EP0398316A1

EP0398316A1 - Package for medical container

Info

Publication number: EP0398316A1
Application number: EP90109291A
Authority: EP
Inventors: Shunji Kawatsu; Yasushi Nakamura
Original assignee: Terumo Corp
Current assignee: Terumo Corp
Priority date: 1989-05-16
Filing date: 1990-05-16
Publication date: 1990-11-22
Also published as: JPH03667A; JP2786882B2

Abstract

A package (11) for medical containers of flexible synthetic resin, comprising a tray part (15) formed in a rectangular shape containing four curved corners and provided along the edge of an opening thereof with a flange part (14) having an edge parallel to said shape and a lid (16) heat-sealed with said flange part (14) through the medium of an adhesive layer in such a manner as to be freely peeled, which package (11) is characterized by the fact that said four corner parts of said lid (16) are projected from the imaginary line of the outer edge (13) parallel to the shape of said flange part (14) of said tray part (15) and, at the same time, two projections (19) are formed in at least one curved part as the part (18) for starting separation of the heat-sealed part (17).

Description

BACKGROUND OF THE INVENTION

Field of the Invention:

The present invention relates to a package for medical container. More particularly, it relates to a blister package for holding medicine-containing containers of flexible synthetic resin, which package exhibits highly satisfactory peelability at the time of its opening and retains highly satisfactory airtightness in its sealed state.

Description of the Prior Art:

In such medical containers of flexible synthetic resin as blood bags and transfusion bags, an anticoagulant for transfusion or blood such as the ACD solution or CPD solution is contained. By the action of the anticoagulant, the blood at the time of its collection or transfusion is prevented from coagulation. The medical containers containing the anticoagulant are stored in an airtight container of synthetic resin adapted for preservation.
As an airtight package of this class, the so-called blister package which comprises a tray part having a flange part formed along the edge of an opening part thereof and a lid heat-sealed to the flange part in such a manner as to be freely peeled to open the package through the medium of an adhesive layer fit for heat sealing has been finding extensive utility recently. Since the conventional blister package of the kind described above uses the tray part which is made of synthetic resin, it is produced in a circular shape by reason of the convenience of molding. When this package is required to be produced in a square or rectangular shape for the convenience of medical container to be contained therein, the corner parts thereof are given a curved contour. As illustrated in Fig. 11, therefore, the lid except for the part used for starting separation thereof by peeling is identical in shape with the flange part whose corners are formed parallelly to the curved contours mentioned above. As regards the part for starting the separation of the lid by peeling, the idea of forming one or three extended edges in the part for facilitating the start of separation of the heat-sealed part has been proposed (JP-A-59-199,463)
The blister package of this class, however, has suffered from a disadvantage that the heat-sealed part thereof in the corners except for the part for starting the separation has no sufficient shock resistance and the heat-sealed part in the part for starting the separation has no fully satisfactory strippability.
An object of the present invention, therefore, is to provide a novel package for medical containers.
Another object of this invention is to provide a package for medicine-containing containers of flexible synthetic resin, which offers highly satisfactory shock resistance and exhibits excellent strippability of the lid at the time of opening.

SUMMARY OF THE INVENTION

The objects described above are accomplished by a package for medical containers of flexible synthetic resin, comprising a tray part formed in a generally rectangular shape containing four curved corners and provided along the edge of an opening thereof with a flange part having an edge parallel to the shape and a lid heat-sealed with the flange part through the medium of an adhesive layer in such a manner as to be freely peeled, which package is characterized by the fact that the four corner parts of the lid are projected from the imaginary line of the outer edge parallel to the shape of the flange part of the tray part and, at the same time, two projections are formed in at least one curved part as the part for starting separation of the heat-sealed part.
The present invention further discloses a package for medicine-containing containers of flexible synthetic resin, wherein the tray part and the lid are made of synthetic resin and the lid has formed on the innermost surface thereof an adhesive layer capable of aiding in heat-sealing the tray part and the lid and, after the formation of the heat-sealed part, allowing separation of the heat-sealed part of the package.
The present invention further discloses a package for medicine-containing containers of flexible synthetic resin, wherein the tray part comprises an outer layer using polypropylene as a main component, an intermediate layer formed of an ethylene-vinyl alcohol copolymer, and an inner layer using polypropylene as a main component and the lid comprises an outer layer formed of polyethylene terephthalate, a first intermediate layer formed of polyvinylidene chloride, a second intermediate layer formed of nylon, and an adhesive layer formed of polypropylene incorporated with polyethylene.
Since the present invention is directed to a package for medical containers of flexible synthetic resin, comprising a tray part formed in a generally rectangular shape containing four curved corners and provided along the edge of an opening thereof with a flange part having an edge parallel to the aforementioned shape and a lid heat-sealed with the flange part through the medium of an adhesive layer in such a manner as to be freely peeled, wherein the four corner parts of the lid are projected from (the imaginary line of) the outer edge parallel to the aforementioned shape of the flange part of the tray part and, at the same time, two projections are formed in at least one curved part as the part for starting separation of the heat-sealed part, the heat-sealed part of the package in all of the four corners truly excels in shock resistance and the heat-sealed part of the package in the part for starting the separation of the lid exhibits highly satisfactory strippability. Further since an adhesive layer for aiding in heat-sealing the tray part and the lid and, after formation of the heat-sealed part, allowing separation of the heat-sealed part or a layer-separating device is formed on the innermost surface of the lid, the package not only excels in seal strength but also retains seal strength and strippability substantially intact in spite of possible variation in the sealing temperature and the sealing time. When this package contains medicine-containing vials of soft synthetic resin such as, for example, blood bags, it is capable of preserving its contents in a sterilized state for a long time without sustaining breakage.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a perspective view of a package according with the present invention,
Fig. 2 is a partially sectioned side view of the package,
Fig. 3 is a plan view of the package,
Fig. 4 is a partial plan view illustrating a heat-sealed part of the package according with the present invention,
Figs. 5A to 7C are schematic diagrams of a peel test performed on packages of the present invention and the conventional technique under application of pressure,
Fig. 6 is a perspective view for illustration of the condition of packing used for the performance of a chemical resistance test,
Figs. 7A and 7B are graphs showing peel strength of heat-sealed parts in the part for starting separation by peeling,
Fig. 8 is a graph showing the relation between the sealing temperature and the seal strength of a package,
Fig. 9 is a graph showing the relation between the sealing time and the seal strength,
Fig. 10 is a graph showing the relation between the sealing temperature and the peel strength, and
Fig. 11 is a plan view illustrating the conventional packaging.

EXPLANATION OF THE PREFERRED EMBODIMENT

Now, one embodiment of this invention will be described below with reference to the accompanying drawings. Specifically, as illustrated in Figs. 1 to 3, a package 11 of the present invention comprises a tray part 15 produced by molding a synthetic resin sheet in the form of a rectangular platter possessing four curved corners and having formed along the edge of an opening thereof a flange part 14 possessing an outer edge 13 parallel to the contour of the platter and a sheetlike lid 16 made of synthetic resin. The tray part 15 and the lid 16 are airtightly heat-sealed in a strip 17 of a prescribed width through the medium of an adhesive layer formed on the inner surface of the lid 16.
The lid 16 mentioned above is required to be formed so that all of the four corners thereof will protrude from the outer edge 13 of the flange part 14 of the tray part 15. The protruding parts are formed, for example, by causing the four corners of the rectangular lid 16 to be curved in a smaller than the corresponding corners in the imaginary line 13 of the outer edge of the flange part 14 parallel to the edge of the opening in the ray.
In the strip of heat-sealed part 17 formed through the medium of the adhesive layer mentioned above, a part 18 for starting separation of the heat-sealed part by peeling is formed in at least one of the four corners mentioned above as illustrated in Fig. 4, so that the strip of heat-sealed part will thrust out in two places relative to the line X-X′ of peeling force exerted on the lid 16. The formation of the part 18 for starting the separation can be accomplished by imparting this shape to the die to be used for the heat-sealing. Where the ease of manual separation of the heat-sealed part is considered on the condition that the seal strength and the seal width between the inner layer of the tray part and the lid are constant, the desirability of the shape of the part for starting separation increases increases in proportion as the sharpness of the leading ends of the protruding parts increases. The part for starting the separation is preferable to be so shaped that, at the time of starting the separation, the length of the heat-sealed part which falls on a straight perpendicular to the line of the peeling strength is shortened. When the spaces available for the part of separation in the four corners of the lid and the ease of manual separation of the heat-sealed part mentioned above are taken into account, the heat-sealed part is desired to have the shape illustrated in Fig. 4. To be more specific, the leading ends of the protruding parts 19 are thrust out at an angle in the range of 90 to 120 degrees.
The material of which the package of the present invention is formed is synthetic resin. As concerns the materials for the tray part, the outer layer and the inner layer thereof each use polypropylene as a main component and each have a thickness in the range of 10 to 70 µm, preferably 30 to 50 µm. Owing to the material and the thickness described above, the tray part is allowed to possess a fully satisfactory shape-retaining property. The inner layer of the tray part exhibits a fully satisfactory heat-sealing property with the lid of the quality to be described specifically hereinafter. The intermediate layer is formed of an ethylene-vinyl alcohol copolymer in a thickness in the range of 10 to 50 µm, preferably 20 to 30 µm. Owing to this intermediate layer, the tray part possesses fully satisfactory moisture proofness and sparing permeability to gas.
In the lid, the outer layer is formed of polyethylene terephthalate in a thickness in the range of 5 to 30 µm, preferably 10 to 15 µm. Owing to this outer layer, the lid exhibits satisfactory mechanical strength mainly in respect to the resistance to the impact exerted by a pointed object. The first intermediate layer adjoining the outer layer is formed of polyvinylidene chloride in a thickness in the range of 10 to 50 µm, preferably 20 to 30 µm. It enables the lid to retain moistureproofness and sparing permeability to gas. The second intermediate layer adjoining the first intermediate layer is formed of nylon, preferably biaxially stretched nylon, in a thickness in the range of 10 to 50 µm, preferably 20 to 30 µm. It imparts the lid highly satisfactory mechanical strength mainly in respect of resistance to tear. The adhesive layer adjoining the second intermediate layer is polypropylene layer incorporating with polyethylene. The weight ratio of polypropylene to polyethylene is from 80 : 20 to 50 : 50. The overall thickness of this adhesive layer is in the range of 20 to 100 µm, preferably 40 to 60 µm. This cohesion-breaking peel layer, on exposure to pressure and heat, is melted and fused with the inner layer of polypropylene in the tray part. When the heat-sealed part of the package is separated by peeling, the adhesive layer is broken and separated at least partly from the adhesive layer mentioned above and allowed to remain fast to the inner layer of the tray part. The term "medicine-containing container of flexible synthetic resin" as used in the present invention refers to a blood bag made of flexible vinyl chloride resin and adapted to contain therein such an anticoagulant as an ACD solution or CPD solution or a transfusion bag made of flexible vinyl chloride resin and adapted to contain therein a transfusion solution. This invention manifests an outstanding effect particularly when the package accomodates blood bags.
Now, the present invention will be described more specifically below with reference to a working example of this invention and controls.

Example

A rectangular tray possessing a flange along the edge of the opening having curves (curvature 41 mm) formed one each in the four corners thereof as illustrated in Figs. 1 to 4 was formed of a laminate composed of an outer layer formed of polypropylene in a thickness of 40 µm, an intermediate layer formed of an ethylene-vinyl alcohol copolymer in a thickness of 25 µm, and an inner layer formed of polypropylene in a thickness of 40 µm.
Triple-bag blood bags were stowed in this tray part. Then, a laminate lid composed of an outer layer formed of polyethylene terephthalate in a thickness of 12 µm, a first intermediate layer formed of polyvinylidene chloride in a thickness of 25 µm, a second intermediate layer formed of biaxially stretched nylon in a thickness of 25 µm, and an adhesive layer (50 µm in thickness) formed polypropylene incorporating with polyethylene (weight ratio of polypropylene to polyethylene is 60 : 40) was thermally fused in a width of about 3 mm to the flange part in such a manner that two projections (about 110° in angle) were thrust out as the part for starting separation of the heat-sealed part expected to be formed in the curved corners mentioned above as illustrated in Fig. 3. The curvature of the lid in the corner in which the part for starting separation was formed was 10 mm and the curvature of the lid in the other corners was 20 mm. The lid measured 311 mm in length and 184 mm in width. The lid and the flange part were jointly trimmed in such a manner that the parallel part (vertical part) of the flange acquired a width of about 9 mm and the four corners of the lid protruded from the imaginary line 13 of the outer edge parallel to the contour of the edge of the opening as illustrated in Figs. 1 to 4, to complete a package. At this time, the curvature of the corners on the separation-starting part side was 10 mm and the curvature of the remaining corners was 20 mm and the lid measured 265 mm in length and 158 mm in width.
In the airtight package consequently obtained, one corner in which the part for starting separation was not formed was pressed to determine the critical level for the occurrence of separation. The results were as shown in Table 1. This test was performed with a tester (produced by Shimadzu Seisakusho Ltd. and marketed under trademark designation of "Autograph DSS-100") at a compression rate of 500 mm/min. The values given in Table 1 are each an average of the values found with 5 sets. Then, a packing box (material: K6) was packed with six packages of the aforementioned construction as illustrated in Fig. 6, sealed, and dropped repeatedly from a height of 1 m with the M surface side directed downwardly to determine the critical number of drops for withstanding the impact of drop variable with the shape of flanges of the packages placed on the M surface side. This test was carried out with three packing containers. The results of this test were as shown in Table 2.

Control 1

A package was obtained by following the procedure of Example 1, except that the shape of the lid in the corners in which the part for starting separation was not formed was substantially identical curvature 49 mm) with the outer edge of the flange part of the tray part as illustrated in Fig. 11. In the package thus obtained, one corner in which the part for starting separation was not formed was subjected to the same pressure test as in the working example. The results of this test were as shown in Table 1. The corner in which the part for starting separation was formed was subjected to the same test as shown in Fig. 5 (C). The results were as shown in Table 1.

The test for resistance to drop was similarly performed, to obtain the results shown in Table 2.

Table 1

Example	(side of part not containing part for starting separation)	12.1 ± 2.8
Example	(side of part containing part for starting separation)	11.8 ± 2.3
Control 1	(side of part not containing part for starting separation)	7.0 ± 1.6

It is clearly noted from Table 1 that the projections formed by the present invention produced entirely the same strength as the side of the part in which the part for starting separation was formed.

Table 2

Example	(side of part not containing part for starting separation) No separation occurred in the 3 boxes even after 70 drops
Example	(side of part containing part for starting separation) No separation occurred in the 3 boxes even after 70 drops
Control 1	(side of part not containing part for starting separation) Separation occurred each on the 15th, 20th, and 35th drops

It is clearly noted from Table 2 that the projections formed by the present invention produced entirely the same strength as the side of the part in which the part for starting separation was formed.

Control 2

A package was obtained by following the procedure of the working example, except that the fusion of the part for starting separation was formed in the form of three crests as shown in Fig. 7A. A corner cut off the package was subjected to a peeling test with a tester (produced by Shimazu Seisakusho Ltd. and marketed under trademark designation of "Autograph DSS-100") at a stretching rate of 200 mm/min at room temperature. The results of this test were as shown in Table 3. The values given in the table each represent an average obtained of 20 samples.
The same test was conducted on the package of the present invention. The results were as shown in Table 3. Table 3

Example 1.7 ± 0.1 (S.D.)

Control 2 2.1 ± 0.4 (S.D.)
In a sensual test performed by a panel of five members, the sample of the working example excelled the sample of Control 2 in separability of heat-sealed part.
The numerical values of peel strength obtained at varying parts of the sample of Control 2 described a chart shown in Fig. 7A and those of the sample of the working example described a chart shown in Fig. 7B.

Control 3

A package was obtained by following the procedure of the working example, except that the lid was composed of an outer layer formed of polyvinylidene chloride-coated polyethylene terephthalate in a thickness of 12 µm, a first intermediate layer formed of polyvinylidene chloride-coated biaxially stretched polypropylene in a thickness of 20 µm, a second intermediate layer formed of biaxially stretched nylon in a thickness of 15 µm, and an inner layer formed of linear low-density polyethylene in a thickness of 50 µm.
A middle portion between the corners of the package obtained as described above was cut off. The lid member and the tray part member of the cut portion of package were pulled away each other with a tester (produced by Shimazu Seisakusho Ltd. and marketed under trademark designation of "Autograph DSS-10") at a drawing rate of 200 mm/min at room temperature to determine the force (seal strength) necessary for causing separation. The results were as shown in Table 4. This test was performed on five sets each of four cut pieces from a given package. The results shown in the table each represent an average of the values obtained of the five sets.
The same test was performed on the package of the working example to determine the seal strength. The results were as shown in Table 4. Table 4

Example 1.3 ± 0.2

Control 3 1.2 ± 0.2
It is clearly noted from Table 4 that the package of the working example showed an improvement of about 8% in strength as compared with that of Control 3.
Samples using varied sealing temperatures were tested for seal strength to determine the effect of the sealing temperature upon the seal strength. The results were as shown in Table 8. It is clearly noted from this diagram that the package of the working example showed an extremely small change in the seal strength due to the variation in the sealing temperature, i.e. a substantially constant value of seal strength evincing the absence of the effect of the sealing temperature.
Further, samples using varied sealing times were tested for seal strength to determine the effect of the sealing time upon the seal strength. The results were as shown in Fig. 9. It is clearly noted from the diagram that the package of the working example showed an extremely small change in the seal strength due to the variation in the sealing time, i.e. a substantially constant value of seal strength evincing the absence of the effect of the sealing time.
Then, corners were cut off the packages obtained in the working example and Controls 2 and 3 in the same manner as in Control 2 and the separation-starting parts of the cut corners were subjected to the peel test. The results were as shown in Table 5. Table 5

Example 2.2 ± 0.3

Control 2 2.1 ± 0.4

Control 3 1.7 ± 0.1
It is clearly noted from Table 5 that the package of the working example showed strippability comparable with that of Control 2.
Samples of the working example and Control 3 using varied peel temperatures were tested for seal strength to determine the effect of the peel temperature upon the seal strength. The results were as shown in Fig. 10. It is clearly noted from the diagram that the package of the working example showed slightly higher peel strength as a whole than that of Control 3 but showed a smaller change in peel strength due to variation in the seal temperature than that of Control 3. Specifically, it showed a substantially constant value of peel strength evincing the absence of the effect of the seal temperature.

Claims

1. A package for medical containers of flexible synthetic resin, comprising a tray part formed in a rectangular shape containing four curved corners and provided along the edge of an opening thereof with a flange part having an edge parallel to said shape and a lid heat-sealed with said flange part through the medium of an adhesive layer in such a manner as to be freely peeled, which package is characterized by the fact that said four corner parts of said lid are projected from the imaginary line of the outer edge parallel to the shape of said flange part of said tray part and, at the same time, two projections are formed in at least one curved part as the part for starting separation of the heat-sealed part.

2. A package according to claim 1, wherein said tray part and said lid are made of synthetic resin and said lid has formed on the innermost surface thereof an adhesive layer aiding in heat-sealing said tray part and said lid and, after the formation of the heat-sealed part, allowing the heat-sealed part to be separated to open said package.

3. A package according to claim 1 or claim 2, wherein said tray part is composed of an outer layer formed mainly of polyopropylene, an intermediate layer formed of an ethylene-vinyl alcohol copolymer, and an inner layer formed mainly of polypropylene and said lid is composed of an outer layer formed of polyethylene terephthalate, a first intermediate layer formed of polyvinylidene chloride, a second intermediate layer formed of nylon, and an adhesive layer formed of polypropylene incorporated with polyethylene.

4. A package according to claim 1, wherein the leading ends of said projected parts are thrust at an angle in the range of 90 to 120 degrees.