Sheet laminate, a blister package and a method of manufacture

Abstract

A sheet laminate for being used as a puncturable top web for a blister package, comprising: an aluminium base sheet layer; at least one tie layer comprising polyolefin; a welding layer comprising polyester or polypropylene; wherein the welding layer and the tie layer are coextrusion coated on the base sheet layer so that the at least one tie layer is disposed between the base sheet layer and the welding layer, whereby the welding layer is attached to the base sheet layer by the at least one tie layer. A blister package, wherein the sheet laminate is attached to a bottom web with product cavities. A method of manufacture of the sheet laminate and of the blister package, wherein the coextrusion coating step of the manufacture of the blister package is carried out simultaneously with extrusion lamination of a paper layer.

Claims

1. A sheet laminate for being used as a puncturable top web for a blister package, comprising: an aluminum base sheet layer, wherein the aluminum base sheet layer has a thickness of less than 10 μm and is annealed; at least one tie layer consisting essentially of polyolefin; and a welding layer consisting essentially of one or more polyesters; wherein the welding layer and the at least one tie layer are coextrusion coated on the aluminum base sheet layer so that the at least one tie layer is disposed between the aluminum base sheet layer and the welding layer, and wherein the welding layer is attached to the aluminum base sheet layer by the at least one tie layer, wherein an accumulated distribution of the at least one tie layer and the welding layer is equal to or less than 10 g/m.sup.2, and wherein a puncture resistance of the sheet laminate is less than or equal to 8 N, the puncture resistance of the sheet laminate being measured according to standard ASTM F1306-90 (1994), adapted so that a sample test diameter is 48 mm.

2. The sheet laminate according to claim 1, further comprising: a paper layer; and at least one extrusion lamination layer provided between the aluminum base sheet layer and the paper layer; wherein the at least one extrusion lamination layer is provided on a major surface of the aluminum base sheet layer positioned oppositely from a major surface of the aluminum base sheet layer on which the at least one tie layer is provided; whereby the paper layer and the aluminum base sheet layer are extrusion laminated to each other by means of the at least one extrusion lamination layer.

3. The sheet laminate according to claim 2, wherein the at least one extrusion lamination layer includes two or more extrusion lamination layers, whereby the paper layer is coextrusion laminated to the aluminum base sheet layer by means of the two or more extrusion lamination layers.

4. The sheet laminate according to claim 2, wherein the at least one extrusion lamination layer comprises polyethylene.

5. The sheet laminate according to claim 1, further comprising: a paper layer; and at least one adhesive lamination layer provided between the aluminum base sheet layer and the paper layer; wherein the at least one adhesive lamination layer is provided on a major surface of the aluminum base sheet layer positioned oppositely from a major surface of the aluminum base sheet layer on which the at least one tie layer is provided; whereby the paper layer and the aluminum base sheet layer are adhesive laminated to each other by means of the at least one adhesive lamination layer.

6. The sheet laminate according to claim 1, wherein the one or more polyesters of the welding layer comprises polyethylene terephthalate.

7. The sheet laminate according to claim 1, wherein the at least one tie layer comprises two or more tie layers.

8. The sheet laminate according to claim 1, wherein the aluminum base sheet layer has a thickness in a range of 2 μm to 10 μm.

9. A blister package comprising: a sheet laminate provided as a top web of the blister package, which sheet laminate comprises: an aluminum base sheet layer, wherein the aluminum base sheet layer has a thickness of less than 10 μm and is annealed, at least one tie layer consisting essentially of polyolefin, and a welding layer consisting essentially of one or more polyesters, wherein the welding layer and the at least one tie layer are coextrusion coated on the aluminum base sheet layer so that the at least one tie layer is disposed between the aluminum base sheet layer and the welding layer, and wherein the welding layer is attached to the aluminum base sheet layer by the at least one tie layer, wherein an accumulated distribution of the at least one tie layer and the welding layer is equal to or less than 10 g/m.sup.2, and wherein a puncture resistance of the sheet laminate is less than or equal to 8 N, the puncture resistance of the sheet laminate being measured according to standard ASTM F1306-90 (1994), adapted so that a sample test diameter is 48 mm; a bottom web comprising cavities; and one or more products for consumption disposed in one or more of said cavities; wherein the top web is arranged with a bottom surface of the welding layer facing and welded to a welding surface of the bottom web, said welding surface surrounding said cavities.

10. The blister package according to claim 9, wherein the sheet laminate further comprises: a paper layer; and at least one extrusion lamination layer provided between the aluminum base sheet layer and the paper layer; wherein the at least one extrusion lamination layer is provided on a major surface of the aluminum base sheet layer positioned oppositely from a major surface of the aluminum base sheet layer on which the at least one tie layer is provided; whereby the paper layer and the aluminum base sheet layer are extrusion laminated to each other by the at least one extrusion lamination layer.

11. The blister package according to claim 10, wherein the at least one extrusion lamination layer includes two or more extrusion lamination layers, whereby the paper layer is coextrusion laminated to the aluminum base sheet layer by means of the two or more extrusion lamination layers.

12. The blister package according to claim 10, wherein the at least one extrusion lamination layer comprises polyethylene.

13. The blister package according to claim 9, wherein the sheet laminate further comprises: a paper layer; and at least one adhesive lamination layer provided between the aluminum base sheet layer and the paper layer; wherein the at least one adhesive lamination layer is provided on a major surface of the aluminum base sheet layer positioned oppositely from a major surface of the aluminum base sheet layer on which the at least one tie layer is provided; whereby the paper layer and the aluminum base sheet layer are adhesive laminated to each other by the at least one adhesive lamination layer.

14. The blister package according to claim 9, wherein a thickness of the aluminum base sheet layer is less than 7 μm.

15. The blister package according to claim 9, wherein the one or more polyesters of the welding layer comprises polyethylene terephthalate.

16. The blister package according to claim 9, wherein the at least one tie layer comprises two or more tie layers.

17. A method for manufacture of a sheet laminate comprising: providing an aluminum base sheet layer, wherein the aluminum base sheet layer has a thickness of less than 10 μm and is annealed; and coextrusion coating at least one tie layer and welding layer onto said aluminum base sheet layer, so that the at least one tie layer is disposed between the aluminum base sheet layer and the welding layer, wherein: the welding layer is attached to the aluminum base sheet layer by the at least one tie layer, the at least one tie layer consists essentially of polyolefin and the welding layer consists essentially of one or more polyesters, an accumulated distribution of the at least one tie layer and the welding layer is equal to or less than 10 g/m.sup.2, and a puncture resistance of the sheet laminate is less than or equal to 8 N, the puncture resistance of the sheet laminate being measured according to standard ASTM F1306-90 (1994), adapted so that a sample test diameter is 48 mm.

18. The method according to claim 17, further comprising: attaching a paper layer to the aluminum base sheet layer by extrusion lamination by extruding at least one extrusion lamination layer between the aluminum base sheet layer and the paper layer; wherein attaching the paper layer and the extrusion coated layers to the aluminum base sheet layer are carried out simultaneously or in one single run.

Description

FIELD OF THE DISCLOSURE

(1) Embodiments of the disclosure will be described in the following detailed description with reference to the drawings in which:

(2) FIG. 1 is a schematic sectional side view of an embodiment of a sheet laminate according to the present disclosure attached to a bottom web so as to form a blister package;

(3) FIG. 2 is a view similar to that of FIG. 1 of another embodiment a sheet laminate according to the present disclosure attached to a bottom web so as to form a blister package;

(4) FIG. 3 is a view similar to that of FIG. 1 of another embodiment a sheet laminate according to the present disclosure attached to a bottom web so as to form a blister package;

(5) FIG. 4 is a view similar to that of FIG. 1 of another embodiment a sheet laminate according to the present disclosure attached to a bottom web so as to form a blister package;

(6) FIG. 5 shows a curve illustrating puncture resistance as a function of distribution of a coextrusion coated layer in samples of a laminate according to FIG. 4; and

(7) FIG. 6 shows a column diagram of puncture resistance of different samples of laminates.

DETAILED DESCRIPTION

(8) FIG. 1 shows an embodiment of a sheet laminate according to the present disclosure, which sheet laminate is for being used as a puncturable top web for a blister package. The laminate comprises an annealed aluminium base sheet layer 1, a tie layer 2 based on polyolefin, especially PE, and a welding layer 3 based on polyester. Alternatively, the welding layer 3 can be based on PP or a PP/PE mixture.

(9) The welding layer 3 and the tie layer 2 are coextrusion coated on the base sheet layer 1 so that the tie layer 2 is disposed between the base sheet layer 1 and the welding layer 3, whereby the welding layer 3 is attached to the base sheet layer 1 by means of the tie layer 2.

(10) The polyester welding layer is of APET and/or PETG, which is sealable to a bottom web or a welding surface thereof of PET, APET, GPET, PVC and PVDC. In case a polypropylene (PP) or a PP/polyethylene (PP/PE) mixture welding layer is applied, the laminate is sealable to PP.

(11) The sheet laminate is sealed or welded to a bottom web welding surface of a bottom web 4 of APET.

(12) The base sheet layer 1 has a first major surface which faces the tie layer 2 and an opposite second major surface, which is an outer major surface facing the environment. The base sheet layer 1 is manufactured in a first, separate process (such as an extrusion process) before the tie layer 2 and the welding layer 3 are coextrusion coated thereon, see further below.

(13) In general, all layers of the variations of the sheet laminate as described with reference to the drawings are each distributed to have substantially uniform thickness or planar weight across substantially an entire planar extent of the sheet.

(14) The distribution of the welding layer 3 is 3 g/m.sup.2, and that of the tie layer 2 is 3.5 g/m.sup.2. The thickness of the welding layer is 3 μm. The thickness of the base sheet layer is 6.35 μm.

(15) The tie layer 2 is of Lotader 4503 as marketed by Arkema in January 2015. The welding layer 3 is of Skygreen PN100 as marketed by SK Chemicals.

(16) The blister package resultant from the layers 1, 2, 3, 4 shown in FIG. 1 comprises the sheet laminate provided as a top web of the blister package and welded to the bottom web 4. The bottom web 4 is a conventional bottom web comprising a number of cavities 7, each containing a product 8 for consumption, such as a medicinal pill, positioned within the cavity 7.

(17) The sheet laminate or top web is arranged with a bottom surface of the welding layer 3 facing and welded to an upper welding surface of the bottom web 4, said welding surface surrounding said cavities 7 on all sides.

(18) The sheet laminate of FIG. 1 is manufactured by an embodiment of a method for manufacture according to the present disclosure, comprising the steps of, in sequence:

(19) providing the aluminium base sheet layer 1 from a roll of extruded, annealed aluminium foil; and

(20) coextrusion coating the tie layer 2 and the welding layer 3 onto the base sheet layer 1, whereby the welding layer 3 is attached to the base sheet layer 1 by means of the tie layer 2.

(21) The extrusion coating step is carried out in a conventional extruder in accordance with the above general description of the present disclosure. The extruder comprises a die for extrusion of the coextrusion coated layers 2, 3. The extruder comprises a feed zone, a transition zone, a metering/mixing zone, and a feed block with a feed block zone, as is conventional within the art.

(22) The blister package shown in FIG. 1 is then manufactured by the subsequent steps of:

(23) unrolling from a roll the sheet laminate as a top web of the blister package;

(24) unrolling from a roll the blister package bottom web 4;

(25) disposing individual products 8 for consumption in each of the cavities 7;

(26) arranging the sheet laminate or top web with its bottom surface of the welding layer 3 facing the upper welding surface of the bottom web 4;

(27) welding the sheet laminate to the welding surface of the bottom web 4;

(28) cutting out or punching suitably sized blister packages from the webs welded together.

(29) These steps are carried out in a conventional manner.

(30) FIG. 2 shows another embodiment, which is identical to that of FIG. 1, except for a paper layer 5 being included. A print and/or ink may be provided on a major surface of the paper layer 5 facing away from the base sheet layer 1. The paper layer 5 is attached to the base sheet layer 1 by means of a solvent-based adhesive lamination layer 6. This adhesive lamination layer 6 is of adhesive/hardener LIOFOL LA 3644/LA 6055 as marketed by LOCTITE as of May 2013 and diluted with ethyl acetate. The adhesive is applied with a distribution of 2.74 g/m.sup.2, the hardener with a distribution of 0.26 g/m.sup.2. During manufacture of the sheet laminate, the coextrusion coating of layers 2 and 3 and the adhesion of the base sheet layer 1 to the paper layer 5 are carried out in separate steps. The adhesion is carried out first and in a conventional manner. Between the coextrusion coating and the adhesion steps, a drying or hardening time is applied to make it possible to carry out the other of the two steps.

(31) The embodiment of the blister package shown in FIG. 2 is manufactured in a manner similar to that of FIG. 1. However, subsequent to manufacture of the sheet laminate shown in FIG. 1, and before manufacture of the blister package, the sheet laminate of FIG. 1 is unrolled from a roll so as to adhere the paper layer 5 to the base sheet layer 1 by means of application of the adhesive lamination layer 6 in a conventional manner.

(32) FIG. 3 shows yet another embodiment, which is identical to that of FIG. 2, except for the following differences: Two tie layers 2a and 2b are applied in the coextrusion coating instead of the one tie layer 2 of FIG. 2, and the paper layer 5 is extrusion laminated to the base sheet layer by extrusion lamination by means of two extrusion lamination layers 6a, 6b.

(33) The tie layer 2b consists of Lotader 4503 as marketed by Arkema in January 2015. The tie layer 2a consists of Escor™ 5110 as marketed by ExxonMobil in January 2015. The distribution of tie layer 2b is 2 g/m.sup.2, and that of the tie layer 2a is 1.5 g/m.sup.2.

(34) The extrusion lamination layers 6a, 6b consist of PE MI 8 and PE MI4, respectively. The thickness of each layer 6a, 6b is 5 g/m.sup.2.

(35) The embodiment of the blister package shown in FIG. 3 is manufactured in a manner similar to that of FIG. 1. However, during manufacture of the sheet laminate, the extrusion lamination step and the extrusion coating step are carried out in one single run in a conventional tandem extruder in accordance with the above general description of the present disclosure. The tandem extruder comprises two extruders, one comprising a die for extrusion of the coextrusion coated layers 2a, 2b, 3 and another for extrusion of the extrusion lamination layers 6a, 6b. Each extruder comprises a feed zone, a transition zone, a metering/mixing zone, and a feed block with a feed block zone, as is conventional within the art. The extrusion lamination is carried out first, and the extrusion coating subsequently.

(36) During transport of the respective materials in the coextrusion coating extruder, i.e. during the course of the coextrusion coating step, the respective materials maintain the following temperatures in ° C. in the above-mentioned different zones of the extruder.

(37) TABLE-US-00009 Metering/ Metering/ Metering/ Feed Transition mixing mixing mixing Zone zone zone zone zone zone Layer 2a 120 250 270 270 270 Layer 2b 110 170 285 285 285 Layer 3 180 275 275 275 275

(38) TABLE-US-00010 Feed block Feed block Zone upper lower Die 1 Die 2 Die 3 All layers 275 275 275 275 275

(39) In the embodiments of FIGS. 1 and 2, where only a single tie layer 2 is present, the extrusion temperatures with respect to the tie layer 2 are identical to the tie layer 2b above. The temperatures with regard to the welding layer 3 are also identical.

(40) In an embodiment alternative to that of FIG. 3, the PET welding layer 3 is replaced by a PP welding layer 3. This alternative embodiment and the manufacture thereof is similar to that of FIG. 3 except for the following differences. Reference is made to FIG. 3 since the schematic layer structure is identical, but the layer materials are different.

(41) As in the embodiment of FIG. 3, the paper layer 5 is extrusion laminated to the base sheet layer 1 by extrusion lamination using the two extrusion lamination layers 6a, 6b.

(42) Two tie layers 2a and 2b are applied in the coextrusion coating. The tie layer 2a is replaced to consist of Nucrel 0609, a PE copolymer comprising EMAA which is selected due to the higher temperature with which the welding layer 3 is extruded, see below. The material of tie layer 2b is identical to that of tie layer 2b in the embodiment of FIG. 3 as described above. The distribution of the tie layers 2a, 2b is identical to the embodiment of FIG. 3.

(43) The extrusion lamination layers 6a, 6b consist of PE MI 8 and PE MI4, respectively. The thickness of each layer 6a, 6b is 5 g/m.sup.2.

(44) The present alternative embodiment of the blister package is manufactured in a manner similar to that of FIG. 3.

(45) During transport of the respective materials in the coextrusion coating extruder, i.e. during the course of the coextrusion coating step, the respective materials maintain the following temperatures in ° C. in the above-mentioned different zones of the extruder.

(46) TABLE-US-00011 Metering/ Metering/ Metering/ Feed Transition mixing mixing mixing Zone zone zone zone zone zone Layer 2a 140 200 165 300 300 Layer 2b 135 195 265 300 300 Layer 3 200 265 305 315 315

(47) TABLE-US-00012 Feed block Feed block Zone upper lower Die 1 Die 2 Die 3 All layers 310 310 310 310 310

(48) FIG. 4 shows yet another embodiment, which is identical to that of FIG. 3, except for the following differences: Only a single extrusion lamination layer 6 of PE MI 8 is included, distribution 10 g/m.sup.2.

(49) As in the embodiment of FIG. 3, the tie layer 2b consists of Lotader 4503 as marketed by Arkema in January 2015. The tie layer 2a consists of Escor™ 5110 as marketed by ExxonMobil in January 2015. The distribution of tie layer 2b is 2 g/m.sup.2, and that of the tie layer 2a is 1.5 g/m.sup.2.

(50) In the present embodiment, the laminate is manufactured in a manner similar to that of FIG. 3, i.e. the layers 5 and 1 are laminated to each other in a first process and, subsequently, the layers 2a, 2b and 3 are coextrusion coated on the layer 1 in a second, separate, process. The second process is similar to that described above in connection with the embodiment of FIG. 1.

(51) In a not shown alternative to the embodiment of FIG. 3, which is comparable to the embodiment of FIG. 1, the layers 5, 6a and 6b are not included in the laminate.

(52) Similarly, in a not shown alternative to the embodiment of FIG. 4, which is comparable to the embodiment of FIG. 1, the layers 5 and 6 are not included in the laminate.

EXAMPLES

(53) Samples no. 1-7 of the sheet laminate according to FIG. 3 were manufactured. An analysis of the puncture resistance of each Sample was then performed. A similar analysis was also performed on comparison Samples no. 8-10.

(54) Initially, a laminate consisting of layers 1, 5, 6a and 6b of FIG. 3 was produced according to the above description, i.e. layers 1 and 5 were extrusion laminated to each other by means of layers 6a, 6b. Layer 5 was a layer of paper type LB 002, revision 02 of 22 Jun. 2012 marketed by LENK Paper, distribution 23 g/m.sup.2, which is referred to as “Pap23” in the following. Layer 6a was of 23L430B as marketed by INEOS as of January 2014, and layer 6b was of 19N430B as marketed by INEOS as of November 2007, each of distribution 5 g/m.sup.2. Layer 1 was an annealed Al layer with a thickness of 6.35 μm. This laminate is referred to as “Pap23/PE10/AL6.35” in the following.

(55) Samples 1-7 were produced with different distributions of coextrusion coated layers 2a, 2b and 3 according to the embodiment of FIG. 3 on the laminate Pap23/PE10/AL6.35. As described in connection with the embodiment of FIG. 3 above, the tie layer 2b consisted of Lotader 4503 as marketed by Arkema in January 2015. The tie layer 2a consisted of Escor™ 5110 as marketed by ExxonMobil in January 2015. The welding layer 3 was of Skygreen PN100. The coextrusion coated layers 2a, 2b, 3 are denoted “CoexPET” in the following.

(56) In all Samples no. 1-7 and 10, the extrusion lamination was carried out in a first extrusion process to produce a laminate of layers 5, 6a, 6b and 1. The coextrusion coating of layers 2a, 2b3 a and 4 was then carried out subsequently.

(57) The distribution of CoexPET in Samples 1-7 is shown below.

(58) TABLE-US-00013 Sample no. Coex PET [g/m.sup.2] 1 59.21 2 29.94 3 15.98 4 10.33 5 7.66 6 5.63 7 5.09

(59) The analysis method applied for determination of puncture resistance of the manufactured laminates was according to standard ASTM F1306-90 as reapproved 1994, but adapted so that the sample test diameter was 48 mm instead of the 34.9 mm suggested in the standard's item 5.4.1. Accordingly, the puncture resistance (force to break) was measured in Newtons, N.

(60) For comparison, in Sample no. 8, puncture resistance was measured for the laminate Pap23/PE10/AL6.35 without CoexPET; and in Sample no. 9, puncture resistance was measured for 20 μm hard (non-annealed) Al with no other layers included.

(61) Puncture resistance was also measured for Sample no. 10, which was a laminate similar to those of Samples no. 1-7, i.e. including CoexPET. However, in Sample no. 10, Pap23/PE10/AL6.35 was replaced by a laminate of layers 5, 6 and 1 manufactured according to the embodiment of FIG. 2 above, i.e. including an adhesive lamination layer 6 of a solvent-based adhesive/hardener, specifically LIOFOL LA 3644/LA 6055 as marketed by LOCTITE as of May 2013 diluted with ethyl acetate. The distribution of layer 3 (the PET welding layer) of CoexPET was selected to 3 g/m.sup.2 in Sample no. 10. This laminate is denoted “Pap23/Al6.35/CoexPET6.5” in the following.

(62) The ratio between the distributions of tie layer 2a to 2b to 3 was about 1.5 to 2 to 3 in all of samples 1-7 and 10 so that the distribution of layer 2a was about 1.5/6.5×total distribution of CoexPET, that of layer 2b was about 2/6.5×total distribution of CoexPET, and that of layer 3 was about 3/6.5×total distribution of CoexPET. For example, in sample 1, the total distribution of CoexPET was about 59.21 g/m.sup.2, that of layer 2a was about 13.71 g/m.sup.2, that of layer 2b was about 18.27 g/m.sup.2, and that of layer 3 was about 27.24 g/m.sup.2.

(63) Pieces of the laminates of Samples no. 1-7 and 10 were welded as top webs to blister pack APET (APET type Sky 125 from manufacturer Skylight) bottom webs similar to the web 4 of the embodiment of FIG. 3 to produce blister packs as shown in FIG. 3 comprising one chewing gum tablet 8 in each cavity 7 of the blister pack bottom web 4. The welding parameters were 160° C., 3.7 bar for 1.6 seconds.

(64) It was then tested if the tablets 8 could be satisfactorily pushed through the sheet laminate top web by means of a finger of a hand. It was found that a satisfactory puncture resistance of the laminate was less than or equal to 6 N although a puncture resistance of up to about 7.5 N was evaluated to be acceptable.

(65) A puncture resistance of about 5.5 to 6 N was evaluated to be optimal. In all of Samples no. 1-7 and 10, the adherence of layer 3 to layer 4 was sufficient to allow for the welding strength not to be so low as to negatively influence the possibility to push out the tablets 8.

(66) The results from the experiments are shown below.

(67) TABLE-US-00014 CoexPET Layer 3 Puncture Sample distribution distribution resistance no. [g/m.sup.2] [g/m.sup.2] [N] 1 59.21 27.24 13.8 2 29.94 13.77 7.8 3 15.98 7.35 6.0 4 10.33 4.75 5.6 5 7.66 3.52 5.5 6 5.63 2.58 5.0 7 5.09 2.34 5.4

(68) TABLE-US-00015 Layer 3 Puncture Sample distribution resistance no. Laminate/layer [g/m.sup.2] [N] 8 Pap23/PE10/AL6.35 — 5.2 9 hard Al 20 μm — 3.2 10 Pap23/Al6.35/CoexPET6.5 3 5.9

(69) FIG. 5 shows the measured puncture resistance in Samples no. 1-7 as a function of the accumulated distribution of CoexPET.

(70) FIG. 6 shows the measured puncture resistance of each of the Samples no. 1-10.

(71) The tests show that when the distribution of CoexPET is at or below approximately 16 g/m.sup.2, the puncture resistance of the laminate is equal to or less than about 6 N. When the distribution of CoexPET is at or below approximately 10 g/m.sup.2, the puncture resistance of the laminate is less than 6 N. Comparably, the puncture resistance of Sample no. 8 was measured to 5.2 N.

(72) Thus, it has surprisingly been shown that a coextrusion coated PET welding layer can be included in a sheet laminate for being used as a top web for a blister package while achieving a satisfactorily low puncture resistance. Furthermore, it has surprisingly been shown that inclusion of the coextrusion coated welding layer does not significantly increase the puncture resistance of the laminate as long as the welding layer has a relatively low distribution, i.e. is relatively thin. The equipment used for manufacture did not allow for applying a thinner welding layer, but it can be expected that the welding layer distribution can be decreased even further while still allowing sufficient welding adherence to the bottom web. Furthermore, the puncture resistance was low enough to allow for satisfactory manual extraction of the tablets contained within the cavities by manually forcing rupture of the laminate.

(73) The puncture resistance of Sample no. 10 was measured to be somewhat higher than what it would be in a laminate according to Samples no. 1-7 having a similar CoexPET distribution. Nonetheless, it has been shown that a suitable puncture resistance may also be achieved using a solvent-based adhesive in accordance with the embodiment of FIG. 2.

(74) Based on the variation of the distribution of CoexPET in the experiments, it is expected that the accumulated distribution of the extrusion lamination layers 6a, 6b of FIG. 3 can be increased to about 15 g/m.sup.2 while maintaining a desired puncture resistance of the resultant sheet laminate.

(75) Further Samples no. 11-17 were manufactured according to the above embodiment described as an alternative to the embodiment of FIG. 3, i.e. where the PET welding layer 3 is replaced with a PP welding layer 3, specifically of WG341C as marketed by Borealis as of 7 Jul. 2015, Ed 1. Otherwise, the Samples were manufactured and the tests performed identically to Samples no. 1-10 above. The resultant coextruded layers 2a, 2b, 3 are denoted “CoexPP” in the following.

(76) The results from the experiments are shown below.

(77) TABLE-US-00016 CoexPP Layer 3 Puncture Sample distribution distribution resistance no. [g/m.sup.2] [g/m.sup.2] [N] 11 51.1 23.58 8.3 12 30 13.85 7.2 13 13.65 6.30 6.3 14 8.6 3.97 6.2 15 6.2 2.86 6.2 16 5.1 2.35 6.2 17 4.83 2.23 5.9

(78) The tests show that when the distribution of CoexPP is at or below approximately 14 g/m.sup.2, the puncture resistance of the laminate is equal to or less than about 6 N. When the distribution of CoexPP is at or below approximately 5 g/m.sup.2, the puncture resistance of the laminate is less than 6 N.

(79) Thus, it has surprisingly been found that a coextrusion coated PP welding layer can be included in a sheet laminate for being used as a top web for a blister package while achieving a satisfactory puncture resistance. Furthermore, it has surprisingly been shown that inclusion of the coextrusion coated welding layer does not significantly increase the puncture resistance of the laminate as long as the welding layer has a relatively low distribution, i.e. is relatively thin. The equipment used for manufacture did not allow for applying a thinner welding layer, but it can be expected that the welding layer distribution can be decreased even further while still allowing sufficient welding adherence to the bottom web. Furthermore, the puncture resistance was low enough to allow for satisfactory manual extraction of the tablets contained within the cavities by manually forcing rupture of the laminate.

(80) Accordingly, the balance between puncture resistance of the laminates manufactured according to the disclosure and the adherence of the PET and PP welding layers to the bottom web of the blister package for allowing pushing out of the product can be achieved with sheet laminates according to the disclosure.