GB1592214A

GB1592214A - Method of providing a heat seal between a paper member and a clear plastic member and detecting a break therein and heat sealed package

Info

Publication number: GB1592214A
Application number: GB2140/78A
Authority: GB
Original assignee: Faser Industries
Current assignee: Faser Industries
Priority date: 1977-01-24
Filing date: 1978-01-19
Publication date: 1981-07-01
Also published as: CA1121764A; IT1192323B; JPS5395093A; IT7867123A0; FR2378274A1; FR2378274B3; JPS5918253B2

Description

(54) METHOD OF PROVIDING A HEAT SEAL BETWEEN A PAPER MEMBER AND A CLEAR PLASTIC MEMBER AND DETECTING A BREAK THEREIN AND HEAT SEALED PACKAGE (71) We, FASER INDUSTRIES a Company organised and existing under the laws of New Jersey, United States of America of Andrea Blvd, Saddle Brook, New Jersey 07662, United States of America, do hereby declare the invention for which we pray that a patent may be granted to us and the method by which it is to be performed to be particularly described in and by the following statement: This invention relates to a method of providing a heat seal between a paper member and a clear plastic member and detecting a break therein and heat sealed package.

Sterilisable packages or pouches made by marginally heat sealing a clear plastic laminate to surgical grade kraft paper or the like have come into widespread use. The paper portion of such packages is designed to be sufficiently porous to permit gas or steam sterilisation but is impervious to bacteria.

The plastic laminate is heat sealable to the paper, stable under sterilisation conditions, impervious to bacteria and permits visual identification of the package contents.

Such packages are used for medical implements that must be sterile prior to use.

The manufacture or user (such as a hospital or clinic) of such medical implements is supplied with a package heat sealed around three sides by the package manufacturer.

The medical implement is then placed in the package and the fourth side is heat sealed to complete the marginal seal between the paper and the plastic. As used herein and throughout the specification, the term "package" refers to a packaging element which is empty or is provided with contents.

After sterilisation, either by exposure to ethylene oxide gas or by steam autoclaving, by the medical implement manufacturer or by the hospital or clinic, the package with its sterile contents can be stored for indefinite periods of time in a sterile condition.

To determine if a sealed package has been subjected to sterilization, it has been common practice to employ indicator inks that change color upon gas or steam sterilization and these indicator inks are typically printed on the exterior and/or interior of the paper member of the sterilizable package.

Prior to use, for example in an operating room, the indicator ink is inspected to make sure the package had been properly sterilized and the marginal heat seal of the package is visually inspected in an effort to detect whether or not the initial heat seal is adequate or whether or not there are any subsequent breaks or ruptures in the heat seal, for example by accidental tampering with the package after sterilization or by shifting of the package contents in such a way that the heat seal becomes broken or ruptured.

Sterilization pouches are conventionally made of clear, colorless plastic film heat sealed to white paper. This combination of materials makes it extremely difficult, if not impossible, to visually determine if the initial seal has subsequently been ruptured or broken by tampering or movement of the package contents.

To more readily ascertain the validity of the initial heat seal, it has been proposed to lightly tint the plastic laminate member or to coat the paper member with a lightly tinted heat seal coating. This approach, however, has been far from satisfactory in that it is not possible to readily ascertain by visual inspection the adeqiracy and completeness of the initial heat seal between the plastic film and the paper member. Moreover, there is no improvement as compared to white paper and colorless plastic film as regards subsequent breaks or ruptures in the heat seal between the plastic and the paper due to tampering with the package or movement of the contents of the package.

The main difficulty with indicator inks printed on either side of the paper member is that the package may be subjected to sterilization conditions which are sufficient to cause a color change in the indicator ink but insufficient to actually sterilize the package contents. With an indicator ink printed on the outside of the paper member the color change will occur as soon as the indicator ink comes in contact with steam or ethylene oxide gas and long before either gas penetrates the paper member and sterilizes the package contents. Printing the indicator ink on the inside of the paper member is an improvement but again, the ethylene oxide gas or steam in passing through the paper member comes in contact with the indicator ink before reaching the package contents.To cope with these problems, manufacturers and hospitals have to follow sterilization procedures with a builtin margin of safety to ensure that the package contents are sterilized which means using high sterilization temperatures over a sustained period of time. Because of these drawbacks, the indicator inks printed on the inside or the outside of the paper member simply say that the package has been put through sterilization but it is left up to the technician to ensure that the correct sterilization procedure has been observed to effectively sterilize the package contents.

According to one aspect of the present invention there is provided a method of providing a heat seal seam between a paper (as herein defined) member and a clear plastic member and detecting any break in the heat seal, which comprises providing the paper member dyed a dark colour, heat sealing the clear plastic member directly to the dyed paper member in the heat seal area, thereafter visually examining the heat seal to detect if the previously clear plastic member takes on a translucent appearance in the area of the heat seal which translucent appearance provides a distinct colour contrast to detect a break in the heat seal.

According to a preferred embodiment of the present invention there is provided a method of providing a heat seal seam between a paper (as herein defined) member and a clear plastic member in a sterilisable package (as herein defined) and detecting any break in the heat seal, which comprises providing the paper member dyed a dark colour which is sufficiently porous to permit gas or steam sterilisation but is impervious to bacteria, heat sealing the clear plastic member directly to the dyed paper member in the heat seal area, thereafter visually examining the heat seal to detect if the previously clear plastic member takes on a translucent appearance in the area of the heat seal which translucent appearance provides a distinct colour contrast to detect a break in the heat seal.

According to another aspect of the present invention there is provided a package (as herein defined) comprising a clear plastic member seamed by heat sealing directly to a paper (as herein defined) member dyed a dark colour such that upon breaking the heat seal the previously clear plastic member takes on a translucent appearance in the area of the broken seal which provides a distinct colour contrast between the break in the heat seal and the dark colour of the paper in any remaining heat sealed area.

According to a preferred embodiment of the present invention there is provided a sterilisable package (as herein defined) comprising a clear plastic member seamed by heat sealing directly to a paper (as herein defined) member which is sufficiently porous to permit gas or steam sterilisation but is impervious to bacteria, said paper member being dyed a dark colour such that upon breaking the heat seal the previously clear plastic member takes on a translucent appearance in the area of the broken seal which provides a distinct colour contrast between the break in the heat seal and the dark colour of the paper in any remaining heat sealed area.

The package may also include a member having the desired indicator ink printed thereon i.e. an indicia bearing portion which is inserted into the package together with the implement to be sterilised prior to completing the heat sealed seam and subjecting the package to sterilisation. The indicia bearing member is provided by printing the indicator inks on a portion of the paper member of the package which extends beyond the area enclosed by the heat sealed seam and making it readily separable from the package. The indicia bearing portion, inserted with the item or implement to be sterilized in the package, can be positioned and oriented such that the indicator ink faces the plastic member of the package which means that the sterilization gas will act on the indicator ink to cause the color change at the same time or after sterilization of the package contents has been accomplished. This provides a much better indication to the ultimate user of the sterile item that it is, in fact, in a sterile condition and not simply that the package has gone through a sterilization procedure.

The method may also include providing a paper member wherein the paper member has a portion extending beyond the area to be enclosed by the heat seal when completed, said portion bearing indicia that changes color upon sterilization, inserting the item or implement to be sterilized into the open-ended package, separating the indicia bearing portion from the package and inserting said separating portion into the package with the indicia visible through the plastic member, heat sealing the open end of the package and subjecting the sealed package to sterilization. Preferably the indicia bearing portion is positioned between the item to be sterilized and the plastic member with the indicia visible through the plastic member. This, of course, depends on the nature and the size of the item or implement to be sterilized.

The present invention will be more fully understood from the following description taken in conjunction with the accompanying drawings wherein: Figure 1 is astop plan view partly broken away of a sterilization package according to the invention marginally heat sealed around three sides of the package and shaded to indicate that the paper member is dark blue; Figure 2 is a top plan view of the sterilization pouch shown in Figure 1 heat sealed marginally along the fourth side of the package to enclose the package contents which, in this instance, is a pair of scissors; Figure 3 is a sectional view taken along line 3-3 of Figure 1; Figure 4 is a sectional view partly broken away taken along line 4-4 of Figure 2;; Figure 5 is a top plan view partly broken away of a sterilization package according to the invention illustrating various ways in which breaks or ruptures in a heat seal can occur; Figure 6 is a bottom plan view of a sterilizable package according to the invention from the paper side and having triangular tear-off indicator portions; Figure 7 is a top plan view of the sterilization pouch of Figure 1 from the plastic side showing the marginal heat seal completed and one of the triangular shaped indicia bearing portions separated from the package and inserted into the package interior with the package contents with the indicia visible through the plastic member.

Figure 8 is a top plan view partly broken away of an alternate embodiment of the present invention of a sterilization package from the plastic side; and Figure 9 is a top plan view, partly broken away, of a further embodiment of a sterilization package of the invention also from the plastic side thereof.

The preferred embodiment of a sterilization pouch shown in Figure 1 and 2 of the drawing is shown to include a paper member 10 having a dark coloration (in this illustration, dark blue) and a clear plastic laminate 12 which is marginally seamed by heat sealing around three sides of the package in Figure 1 and around the fourth side of the package in Figure 2 to close the package.

The chevron configuration at the top of the package is used to facilitate manual opening or peeling apart of the package to gain access to the package contents which is shown in Figure 2, for illustrative purposes, as a pair of scissors 16.

The paper member 10 is dyed the desired dark color, for example dark blue, dark green, dark red, dark brown, dark grey, or black. The dye, should be selected so as to be stable under sterilization conditions Readily available surgical grade kraft paper having the desired porosity characteristics can be readily dyed to provide the desired dark coloration for the paper member 10.

The term "paper" as used herein also applies to synthetic or artificial paper materials made from, for example, plastic fibers as well as conventional paper products preferably having the characteristics for use in sterilization pouches. An example of synthetic paper is a spun bonded polyethylene sold by DuPont under the Registered Trademark "TYVEK".

The plastic member 12 is preferably a laminate of a polyester, such as polyethylene terephthalate sold under the Registered Trademark "MYLAR", and a heat sealable thermoplastic material such as polyethylene, ethylene vinyl acetate, an ionomer such as DuPont's "SURLYN" (Registered Trademark), co-polymers and mixtures of the foregoing. The polyester layer forms the exterior of the package and the heat sealable thermoplastic material interfaces with the paper member 10 and forms the marginal heat seal 14.

Heat sealing the plastic member 12 to the paper member 10 around the margin of the package as shown in Figures 1 and 2 of the drawing can be accomplished using conventional heat sealing equipment and techniques. Generally, the heat seal is made wide enough to guarantee an adequate and complete seal around the margin of the package initially formed with a heat seal around the three sides with the fourth side completed after the package contents are inserted therein as shown in Figure 2. If desired, a number of parallel spaced apart seals can be effected in the area of the marginal heat seal 14. This is commonly known in the industry as a rib seal and is employed to impart additional peel strength to the heat seal between the plastic member 12 and the paper member 10.

According to the invention, the plastic member 12 exhibits a translucent appearance which can be described as cloudy or milky as compared to the clear member itself, upon rupture or breaking of the heat seal area 14. This cloudy or milky appearance is believed to result from the heat sealing operation and only comes into being when the heat seal is ruptured or broken.

This phenomenon is believed to result from a surface conformation by the plastic member 12 to the surface of the paper member 10. The paper member 10 usually has a dull or matte finish and this is duplicated in the seal area of the film in a cloudy or milky appearance upon rupture or breaking of the heat seal 14.

Figure 5 of the drawing is intended to illustrate how the present invention provides a visual contrast for readily detecting breaks or ruptures in the heat seal between the paper member 10 and the plastic member 12, whether due to partial opening of the package, either intentionally or unintentionally, or by shifting of the package contents. In Figure 5 the plastic member 12 is shown pulled back and separated from the chevron portion of the heat seal area 14.

The left side of the figure shows the cloudy or milky appearance 18 from the heat seal side of the plastic member 12, whereas the right side of the figure shows the contrast that results from the exterior side of the plastic film 12. Note especially the marked contrast of the broken heat seal area 18 with respect to the dark coloration of the paper member 10 itself and the remaining sealed area 14. It should also be noted that the sealed area 14 has a glossy, clear appearance which is in contrast to the dull or matte finish appearance of the paper member 10 through the plastic member 12 outside of the seal area 14. This contrast can be used to detect voids or defects in the heat seals made by the package manufacturer and also the packager.

Also illustrated in Figure 5 is the visual contrast that results when the package contents such as the pointed end of scissors 16 shifts and pierces or ruptures the heat seal 14. As can be seen, this results in a readily discernible translucent appearance 18 which is in distinct color contrast with the dark coloration of the paper member 10 through the plastic member 12 in the unsealed areas of the package and is also in distinct color contrast with the remaining heat sealed area 14 which shows the coloration of the paper member 10 in a clear and glossy fashion.Thus, in the case of a dark blue paper member 10, the user of a sterilized package such as shown in Figure 2 can readily determine by a simple visual examination if the package, after sterilization, has been opened, either intentionally or unintentionally, that is, by peeling apart the two member 10 and 12 or whether the package contents, such as the scissors 16 has shifted and pierced or ruptured the heat seal 14. In either instance, the translucent portion 18 which has a cloudy or milky appearance is in distinct color contrast with the dark coloration of the paper member 10 itself, which in this case is dark blue, and the remaining heat sealed area which has a clear, dark blue coloration, but is glossy in appearance as compared to the matte or dull finish of the paper member 10 itself outside the seal area.

The same, highly visual color contrast results from imparting to the paper member 10 a dark coloration such as dark blue, dark green, dark red, dark brown, dark grey, or black.

Referring now to Figures 6 and 7 the triangular shaped portions 20 extending beyond the inverted V-end seal which is beyond the area to be enclosed by the marginal heat seal 14 when completed (Figure 7). As shown in Figure 6, the paper 10 may have a white area or block printed thereon so that portions 20 can bear indicia that changes color upon sterilization, one portion bearing indicia that changes color upon stream sterilization and the other portion 20 indicia that changes color upon gas sterilization such as ethylene oxide gas.

The indicia which is commonly referred to as indicator inks is generally shown by the reference numeral 22.

Suitable indicator inks for the indicia 22 are any of the commercially available and commonly used indicator inks for sterilization pouches. A typical indicator ink for use with steam autoclaving is a chemically active ink that changes from pink to dark brown during steam autoclaving. A typical indicator ink for use with ethylene oxide sterilization is a chemically active ink that changes color from light brown or tan to orange upon exposure to ethylene oxide gas sterilization.

Steam autoclaving and ethylene oxide gas are known sterilization techniques and the present invention is well adapted to these procedures.

An item to be sterilized such as the scissors 16 shown in Figure 7 is inserted through the open end of the pouch shown in Figure 6. Depending on the sterilization procedure to be employed, the technician separates the proper indicia bearing portion 20 each of which is attached to the paper portion 10 at 25 and precut therebetween along line 24. The technician or operator then inserts the separated portion 20 into the package with the indicia 22 visible through the plastic member 12 as shown in Figure 7. The marginal heat seal 14 is then completed and the package is ready for sterilization.

During sterilization, the sterilizing medium, steam or ethylene oxide gas, sterilizes the scissors 16 and at the same time or afterwards, reaches the indicia 22 which then undergoes the indicated color change to indicate that the package contents and not just the package itself are sterile. Depending on the nature and size of the item or implement to be sterilized, it is preferred to position the portion 20 which is inserted into the pouch between the item to be sterilized and the plastic member which ensures that the sterilization medium will not cause a color change in the color sensitive indicia until after the sterilizing medium has contacted the item to be sterilized. In any event, the indicia 20 must be visible through the plastic member 12 when the portion 20 is separated from the package and inserted into the interior thereof with the item to be sterilized.

The preferred embodiment shown in Figures 6 and 7 has a further advantage in that sealed packages ready for sterilization can be segregated by the intended sterilization procedure to be employed by virtue of the fact that one of the indicia-bearing portions 30 is missing from either the left or right side of each sealed pouch when the pouches are lined up and oriented in the same direction.

Thus, it is easy to detect if a package designated for steam sterilization has become mixed in which packages designated for ethylene oxide sterilization.

Figures 8 and 9 show alternate embodiments of the present invention. In Figure 8, the indicia bearing portions 20 are defined via perforated lines 24 at the bottom or open end of the sterilization pouch. After the item to be sterilized is inserted into the pouch under plastic member 12, the desired portion 20 of the paper member 10 is separated and inserted into the pouch with the item to be sterilized with the indicia 22 visible through the plastic member 12. The transverse heat seal across the bottom shown by dash lines is then made to complete the marginal heat seal 14.

The embodiment shown in Figure 9 is similar to the embodiment shown in Figure 6 except the end seal opposite the open end of the pouch is a straight transverse seal and the portion of the paper member 10 extending beyond the area to be enclosed by the marginal heat seal 14 is divided into two rectangular indicia bearing portions 20 via perforated line 24.

The sterilization package will typically bear other indicia as shown in Figure 6, for example, on the exterior side of the paper member 12, preferably in a whitened area, to designate for example the package contents, the sterilization date, the expiration date and the like.

The color sensitive indicia 22 is commonly printed on the paper member 10 using known techniques.

WHAT WE CLAIM IS: 1. Method of providing a heat seal seam between a paper (as herein defined) member and a clear plastic member and detecting any break in the heat seal, which comprises providing the paper member dyed a dark colour, heat sealing the clear plastic member directly to the dyed paper member in the heat seal area, thereafter visually examining the heat seal to detect if the previously clear plastic member takes on a translucent appearance in the area of the heat seal which translucent appearance provides a distinct colour contrast to detect a break in the heat seal.

2. A method of providing a heat seal seam between a paper (as herein defined) member and a clear plastic member in a sterilisable package (as herein defined) and detecting any break in the heat seal, which comprises providing the paper member dyed a dark colour which is sufficiently porous to permit gas or steam sterilisation but is impervious to bacteria, heat sealing the clear plastic member directly to the dyed paper member in the heat seal area, thereafter visually examining the heat seal to detect if the previously clear plastic member takes on a translucent appearance in the area of the heat seal which translucent appearance provides a distinct colour contrast to detect a break in the heat seal.

3. A method according to Claim 2 wherein the paper member is surgical grade kraft paper.

4. A method according to any of Claims 1 to 3 wherein the plastic member is a laminate of a polyester and a heat sealable thermoplastic material.

5. A method according to any of Claims 2 to 4 wherein the paper member has a portion extending beyond the area to be enclosed by the heat seal when completed, said portion bearing indicia that changes colour upon sterilisation, inserting the item to be sterilised into the package before it is completely sealed, separating the indicia bearing portion from the package and inserting said separated portion into the package with the indicia visible through the plastic member, completely heat sealing the package and subjecting the sealed package to sterilisation.

6. A method according to Claim 5 wheren the indicia bearing portion is positioned between the item to be sterilised and the plastic member with the indicia visible through the plastic member.

7. A package (as herein defined) comprising a clear plastic member seamed by heat sealing directly to a paper (as herein defined) member dyed a dark colour such that upon breaking the heat seal the previously clear plastic member takes on a translucent appearance in the area of the broken seal which provides a distinct colour contrast between the break in the heat seal and the dark colour of the paper in any remaining heat sealed area.

8. A sterilisable package (as herein defined) comprising a clear plastic member seamed by heat sealing directly to a paper (as herein defined) member which is sufficiently porous to permit gas or steam

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

sterilized and the plastic member which ensures that the sterilization medium will not cause a color change in the color sensitive indicia until after the sterilizing medium has contacted the item to be sterilized. In any event, the indicia 20 must be visible through the plastic member 12 when the portion 20 is separated from the package and inserted into the interior thereof with the item to be sterilized.

The preferred embodiment shown in Figures 6 and 7 has a further advantage in that sealed packages ready for sterilization can be segregated by the intended sterilization procedure to be employed by virtue of the fact that one of the indicia-bearing portions 30 is missing from either the left or right side of each sealed pouch when the pouches are lined up and oriented in the same direction.

Thus, it is easy to detect if a package designated for steam sterilization has become mixed in which packages designated for ethylene oxide sterilization.

Figures 8 and 9 show alternate embodiments of the present invention. In Figure 8, the indicia bearing portions 20 are defined via perforated lines 24 at the bottom or open end of the sterilization pouch. After the item to be sterilized is inserted into the pouch under plastic member 12, the desired portion 20 of the paper member 10 is separated and inserted into the pouch with the item to be sterilized with the indicia 22 visible through the plastic member 12. The transverse heat seal across the bottom shown by dash lines is then made to complete the marginal heat seal 14.

The embodiment shown in Figure 9 is similar to the embodiment shown in Figure 6 except the end seal opposite the open end of the pouch is a straight transverse seal and the portion of the paper member 10 extending beyond the area to be enclosed by the marginal heat seal 14 is divided into two rectangular indicia bearing portions 20 via perforated line 24.

The sterilization package will typically bear other indicia as shown in Figure 6, for example, on the exterior side of the paper member 12, preferably in a whitened area, to designate for example the package contents, the sterilization date, the expiration date and the like.

The color sensitive indicia 22 is commonly printed on the paper member 10 using known techniques.

WHAT WE CLAIM IS:

1. Method of providing a heat seal seam between a paper (as herein defined) member and a clear plastic member and detecting any break in the heat seal, which comprises providing the paper member dyed a dark colour, heat sealing the clear plastic member directly to the dyed paper member in the heat seal area, thereafter visually examining the heat seal to detect if the previously clear plastic member takes on a translucent appearance in the area of the heat seal which translucent appearance provides a distinct colour contrast to detect a break in the heat seal.

2. A method of providing a heat seal seam between a paper (as herein defined) member and a clear plastic member in a sterilisable package (as herein defined) and detecting any break in the heat seal, which comprises providing the paper member dyed a dark colour which is sufficiently porous to permit gas or steam sterilisation but is impervious to bacteria, heat sealing the clear plastic member directly to the dyed paper member in the heat seal area, thereafter visually examining the heat seal to detect if the previously clear plastic member takes on a translucent appearance in the area of the heat seal which translucent appearance provides a distinct colour contrast to detect a break in the heat seal.

3. A method according to Claim 2 wherein the paper member is surgical grade kraft paper.

4. A method according to any of Claims 1 to 3 wherein the plastic member is a laminate of a polyester and a heat sealable thermoplastic material.

5. A method according to any of Claims 2 to 4 wherein the paper member has a portion extending beyond the area to be enclosed by the heat seal when completed, said portion bearing indicia that changes colour upon sterilisation, inserting the item to be sterilised into the package before it is completely sealed, separating the indicia bearing portion from the package and inserting said separated portion into the package with the indicia visible through the plastic member, completely heat sealing the package and subjecting the sealed package to sterilisation.

6. A method according to Claim 5 wheren the indicia bearing portion is positioned between the item to be sterilised and the plastic member with the indicia visible through the plastic member.

7. A package (as herein defined) comprising a clear plastic member seamed by heat sealing directly to a paper (as herein defined) member dyed a dark colour such that upon breaking the heat seal the previously clear plastic member takes on a translucent appearance in the area of the broken seal which provides a distinct colour contrast between the break in the heat seal and the dark colour of the paper in any remaining heat sealed area.

8. A sterilisable package (as herein defined) comprising a clear plastic member seamed by heat sealing directly to a paper (as herein defined) member which is sufficiently porous to permit gas or steam

sterilisation but is impervious to bacteria, said paper member being dyed a dark colour such that upon breaking the heat seal the previously clear plastic member takes on a translucent appearance in the area of the broken seal which provides a distinct colour contrast between the break in the heat seal and the dark colour of the paper in any remaining heat sealed area.

9. A package according to Claim 7 or Claim 8 in which clear plastic member is marginally heat sealed to the paper member.

10. A package according to Claim 8 or Claim 9 when dependent upon Claim 8 wherein the paper member is surgical grade kraft paper.

11. A package according to Claim 9 or Claim 10, wherein the plastic member marginally heat sealed around three sides to a first portion of the paper member so as to leave an opening at one end for inserting the package contents, said paper member having a second portion extending beyond the area to be enclosed by the marginal heat seal when completed, said second portion bearing indicia that changes colour upon sterilisation and means releasably joining said first and second portions for separating said second portion from said first portion for insertion together with the package contents into the package prior to completing the marginal heat seal and sterilisation of the package contents to indicate that the package contents have been subjected to sterilisation.

12. A package according to Claim 11, wherein said second portion extending beyond the area to be enclosed by the heat seal has two parts, one part bearing indicia that changes colour upon steam sterilisation and the other part bearing indicia that changes colour upon gas sterilisation and wherein the releasable joining means includes means enabling the individual separation of each part from the package, to signify on its face to a user that the package is to be subjected to steam sterilisation if the one part is removed and to gas sterilisation if the other part is removed.

13. A package according to any of Claims 9 to 12 wherein the marginal heat seal includes an inverted end V-seal joining two side seals and the indicia bearing portion of the paper member extending beyond the inserted V-seal is at least one triangular shaped member.

14. A package according to Claim 13, wherein two triangular members are provided, one member bearing indicia that changes colour upon steam sterilisation and the other member indicia that changes colour upon gas sterilisation and wherein the releasable joining means includes means enabling individual separation of each triangular member from the package to signify on its face to a user that the package is to be subjected to steam sterilisation if the one member is removed and to gas sterilisation if the other member is removed.

15. A package according to any of Claims 10 to 13, wherein the releasable joining means comprises a partially precut or perforated line in the paper member.

17. A method of providing a heat seal seam between a paper (as herein defined) member and a clear plastic member and detecting any break in the heat seal substantially as herein described.

18. A sterilisable package substantially as herein described with reference to, and as shown in, the accompanying drawings.