US 2990948 A
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y 1961 E. A. ZACKHEIM 2,990,948
STERILE PACKAGE Filed April 4, 1958 INVENTOR [-21 A ZfC/V/lf/M ATTORNEY United States Patent 2,990,948 STERILE PACKAGE Eli A. Zackheim, South Plainfield, 'N.J., assignor to Johnson & Johnson, a corporation of New Jersey Filed Apr. 4, 1958, Ser. No. 726,458 6 Claims. (Cl. 20646) The present invention relates to the packaging of sterile articles and more particularly to readily openable sealed packages the interior of which can be sterilized after the package has been scaled shut.
When packaging sterile articles, for example, as sterile dressings, it is desirable that the package be of a nature that its contents can be sterilized after sealing. Also, the package should be of a design that it can be readily opened and the contents removed without touching the exterior or unsterile portions of the container either during opening of the package or during removal of the dressing so as to avoid contamination.
One method of making a package, the interior of which can be sterilized after scaling, is to form either the whole or a portion of the package of a porous material so as to permit the entry of steam where steam sterilization is used or the entry of sterilizing chemical gases where chemical sterilization is employed. However, one difficulty with the use of porous materials is that they tend to breathe. For this reason, the effective pore size should be such as to substantially prevent the entry of harmful organisms. Also, the package should be relatively stiif to prevent too much flexing of the package since flexing results in increased transfer of air through the porous portion.
It is frequently encountered in the packaging of articles in cardboard, paper and other similar materials that when the seal is broken and the cover removed there is a tendency for the cover or the container to tear or de laminate. Where the contents of the package are sterile, this condition makes it diflicult to remove the contents without contacting the same with an unsterile portion of the container, such as a ragged edge or unsterile delaminated strip.
It is an object of the present invention to prepare relatively stifi porous sealed packages, the contents of which can be sterilized after sealing and which will remain sterile until the seal is broken.
Patented July 4, 1961 FIG. 4 is a cross-sectional view of the package taken along line 4-4 of FIG. 2.
Referring to the drawings, the container portion 12 of the package is a molded fibrous pulp container formed by any of the conventional processes for molding pulped fibers into various forms, one method of molding such containers, for example, being described in the patent to Roy, 1,590,956 of June 29, 1926. The container, as shown has a dished shape and comprises a bottom 14, sides 15 and a rim 1-6.
The container 12 has placed therein a plurality of gauze sponges 11 and is sealed shut by cementing a paper cover to the top surface of the flanged rim 16.
- It will be noted in the container illustrated that the corners 17 of the container 12 are rounded, whereas the corners of the cover 20 are not. This results in the corners extending beyond the container so as to form readily accessible tabs 22 which can be readily grasped when removing the cover 20.
In opening the package 10 the container body 12 is held in one hand as illustrated in FIG. 1. One of the tabs 22 is then grasped and the cover 20 peeled back off the container 12 as illustrated. Since the cover 20 separates readily from the rim without leaving any jagged or torn edges, the sterile sponges 11 can readily be removed, without fear of contamination, either by forceps or by inverting the open container and letting the sponges fall out.
In molded fibrous pulp, the fibers are randomly disposed and relatively loosely bonded. This resultsin a porous body in which any openings through the body are in the form of tortuous paths which, although permitting entry of air, effectively act to filter out harmful microorganisms which generally have an average size of about one micron. In preparing the sterile packages of the present invention, not only is advantage taken of the ability of the porous fibrous body to filter out bacteria while permitting the entrance of sterilizing gases, but advantage is also taken of the randomly arranged and loosely bonded nature of the fibers, particularly the surface fibers 13 on the surface of the rim 16 to form the new and novel seal of the present invention, whereby the cover It is a further object to prepare packages which can be a readily opened without tearing or the forming of jagged edges and from which the contents can be easily removed without contact of the contents with any exterior or contaminatcd portion of the package.
It has been found that these and other objects and advantages are obtained by using a molded pulp container and closing or sealing the container in the manner hereinafter more fully described.
The use of a molded pulp container in preparing a package of this type has many advantages. The container itself is relatively inexpensive to manufacture. It is relatively stiff yet sufiiciently porous to permit sterilization of the contents of the package after they have been scaled therein. Also, the random arrangement and loose bond between the fibers from which the container is member 20 can be readily removed from the container 12 without peeling or tearing.
In sea-ling the container, adhesive 21 is first applied around the edge of the cover 20. The cover 20, with adhesive face down, is then placed on the container so as to cover the same with the adhesive 20 contacting the surface fibers 13 on the container rim 16. The adhesive acts to bond the cover 20 to these surface fibers 13 and thus seal the container closed. In the preferred practice of the invention, the adhesive is of the thermoplastic type. It has been found that the best results are obtained where the coating of thermoplastic adhesive on the cover member is relatively thin and the cover is secured to the rim 16 of the container with substantial pressure as well as heat. Excellent results have been obtained by using pressures of about 40 to pounds per square inch. When the cover 20 is removed, as illustrated in FIG. 1, the surface fibers 13 adhere to the adhesive 21 as shown at 13a, the surface fibers 13 being readily separated from rim 16 because of their relatively loose bond. Due to their random arrangement, there is no tearing or delamination of strips off the container surface as would occur, for example, with cardboard, where the fibers are generally oriented primarily in one direction. As a result, a clean and easy separation of the cover'20 from the container 12 is obtained.
If the adhesive 21 is applied to the rim 16 rather than to the cover 20, it is found that difficulty is encountered in removing the cover which may result in tearing the cover if it is formed of paper. It is also found that some peeling of the rim 16 of the container occurs. This is probably due to the fact that the adhesive bonds the sur face fibers 13 to each other and to the lower layer of fibers in a much stronger bond than normally exists, with the result that the surface fibers 13 do not readily release from the rim 16 when the cover 20 is removed. As a result, either the paper cover 20 is torn or a substantial portion of the other fibers to which the surface fibers 13 are now firmly bonded are also removed, the whole peeling off in strips. Either result is undesirable since this leaves protruding and jagged sections against which the dressings 11 may come into contact. This may possibly be overcome by using as an adhesive a very viscous and non-penetrating material that would only coat the surface fibers and not penetrate the container rim, thus avoiding bonding the surface fibers to those below. However, it is difiicult to apply an adhesive of just the right consistency and in such manner as to avoid bonding the lower fibers where application is made to the container rim.
After the contents 11 have been placed into container 12 and the cover 20 sealed onto rim 16 the completed package 10 is sterilized as, for example, by steam sterilization. The package is then ready for storage or shipment and will maintain the contents 11 in sterile condition until the seal between the cover 20 and container rim 16 is broken or the package otherwise opened to expose its contents.
In preparing the packages of the present invention, care should be taken that the bottom and side walls of the container 14 and 15 are sufficiently thick to filter out harmful organisms that would otherwise affect the sterility of the package contents. In order to be sure that harmful organisms will not pass through the molded pulp container, the container should be such that when sealed in the manner described and subjected to the following dye test no dye will be found to have penetrated into the interior of the container. In this test a container is sealed as described and then placed in a vessel which is evacuated to a gauge pressure of inches of mercury. After remaining in an evacuated vessel for a period of minutes, which is a sufiicient time for the interior of the package to assume the same pressure as the interior of the vessel, air is admitted into the vessel at atmospheric pressure. At the point of air entry is placed a small amount of a water soluble dye, such as D and C Black No. 1, of such fineness that about 30% of the particles have a maximum size of one micron or less. The air rushing into the chamber disperses the dye forming essentially an aerosol. After sufficient time has been allowed to again permit the pressure inside the package to reach equilibrium with that outside, the package is removed and the interior of the package is sprayed with water. If there has been any penetration of the dye, the water immediately turns a deep blue. If the water remains clear, then the effective pore size or filtering properties of the container are sufficient to permit use of the container for the sterile packages of the present invention. Since the dye test has been compared with actual contamination tests made with bacteria and has been found in many cases to be more severe than the generally used bacteria test for testing the effective sealing of sterile packages, the test may be used for determining effective pore size.
In describing the package of the present invention, a particular embodiment has been given for purposes of illustration; also the package has been described with the preferred method of sealing. The invention, however, is
not limited to the specific embodiment used to describe the same, but is only to be limited in accordance with the claims.
Having thus described my invention, I claim:
1. A package, the contents of which are sterile, com prising a substantially rigid molded fiber pulp container, the fibers from which said container is formed being randomly dispersed, an opening in said container, a substantially horizontally extending rim around said opening, the randomly dispersed fibers on the surface of said rim being bonded to adjacent fibers with a bond sufficiently low to permit removal of said surface fibers without delamination and peeling, a cover member for said container bonded to said surface fibers to seal the interior of said container from contamination, the bond between said surface fibers and cover member being substantially greater than the bond between said surface fibers and adjacent fibers on said container rim.
2. A package of claim 1 in which the cover member is flexible.
3. A package of claim 2 in which a portion of the cover member extends beyond the rim of said container.
4. A package of claim 3 in which the corners of the rim of said container are rounded and the corners of said cover are square, the square corners of said cover extending beyond the rounded corners of said rim to provide opening tabs.
5. The method of sealing a flexible cover sheet to the rim of a molded fiber pulp container formed of nonoriented bonded fibers, in which the fiber-to-fiber bond is sufiiciently low to permit removal of surface fibers without delamination and peeling, comprising lightly coating the surface of said cover sheet adapted to be bonded to said rim with an adhesive capable of forming a bond stronger than the bond between said non-oriented fibers and then pressing said adhesive-coated surface of said cover sheet against the non-oriented, loosely bonded fibers on the surface of said rim while said adhesive is tacky to bond said cover sheet to the upper surface of the fibers on said rim while avoiding substantial penetration of said adhesive down into said rim between said fibers.
6. The method of sealing a flexible cover sheet to the rim of a molded fiber pulp container formed of nonoriented bonded fibers, in which the fiber-to-fiber bond is sufliciently low to permit removal of surface fibers without delamination and peeling, comprising lightly coating the surface of said cover sheet adapted to be bonded to said rim with a thermally activated adhesive capable of forming a bond stronger than the bond between said nonoriented fibers and then pressing said adhesive-coated surface of said cover sheet against the non-oriented, loosely bonded fibers on the surface of said rim while heating said adhesive to activate the same to cause said thermally activated adhesive to bond said cover sheet to the upper surface of the fibers on said rim while avoiding substantial penetration of said adhesive down into said rim between said fibers.
References Cited in the file of this patent UNITED STATES PATENTS 829,923 Lee Aug. 28, 1906 1,554,077 Fay Sept. 15, 1925 2,402,981 Beal et a1. July 2, 1946 2,433,056 Masci Dec. 23, 1947 2,634,856 Perkins Apr. 14, 1953 2,736,656 Marshall Feb. 28, 1956 2,814,428 Magill Nov. 26, 1957 2,897,962 Zackheim Aug. 4, 1959