Abstract
The present invention relates to a blister pack that comprises a base laminate with a sealing layer and a lid laminate with a sealing layer, the base laminate having at least one cavity housing a product. The base laminate and the lid laminate are directly sealed to each other via their identical sealing layers whereby the seal comprises two different sealing subzones, a first sealing subzone providing a permanent seal and a second sealing subzone providing a peelable seal.
Claims
1. A blister pack comprising a base laminate with a sealing layer and a lid laminate with a sealing layer, the base laminate having at least two cavities, a first cavity housing a first product, and a second cavity housing a second product, whereby the base laminate and the lid laminate are directly sealed to each other via their sealing layers characterized in that the seal comprises two different sealing subzones, a first sealing subzone providing a permanent seal and a second sealing subzone providing a peelable seal, the first sealing subzone defining a sealed perimeter forming the closed blister pack, the second sealing subzone being internal to the first sealing subzone and at least partly separating the first and second cavity.
2. Blister pack according to claim 1, characterized in that the second sealing subzone delaminates upon sustained manual pressure applied on one of the cavities, thereby providing a communicating passage between the first and the second cavity allowing the mixture of the first and the second product.
3. Blister pack according to claim 1, characterized in that the first sealing subzone and the second sealing subzone define a sealed perimeter having a first end and a second end and two opposed sides forming the closed blister pack, whereby the first sealing subzone is arranged at the second end providing a peel stop and thereby preventing complete separation of the lid laminate and the base laminate in an opened state of the blister pack.
4. Blister pack according to claim 1, characterized in that the base laminate and the lid laminate comprise an identical sealing layer.
5. Blister pack according to claim 1, characterized in that the lid laminate sealing layer comprises a blend of polyethylene and several functionalized ethylene copolymers.
6. Blister pack according to claim 5, characterized in that the polyethylene is a low density polyethylene having a density in the range of 0.921 g/cm.sup.3 to 0.924 g/cm.sup.3.
7. Blister pack according to claim 5, characterized in that the functionalized ethylene copolymers are copolymers of ethylene and an unsaturated co-monomer having an organic functional group containing a carbon atom double bonded oxygen atom and being linked to an additional oxygen atom.
8. Blister pack according to claim 5, characterized in that the functionalized ethylene copolymers are derived from acid copolymers by partially neutralizing the acid moiety of the acid copolymer with a cation.
9. Blister pack according to claim 5, characterized in that the functionalized ethylene copolymers are ethylene acrylic acid copolymers and are non-cation neutralized copolymers derived from ethylene and an acrylic acid comonomer, preferably acrylic acid or methacrylic acid.
10. Blister pack according to claim 5, characterized in that the functionalized ethylene copolymer is ethylene vinyl acetate copolymer having a vinyl acetate content of up to 30 weight percent based on the weight of the ethylene vinyl acetate copolymer.
11. Blister pack according to claim 1, characterized in that the base laminate comprises three adhesively bonded layers, an outer layer of oriented polyamide, an intermediate layer of aluminium, an inner sealing layer made of a blend of ethylene acrylic acid and an ionomer resin, and an optional primer layer.
12. Blister pack according to claim 11, characterized in that the outer layer of the base laminate has a thickness in the range of 10 μm to 40 μm, the intermediate layer of the base laminate has thickness in the range of 30 μm to 60 μm, and the inner sealing layer of the base laminate has a thickness in the range of 30 μm to 90 μm.
13. Blister pack according to claim 1, characterized in that the lid laminate consists of three adhesively bonded layers, an outer layer made of polyethylene terephthalate, an intermediate layer made of aluminium and an inner sealing layer made of a blend of ethylene acrylic acid and an ionomer resin.
14. Blister pack according to claim 13, characterized in that the outer layer of the lid laminate has a thickness in the range of 6 μm to 18 μm, the intermediate layer of the lid laminate has thickness in the range of 10 μm to 30 μm, and the inner sealing layer of the lid laminate has a thickness in the range of 30 μm to 90 μm.
Description
(1) The method for forming packaging materials and the packaging materials according to the present invention are explained in more detail below with reference to exemplary embodiments in the drawings, in which, purely schematically:
(2) FIG. 1 shows a cross-sectional view of a base laminate according to the present invention;
(3) FIG. 2 shows a sectional view of a lid laminate according to the present invention;
(4) FIG. 3 shows a first embodiment of a blister pack according to the present invention;
(5) FIG. 4 shows a second embodiment of a blister pack according to the present invention;
(6) FIG. 5 shows a third embodiment of a blister pack according to the present invention;
(7) FIG. 6 shows a diagram illustrating the seal strength in dependence of the sealing temperature of a sealing layer according to the present invention.
(8) FIG. 7 shows a diagram illustrating the seal strength in dependence of the sealing temperature of polyethylene based sealing layers known in prior art.
(9) FIG. 1 shows a cross-sectional view of a base laminate 1 according to the present invention. The base laminate 1 comprises three layers that are adhesively bonded. From outside to inside the layers are an outer layer 3, an intermediate layer 7 and an inner sealing layer 11. The three layers are adhesively bonded by interposed adhesive layers 5 and 9. The order of the layers from outside to inside means that the outer layer faces the outside of the blister pack whereas the inner sealing layer faces either the sealing layer of the respective lid laminate or alternatively a product space (not shown).
(10) FIG. 2 shows a cross-sectional view of a lid laminate 13 comprising the following layers, an outer layer 15, an intermediate layer 19 and an inner sealing layer 23. The three layers of the lid laminate 13 are also adhesively bonded by two interposed adhesive layers 17 and 21. Thus, adhesive layer 17 is interposed between the outer layer 15 and the intermediate layer 19. The adhesive layer 21 is interposed between the intermediate layer 19 and the inner sealing layer 23. Again, the order of layers is from outside to inside of the blister pack (not shown).
(11) FIG. 3 depicts a first embodiment of a blister pack according to the present invention. The figure shows a plan view of base laminate side of the blister pack 25. A first cavity 31 and a second cavity 33 housing two different products (not shown) are delimited by a first sealing subzone 27 and a second sealing subzone 29. While the first sealing subzone 27 provides a permanent seal, the second sealing subzone 29 provides for a peelable seal. The first sealing subzone 27 extends from the outer edges of the blister pack 25 to the boundaries of the cavities 31 and 33 as well as to the boundaries of the second sealing subzone 29. The first sealing subzone forms a circumferential permanent seal of the blister pack 25. The second sealing subzone 29 is arranged internal to the first sealing subzone 27. Said second sealing subzone 29 is further arranged between the first and second cavities 31 and 33. Another second sealing subzone 29 is arranged between the second cavity 33 and an outlet zone 34. Said outlet zone 34 becomes accessible when an end region 36 is torn off. The tearing action may be initiated at a notch 35 arranged at an outer edge of the blister pack 25.
(12) FIG. 4 shows a second embodiment of a blister pack according to the present invention. Shown is again a plan view of the base laminate side of the blister pack 37. The blister pack 37 comprises four cavities 43, 45, 47 and 49. Said cavities may house up to four different products, e.g., different liquids or liquids and powders. The first sealing subzone 39 extends between the outer edge of the blister pack 37 and at least a part of the boundaries of the cavities 43, 45, 47 and 49. Between all of the four cavities 43, 45, 47 and 49 is a second sealing subzone 41 arranged in the form of a strip which upon being broken provides for a communicating passage with at least one other cavity. The cavity 45 is interconnected with all of the other three cavities 43, 47 49 by such a second sealing subzone 41. These second sealing subzones 41, arranged between the different cavities 43, 45, 47 and 49 have the form a strip of different width. Of course these second sealing subzone interconnecting the four cavities 43, 45, 47 and 49 may also have another shape, for instance a curved shape. The cavity 45 is further interconnected with an outlet 51 by a second sealing subzone 41 having a strip shape and providing a communicating passage between cavity 45 and the outlet zone 51 once the peelable seal of the respective second sealing subzone 41 is broken. The outlet zone 51 may comprise opening or withdrawal means allowing withdrawal of the composition comprising the products housed in the four cavities (not shown).
(13) FIG. 5 shows a third embodiment of a blister pack according to the present invention. The blister pack 53 has a rectangular shape. However, different shapes are also conceivable. The blister pack 53 comprises a cavity 59 housing a product, e.g. a powder (not shown), a first sealing subzone 55 and a second sealing subzone 57. The first sealing subzone 55 is arranged at one end of the blister pack 53. Adjacent to the first sealing subzone 55 the second sealing subzone 57 is arranged. This second sealing subzone 57 completely surrounds and delimits the cavity 59. At the end of the blister pack opposite to the end the first sealing subzone 55 is arranged at, there are triangular areas 61. In said areas 61 the base laminate and the lid laminate are not sealed to one another such that the lid laminate may be lifted and peeled off. A boundary line 63 delimiting the first sealing subzone 55 from the second sealing subzone 57 limits the extent to which the lid laminate may be peeled off. The first sealing subzone thus prevents that the lid laminate may be completely peeled of the base laminate.
(14) FIG. 6 depicts a diagram illustrating the seal strength in dependence of the sealing temperature of a sealing layer according to the present invention. Curve A relates to a peel angle of 90° whereas in the case of curve B the peel angle is 180°. The dwell time during sealing was 1 s and the sealing pressure applied was 50 N/cm.sup.2. The peel speed applied was 100 mm/min. Both curves show an extended sealing temperature range wherein the seal strength remains nearly constant between sealing temperatures from 110° C. to 140° C.
(15) FIG. 7 shows a diagram illustrating the seal strength in dependence of the sealing temperature for polyethylene sealing films known in prior art. While the lower seal strength curve (squares) illustrates the seal strength of a polyethylene film providing a peelable seal, the upper seal strength curve (circles, dashed line) illustrates the seal strength of a polyethylene film providing a permanent seal. The sealing device used is a Brugger, 10 mm, sealing time was 1 sec and the sealing pressure 600N. The seal strength has been tested on a Zwick, Parameter SS1, Tearing angle 180° C., n=2
