CA1053188A - Sterile pack - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

A sterile pack blank is provided which comprises an enclosure determined by a substrate of predetermined porosity and a discrete plastic film overlying the porous substrate. That film and porous substrate are adhesively connected by a cohesive or self-sealing adhesive. The porous substrate is printed with a continuous adhesive track, while substantially an entire sur-face of the plastic film is adhesive coated. An end flap of the film is folded back upon itself along a fold line to provide access to she enclosure, interior. After introduction of an instrument into the enclosure, the film end flap is hingedly connected to the substrate, along respective adhesively coated areas thereof, according to the sealing method of the invention.
The adhesive is characterized by the fact that it is self-adher-ing. Therefore, only interfaced areas of the film and substrate that are respectively coated with the adhesive may be adhesively connected. The adhesive coating on the film is farther charac-terized by a predetermined tack value for thereby providing for secure sterile delivery of an instrument from the pack. The porous substrate is provided, respectively, with exterior and interior sterilization indicators. The indicators comprise respective pairs of steam and ethylene oxide sensitive inks. The exteriorly located indicators are immediately sensitive to the sterile ambience of the pack, while the interiorly located in-dicators are sensitive to a sterile environment within the pack enclosure.

1.

Description

- IL ~o~3~8 ACKC I~OU ~ D O F TH E I NVLNTl ON
The instant invention relates to a novel sterile packet I ~ ;
,, for sterili~ing medical instrumeni~:s and i~he like, and to the ,,method for sealing tl~e instrumen~ in the packet. ~lore par'ticu~
i' larly, this inventi3n relates to a composite packet having a ' , .
~ lltransparent face and an opaque face provi~ed witll interior and : 'I exterior sterilization indicators, including means ~or preventing ~slippage durin~ s~erile deLivery o~ tlie ins~rument.
, While various sterile packs are co~riercially available, I ;
none inc'ludes the requisi~e com'bination of desirable qualities. `'`~
'`The optimal sterile packet should have lnterior and exterior '~ sterilization indica~ors'; i~ should have a positive seal on all l;
sides to avoid con~amina~ion; it should lnclude means for pre- !
enting slippage o~ the instrument from the packet interior dur~
!l ing sterile delivery thereof; and the substrate of which the~pack ' is fabricated should be~suitably~ porous so as to permit the llsterilization mediu~ to sterilize the enclosed instrument, but pre~lude entry of microorganlsms therein. It is also deemed ``~
highly desirable to provide a sterile pack: that may~be opened .
and closed witbout contacting the interlor side walls ~hereof. '.`
Accordingly, a sterile pack wî~hi.n tlle scol~e o~ tlne 1 instan~ invention includes this com~ination ~f ~dvan~ages, includ~
. . jiing a novel sealing method~ Th~ pack periorms lligl-l.y satisfac~
,torily under conventional steam or ethylene oxide sterilization procedures, S~RY OF TH~ INVENTION
~: - ,, Generally speaking, in accordance with tlle invention, ~a sterile~pack blank is provided which comprises an enclosure ~5 3 ¦determine~ ~y a su~s~rate o predetermined porosity and a discrete ¦plastic film overlying the porous substrate, The film and porous substrate are adhesively connec~ed by a coliesive or self-sealing adhesive. The porous substrate is prin~ed with a continuous I adhesive track, while substan~ially an enti~e surface of the ¦ plastic film is adhesive coated. An end flap of the film is I ~
folded back upon itself along a fold line to provide access to ¦ ~ ;
¦Ithe enclosure interior. ~ter intro~uc~ion o~ ~n instrument into ¦
¦~the enclosure, ~he film end flap is hingedly connected to the ¦
!I substrate~ along respective adhesively coated areas thereof, l¦according to the sealing method o the invention.
I
The adhesiye is characterized by the fact that it is self-~dhering. Therefore, on~y interfaced areas of the film and substrate that are respectively coated with the adhesive may be ¦ adhesively connected. The adhesive coating on ~he film is further characterized by a predetermined tack value for thereby providing for sterile delivèry of an instrument from the pack.
~¦ The porous substrate 1~ provided, respectively with lexterior and interior~sterili2ation indicators. The indicators ¦
; comprise respective pairs of s~eam~and ethylene oxi~e sensitive ¦ inks, The exteriorly located indicators are in~edi.ately sensitive i the ¦ to/s~erilizing ambienc ~of the pack, while the inte~iorly located ¦ indicators are sensitive/a sterilizi~ environment withLn che pack I enclosuL-e .
- ¦ ~ ~ Accordlngly, it is an o~ject of this invention to~ j provide a sterile pack having a novel construction.

- ~ Os ~ ~ 8 Another o~ject oE ~he inventi.on is to provide a steri;el pack having internal and external indica~ors'for respective'ly~ '' showing a sterile environment wi~hin the pack enclosure and a ¦
' sterile ambience for the pack.
Still another objec~ o the invention is to provide a sterile pack which includes means for preventing slippage of an instrument therefrom to tl~ere~y cna~le sterile delivery of ,~ ,~
i' the instrument from ~he pack. ~
;~,! Yet another object of the instan~ invenLion is to provide a novel method ~or sealing the sterile pack a~ter the ' ,.

instrument is introduced therein.
' Still other objects and advantages of the invention ~ will in part be obvious and'~ill in part be apparent from the `~" ''¦ specification,.
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' The inveneion accordingly~comprises an article~of " ,manufacture possessing the ~eatures~ properties,~and the relation , , , .. ~ .
, of elements which will be exemplified in ~he article hereinafter !i ' ~" described, and~the~;several steps for sealing the article and the relation of one or more of such steps wlth respect to each o the others thereo~ which will be exemplified in the metho~
hereinafter disclosed, and the scope of the tnvent;on will be "indicated in the c~laims.
,i ' BRIEF DESCRIPTION 01~ TII~ ~KAWINGS
' For a fuller understanding~' of ~he invention, reference~
' is had~to the follo~'~in~ description taken in Lonnectlon wlth the~
accompanying drawings, in which~

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'',~il ' , ', ,,. l.
~0531E~3 -~ig, 1 i's a bottom ~lan view o a sterile pack within I
the scope of the instant invention;
li Fig. 2 is a top plan view of tlle em~odiment shown in j~ Fig. 3 is a sectional view taken along line 3-3 of the ¦embodiment s~en in Fi~. 2;
Figs. 4-6 are detail views sequen~ially showing method steps for seallng the pack after lntro~uc~ion oE the ins~rumen~
¦therein; ~ ~ ~ ;
i Fig. 7 is a sectlonal view taken along line 7-7 of ~ ' iFig. 6 showing an instrument sealed within the pacl;;~
Fig. 8 is a perspective view showing the manner of ~presentation o~ the instrument af~er sterilization;~and ~igs. 9 and 10 are'fragmentary details respec~ively ;~
showing gas and steam indicators provided on the pack.
. DESCRIPTION OF THE PREl;'ERRl~D ~2IBODI~IENT ~
:` I ~
¦ ~ Referring now to Figs.~1-3 and~7~ O,~a non-woven~sub-strate ll, for~instance~of paper, paper board,fiber-bonded syntheti¢ and the like of generally rectangùlar shape, is pro- --~ided~with a~continuous printed a~dhesive ~rack L2 along the sur-~ I face 13 thereof. Adhe~sive track 12 consisting oE an adhesive -~ ¦12' is of substantially~'~uniform~width and,~ln goneral, runs~' ~ ~ lalong~the margin~o surface l3 of`~the substrate. At the top l4 ,!, ~ , of the packet, su~stan~ially symmetrical segments 15, 15' of;the track detour acutely~inwardly relative to top end~l4 of the ' packet and converge at~ a~vertex 16 ~for a purpose which will be hereina~ter describ'èd. ~Provided-in substr'ate ll are resp ctive 5~ '`
, :: . , ~ ~. . ., . , 31 ~.8 :
pairs 17, 17' ~nd 18, 18' oL steriliza~ion indicators. One mem-~ber 17, 18 of eacll respective pair of in.licators is located on I ~;
the surface 19 of substrate 11, and eacl~ corresponding member , :
17', 18' o~ the pair is located on the sur~ace 13 o~ subs.ra.e 1111. As seen in the F~gures., respe.^tive members of each pair.of I . ~ :-: ~indicators overlie each other.
Overlyin,~, surface 13 of subsLLa~:c 11 is a ~liscre~e , subs~antially rectangula~ section o~ ~ clear plastic ~ilm 20, fabricated for instance of high or low densi~y polyethylene, ,Ipolypropylene or polyetheyleneterephthala.~e.The surface 21 thereof which inter~aces with-surface 13 of su~strate 11 is substantially complerely coa~ed with adhesive 12'. Overlapping adhesively ¦coated areas of substrate 11 and film 20 are adhesively connected ...
~` ~hereby determining an enclosure 22 into which access may be had 1 ~.

, through an inlet slot 2~

~ ~l At top end 14 of the pack, end wall 24.of film 20 is :~ j'substan~ially uniformly foreshortened relative to end wall 25 :

jif substrate ll for a purpose which is hereinafter described ~ An end flap 26 of film 20 is ~olded back upon itself along a ! ;
:. l : .:
fold line 27 for thereby definin~access slo~23. ~.er intro-I¦ duction of an instrument 28 into enclosure 22, ~lap 26 may be ; ~I hingedly connected to substrate 11, along respective adhesively -coated areas thereof, according to~tbe sealing m~hod within the .

~scope oE the invention.

. Adhesive 12' is a cold or cohesive seal type commercially ,1 ~
- ~ .i svailable self-adhering a.-lhesive.~:~These adhesives are typic-ally . ~ of the rubber la~ex type. Therefore, only con~only adhesively - ~, coated areas of subs.~rate 11 and film 20 may be adhesively sealed.

1053~8~

In ~abricatill~ tl~e blanlc 29, as best seen in ~ig, 2, adhesive ¦
~rack 12 of su~sta~e 11 may be sealed a~ainst the adhesively ¦
coated surface 21 of ~ilm 20 by convell~ional mechanical me~ns.
The in~erior o~ surface 13 o~ subs~ra~e 11 is uncoa~e~ and ~hPre- !
fore presents a foreign subs~ance along i~s interface with adhes-ively coated surEace 21 o film 20 which does not seal therewith, thereby ~e~inin~ enclosure 22. ~nd ~lap 26 lS overcoate~ wi~h adhesive 12' and there~ore remains ~ree because o~ ~lle collesive character thereof, until it is pivoted outwardly into sealed overlying relationship on track 12 of substrate 11. While the cohesive cliaracter o`f ~dhesive 12' assures that no substantial adhesion occurs between adhesively coated surface 21 of film 20 . ~ ,. .
and instrument 28 introduced into enclosure 22 of blank 29, the adhesive 12' on surface 21 o film 20 is preferably character-¦
ized by a pxedetermined tack for inhibiting accidental slippage of instrumen~ 28 rom the pack upon s~erlle presentation thereof, for there~y assuring sterile delivery of instrument 28.
The statistical ;likelihood o~ success~ul sterile deliv-ecy after sterlle presentaLion o~ instrument 28 is optimlzed wl~en the tack value of a~hesivc 121 on sur~a~e 21 of ~ilm 20 is ~etwecn about 0.5 to about 60.0 sec., and prefera~ly betweell about 2.5 ~! -~and about 12.0 sec., as measured according to a mc~ ied version~
or~psTc-l4 (11/70~. The modiLicatLon was introduce~ to account f~r ~ E -t ~h-- ins~r~e~ 28 I; o~en c~-,nlo s sce~

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! I , tungsten steel and the like. According to the test method - `~

2 x 5 x 1¦16 inch stainless steel substrates, type 302, finish No. 4 were provided. The test substrates were scrubbed with surgical gauze saturated with diacetone~alcohol, wiped dry, scrubbed a second time with surgical gauze saturated with isopropyl alcohol, and air dried 2 x 2 inch paper masks were ;`~
cu~ (max. paper thLckness 0.002 inch) and rectangular windows or slots of the dimensions, 1 x l ~ O.Ol inches, were provided -;
in the middle thexeof. ~
Strips, approximately 5 x(1.5 - 1.8)inches, of àdhesive coated plastic film were CUt. The tes~ specimens were ~' laLd on a flat surface~ adhesive side up, and a màsk was placed '`
over each specimen whereby the l x 1 windows therein covered ' respective test specimens. The masks were pressed onto respective specimens with care taken to press only'the paper ~ ~
surfaces of the masks. ' ' ;~ ;
The specimens were lifted by their ends9 inverted and '~; ;
placed on respective test substrates, whereby the respective ' windows there~of were locat'ed at the approximate centers of the "
re~pective substrates. Each test specimen was pressed onto its -substrate'by a mechanically operated roller having a rubber covered wheeL. The roller weighed 4.5 ~ 0.1 lbs., had a ~' diameter of 3.25 ~ 0.1 inches, and a width o~ 2 5 ~ 0,1 inches The rubber surface was approximately 1/4 inches thick and had a .;~
durometer hardness value of 70-80, The roller was' moved over the t'es~ specimens at a speed of 12 inches per minute, once forward and once reversed. ' ~,.' ' ':
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10531Y13 1 ~ ~
A test weigllt consistin~ o~ a narrow metal strip ~: :
having a l ~ l/2 inch adllesive tape a~ached ~o an end thereo was provided. ~ l/2 x l/2 inch por~ion oE the adhesive tap~
projected beyond the edge o~ the metal strip. ~he test weight, including ~he adllesive weighed l ~ O.Ol grams.
Each test specimen was tril~led by cutting it across the n rrow side exac~ly at the edge oE ~lle ~aper mask ~herein ;
and~excised portion was discarded~ The test weight was attached to the edge o~ ~he mask a~ the center of the trimmed side oE ;
the test specimen. ~ ;
While holding ~he test weig~t ana pressing the mask ; ;
against the surface o~ the test substrate, the entire assembly was inverted and horizontally-~mounted. The pressure securing the test weigllt against the substrate was gently relieved to , .: . . ~ .
.i~ avoid imparl:ing a shoclc load~ on the specimen, and simultaneously : `~
the interval . -:
~ therewith a timer was actuatedO The timer recorded/until the`~ ;~
.~ ., entire area of tlle specimen~within the l x~ l~ window ;~Oe tlle mask was disconnected Erom the substrate. Values~ were calculated as set forth ln the PSTC-14 test method. ActuaL values recorded for ~ ;
,, the test specimens were, respec~ively, 2.5, 2.5, 3,0, 3.5j 4Oo, . secon ds. `
. .~ 12.0, 1200, 15.5, 52 and~ 54/ The-adhesive cnmp~siti~n was a~ ~ ` :
;` , constant for all the ~tests performed.
'! It is a significant feature of t1~e inventi~oll that the :
~1 adhesive seal between substrate;ll and film 20 does not breach during the 5terilization procedure. In general this , feature relates to th- functiunal~relationshLp whic~ prevails-... ... . ~ . ... . . .. ... .

11 iO53~8~ ~
i : between the porosity of subs~rate ll and the adhesive value of : adhesive 12'. Under typical sterilization conditions, a : substrate porosity of between abowt lO and about 150 gurlies and preferably from abou~ 18 to lO0 gurli.es provides highiy '.
: satisfactory results. The porosi~y, expressed in gurlies, is measured on the Gurley-Hill S-P-S tester~ the units are ~i seconds/lO0 ml. Higher porosities may render ~he sterile enclosure accessible ~o microorganisms, and at lower porosities `
the integrity o~ the cohesive seal ma~`be fractured. Con-: comitantly therewith, a cold seal adhesive having a peel . strength of about lO.0 to about 18 oz. b.efore sterilization l.
~. and about 6.0 to about l4 oz. after sterilization .as determined j~~ by PSTC-l (last-revised ll/70) is ~ound to have'a satisfactory ,:
. adhesive value under typical steriLization conditions. For . high-vacuum and/or pulsing type sterilization procedures, as ~ the porosity of the substrate is decreased, the adhesive value .... or corresponding peel'strength of the adhesive must be pro~
portionately increased so as to avoid breaching the adhesive ~' seal in the pack. The peel strength o~.the adhesive may be ' ` . increased, for instance', by overcoating it wi.th a primer or 1~
.. by admixing a conventional adjuvant therewith. :
.~ Located above printed indicators l8, 18', as seen in : Figs, l and lO is the legend STEAM, with a r.ecognition blank ~ .
. 30 printed adjacent theretoO When the sterilization procedure " ':
: ~: - to 'be employed utilizes steam, bIank 30 may be marked for thereby directing the technician's attention as to the type of steriliza-tion to be employed. Typically~'indicators 18, L8' may be a :' ~
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: :
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li :lLOS3~L8~3 : ~-¦I chemically ac~ive ink whicll cLlanges color aE~er a predetermined ! period of time upon exposure to pressure steam, such as/employed in autoclave sterilization procedures. For instance, ~he ster-ilization procedure may trigger a yellow to gray-black color ¦ chan~e in indicators 18, 18', Typical conditions of the color I cycle are 4-5 minutes at 272 F. OL- 20 minutes at about 250 F.
i ii Under either set o~ conditions, sterilization must occur in the - !I substantial a~sence o~ air, viz., 98 to 100% pure steam"
¦¦ Alternatively, located ~elow printed indicators 17, ¦ 17', as seen in Figs. l and 9, is the legend GAS,, with ~a recog-¦ nition blank 31 printed adjacent theretoO When the sterilization procedure to be employed utillzes a gas, for instance ethylene oxide, blank 31 may be marked or thereby directing the~techni-cian's attention as to the~type of sterilization to be employed.
¦¦ Typically, indîcators 17, 17l may be a chemically active ink ¦ which changes color after exposure to e~hylene oxide. For in- ~ ;~
; ~ ¦ stance, the s~erLlization procedure~may~trigger a red to green ~ ~ ;
~ ~color change in indlcators 17, L7'.-`A~typical`color change cycle ~ ~
. ~ , ~ , . .
¦ occurs at 130~ F., 50% RH,~600~to 700 mgs. oi ethylene oxide per ~ r' ' ' liter of sterilizing volume for about 1-3/4 hours. ~ `~

The pack is therefore adapted to function within any I known /steriLizing envlronment for¦which~its purpose;may be ~suited.
It iS~ moreover, a significant aspect of the invention~that indicators 17' and 18' are printed on~the substrate sur~ace ~ I ~1 wi~bi ~be pack enclosure¦f r ~heleby ndic-~lng the ~re G ence~oL ¦

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)53~38 ~;
s~erilizing environn~ent witllin the enclosure. This feature safe-¦ guards against the incidence of a color ~hange in exterior indi-¦ cators 17 and ~8 be~ore a corresponding color change in indicator~
!1 17~ and 18' provides notice of a defective production sample, :
and prevents inadvertent ~oresllor~ening of the period of steril-, ¦ ization. ' Referring now to Flgs. 2-7, in practice instrument 28 - l~ is introduced into blank 29 in the manner ~est seen in Figs. 2 and 3. The~instrument is introduced into enclosure 22 ~rom the , ~, I bottom end 32 of the blank in the direction shown by arrow 33.
; I After ins~rument 28 is introduced into enclosure 22, the pack is '', sealed irom bottom end 32 as best seen in Figs. 4-6. To seal ¦ the pack3 it is placed upon a~flat surface with film 20 facing upwardly and bottom end 32 facing~away from the sealer. The bottom end is manually sealed by placing index fingers under flap 1 26, thereby'rotating it 180 ar~ound fold~'line 27 until it~over- ¦
lies surface 13'of substrate ll;.~'As ~particularlv seen in Fig. 4,1 ~
the index fingers are centered`on fold line 27 and moved~toward I l;
respective edges of;¦the pack in the respective directLons illus- ,~
! tr~ated by arrows 34,~34~Lor~thereby formin~ the firs~ section of the seal.
I As particularly seen in Fig. S,~the second phase of ; ~"~
- ~the~lseal is~obtained by replacing~he index fln~ers a~ tl~e mlddle of score line 27 facing toward~lbottom end 32 and moving ~¦1 each index finger ~diagonally toward respective opposed -~ 2r~ co~ tn~ ~2 ~ ~ b~ rro~ 35, 35~

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i l ~

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iO5318~ ~
To perEorm the final stage o~ t~e sealing operation, '~ the index fingers a~e returned to their respective positions in the middle of score line 27 and moved initially forwardly to the edge o~ bottom end 32 and across the edge of bottom end 32 toward¦
the respective opposed corners ~hereof., Each side seal ls secured ,I by running over it with the flat of the index finger then the flat ;i of the inger nail or a smooth hard instrument, .~ , ` ~ As best seen în ~ig. 7, the pack is in condition ~or .:: '!
sterile treatment, A~ter the sterile treatmen~ has been effected according to one of the heretofore prescribed procedures, sterile presentation of instrument 28 may be had ~y gripping -end ~alls 24 and 25 respectively-of film 20 and substra~e 11 by , the thumb and ~ore~inger and applying opposed tensile ~orces thereon until the opposed tensile forces break the adhesive seal ~:
ii between fiLm 20 and substrate ll at vertex 16 of track 12. The ~ .
'"! purpose for configuring track 12 ~hrough respective segments 15, `~

I5' is to provide a~l~ocus 16 on which opposed tensile forces may~

'' act over the smallest area to thereby concentrate the opposed I ,'~orces for breaking~the seal,~ Upon breaking the seal, additional ~, fo~ce is exerted until the adhesive connections along segments 15, 15' of track 12 are breached. Due to ~heir conEiguration, ~, the opposed tensile forces concentrate upwardly alang the track and thereby breach ehe seal w~ith minimum e~fort. Once the seal . , ~ . .
,l is substantially breached there is a sterile presentation of ostrument 28 ahd s~erlle delivery therect nay be had as desired.¦

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~ ~5 31 ~ ~
Thus, it is seen tllat steps of ~he sealing method provide a secure seal, and once the bo~tom end of the pack is adhesively sealed i~ is not reopened. On the other hand, after completion o~ the sterilization procedure, the pack may be opened with reasona~le facility ~rom ~he ~op end or s~erile presenta-tion and delivery o the instrument. ~he ~acky interior sur~ace of film 20 prevents slippage of the instrument during sterile delivery thereoE. Tlle in~erior and exterior sterilization indi- ~ :
cators provide a double safety check for completion of the sterilization procedure. It is also ~ound that the integrity of the pack is maintained under various s-terilization procedures, and wlthin the parameters set forth herein, ~he paclc construction¦

may be modlfied to accommodate variations in di~erent steriliæa-l ;
. . . ' tlon procedures.
It will thus be seen that the objects set forth above, among those made apparent from the preceding~desçription, are ~ ;~
efficiently attained and, since certain changes may be made in , j - I
~: ' the above constructions without departing from the spirit and .' scope of the invention, it is intended that all matter contained ;j in tlie a~ove description or shown in ~he accom~anyin~ ~rawin~s : i! shall be interpreted as illustrative and not in a lL~iting sense. ~:;
¦ ~ Ie i~s also to be~undersLood~tha~ the following clalms .: l are inten~ed to cover all o the;generic and speciflc ~eatures of the inven~ion herein~deseribed,~and all statements of the scope i of the invention wllich, as a matter of language, might be said;
. to ~all therebetween.~

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Claims (12)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A sterile pack blank comprising a substrate of pre-determined porosity, a discrete plastic film overlying said substrate, said substrate and film being adhesively connected for defining an enclosure therebetween, said enclosure including a sealable inlet thereto, said film including a fold line therein a predetermined distance from an end thereof, and an end flap in said film determined by said fold line, said flap normally over-lying said film, said flap being rotatable about said fold line into adhesive connection with said substrate, said enclosure de-fined between said adhesively connected substrate and film having interior and exterior side walls, and at least one pair of sterili-zation indicators located in said substrate, one member of said pair being arranged on said exterior side wall of said enclosure, and said other member of said pair being arranged on said interior side wall of said enclosure.

2. The sterile pack blank as claimed in claim 1 wherein said substrate is characterized by a porosity of between about 10 and about 150 gurlies.

3. The sterile pack blank as claimed in claim 1 wherein said film includes an adhesively coated surface facing inwardly towards said enclosure, said adhesive coating having a tack value of between about 0.5 and about 60.0 seconds.

4. The sterile pack blank as claimed in claim 1 includ-ing an adhesive track of substantially uniform width along a sur-face of said substrate facing inwardly toward said enclosure, said adhesive track consisting of a cold seal adhesive, said adhesive track including a pair of symmetrical segments which detour acute-ly inwardly and converge at a vertex substantially at a midpoint of said substrate surface, said track segments being arranged at an end of said substrate which is opposed to an end thereof adapted to adhesively connect with said flap end of said film.

5. The sterile pack blank as claimed in claim 1 wherein said adhesive connection between said substrate and said film is characterized by a before sterilization peel strength of from about 10.0 to 18.0 ounces.

6. The sterile pack blank as claimed in claim 1 wherein said adhesive connection between said substrate and said film is characterized by an after sterilization peel strength of from about 6.0 to about 14.0 ounces.

7. The sterile pack blank as claimed in claim 1 wherein an end of said film opposed to said end thereof in which said end flap is determined is substantially uniformly foreshortened rela-tive to a corresponding end of said underlying substrate.

8. A method for fabricating a sterile pack comprising providing a porous substrate with at least one pair of steriliza-tion indicators located in said substrate, one member of said pair being arranged on one surface of said substrate and the other on the other surface of the substrate, printing a predetermined pressure sensitive adhesive track on a surface thereof, providing a strip of clear plastic film having substantially the same length and width as said substrate, coating a surface of said film with said pressure sensitive adhesive, folding an end portion of said film back upon itself whereby said folded end portion of said film contiguously overlies an uncoated surface of said film, mounting said film on said substrate whereby respective adhesive surfaces thereof are contiguous, and mechanically applying pressure to over-lying adhesive areas of said substrate and film for thereby sealing said respective overlying adhesive areas so as to provide a compo-site envelope.

9. The method as claimed in claim 8 including rotating said folded end portion of said film to overlie said substrate and sealing said end portion to said substrate along respective adhe-sive areas thereof.

10. The method as claimed in claim 9 including sealing said end portion to said substrate by applying pressure at the mid-point of the fold provided in said film, moving said pressure symmetrically outwardly substantially simultaneously toward opposed sides of said film, reapplying said pressure at the midpoint of said film, moving said pressure symmetrically diagonally substanti-ally simultaneously towards opposed corners of said film, reapplying said pressure at the midpoint of said fold, and moving said pressure symmetrically upwardly and outwardly, substantially respectively simultaneously, toward an end of said film and respec-tive opposed corners thereof.

11. A sterile pack blank as defined in claim 1 wherein the members of said pair of sterilization indicators overlie each other.

12. A sterile pack blank as defined in claim 1 wherein the number of pairs of sterilization indicators is two, one of said pairs being for indicating sterilization by steam and the other being for indicating sterilization by an effective chemical.