of the pleated sheet being in contact with self-adhesive when the flap is folded over the pleated sheet to seal the pouch. In a second embodiment, the pleat intersects the access opening at an angle other than 90 degrees in order to provide a seal at the pleat having greater sterile integrity.

BACKGROUND OF THE INVENTION 
Plastic pouches used to sterilize and store sterile items for dental and 
medical use have been available for many years. Such pouches often consist 
of two similarly sized rectangular sheets in face to face contact, sealed 
around their periphery. At the time the pouch is manufactured, only three 
edges are sealed, leaving an access opening to insert items to be stored 
at a later date. The fourth seal, to seal the access opening, is made 
after the item to be kept sterile has been inserted into the pouch. After 
the item to be stored is inserted in the pouch, and the pouch sealed, the 
item in the pouch is sterilized by steam autoclaving or by using another 
sterilizing gas such as ethylene trioxide (ETO). In either case, 
maintaining the item in a sterile state until use depends on the package 
being adequately sealed to prevent the entry of bacteria. 
The three edge seals made at the time of manufacture of the pouch are 
usually made by applying heat and pressure along relatively narrow lines 
near the edges to be sealed. The fourth seal, made after the pouch is 
loaded, may also be a heat seal, but often heat sealing equipment is not 
available at the location where the pouch is loaded. In particular, many 
health care offices, including offices of both doctors and dentists, do 
not have the equipment for making heat seals; hence, for these locations 
other sealing systems must be used to seal the pouch. 
Pouches to be loaded and sealed where heat sealing equipment is not 
available are generally made to be sealed adhesively. Adhesively sealed 
pouches for this application are commonly made with one sheet overhanging 
the other in a manner similar to an envelope flap. The flap is covered 
with self-adhesive which, at the time the pouch is to be sealed, is folded 
over the access opening such that the adhesive covers the opening. So long 
as the two components of the pouch are flat sheets, such construction has 
been found to be satisfactory. However, the capacity of pouches made of 
flat sheets is somewhat restricted, and it would be desirable to have 
gussets or pleats in one of the sheets to allow the pouch to expand and 
thereby hold larger items. If pleats were to be included in prior art 
pouches, it would be found that there are three thicknesses of material at 
the pleat, which are difficult to seal with an adhesive covered flap. In 
order to create a seal at the pleat, the adhesive must seal to the edge of 
all three thicknesses of material, which is not likely to occur 
consistently. Hence, such a pouch would be considered to be unreliable as 
a container for sterile articles. 
SUMMARY OF THE INVENTION 
The presently preferred embodiments of the herein described invention 
include two flexible substantially rectangular sheets in face to face 
contact, sealed to each other around three edges, with the fourth being 
left open to receive a product to be stored. One of the sheets, called a 
"base sheet" is flat, whereas the other sheet, called the "face sheet" has 
one or more pleats which intersect the open edge of the pouch. The 
pleat(s) allow the pouch to expand to hold larger objects than if both 
sheets were flat. The base sheet extends beyond the end of the face sheet 
at the open edge in a manner similar to an envelope flap. 
The flap is coated with self-adhesive which, when folded over the opening, 
seals the opening. In a first embodiment of the invention disclosed, the 
self-adhesive extends into the opening under the face sheet as well as 
covering the exposed flap, so that both sides of the face sheet are in 
contact with adhesive when the flap is folded over the opening. Having the 
adhesive seal to both sides of the face sheet makes possible a relatively 
reliable seal for the fourth edge of the pouch, since with such 
construction it is not necessary that the end of the ply of the pleat 
adjacent the base sheet be sealed to achieve pouch integrity; 
To make the seal even more reliable, a second embodiment of the invention 
is disclosed wherein the pleat intersects the open edge of the pouch at an 
angle other than 90 degrees. So doing provides a surface for the adhesive 
to seal against rather than an edge, which makes a more dependable seal.

DETAILED DESCRIPTION OF THE INVENTION 
The pouch illustrated in FIG. 1 is known in the trade as a "chevron" pouch 
because of the shape of the seal at one end. It basically consists of two 
sheets, base sheet 10 and face sheet 11, in face to face contact, and 
sealed around three edges with heat seals 12, 13, and 14. The seals can be 
single line seals or preferably, as illustrated, each formed of two or 
more spaced parallel line seals. Heat seals are made by applying heat and 
pressure in the areas intended to be sealed. A pleat 15, which intersects 
the open edge of the pouch (i.e., the edge 18 of the face sheet 11), is 
formed in face sheet 11. For purposes of explanation, face sheet 11 is 
divided into three portions, 11-1, 11-2, and 11-3. These portions form the 
plies of pleat 15, 11-1 being the inner ply, 11-2 being the middle ply, 
and 11-3 being the outer ply. 
A portion of base sheet 10 extends beyond the edge 18 of face sheet 11 to 
form a flap 10' which, as will be described below, will be folded over 
face sheet 11 after the pouch is loaded, to make the final seal. 
There are many compatible and suitable materials from which the walls of 
the pouch could be made, but for illustrative purposes, base sheet 10 
could be made of high porosity surgical grade kraft paper having a caliper 
of 3.5 to 4 mils, and face sheet 11 could be 48 gauge polyester laminated 
to 1.5 mil polypropylene film. Sheets made of these materials can easily 
be sealed to each other with heat seals, as is well known in the art. For 
clarity, sheets 10 and 11 are shown spaced from each other in the 
partially exploded figures, but it will be appreciated that in an actual 
pouch they are in contact. 
A coating of a self-adhesive 16 occupies at least a portion of the area of 
flap 10', and also extends some distance into the area between base sheet 
10 and face sheet 11 (to edge 19 in the embodiment illustrated). The 
self-adhesive 16 (which may conveniently be about 2 mils thick) is covered 
with a release liner 17 which can be peeled off after the pouch is loaded, 
to expose the adhesive. Normally, the adhesive 16 and the release liner 17 
are purchased in the form of what is known as "self-seal tape" and applied 
to the base sheet 10 as a single item during manufacture of the pouch. The 
adhesive in this product is coated onto the release liner, and extends to 
its edge. At the time of use, the release liner can be peeled away, and 
the adhesive will remain on the base sheet. In order to assure the sterile 
integrity of the pouch, it is important that release liner 17 at edge 19 
not overhang the edge of the underlying adhesive. It has been found that 
the self-adhesive on self-seal tape provides an adequate seal to heat 
seals 12 and 13 (which cross edge 19). The release liner material is such 
that no seal will be formed between it and face sheet 11 when heat seals 
12 and 13 are made, even though the the heated iron which forms the heat 
seals extends over release liner 17 (as indicated on FIG. 1). Since many 
of the users of pouches of the type being described in this specification 
will desire to autoclave the pouch after loading, it is preferred that the 
self-seal tape, and the other components of the pouch, be autoclavable. 
It is preferred that a lip 21 of base sheet 10 extend beyond the edge of 
release liner 17 in order to facilitate the peeling of the release liner 
from the base sheet when the pouch is to be sealed. Also, a score 20 is 
preferably provided in flap 10' to provide a guide for folding the the 
base sheet over to make the final seal. 
By making the area of self-adhesive extend under the face sheet 11, as can 
be seen in FIGS. 1-4, the necessity of sealing the ends of the plies at 
the interface between plies 11-1 and 11-2 is avoided. The path to the 
interior of the pouch by contaminants entering between plies 11-1 and 
11-2, and proceeding over edge 18, and then between base sheet 10 and ply 
11-1 is blocked by the self adhesive between base sheet 10 and ply 11-1. 
Self-adhesive has a special affinity for other self-adhesive, and hence the 
construction described above would improve the sealing properties of a 
pouch as described above, even if there were no pleats in the face sheet. 
A second embodiment of the invention is illustrated in FIGS. 5-8, which 
creates an even more positive seal for the pouch. Base sheet 60, 
self-adhesive 66, and release liner 67 are similar to the corresponding 
elements of the first embodiment. The pleat 65 in face sheet 61, however, 
is not at right angles to the end 68 of the face sheet as in the first 
embodiment. In the first embodiment of the invention discussed above, the 
integrity of the pouch depends upon a seal being made to the end of the 
face sheet at the middle ply of the pleat. While reasonably reliable, as 
discussed, an even more reliable seal would result if the seal were to be 
made to a surface of the sheet, rather than to an end. By making the pleat 
65 intersect the end 68 of face sheet 61 at an angle other than 90 
degrees, as can be seen in FIG. 6, a sealing surface is created at the 
pleat on the top of the middle ply 61-2 and the inner ply 61-1. The 
deviation from 90 degrees need not be very much, angles of the order of 
about one degree from the vertical have been found to be sufficient. The 
angle shown in the figures is exaggerated for clarity. 
The creation of surfaces against which to seal in the pleat area, results 
in an adequate seal even if the self-adhesive 66 does not extend under the 
face sheet. This alternative is illustrated in FIG. 9 where self-adhesive 
66' is shown as being only in the area 60' of the base sheet, and not 
extending under the face sheet. FIG. 9 shows the end of a pouch similar to 
that illustrated in FIGS. 5-7 except that the self-adhesive does not 
extend into the area between the face and base sheets. The figure shows 
the pouch after it has been sealed. 
FIGS. 10 and 11 illustrate a variant of the embodiment shown in FIGS. 5-8. 
The pleat 105, as shown in FIG. 10 is square with the edge 101 of face 
sheet 111 (the pleat being formed of plies 111-1, 111-2, and 111-3). The 
angularity which causes there to be a surface on each ply of the pleat for 
the adhesive to adhere to is created by making a triangular cutout 102 on 
the edge of the sheet. An additional feature shown is cutout 103 (shown as 
rectangular, but is not necessarily so). Cutout 103 (which could as well 
be applied to the embodiment of FIGS. 5-8 if desired) provides an extra 
measure of security at the "outer" corner 106 of pleat 105. The term 
"outer" indicates that it is the corner of the pleat away from, as opposed 
to against, the base sheet. The triangular cutout 102 can be used with or 
without the cutout 103. It will be appreciated that while triangular 
cutout 102 is shown as extending only partially across the width of the 
pouch, there need be no edge 101 at all, and a non-square edge 102 could 
extend completely across the width of the pouch and have the same effect. 
FIGS. 12 and 13 illustrate a pouch utilizing the principles of the present 
invention which includes two pleats 125 and 126, rather than only one, and 
wherein the pleats are angled as shown in FIG. 6, and also including 
cutouts 123 and 124 in the edge of the facing sheet to provide extra 
security at the outside corners of the pleats, as discussed in connection 
with FIG. 10. It may be noted that as shown in FIG. 12, the pleats face 
oppositely, but they could as easily face the same direction, if desired. 
As before, the angle of the pleats is exaggerated for illustrative 
purposes.