US 3319782 A
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May 1957 D. R. BOWES STERILE SURGICAL PACKAGE Filed June 28, 1963 Z5 Tia-E Tic! .4.
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ATTORNEY 3,319,722 STERILE SURGHIAL PACKAGE Donald R. Bowes, Fanwood, N.J., assignor to Ethicon, Inc, a corporation of New Jersey Filed June 28, 1963, Ser. No. 291,482 6 Claims. (Cl. 20663.3)
The present invention relates to surgical packages of the type which are used to contain sterile absorbable catgut sutures and other sutures and surgical products.
Surgical packages intended for use in the sterile zone in hospital operating rooms must meet the exacting requirement of being sterile both inside and out. Under some circumstances, the exterior of the package is maintained sterile prior to use by immersing the package in a formaldehyde sterilizing solution enclosed in a secondary container. Often this type of package is packed by the manufacturer in a formaldehyde containing secondary unit of this type. When surgical gut is involved, a suture softening solution, which normally is alcohol-based, is included inside the package. Thus, the individual package must be capable of preventing permeation of the formaldehyde sterilizing solution into the package and leakage of the suture softening solution out of the package. If the sterilizing solution reaches the suture inside the package, the suture is hardened and may become nonabsorbable. On the other hand, if the softening solution leaks out, the gut becomes brittle and nonuseable. It is necessary then that surgical packages of this type be capable of resisting the permeation of such fluids for an indefinite period of time since one cannot determine how long it will be before one of the packages is used.
For a number of years, sealed glass tubes were used for this purpose. While they were capable of resisting the permeation of these fluids, they were fragile and often broke in transit. Perhaps more importantly, they were opened by breaking the glass. This was, not only difiicult, but dangerous and a source of possible contamination.
It has been proposed to use envelopes of various materials for this purpose. The only single plastic sheet material which is capable of resisting the permeation of these fluids for the length of time required is polychloro-trifiuoroethylene. However, the cost of this material for this purpose is prohibitive and it also becomes brittle during sterilization by irradiation. Recognizing that a film of a single material is not satisfactory for this purpose, laminates of various materials have been employed. None of these have been completely satisfactory.
The most commonly used laminate is one comprising an outside layer of aluminum foil and an inside layer of a heat scalable film of a thermoplastic material such as polyvinyl chloride. Packages formed from this type of laminate are satisfactory up to a point. For instance, aluminum foil of the proper thickness makes a perfect barrier to the permeation of formaldehyde containing sterilizing solutions and alcohol-based suture softening fluids. However, aluminum 'foil is very susceptible to moisture induced electrolytic corrosion and to heavy metals attack. Quite often foil packages of this type are washed in water to remove blood stains, or the like. This can and does cause holes to be corroded through the foil. Obviously, once the holes appear, permeation of the fluids begins and then becomes increasingly worse. Another disadvantage of the aluminum foil on the exterior of the package is that the foil, itself, has very little capacity for elongation and therefore is susceptible to being broken or punctured during removal of the packages from the secondary container with the various forceps in use for this purpose. It also has been common in foil-plastic packages of this type to use a laminating film on the nited States ate inside of the package for the additional reason that the film provides a secondary barrier to permeation through the package in case a pin hole is formed in the foil. Such films normally are plasticized to give them the necessary flexibility. Thus, another problem occurs because the alcohol in the suture softening solution leaches out the plasticizer in the film and the plasticizer contaminates the suture.
In accordance with the present invention, a sterile surgical package is provided which solves all of these problems. This package comprises opposed panels of an impervious laminate having an alcohol resistant heat sealable layer interposed between them. Normally the laminate is impervious to formaldehyde and other sterilizing components. The heat scalable layer seals the panels together around their edges to completely enclose and hermetically seal off a central space in which the panels are unattached to one another, and a sterile surgical product such as a suture is enclosed in said space. Each of the panels comprises an inner layer of aluminum foil and an outer layer of a polyester film, and the foil and the film are joined by a polyester adhesive. The aluminum foil layer normally provides an effective barrier to all gases and fluids with which the package might come in contact, and the polyester film protects the foil from external moisture induced electrolytic corrosion and heavy metals attack and from mechanical damage during handling. At the same time the foil-film laminate is capable of being torn easily for opening the package along a tear line adjacent one end thereof.
The polyester film possesses the following combination of properties for the above purposes:
(a) Toughness, i.e., high tensile (b) Good tearability,
(c) Low rates of moisture absorption and moisture vapor transmission, and
((1) Strong adhesion to the aluminum foil through the polyester adhesive.
and impact strength, i.e., moderate to low tear strength In addition, the polyester film possesses very low permeability to gases and acts as a secondary barrier to penetration or permeation of the package by gases and fluids. Furthermore, the package according to this invention is sterilizable by irradiation, using an electron beam or similar means, without degradation of any of the materials making up the package.
Preferably, the polyester film is formed from a polyethylene terephthalate such as Mylar film sold by E. I. du Pont de Nemours & Co. Inc. and the film possesses a tensile strength of at least about 15,000 p.s.i. and a puncture resistance of at least about 25 kilograms per centimeter to give it the desired toughness to protect the foil from mechanical damage and chemical attack.
Preferably also, the polyester film of the package of this invention is transparent and the inner surface of the transparent film of at least one of the panels is printed in reverse to describe the contents of the package in such a way that the printing can be read from the outside of the package through the printed film. This protects the printing from being scuffed off the package or reacting with the sterilizing solution and thereby assures accurate description of the contents of the package at all times.
Other and further advantages of the invention will be apparent from the following description and claims taken together with the drawings wherein:
FIG. 1 is a partially broken away plan view of a sterile suture package according to one embodiment of this invention;
FIG. 2 is an enlarged sectional view taken along the line 2-2 of FIG. 1;
FIG. 3 is a greatly enlarged sectional view of the en circled portion of FIG. 2 showing the adjacent top and bottom panels of the package before they are heat sealed to one another;
FIG. 4 is a greatly enlarged sectional view of the panels of FIG. 3 after they are heat sealed to one another.
Referring to the drawings, there is shown a sterile suture package comprising a top panel 11 and a bottom panel 12 of a formaldehyde impervious laminate. Said panels 11 and 12 are superimposed and sealed to one another along their edges to completely enclose and hermetically seal off a central space 13 in which the panels are unattached to one another. A coiled sterile surgical suture 14 inside a paper sleeve 15 is enclosed within the central space 13. A tab 16 at one end of the sleeve .15 fits between the panels 11 and 12 at one end of the package and is thereby sealed to the panels. If the suture 14 is of absorbable surgical gut, a small amount of a suture softening, or pliabilizing solution, not shown, is included within the central space 13. A typical softening fluid for this purpose is a 90% solution of isopropyl alcohol in water. The suture package, itself, may be enclosed within an outer container, not shown, and immersed in a formaldehyde containing sterilizing solution for maintaining the exterior of the package sterile. A tearing notch 17 is located adjacent one end 18 of the package along its top edge and a tear line 19 is marked on one side of the package extending from the notch 17 to the opposite side thereof. The package is intended to be opened by gripping it on opposite sides of the notch 17 and tearing downwardly along the tear line 19 to remove the end 18 of the package.
As shown most clearly in FIGS. 3 and 4, both the top and bottom panels of the package are made up of an inner aluminum foil barrier layer 21 and an outer moisture-impermeable plastic protective layer 22 of a tough polyester film. The inside of the foil layer is coated with an alcohol resistant heat sealable layer 23 and the outer surface of the foil layer is coated with a polyester adhesive layer 24. The outermost layer of the panel laminate is a transparent non-slip layer 25 having a high wet coefficient of friction and preferably comprises a dispersion of silica particles in a transparent polyester base. This non-slip feature is specifically claimed in copending application Ser. No. 291,399, filed June 28, 1963, in the names of Donald R. Bowes and Oliver T. Smith, and now Patent No. 3,221,873.
As shown in FIG. 4, the top and bottom panels 11 and 12 are placed together and heat sealed by the application of heat and pressure in such a way that the two heat sealable layers 23 adhere and more or less blend into one another in the sealed areas. The edge 26 of the blended heat sealable layers is so thin and presents such a small area to the outside of the package and the width of the seal, i.e., the distance between the edge 26 and the cavity 13, is comparatively so great, that there is virtually no opportunity for permeation of fluids through the seal itself. Elsewhere, the foil plastic laminate described makes a perfect barrier to the permeation of fluids inwardly or outwardly of the package, and the plastic protective layer 22 protects the foil layer 21 from external moisture induced electrolytic corrosion and heavy metals attack, and from mechanical damage. As mentioned hereinbefore, the polyester film 22, itself, preferably possesses a low permeability to gases and fluids and acts as a secondary barrier to penetration of the package in case any holes should be formed in one of the foil layers. In this connection, it should be noted that preferably the foil layer in the panel which is distorted the most to form the central space or cavity 13 in the package is somewhat tliicker than the foil layer in the other panel in order to provide additional strength in the panel and minimize the likelihood of cracking the foil. In the embodiment shown, the foil layer 21 of the bottom panel 12 is somewhat thicker than the foil layer 21 of the top panel 11 for this reason.
The inside surface of the transparent polyester protective layer 22 of the top panel 11 preferably is printed in reverse with material intended to describe the contents of the package and the printing, shown in part in FIG. 1, can be read through the protective layer 22 and through the transparent non-slip layer 25. Thus, the printing, itself, and the ink used therefore, is completely shielded against reaction with chemicals and fully protected from scuffing.
In a typical package according to this embodiment of the invention, the bottom panel 12 is formed from a layer 21 of dead-soft, high purity aluminum foil approximately two mils thick and a protective layer 22 of Mylar polyethylene terephthalate film approximately 0.25 mil thick; whereas the top panel 11 is formed from a similar aluminum foil layer 21 approximately 1.5 mils thick and a protective layer 22 of the same Mylar polyester approximately 0.35 mil thick. The alcohol resistant heat sealing layer 23 in each case is applied in a first coat of about 3 pounds per ream of a primer comprising copolymers of vinyl chloride and vinyl acetate and a second coat of about 3 pounds per ream of an unplasticizcd heat sealing material which consists predominately of a copolymer of vinyl chloride and vinyl acetate. The adhesive 24 between the foil layer 21 and the Mylar polyester protective layer 22 is a polyethylene-terephthalate adhesive. In the bottom panel 12 only about 3 pounds per ream of the polyester is applied, but in the top panel 11 the polyester adhesive 24 is pigmented white and applied in the amount of about 6 pounds per ream. The non-slip layer 25 is a similar transparent polyester adhesive with very small silica particles dispersed therein to achieve a high wet coeflicient of friction. When the inside surface of the transparent protective layer of the top panel is reverse printed as described hereinbefore, the white pigment in the polyester adhesive provides a background for the printing so that it may be read more easily.
Various important qualities of this polyester protective film 22 have been described hereinbefore. For instance, the film should possess a tensile strength of at least about 15,000 psi, and a puncture resistance of at least about 25 kilograms per centimeter to provide the desired toughness nad impermeability. On the other hand, to provide good tearability which is necessary to facilitate removal of the end of the package by tearing as described above, moderate to low tear strength and elongation are required. For instance, a film possessing an elongation of about 70100% combined with a tear strength of about 15 grams per mil should have ideal tearing qualities. One additional important feature when the package is to be heat sealed from the outside, i.e., the top and bottom, is that the polyester protective film 22 and the non-slip layer 25 be capable of resisting the temperature of the heat sealing shoes or dies employed. Polyethylene terephthalate films of the type described possesses a melting point about 350-380 F., which is satisfactory for this purpose. Furthermore, these films possess very low water vapor transmission rates and, perhap more importantly, a low rate of moisture absorption. It is the combination of these qualities which protects the exterior surface of the foil from electrolitic corrosion. These films also possess excellent resistance to acids, bases, grease and oil, and for these reasons are ideal for protecting the foil barrier.
Having now described the invention in specific detail and exemplified the manner in which it may be carried into practice, it will be readily apparent to those skilled in the art that innumerable variations, applications, modifications, and extensions of the basic principles involved may be made without departing from its spirit or scope.
The invention claimed is:
1. A sterile surgical package which comprises opposed panels of an impervious laminate having an alcohol resistant heat-sealable layer interposed between them, said panels being heat-sealed together around their edges through said heat sealable layer to completely enclose and hermetically seal oiT a central space in which the panels are unattached to one another, and a sterile surgical product in said space, said panels each comprising an inner layer of aluminum foil and an outer layer of a polyester film joined to one another by a polyester adhesive, said aluminum foil layer normally providing an effective barrier to all gases and fluids with which the package might come in contact, and said polyester film being adapted to protect the foil layer from external moisture induced electrolytic corrosion, heavy metals attack and mechanical damage and possessing the following combination of properties for these purposes:
(a) toughness, i.e., high tensile and impact strength,
(b) good tearability, i.e., moderate to low tear strength and elongation,
(0) low rates of moisture absorption and moisture vapor transmission, and
(d) strong adhesion to the aluminum foil through the polyester adhesive, said polyester film also possessing very low permeability to gases and acting as a secondary barrier to penetration of the package by gases and fluids, said package being steriliza ble by irradiation without degradation of any of the materials making up the package.
2. A sterile surgical package according to claim 1, wherein the polyester film comprises polyethylene terephthalate.
3. A sterile surgical package according to claim 1, wherein the polyester film possesses a tensile strength of at least about 15,000 p.s.i. and a puncture resistance of at least about 25 kilograms per centimeter.
4. A sterile surgical package according to claim 3, wherein said package is adapted to be opened by tearing off one end of the package along a tear line provided for this purpose.
5. A sterile surgical package according to claim 1, wherein said surgical product is an absorbable suture and said central space also contains an alcohol based suture softening solution.
6. A sterile surgical package according to claim 1, wherein the polyester film of at least one of said panels is transparent and the inner surface of said transparent film is printed to describe the contents of the package in such a way that the printing can be read from the outside of the package through the printed film.
References Cited by the Examiner UNITED STATES PATENTS 2,203,591 6/1940 Brown 206-56 2,332,857 10/1943 Karg 20646 2,737,290 3/1956 Volckening et al.
2,750,075 6/1956 Land.
2,923,404 2/1960 Adell 206-56 2,951,765 9/1960 Robson 20656 2,956,723 10/ 1960 Tritsch 229-3.5 2,993,589 7/1961 Zoller et al. 20663.3 3,056,491 10/1962 Campbell 206-56 3,136,418 6/1964 Stacy et a1 206-63.3
OTHER REFERENCES Protective Packaging of Frozen Foods, Refrigerating Engineering, February 1954, pp. -48.
LOUIS G. MANCENE, Primary Examiner.
UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,319,782 May 16, 1967 Donald R. Bowes It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.
Column 3, line 44, for "Ser. No 291,399" read Ser. No 291,339 column 4, line 44, for "nad read and line 57, after "point" insert above Signed and sealed this 21st day of November 1967.
Edward M. Fletcher, Jr. EDWARD J. BRENNER Attesting Officer Commissioner of Patents