Patent Application
20090145876
This application claims the priority of Japanese Patent Application 2007-318691 filed Dec. 10, 2007, which is incorporated herein by reference.
This invention relates to a plastic-made cap for a vial, and more specifically to a plastic-made cap for a vial having a lip, said plastic-made cap being capable of sufficiently holding a plug applied to the vial even when the lip of the vial is somewhat low in dimensional accuracy.
As storage containers for various medicaments such as drugs, so-called vials have been widely used over years. As these vials, two types are employed, one being glass-made vials and the other plastic-made vials. Of these, the glass-made vials are equipped with very high gas barrier properties compared with the plastic-made vials, and therefore, are used as medicament containers for which high gas barrier properties are required.
After a medicament is stored in such a vial, its mouth is sealed with a plug such as a rubber plug. When the vial is subjected to treatment such as heat sterilization, the plug may slip out of the vial mouth due to a rise in the internal pressure of the vial. It is, therefore, a common practice to fit a cap, which is made of aluminum or a plastic, on the mouth of the vial such that the cap encloses the plug therein and extends onto an underside of a lip of the mouth to keep the plug in close contact with the mouth, to prevent the separation of the plug and to assure the sealing of an interior of the vial (JP-A-2007-282891).
An aluminum-made cap is crimped at a lower part thereof below the lip of the mouth of the vial by making use of its superb deformability, and therefore, is equipped with excellent separation-preventing properties. An aluminum-made cap is, however, accompanied by a problem that fine aluminum particles occur and scatter through its contact with other aluminum-made caps and also by a problem that segregated disposal of aluminum is difficult after its use. There is, accordingly, a tendency to avoid the use of aluminum-made caps in recent years.
A plastic-made cap, on the other hand, is free of such problems of the aluminum-made cap, but due to the lower deformability of a plastic than aluminum, is accompanied by a problem that its engagement with a vial cannot be as tight as that available from an aluminum-made cap. Described specifically, when an aluminum-made cap is crimped at a lower part thereof on a lip of a vial mouth, the lower part is caused to deform along the lip and is readily crimped by making use of its excellent deformability. In the case of a plastic-made cap, on the other hand, the cap is provided with engagement claws, and upon capping, these claws are brought into engagement with a lip of a vial mouth. The above-described problem of the plastic-made cap can be attributed to the above-mentioned difference in structure.
The plastic-made cap easily separates from the vial because the engagement between the vial and the plastic-made cap is not tight as described above. This problem can be solved if the engagement between the vial and the cap is made tight. However, the capping itself becomes harder as an attempt is made to establish tighter engagement. As appreciated from the foregoing, the cap and the vial are both required to have high dimensional accuracy. If a cap and a vial are both made of plastics, their dimensional accuracy can be improved to certain extent because they can be molded into predetermined shapes while taking into consideration even shrinkage deformations which take place upon cooling.
On the other hand, a glass-made vial has a dimensional error greater by one digit than a plastic-made vial because it is produced while adjusting its shape. No matter how much the dimensional accuracy of a plastic-made cap is improved, its application to a glass-made vial still involves a problem that the separation of the cap can be hardly prevented to sufficient extent. Under these circumstances, extremely high dimensional accuracy is required for both of a glass-made vial and a plastic-made vial to bring the plastic-made cap into tight engagement with the glass-made vial compared with the engagement of an aluminum-made cap. There is, however, a limitation to how much the dimensional accuracy of the glass-made vial can be improved. Even if plastic-made caps are provided with high dimensional accuracy, they are hence accompanied by a problem that, when they are applied to glass-made vials, the percentage of acceptable plastic-made caps is extremely low because of large dimensional errors of the glass-made vials.
An object of the present invention is, therefore, to provide a plastic-made cap which, even when used for a vial having a large dimensional error like a glass-made vial, to say nothing of a plastic-made vial, can absorb the dimensional error of the glass-made vial to tightly hold a plug, which has been applied to the glass-made vial, on the glass-made vial.
The above-described object can be achieved by the present invention to be described hereinafter. In a preferred first embodiment of the present invention, there is thus provided a plastic-made cap for a vial having a lip, said cap being useful as a separation-preventing cap for a plug that seals up an opening of the vial, comprising:
a top wall portion having an outer circumference and centrally defining an opening, and
a cylindrical skirt portion extending downwardly from the outer circumference of the top wall portion and being open at a lower end thereof,
wherein the skirt portion has an inner diameter greater than an outer diameter of the lip of the vial, and the skirt portion is provided on an inner wall thereof with at least two ribs formed at an angular interval in a direction perpendicular to the top wall portion such that, upon application of the cap onto the lip with the opening of the vial being sealed with the plug, the ribs can be elastically deformed to facilitate the application of the cap onto the lip and further to prevent separation of the cap from the lip.
In the preferred first embodiment, plural ribs may preferably be arranged in pairs at equal angular intervals between the respective pairs of ribs. Preferably, the at least two plural ribs may each have a height of 0.1 to 3 mm and a width of 0.5 to 5 mm. The skirt portion may preferably have aft inclined portion on the inner wall thereof along the lower end of the skirt portion, and the at least two ribs may preferably be arranged on the inner wall other than the inclined portion.
In the preferred first embodiment, the plastic-made cap may preferably further comprise a cover finger-removably arranged on the top wall portion. The cover may preferably be finger-removably secured on the top wall portion via protuberances. The cover may preferably be provided at an outer circumference thereof with at least one finger stop, and the skirt portion may preferably be provided on an outer wall thereof with at least one shallow groove portion in registration with the at least one finger stop to facilitate finger-removal of the finger-removable cover.
In a preferred second embodiment, the plastic-made cap may further comprise at least two engagement claws formed on the inner wall of the skirt portion at positions between the at least two ribs, respectively, such that the engagement claws can be brought into engagement with an underside of the lip of the vial to assure the prevention of unintentional separation of the cap from the lip. The cap may preferably be provided through the top wall portion with at least two slots formed along the outer circumference of the top wall portion at positions in registration with the engagement claws, respectively, to facilitate formation of the engagement claws. The plastic-made cap may preferably further comprises at least two recessed portions formed on the inner wall of the skirt portion, in registration with the at least two ribs, and between the engagement claws and the slots, respectively, such that the recessed portions can facilitate elastic deformation of the engagement claws toward the inner wall of the skirt portion.
In the preferred second embodiment, plural ribs may preferably be arranged in pairs at equal angular intervals between the respective pairs of ribs, and plural engagement claws are arranged on the inner wall at positions between the respective pairs of ribs such that the engagement claws can be brought into engagement with an underside of the lip of the vial. The cap may preferably be provided through the top wall portion with slots formed along the outer circumference of the top wall portion at positions in registration with the engagement claws, respectively, to facilitate formation of the engagement claws. The plastic-made cap may preferably further comprise plural recessed portions formed on the inner wall of the skirt portion, in registration with the pairs of plural ribs and between the engagement claws and the slots, respectively, such that the recessed portions can facilitate elastic deformation of the engagement claws toward the inner wall of the skirt portion.
In the preferred second embodiment, the plastic-made cap may preferably further comprise a cover finger-removably arranged on the top wall portion. The cover may preferably be finger-removably secured on the top wall portion via protuberances. The cover may preferably be provided at an outer circumference thereof with at least one finger stop, and the skirt portion is provided on an outer wall thereof with at least one shallow groove portion in registration with the at least one finger stop to facilitate finger-removal of the finger-removable cover.
The plastic-made cap according to the present invention can absorb a dimensional error of a vial and can tightly hold the plug that seals up the vial, even when the vial has a large dimensional error like a glass-made vial, to say nothing of the case that the vial is a plastic-made vial.
The present invention will next be described in further detail with reference to the accompanying drawings showing best modes for practicing the present invention. A plastic-made cap 30 according to the first embodiment of the present invention for a vial 10 is a separation-preventing cap for a plug 20 sealing up an opening 11 of the vial 10, as depicted in
In
The top wall portion 32 of the cap 30 is in the form of a disk, and a circular opening 31 is centrally formed through the top wall portion 32 to permit insertion of a syringe needle or the like therethrough. No particular limitation is imposed on the size of the circular opening 31 insofar as the above-described function can be performed. It is also to be noted that the opening 31 is not limited to the circular shape and may have any other appropriate shape insofar as the above-described function can be performed. An inclined portion 36 is formed on the inner wall of the skirt portion 33 along the lower end of the skirt portion 33 to facilitate the application of the cap 30 onto the vial 10.
As described above, the plural ribs 34 (ten ribs in the illustrated embodiment), which primarily characterize the present invention, are arranged on the inner wall of the skirt portion 33 as shown in
The ribs 34 has a function that upon application of the cap 30 onto the vial 10, the ribs 34 are brought into contact with an outer circumferential wall of the lip 12 around the opening 11 of the vial 10 to absorb a dimensional error of the lip 12 of the vial 10. Described specifically, the diameter (c) of a circle, which is defined by the top walls of the ribs 34, is set either equal to or slightly smaller than the outer diameter (b) of the lip 12 of the vial 10 (
In general, the dimensional error of the lip 12 of the vial 10 does not occur evenly along the entire outer circumference of the lip 12. Even with the same vial, its direction (plus/minus) and extent (magnitude) thus differ depending on the location where the measurement is made. Even in such as case as mentioned above, the cap 30 according to the present invention can tolerate the maximum point of the outer diameter (b) of the lip 12 provided that the maximum point is positioned between one of the paired ribs 34 and their adjacent paired ribs 34. Concerning the minimum point of the outer diameter (b) of the lip 12, on the other hand, the cap 30 according to the present invention can also reduce the looseness of the cap 30 applied on the lip 12 provided that the minimum point is positioned between one of the paired ribs 34 and their adjacent paired ribs 34.
The ribs 34 are arranged in the direction perpendicular to the top wall portion 32 on the inner surface of the skirt portion 33 at the area other than the inclined portion 36. No particular limitation is imposed on the lengths or widths of the ribs 34 insofar as the ribs 34 are located opposite the outer circumferential wall of the lip 12 of the vial 10. The top walls of the ribs 34 may be planar or may be angled. The height (d) and width (e) (see the enlarged fragmentary bottom view of
A cap 50 according to the second embodiment of the present invention will next be described with reference to
Upon fitting the cap 50 onto the vial 10, these engagement claws 55 progressively undergo elastic deformation outward in the radial direction as the cap 50 is pressed downward. In a downwardly pressed position, the engagement claws 55 are kept in engagement with an underside of the lip 12 and serve to prevent separation of the cap 50. The engagement claws 55 are formed one by one between the respective paired ribs 54, that is, as many as five in total (see
Numeral 56 in
As illustrated in
With reference to
After the vial 10 is filled with a desired medicament, the plug 20 such as a rubber plug is fitted in the opening 11 of the vial 10 to seal the vial 10. In this state, there is a potential risk that the plug 20 may separate due to a rise in the internal pressure of the vial during handling of the vial 10, for example, during heat sterilization or the like. When the cap 50 is being fitted onto the vial 10 sealed with the plug 20 as depicted in
Upon fitting the cap 50, the diameter (c) (see
In the second embodiment of the present invention, the dimensional error of the vial 10 has been taken into consideration. Described specifically, the inner diameter (a) of the skirt portion 53 is set greater by the dimensional error, which is expected on the vial 10, than the outer diameter (b) of the lip 12 of the vial 10. In addition, the above-described ribs 54 are arranged on the inner wall of the skirt portion 53, and the diameter (c) of the circle defined by the top walls of the ribs 54 is set smaller by the expected dimensional error than the inner diameter (a) of the skirt portion 53. When the dimension of the lip 12 of the vial 10 varies up, this dimensional error can, therefore, be absorbed through the elastic deformation of the ribs 54. Even when the dimension of the lip 12 of the vial 10 varies down, on the other hand, the outer circumferential wall of the lip 12 comes into contact with the top walls of the ribs 54. When the lip 12 of the vial 10 has the predetermined dimension, the outer circumferential wall of the lip 12 comes into contact with the ribs 54 while causing the top walls of the ribs 54 to undergo elastic deformation to some extent. In each of these cases, the contact between the skirt portion 53 and the outer circumferential wall of the lip 12 upon fitting takes place at the ribs 54 the areas of contact of which are small, and therefore, the cap 50 does not require large force for its application and can show excellent capping performance.
Even when the cap 50 according to the second embodiment of the present invention is applied to the vial 10 with the lip 12 the dimension of which is liable to a variation as in a glass-made vial, the cap 50 can absorb the dimensional error of the vial 10 so that no large force is required upon fitting the cap 50. Moreover, as the inner wall of the skirt portion 53 and the outer circumferential wall of the lip 12 always remain in contact with each other, the cap 50 does not come loose so that the separation of the cap 50 can be prevented. It is, therefore, possible to pronouncedly improve the percentage of acceptable caps in use. It is to be noted that the cap according to the present invention is useful not only for a glass-made vial but also for a plastic-made vial.
The present invention will next be described more specifically based on Examples and Comparative Examples.
Polypropylene-made caps having the structure of the second embodiment of the present invention (the configurations of
Caps of the same structure and dimensions as in Example 1 except that the ribs 54 were not arranged inside the caps and the dimension of the inner diameter (a) of each cap was changed to 32.25 mm were produced as Comparative Example 1. Caps of the same structure and dimensions as in Example 1 except that the dimension of the inner diameter (a) of each cap was changed to 31.75 mm were produced as Comparative Example 2.
The samples (caps) of Example 1, Comparative Example 1 and Comparative Example 2 were used as many as ten (10) per example. For the caps of the respective examples, the same glass-made vials (ten vials in total) were used. With respect to the caps of each example, rubber plugs made of chlorinated butyl rubber were applied to the respective vials and the caps were then applied to determine the maximum values of capping pressures needed for their applications. For the measurement of the capping pressures, “AUTOGRAPH AGS-H” (trade name, manufactured by Shimadzu Corporation) was used, and the test speed was set at 500 mm/min. It is to be noted that, whenever the capping pressure exceeded 500 N in the course of the test, the test was stopped for the sake of assurance of safety and was determined to be “a capping failure”. The results of the test are shown in Table 1. It is appreciated from Table 1 that with the caps of Example 1, no capping failure took place and the capping pressure was 436 N on average. It is also envisaged from Table 1 that with the caps of Comparative Example 1, no capping failure took place and the capping pressure was 345 N on average and was generally lower than that for the caps of Example 1. It is also understood from Table 1 that with the caps of Comparative Example 2, a capping failure took place on four of them and the capping pressure was 470 N on average, that is, the highest.
The vials capped with the caps of Example 1, Comparative Example 1 and Comparative Example 2 in the capping pressure test (ten vials in the case of the caps of Example 1 and the caps of Comparative Example 1, and only six vials successfully capped in the case of the caps of Comparative Example 2) were placed in an autoclave (“HICLAVE HV-25”, trade name; manufactured by Hirayama Manufacturing Corporation) separately depending on the example. The capped vials were held at 121° C. for 60 min, and each vial was checked for the separation of the cap. The test results are also shown in Table 1. From the results shown in Table 1, no separation was confirmed with respect to the caps of Example 1. Concerning the caps of Comparative Example 1, separation was confirmed with three of them. As to the caps of Comparative Example 2, no separation was confirmed.
| Number | Date | Country | Kind |
|---|---|---|---|
| JP2007-318691 | Dec 2007 | JP | national |
