VAN WISSE, Cornelis (Swensweg 5, GA Haarlem, NL-2031, NL)
| CLAIMS 1. Method for manufacturing a cold-form foil (22) for a blister pack (1), especially a blister pack (1) for medicine units (40), wherein an aluminum foil (22) is provided, and wherein a die (30) is applied, wherein the die (3o0) and the aluminum foil (22) are pressed against each other in order to realize impressions (10) in the aluminum foil (22) for forming cavities for receiving the medicine units (40), wherein the die (30) comprises a forming part (31) with a forming surface (32) that is destined to be brought into contact with the aluminum foil (22) for the purpose of forming an impression (10), wherein substantially rectangular impressions (10) are realized in the aluminum foil (22), wherein a single movement of the die (30) and the aluminum foil (22) with respect to each other is performed for realizing the impression (10), and wherein an orientation of the die (30) with respect to the aluminum foil (22) is employed in which a portion (47) of the forming surface (32) extends initially- at an angle (η) that is larger than 50° with respect to the aluminum foil (22) . 2. Method according to claim 1, wherein an orientation of the die (30) with respect to the aluminum foil (22) is employed in which a portion (47) of the forming surface (32) extends initially at an angle (η) that is in a range of 51° to 60° with respect to the aluminum foil (22) . 3. Method according to claim 1 or 2, wherein an orientation of the die (30) with respect to the aluminum foil (22) is employed in which a portion (47) of the forming surface (32) extends initially at an angle (η) that is in a range of 57° to 58° with respect to the aluminum foil (22). 4. Method according to any of claims 1-3, wherein the forming surface (32) of the forming part (31) of the die (30) that is applied comprises at least one portion (47) that extends at an angle (η) that is larger than 50° with respect to an imaginary tangent plane (33) at the top of the forming part (31), which tangent plane (33) extends perpendicular to a direction in which the forming part (31) and the aluminum foil (22) are pressed against each other. 5. Method according to claim 4, wherein the said portion (47) of the forming surface (32) extends with respect to the imaginary tangent plane (33) at the top of the forming part (31) at an angle (η) that is in a range of 51° to 60°. 6. Method according to claim 4 or 5, wherein the said portion (47) of the forming surface (32) extends with respect to the imaginary tangent plane (33) at the top < of the forming part (31) at an angle (η) that is in a range of 57° to 58°. 7. Method according to any of claims 3-6, wherein the die (30) that is applied has a mirror-symmetric appearance, and wherein the forming surface (32) of the forming part (31) of the die (30) has two portions (47) of which each portion (47) extends at an angle (η) that is larger than 50° with respect to the imaginary tangent plane (33) at the top of the forming part (31) . 8. Method according to claim 7, wherein each of the said two portions (47) of the forming surface (32) extends at an angle (η) that is in a range of 51° to 60° with respect to the imaginary tangent plane (33) at the top of the forming part (31) . 9. Method according to claim 7 or 8, wherein each of the said two portions (47) of the forming surface (32) extends at an angle (η) that is in a range of 57° to 58° with respect to the imaginary tangent plane (33) at the top of the forming part (31) . 10. Method according to any of claims 7-9, wherein the forming surface (32) of the forming part (31) of the die (30) that is applied has more portions (41, 42, 43, 44, 45, 46) that extend at an angle with respect to the imaginary tangent plane (33) at the top of the forming part (31), and wherein each of these other portions (41, 42, 43, 44, 45, 46) extends at an angle (α, β, Y, δ, ε, ζ) that is smaller than 50° with respect to the imaginary tangent plane (33) at the top of the forming part (31)". 11. Method according to any of claims 1-10, wherein impressions (10) having a depth in an order of "several millimeters, and a length and a width in an order of several tens of millimeters are realized in the aluminum foil (22) . 12. Method for manufacturing a blister pack (1), especially a blister pack (1) for medicine units (40), wherein a cold-form foil (22) is manufactured by applying the method according to any of claims 1-11, wherein the medicine units (40) are placed in the cavities (10) of the cold-form foil (22), wherein a cover foil (25) is provided, and wherein the cover foil (25) is connected to the cold-form foil (22) in a position in which the cover foil (25) seals the cavities (10) and the medicine units (40) placed therein. 13. Aluminum cold-form foil (22) for application in a blister pack (1), especially a blister pack (1) for medicine units (40), having substantially rectangular impressions (10) which are arranged in the foil (22) by means of a cold forming process, and which are intended to serve as cavities for receiving the medicine units (40), wherein a portion of the foil (22) that is located at the position of the impressions (10) extends at an angle that is larger than 50° with respect to a portion of the foil (22) that is located outside of the impressions (10) . 14. Aluminum cold-form foil (22) according to claim 13, wherein a portion of the foil (22) that is located at the position of the impressions (10) extends at an angle that is in a range of 51° to 60° with respect to a portion of the foil (22) that is located outside of the impressions (10). 15. Aluminum cold-form foil (22) according to claim 13 or 14, wherein a portion of the foil (22) that is located at the position of the impressions (10) extends at an angle that is in a range of 57° to 58° with respect to a portion of the foil (22) that is located outside of the impressions (10). 16. Aluminum cold-form foil (22) according to any of claims 13-15, wherein the impressions (10) have a depth in an order of several millimeters, and a length and a width in an order of several tens of millimeters . 17. Blister pack (1) for medicine units (40), comprising an aluminum cold-form foil (22) according to any of claims 13-16, medicine units (40) that are placed in the cavities (10) of the cold-form foil (22), and a cover foil (25) that is connected to the cold-form foil (22) , and that seals the cavities (10) and the medicine units (40) placed therein. 18. Blister pack (1) according to claim 17, wherein the medicine units are capsules (40) filled with a medicine. 19. Blister pack (1) according to claim 17, wherein the medicine units are pills filled with a medicine. |
The present invention relates to a method for manufacturing a cold-form foil for a blister pack, especially a blister pack for medicine units, wherein an aluminum foil is provided, and wherein a die is applied, wherein the die and the aluminum foil are pressed against each other in order to realize impressions in the aluminum foil for forming cavities for receiving the medicine units, and wherein the die comprises a forming part with a forming surface that is destined to be brought into contact with the aluminum foil for the purpose of forming an impression.
Such a method is known, for example from international patent publication WO 99/41027. According to the known method, the cold- form foil is obtained by placing a flat piece of aluminum foil between two mould parts, and moving the die such as to push a portion of the foil into an open space of one of the mould parts. In the process, local deformation of the foil takes place, and a permanent impression is formed in the foil. The type of deformation process as described in international patent publication WO 99/41027 is well-known, and is normally referred to as cold forming process.
Aluminum foil, which may be an aluminum composite foil that is coated on both sides with plastic material as known from
international patent publication WO 99/41027, for example, is applied in blister packs in situations in which it is important for medicine units to be shielded from environmental influences, particularly influences of moisture in ambient air, oxygen and light. In those situations, it is very important for the aluminum to be completely closed, wherein, among other things, the aluminum is impermeable to vapor/humidity. Therefore, it is very important that in the cold forming process, the aluminum is not stretched so far that tiny pin holes, tiny cracks or any other type of damage of the aluminum is obtained. On the basis of this fact, limitations to the particular shape of the impressions to be formed during the cold forming process need to be taken into account when designing the impressions . In general, the impressions are dome-shaped, such as to be capable of functioning as a cavity for receiving and accommodating a medicine unit such as a pill or a capsule. A critical area of the dome-shaped impressions is constituted by a transition area between a top portion of the dome and a side wall of the dome. In this area, tiny pin holes, tiny cracks and any other type of damage are likely to occur when the transition from the top portion to the side wall is too abrupt, i.e. when the side wall of the dome is bent downward with respect to the top portion over an angle that is too large. In the following, the angle as mentioned will be referred to as top shape angle.
In the field of blister packs for medicine units, especially blister packs having an aluminum cold-form foil, a maximum value of 50° is used as a maximum value of the top shape angle of the impressions. It is believed that this value of 50° is the maximum that can be achieved without damage of the aluminum. Therefore, until now, manufacturers of blister packs for medicine units refrain from making aluminum foils having impressions in which the top shape angle is larger than 50°. The value of 50° is believed to be a safe value, wherein normally no deterioration of the sealing capacity of the aluminum takes place. An important reason for using a safe maximum value is found in the fact that tiny pin holes, tiny cracks and the like are not easy to detect. The use of X-rays is a well- known detection method, but it is preferred not to apply this method in the context of medicine. Alternatively, infra red detection may be used, but that kind of detection is only suitable for detecting holes and cracks having dimensions which are larger than
approximately 25 μm. As a consequence, tiny holes may be overlooked, leading to an undesirable ageing process of the medicine units inside the blister packs.
A limitation to the top shape angle of the impressions involves a limitation to the number of impressions that can be realized in a given area. When there would be no risk of damage to the aluminum, an ideal design of the impressions would be a design in which the medicine units fit exactly inside the impressions, with no empty space inside the impressions. However, in many practical cases, such a design is not possible when taking into account the requirement according to which a higher value than 50° of the top shape angle is not allowed. In the field of medicine, no compromise may be made as far as the sealing capacity of the aluminum foil is concerned, and therefore, there is no other solution than designing the impressions with a less steep side wall. This means that the limitation existing in respect of the top shape angle involves a limitation to the maximum number of impressions to be made in a certain area.
Consequently, the number of medicine units that can be packed in a blister pack of a given size is limited, or the size of the blister pack needs to be larger in order to be capable of accommodating a given number of medicine units.
It is an objective of the present invention to provide a practical method for manufacturing an aluminum cold-form foil for a blister pack, especially a blister pack for medicine units, by means of which it is possible to have more impressions in an area of a given size, or a given number of impressions in a smaller area, especially impressions having a substantially rectangular shape, without increasing the risk of obtaining tiny pin holes, tiny cracks and the like in the aluminum foil during the cold forming process. The objective is achieved by means of a method according to which a single movement of the die used in the cold forming process and the aluminum foil with respect to each other is performed for realizing the impression, wherein the orientation of the die with respect to the aluminum foil is an orientation in which a portion of the forming surface of the forming part of the die extends initially at an angle that is larger than 50° with respect to the aluminum foil.
The present invention does not so much reside in the insight that it is desirable to have a steeper side wall in the dome shape of the substantially rectangular impressions, while maintaining the excellent sealing qualities of aluminum. This is the problem underlying the present invention, that was thought to be insolvable in the field of packing medicine units. However, the present " invention does reside in the insight that it is possible to go beyond the limit of 50° in respect of the top shape angle, and still realize perfect sealing without formation of tiny pin holes, tiny cracks and the like. According to the present invention, the impression is formed in one single movement, so that the
manufacturing process may be as simple as possible. This is
different from the process that is described in international patent publication WO 99/41027, according to which the impressions are formed in two steps, wherein an area of the aluminum foil is subsequently pressed in open spaces of different mould parts, and wherein the open space of a mould part that is used later in the process is smaller than the open space of a mould part that is used earlier in the process. Furthermore, the process known from WO
99/41027 is applicable to forming impressions having a circular shape rather than a substantially rectangular shape.
Hence, the achievement of the present invention is found in not following a bias, but going beyond the limits that were thought to be fixed limits instead. Thorough research has proved that it is possible to have a desired combination of a single cold forming movement, a substantially rectangular shape, and a top shape angle that is larger than 50 0 C, and to have an aluminum cold-form foil that is still very well capable of providing a vapor/humidity-tight seal for medicine units, i.e. to have a cold-form foil that is fully intact and does not have tiny pin holes, tiny cracks or the like.
When the method according to the present invention is applied, the die that is used in the cold forming process of an impression is orientated in such a way that a portion of the forming surface of the forming part of the die extends initially at an angle that is larger than 50° with respect to the aluminum foil. Hence, in the cold forming process, the aluminum foil is forced to assume a shape in which a transition is present at an angle that is larger than
50°. In this way, it is possible that impressions are formed which can be provided with a steeper side wall than usual, so that a larger number of impressions can be situated in an area of a given size, or the size of an area where a given number of impressions is situated can be smaller.
Advantageously, when the method according to the present invention is applied in the cold forming process of an impression in an aluminum foil, wherein the cold forming process is performed in the context of a manufacturing process of a cold-form foil for a blister pack for medicine units, an orientation of the die with respect to the aluminum foil is employed in which a portion of the forming surface of the forming part of the die extends initially at an angle in a range of 51° to 60° with respect to the aluminum foil. In particular, the angle as mentioned may be in a range of 57° to 58°.
In a practical situation in which dome-shaped impressions are formed, the design of the die that is applied in the cold forming process may be such that the forming surface of the forming part of the die comprises at least one portion that extends at an angle ' that is larger than 50° with respect to an imaginary tangent plane at the top of the forming part, which tangent plane extends perpendicular to a direction in which the forming part and the aluminum foil are pressed against each other. In particular, the angle as mentioned may be in a range of 51° to 60°. More in particular, the angle as mentioned may be in a range of 57° to 58°.
The die that is applied when the method according to the present invention is carried out may have a mirror-symmetric appearance, wherein the forming surface of the forming part of the die may have two portions of which each portion extends at an angle that is larger than 50° with respect to the imaginary tangent plane at the top of the forming part. In particular, the angle as
mentioned may be in a range of 51° to 60°. More in particular, the angle as mentioned may be in a range of 57° to 58°.
It may be so that the forming surface of the forming part of the die that is applied has more portions that extend at an angle with respect to the imaginary tangent plane at the top of the forming part, wherein each of these other portions extends at an angle that is smaller than 50° with respect to the imaginary tangent plane at the top of the forming part.
The present invention is applicable to the formation process of impressions of various sizes. For example, the formation process may be a process in which impressions having a depth in an order of several millimeters, and a length and a width in an order of several tens of millimeters are realized in the aluminum foil.
It is noted that WO 00/09313 discloses a process for creating one or more blisters in a blister film, which involves a single pass of a blister forming punch or pin, wherein a cold-forming process of the film takes place. The film can comprise a metal material like aluminum, and the pin can have two or more frusto-conical sections, wherein an apex angle of the frusto-conical cone adjacent the end face of the pin is substantially 60°, and wherein the apex angle of the frusto-conical section contiguous thereto is around 30°.
However, the disclosure of WO 00/09313 is not particularly
applicable for solving the problem underlying the present invention. In the first place, the known process is suitable to be used for creating blisters having a circular shape, which is easier to do than creating blisters having a more or less rectangular shape, as a circular shape is a shape that is more natural and that does not induce too much tension in view of the fact that tensions are evenly distributed over the circular circumference. In the second place, the blister is supported as soon as it is formed, -which also leads to a reduction of tensions, whereas the method according to the present invention does not necessarily involve such a supporting action.
The present invention furthermore relates to a method for manufacturing a blister pack, especially a blister pack for medicine units, wherein a cold-form foil is manufactured by applying the method as described in the foregoing, i.e. the method according to which the aluminum foil is formed with a top shape angle that is larger than 50°, wherein the medicine units are placed in the cavities of the cold-form foil, wherein a cover foil is provided, and wherein the cover foil is connected to the cold-form foil in a position in which the cover foil seals the cavities and the medicine units placed therein.
The present invention furthermore relates to an aluminum cold- form foil for application in a blister pack, especially a blister pack for medicine units, having substantially rectangular
impressions which are arranged in the foil by means of a cold forming process, and which are intended to serve as cavities for receiving the medicine units, wherein a portion of the foil that is located at the position of the impressions extends at an angle that is larger than 50° with respect to a portion of the foil that is located outside of the impressions. In particular, the angle as mentioned may be in a range of 51° to 60°. More in particular, the angle as mentioned may be in a range of 57° to 58°. One example of the size of the impressions is a depth in an order of several millimeters, and a length and a width in an order of several tens of millimeters .
The present invention furthermore relates to a blister pack for medicine units, comprising an aluminum cold-form foil as described in the preceding paragraph, medicine units that are placed in the cavities of the cold-form foil, and a cover foil that is connected to the cold-form foil, and that seals the cavities and the medicine units placed therein. It is noted that the medicine units may be of any suitable type. For example, the medicine units may be a capsule filled with a medicine . The present invention will now be explained on the basis of the following description of a blister pack, a manufacturing process of the blister pack, and a die that is used in this manufacturing process, with reference to the drawing, in which equal reference signs indicate equal or similar components, and in which:
figures 1 and 2 diagrammatically show two views of a blister pack; figure 3 diagrammatically shows a production line of the blister pack;
figure 4 diagrammatically shows an impression that is part of the blister pack, and that serves as a cavity for receiving and
accommodating a capsule filled with medicine, and a surrounding portion of the blister pack;
figures 5 and 6 diagrammatically show two views of a die that is used in the production line of the blister pack; and
figures 7 and 8 diagrammatically show sectional views of the impression that is part of the blister pack, wherein a capsule that is located inside the impression is shown as well.
Figures 1 and 2 show a blister pack 1, especially a blister pack 1 for medicine units such as blisters or capsules.
It is noted that a blister pack 1 for medicine units is generally known. Blister packs 1 come in various sizes, shapes and materials. For example, a circumference of the blister pack 1 may be rectangular or circular, and the materials of the blister pack 1 may be a suitable plastic, aluminum, or another suitable material. The present invention relates to blister packs 1 having an aluminum cold-form foil.
In general, a blister pack 1 comprises several impressions 10 which serve as cavities for accommodating the medicine units, wherein the impressions 10 are arranged in the cold-form foil as mentioned. Besides the cold-form foil, the blister pack 1 comprises a cover foil for sealing the cavities, so that the medicine units contained therein are shielded from environmental influences. The cover foil is connected to the cold-form foil. The cover foil may be arranged such as to be peeled off the cold-form foil by a user who wants to release one or more medicine units, but it is also possible for the cover foil to be arranged such as to be broken when the user presses on an impression from the side of the cold-form foil, wherein the medicine unit is pressed against the covering foil.
According to another well-known option, there may be
perforations 11 in the foils of the blister pack 1 at positions between the impressions 10, so that blister units 12 having a defined number of impressions 10, for example, one impression 10, are defined, and may be easily detached from the blister pack 1 by a user without the risk of prematurely opening the impression (s) 10.
The impressions 10 are shaped such as to be a kind of dome that is suitable for enclosing a medicine unit, as can be seen in the view of the blister pack 1 that is shown in figure 2. The
impressions 10 are realized in a cold-forming process, i.e. a process in which a die is used, wherein the die and the aluminum foil in which the impressions 10 are to be arranged are pressed against each other, and the die is used to cause a local deformation of the foil. The manufacturing process of the blister pack 1 will now be explained on the basis of figure 3.
Figure 3 serves to illustrate a production line 20 of a blister pack 1. The production line 20 comprises a roller 21 for supplying foil 22 to be subjected to a cold forming process, a station 23 where the cold forming process is performed by means of a mould and a die (not shown) , a roller 24 for supplying cover foil 25, and a sealing station 26 where medicine units (not shown) are placed inside the impressions 10 of the cold-form foil 22, and where the cold-form foil 22 and the cover foil 25 are connected.
The foil 22 to be subjected to the cold forming process is an aluminum foil, i.e. a foil comprising aluminum, which is in a flat condition. In the cold forming station 23, the foil 22 is clamped in a mould. In a manner that is well-known, the mould comprises at least two parts, wherein a first part has a cavity or hole, and wherein a second part has a hole for guiding a die. When the die and the foil 22 are pressed against each other, it is achieved that the foil 22 is deformed at the location where there is no support of the foil 22, namely the location where the cavity or hole is present in the first mould part, wherein the die is pressed further and further until the impression 10 that is obtained in this way has a required depth. According to the present invention, the cold forming process is carried out in one step, and involves just one relative movement of the die and the foil 22. The cold-form foil 22 having the impressions 10 is transported further to the sealing station 26, where it is joined with the cover foil 25. Before a connection between the foils 22, 25 is made, medicine units are placed inside the impressions 10 of the cold form foil 22. In a subsequent process of realizing a connection between the foils 22, 25, the medicine units are sealed inside the
impressions 10. The connection may be realized in any suitable manner, for example, by applying a suitable adhesive.
It is noted that the cover foil 25 may also be an aluminum foil, wherein the foil may be with or without additional layers for special purposes or qualifications. Normally, this foil 25 is not subjected to any deformation process, but is kept in a flat
condition instead. Hence, the size of the impressions 10 in the cold form foil 22 need to be adapted to the size of the medicine unit, such that the impressions 10 are capable of receiving and
accommodating the medicine unit, wherein the medicine unit needs to be entirely located inside the impressions 10, so that there are no parts projecting from the impressions 10.
When the foils 22, 25 and the medicine units have passed the sealing station 26, the blister pack 1 is ready, albeit as a part of a long row of blister packs 1 which need to be separated by means of a cutting action or the like at a later stage in a separating station 28. Optionally, perforations 11 are made in the foils 22, 25 of the blister pack 1 such as to define blister units 12 in the blister pack 1. To this end, the blister pack 1 may be guided through a perforation station 27, which is situated between the sealing station 26 and the separating station 28.
The present invention is about the cold forming process of the aluminum foil 22, and the specific shape of the impressions 10 which are obtained in this process. Figure 4 shows an impression 10 that is part of a blister pack 1 according to the present invention, and a surrounding portion of the blister pack 1. In the shown example, the circumference of the impression 10 at the basis of the
impression 10 is more or less rectangular, particularly rectangular with round corners. Figures 5 and 6 show views of the die 30 that is used in the cold forming process of the impression 10. Figure 5 shows a view of a short side of the die 30, and figure 6 shows a long side of the die 30.
The die 30 comprises a forming part 31 having a forming surface 32 that is actually intended for contacting the aluminum foil 22 to be deformed. The shape of the forming surface 32 is practically the same as the shape of the impression 10 to be formed. In this respect, it is noted that in practice, a springback effect is obtained in the aluminum after the cold forming process has taken place and the pressure is released, so that small deviations of the shapes are realized.
Figure 5 shows that in one direction, i.e. the direction in which the short side of the die 30 is extending, the forming surface 32 is V-shaped, wherein the V-shape has a small basis, and wherein the V-shape comprises several portions which are orientated at different angles with respect to an imaginary tangent plane 33 at the top of the forming part 31 of the die 30, which is the basis of the V-shape, and which is perpendicular to a central axis of the die 30 and a direction of movement of the die 30 during the cold forming process. When going from the basis of the . V-shape to the open side of the V-shape, the angle that is present between the respective portion of the V-shape and the imaginary tangent plane 33 increases. In the shown example, the angle at a first portion 41 of the forming surface 32, which is present at the basis of the V-shape,. is 18°, the angle at a second portion 42 of the forming surface 32 is 28°, the angle at a third portion 43 of the forming surface 32 is 37°, and the angle at a fourth portion 44 of the forming surface 32 is 47°. The respective angles are indicated in figure 5 as α, β, Y, and δ.
The shape with the increasing angles a, β, Y, δ contributes to a process of gradually deforming the aluminum foil 22, wherein the risk of tiny pin holes, tiny cracks and the like is minimized. In the cold forming process, the" foil 22 is made to fold around the forming part 31 of the die 30, at it were.
Figure 6 shows that in the direction in which the long side of the die 30 is extending, the forming surface 32 has a flat top and a curved surface extending from the top, wherein the curved surface has a similar shape as the legs of the V-shape of the forming surface 32 in the other direction, implying that the curved surface also comprises portions that are extending at different angles with respect to the imaginary tangent plane 33. In the shown example, the angle at a first portion 45 of the forming surface 32, which is present at the top, is 18°, the angle at a second portion 46 of the forming surface 32 is 28°, and the angle at a third portion 47 of the forming surface 32 is 57,5°. The respective angles are indicated in figure 6 as ε, ζ, and η.
Figures 7 and 8 illustrate the shape of the depression 10 that is obtained by using the die 30 as specified in the foregoing.
Furthermore, figures 7 and 8 illustrate how a capsule 40 is placed inside the depression 10.
For sake of completeness, it is noted that in the shown example, the die 30 has a mirror-symmetric appearance. Therefore, the specific portions and angles as mentioned are present at two sides of the die 30. Furthermore, it is noted that due to the mirror-symmetric appearance of the die 30, the impression 10 is given a mirror-symmetric appearance as well. That does not alter the fact that in principle, it is also possible to have an asymmetric appearance .
The concept of having an angle η of the forming surface 32 with respect to the imaginary tangent plane 33 at the top of the forming „ part 31 of the die 30 that is larger than 50° is out of the
ordinary, and is a particular feature of the present invention.
Tests have proven that it is possible to have the angle η that is too large according to state of the art standards, without the risk of tiny pin holes, tiny cracks or the like in the aluminum foil 22.
In particular, a test has been performed with details as listed in the following.
- Capsule geometry:
diameter = 5.90 mm
length = 16.00 mm - Impression geometry:
width including radius of curvature 0.5 mm = 16.60 mm
length including radius of curvature 0.5 mm = 23.00 mm
forming depth „ = 6.60 mm
estimated forming force = 600 N
- Materials:
1) foil to be subjected to cold forming process
Formpack® by Alcan Packaging, Singen, Germany
laminate foil comprising 25 μm oPA, 45 μm Al, and 60 μm PVC (oPA = oriented polyamide; Al = aluminum; PVC = polyvinyl chloride)
2) die to be used in cold forming process
Teflon Lubrifon®, virgin white
by Angst+Pfister, Zurich, Switzerland
It is noted that this invention is " also applicable to other cold- form laminates, but the estimated forming force is only valid in respect of the specific materials as mentioned.
The impressions that were obtained during the test were checked for pin holes, cracks and possible other damage of the foil. In the process, various detection techniques were used, including visual inspection, wherein use can be made of a pattern to be printed on " the depression area for detecting overstrained portions, and
inspection by means of infrared, wherein the test blister pack is not filled with a medicine unit. No pin holes, cracks or the like were found, despite of the large angle 57,5° of the orientation of a portion of the forming surface of the forming part of the die, and it is found that it is possible to have such an angle, which is significantly larger than the state of the art maximum, which is at 50°.
It will be clear to a person skilled in the art that the scope of the present invention is not limited to the examples discussed above, but that several amendments and modification thereof are possible without deviating from the scope of the invention as defined in the appended claims.
In respect of the blister pack 1, it is noted that the number of impressions 10 in the cold-form foil 22 may be chosen freely within the scope of the present invention, and that the same is applicable to the positioning of the impressions 10 in the blister pack 1. All options that are normally applicable to a blister pack, such as the option of having a peelable cover foil 25, a push- through cover foil 25, or a combination of these two, the option of having perforations 11 or not, etc. are applicable to the blister pack 1 according to the present invention as well.
Furthermore, it is noted that where it says that the die and the aluminum foil are pressed against each other in order to realize impressions in the aluminum foil for forming cavities for receiving the medicine units, this should be understood such as to cover a practical option of retaining the aluminum foil by clamping the foil in a suitable mould device and pushing the die into the foil, besides other options existing within the concept of a relative movement of the die and the foil.
With respect to the term medicine units as used in this description, it is noted that this should be understood such as to cover anything containing medicine, including a capsule, a pill, a quantity of powder, etc.
The present invention may be summarized as follows.
A method for forming impressions 10 in an aluminum foil 22 that is intended to be used in a blister ' pack 1 for medicine units 40 comprises the conventional steps of providing the aluminum foil 22, and applying a die 30, wherein the die 30 and the aluminum foil 22 are pressed against each other in order to realize substantially rectangular impressions 10 in the aluminum foil 22 for forming cavities for receiving the medicine units 40. The die 30 that is applied in this cold forming process of the aluminum foil 22 comprises a forming part 31 with a forming surface 32 that is destined to be brought into contact with the aluminum foil 22 for the purpose of forming an impression 10.
According to the present invention, a single movement of the die 30 and the aluminum foil 22 with respect to each other is performed for realizing the impressions 10, where ' in the orientation of the die 30 with respect to the aluminum foil 22 is an orientation in which a portion 47 of the forming surface 32 of the forming part 31 of the die 30 extends initially at an angle η that is larger than 50° with respect to the aluminum foil 22.
When the method according to the present invention is applied, it is possible to realize a blister pack 1 having more impressions - 10 at a given area, or a smaller blister pack 1 for a given number of impressions 10, or a combination of these two effects, due to the fact that a side wall of the depression 10 can be steeper and a contour of the medicine unit 40 can be followed more closely.
According to the present invention, a state of the art bias, implying that it is necessary to have an angle that is not larger than 50° in order to ensure a safe cold forming process in which the formation of tiny pin holes, tiny cracks or other types of damage to the aluminum is avoided is not followed.