DEVICE FOR REDUCING MICROBIOLOGICAL CONTAMINANTS OF CONTAINER PRODUCTS

Abstract

The invention relates to a device for reducing the microbiological contaminants of container products which consist predominantly of plastics materials. In said device a plastics granulate is fed to an extruder assembly (19) which melts the granulate, said granulate being subsequently supplied to a form fill seal machine for producing the relevant container product. The device also comprises a guide assembly (35) for the targeted guidance of the plasticated plastics material from the extruder assembly (19) to said machine. The device is characterised in that at least one guide assembly (35) has at least one flow or channel guide (41) for the melted plastics material, so that microbiological contaminants are guided predominantly into the interior of the wall of the polymeric tube, said interior being enclosed by regions of the plastics material that are less contaminated.

Claims

1. A device for reducing the microbiological contaminants of container products (11), which are mainly made from plastic material, in which a plastic granulate is supplied to an extruder device (19), which melts the granulate, which granulate is subsequently transferred to a blow molding, filling and sealing production machine (1) for obtaining the respective container product (11), with a guide device (35) for targeted guiding of the plasticized plastic material from the extruder device (19) to said production machine (1), characterized in that at least one guide device (35) has at least one flow guide or channel guide (41, 55) for the molten plastic material in such a way that microbiological contaminants are mainly guided to the wall interior (71) of the polymer hose, which is surrounded by less contaminated plastic material regions (72).

2. The device according to claim 1, characterized in that the extruder device (19) is equipped at the outlet side and in the direction of the production machine (1) with a mainly distributively mixing mixer device (31).

3. The device according to claim 1, characterized in that the mixer device (31) is a statically designed melt mixer with a flow guide or channel guide (41), which distributes microbiological contaminants in a non-homogeneous manner in the plastic strand (43).

4. The device according to claim 1, characterized in that the guide device (35) has, in addition to or alternatively to the respective mixer device (31) of the extruder device (19), a hose head with an oval-like cross section (oval sleeve 67) for the plastic material discharge to the molding tools (7) of the production machine (1), which is formed in the manner of a slit and initiates a linear shell outlet (51) starting from a central discharge point (47), which is supplied by the outlet (49) of the extruder device (19).

5. The device according to claim 1, characterized in that the hose head (33) has a housing (53), in which two guide tracks (55) are arranged as part of the guide device (35), each of which has, starting from a highest feed point (59) for the plastic melt, two supply lines (56) lying in a plane descending outwards in this plane.

6. The device according to claim 1, characterized in that the two supply lines (56) with involvement of the feed point (59) supply to all sides starting from this plane the slit-like discharge cross section (45) in the hose head housing (53).

7. The device according to claim 1, characterized in that the respective two guide tracks (55) taper in the direction of the production machine (1) initially with a constant discharge cross section in the manner of a crack in the direction of the production machine (1) such that, on the side of the shell outlet (51) a constant discharge speed is obtained with respect to this shell outlet (51).

8. The device according to claim 1, characterized in that the two guide tracks (55) are arranged extending symmetrically (FIG. 3b) in a longitudinal axis (57) of the hose head (33) parallel to the discharge direction of the extruder device (19).

9. The device according to claim 1, characterized in that the two guide tracks (55) in the hose head (33) delimit at the external circumference receptacles (69), which can be penetrated by filling pins of the production machine (1).

10. The device according to claim 1, characterized in that the two guide tracks (55) in the hose head (33) are delimited at the external circumference in the housing (53).

11. The device according to claim 1, characterized in that, by means of the extruder device (19) a co-extrusion method is realized, which leads to a multilayer construction of the wall of the closed and filled container product (11) and, in that only the polymer forming the inner surface of the thus co-extruded container (11) is subjected to the reduction of microbiological contaminants.

12. A hose head, in particular for use in a device according to claim 1, characterized in that the hose head (33) has a housing (53), in which two guide tracks (55) are arranged as part of the guide device (35), which each have, starting from a highest feed point (59) for the plastic melt and lying in a plane, two supply lines (56) descending outwards in this plane which, with the involvement of the feed point (59) to all sides starting from this plane, supply the slit-like discharge cross section (67) in the hose head housing (53) for the purpose of discharge of a closed plastic shell for the subsequent container production.

Description

[0023] The device according to the invention and the hose head shall be explained in detail below with reference to an exemplary embodiment according to the drawings. Said drawings show, in schematic and not to scale depictions:

[0024] FIG. 1 a highly simplified overall depiction of an exemplary embodiment of a blow molding, filling and sealing production machine, in particular according to the teaching according to document DE 10 2008 006 073 A1 (production machines of type 460 by the company rommelag);

[0025] FIG. 2 a highly simplified overall depiction, partially drawn in the longitudinal section, of a standard extruder device with input-side feeding hopper for the plastic granulate and a hose head arranged on the output side, which discharges the molten plastic material at the input side on the top side of the BFS device according to FIG. 1 to said BFS device;

[0026] FIGS. 3a, b, c in longitudinal depictions, in a top view and cut and in elevation, a side depiction of the hose head according to FIG. 2, and

[0027] FIG. 4 a schematic cross section through a filled container product (oval ampule) produced according to the invention with an advantageous non-homogeneous distribution of microbiological contaminants, in other words, regions with different contamination concentrations.

[0028] FIG. 1 depicts a production section lying at the top in the figure identified as a whole with the reference numeral 1 and a demolding device connected thereto at the bottom identified as a whole with the reference numeral 3. The production section 1 is a machine device for carrying out a so-called blow molding, filling and sealing method in accordance with the well-known bottelpack system, and in an embodiment in which various molding steps are carried out at various stations along a production line 5. In a type of carousel arrangement, individual molding parts 7, only some of which are numbered in FIG. 1, are moved in pairs towards one another on a kind of virtual circular arc track in order to form a closed production mold, and are moved apart from one another again in order to open the respective mold. Because machine devices functioning according to the bottelpack method are known per se, further description of the details of the production section 1 of FIG. 1 is not necessary.

[0029] As can also be seen from FIG. 1, the container chain 9 formed by the individual molding parts 7 extends along the production line 5 and, at the bottom end of the production section 1, projects out of same and arrives, at the input side, at the demolding device 3. The container chain 9 is a wide container chain conveyor, in which a number of individual container 11 having an ampule-type design as plastic container products are arranged in the container chain 9 side by side and lying next to one another projecting into the drawing plane of FIG. 1.

[0030] To assist with the removal of the containers 11 and thus of the container chain 9 from the walls of the individual molding parts 7 which move apart from one another at the discharge region, the demolding device 3 conveys a displacement movement to the container chain 9, as indicated in FIG. 1 with a double arrow 13. For this purpose the demolding device 3 has a carrying arrangement 15 which, in geared connection with an electric drive motor 17, generates the displacement movement of the container chain 9 in order to reliably detach the containers 11 from the mold wall parts of the molding parts 7. Further details concerning the further construction of this production machine 1 together with the demolding device 3 can be obtained from document DE 10 2008 006 073 A1.

[0031] This blow molding, filling and sealing machine 1 together with the demolding device 3 according to FIG. 1 forms, as part of the overall production method, an additional production chain 9 that connects to a first production chain, the major components of which are the subject of FIG. 2. This first production chain comprises an extruder device identified as a whole with the reference numeral 19 using a so-called screw extruder, the screw conveyor 21 of which can be driven by a drive 23. At the external circumference side heating devices 25 are arranged on the rotatable screw conveyor 21 in order to plasticize or to liquefy the plastic granulate (not depicted) which is supplied by means of a feeding hopper 27. While the feeding hopper 27 is located on the right input side of the screw conveyor 21, a mixer device 31 is arranged on its output side, which transfers the plasticized or partially liquefied plastic material to a hose head 33. This hose head 33 has a kind of oval cross section, as shall be explained in further detail below, in order to thus discharge in the manner of a curtain a plastic hose, closed at the shell side, to the production machine 1. For the sake of simpler depiction, the other production devices of the blow molding, filling and sealing production machine 1, for example in the form of the filling pins for the introduction of the liquid container contents to be stored in the container, were dispensed with as were any blow pins for producing the blow mold and any vacuum devices present for improved contact of the plastic material on the mold inner wall of the individual molding parts 7 of the production machine 1. These production measures are known per se and will therefore not be addressed in further detail here.

[0032] The working temperature of polyethylene as the plastic material used is ca. 170 C. to 200 C. and is ca. 180 C. to 250 C. in the case of polypropylene materials, with the discharge pressure behind the extruder device 19 with the mixer device 31 at the point of transition to the hose head 33 conventionally being approximately 100 to 400 bar.

[0033] According to the invention, the extruder device has in the context of the mixer device 31 a guide device 35, which permits flow guidance for the molten plastic material in such a way that the potentially present microbiological contaminants migrate to the inside of the plastic strand 37, which are enclosed by less contaminated plastic material regions 39. The mostly distributively mixing parts of the respective mixer device 31 form statically designed melt mixers, with a channel guide 41, which distributed plastic content contaminated with biological contaminants such as spores, bacteria or endotoxins, etc., by means of the extruder device 19 in a non-homogeneous manner in the produced plastic strand 43, which leads in a surprising manner to contaminants also in the polymer hose and thus in the wall (FIG. 4) of the container product 11 becoming concentrated mainly on the inside 71 of the wall and which are enclosed by less contaminated plastic content 72, which significantly reduces the action of said contaminants relative to the filling material 73 in the plastic product 11 and thus their damaging effects.

[0034] As static mixer devices 31 mixing elements without mobile parts for example are used, of the kind which can be procured with the type designations SMX and SMX plus from the company Sulzer Chemtec AG, Winterthur, Switzerland. SMB plus melt mixers from the company Promix Solutions, Linden, Germany or the melt mixer CSE-X from the company Fluitec, Neftenbach, Switzerland, are likewise suitable for this purpose. Furthermore, such static mixing devices can be used on the basis of their technical construction as described in the U.S. Pat. No. 7 077 561 B2 and in the US patent publication 2012/0106290 A1.

[0035] According to the invention, said static mixer devices 31 demonstrate achievement of the desired inherently non-homogeneous distribution of microbiological contaminants, although these mixers are actually used for the homogenization of polymer melts, in particular when dyes, filling materials, etc. are added.

[0036] In a surprising manner it was thus found that static mixers which are known per se demonstrate a completely different mixing behavior: while dyes, filling materials, reinforcing fibers, etc. and similar particles are homogeneously distributed in the container wallas is always necessary for dyes for optical reasons, in the case of microbiological contaminants, the described rather non-homogeneous distribution that is advantageous according to the invention, the described encapsulating effect, is obtained.

[0037] As already explained, in a surprising manner the advantageous non-homogeneous distribution of the solid plastic melt strand 43 is advantageously maintained even in the case of forming of the polymer hose and thus in the cross section (FIG. 4) of the container 11.

[0038] The reason for this is not known, but it is suspected that this is due to a complex interaction of several factors. On the one hand this involves the surface chemistry and structure of the microbiological contaminants, probably in particular their physical wettability and chemical interactions with hot polymer melts, and on the other hand their size and form factors, which influence the alignment of the microbiological contaminants in the melt flow. It should be taken into account that the rheological properties of the polymer are highly dependent on the temperature, the shear forces and the molecular weight distribution of the polymers themselves, and thus their distribution across the strand cross section or hose cross section.

[0039] The previously described guide device for the plastic strand 43 can, additionally or alternatively to the respective mixer device 31, comprise the hose head 33 in the production line before the production machine 1 with an oval-like cross section for the plastic material discharge to the molding tools 7 of the production machine 1. This discharge cross section 45 is formed in the manner of a slit (cf. FIGS. 3a, 3b) and is supplied from a central discharge point 47, which is in turn supplied from the outlet 49 of the extruder device 19 and thus permits a curtain-like circumferentially closed shell outlet 51 on the output side of the hose head 33.

[0040] As FIG. 3a and the subsequent figures also show, the hose head 33 has a housing 53, in which two guide tracks 55 which are separated from one another extend as part of the guide device 35. The two guide tracks 55 lie, viewed in the viewing direction of FIG. 3b, symmetrically on opposite sides of a longitudinal axis 57 of the hose head 33, which longitudinal axis is arranged parallel to the conveying direction of the extruder device 19. The two pairs of guide tracks 55 are, starting from a highest feed point 59, supplied for the plastic melt lying in a plane which, in the form of supply lines 56 arranged in pairs, descend towards the outside starting from this plane. Viewed in the viewing direction of FIG. 3b, the outlet 49 of the extruder device 19 expands conically in the direction of the hose head 33 and has on the inside a supply channel 61 which, via an additional channel section 63 in the hose head 33 opens into a sheet feeding 65, which supplies the feed point 59. Due to the symmetrical construction of the hose head 33, the supply arrangement described in this respect is also comparably arranged, viewed in the viewing direction of FIG. 3b, relative to the longitudinal axis 57 of the device in a plane lying under same. To this extent, via the respective guide device 35 with the highest feed point 59 the oval sleeve 67 of the hose head 33 is supplied.

[0041] The two respective supply lines 56 as part of each guide track/distributor channel 55 with the involvement of the top feed point 59 and towards all sides, starting from the corresponding discharge plane, permit the supply of the slit-shaped discharge cross section 45 at the bottom side of the hose head housing 53. According to the depiction of FIG. 3c, this slit tapering occurs directly after the plastic material leaves the region of the guide tracks 55 or of the supply lines 56.

[0042] The guide tracks 55 in the hose head 33 delimit at the external circumference receptacles 69, which can be penetrated by filling pins (not depicted) of the production machine 1. The blow-molded plastic containers can thus be filled in a sterile manner with a filling medium. Thanks to the consistent residence time of the polymer for the container wall and the through-flow in the thin-faced distributor channels which form the slit-like discharge section 45, there is a non-homogeneous alignment of the microbiological contaminants to the inside of the thus formed polymer hose, which is supplied, viewed in the viewing direction of FIG. 1, to the production machine 1 from the top.

[0043] In the context of practical testing of the device solution according to the invention, for all of the exemplary embodiments materials, container sizes and machine settings were selected which represent the worst case regarding the mechanism of reduction of microbiological contaminants. As an example of microbiological contaminants resistant spores of bacillus atrophaeus and bacillus pumilus were selected as test bacteria, as is standard in sterility testing. As container materials, polymers that have low BFS working temperatures were additionally used in order to keep at low levels the thermal effects on the artificially added spores. In addition, process parameters were selected which have only minimal effects on the spores, but which lead to container products with useable quality and standard output quantities. The throughput of polymer through the extruder device 19 was thus set to the upper limit in order to thus minimize the duration of the heat effect on the artificially added spores.

[0044] Furthermore, a BFS system of the type 460 from the company rommelag, Waiblingen, Germany, was used, as is partially depicted in FIG. 1, with a cycle time for the entire container production of ca. 3.5 seconds. As plastic granulate, which is supplied via the feeding hopper 27 to the extruder device 19, polymers were used such as Purell LDPE of the type 1840 H from the company LyondellBasell and Ineos LDPE of the type Eltex MED 30 PH 23H630 with working temperatures of the extruder 19 and also of the hose head 33 in the range between 160 C. and 165 C.

[0045] To produce the contaminated granulate tests endosphores of bacillus atrophaeus ATTC 9372 with a D-value D.sub.1600-c=0.2850.08 min were used. In a similar manner, spores of the very small reference bacteria, bacillus subtilis 1031, were used. The spores were uniformly distributed on the plastic granulate used and the spore content was verified under laboratory conditions. The concentration range was 10.sup.3 to 10.sup.6 CFU per gram. 10 ml containers 11 filled with 6 ml liquid CASO nutrient solution were also produced.

[0046] For further clarification: CASO nutrient solution is a complex medium, to which is added, besides glucose, peptone obtained proteolytically from milk protein (casein peptone) and peptone obtained proteolytically from soy flour (soy flour peptone). Casein peptone is rich in free amino acids and the soy flour peptone is distinguished by a high carbohydrate and vitamin content. Such nutrient media are particularly well suited for cultivation of fastidious microorganisms.

[0047] For each test batch more than 12,000 container products were produced, with the analytical procedure otherwise corresponding to the content of the above-mentioned article by Frank Leo et al. Evaluation of Blow-Fill-Seal-extrusion through Processing Polymer Contaminated with Bacterial Spores and Endotoxin.

[0048] In a first step, three reference batches, i.e. without application of the methods according to the invention, were prepared for the spore inactivation. For this purpose, a pin wrench distributor with holes, which is standard in extrusion technology, was used as a dynamic mixer device (as shown in the book by W. Michaeli) and a hose head with a circular cross section and a circular cylindrical sleeve was used, with a bacteria count reduction being obtained, in particular due to thermal effects, of on average 10.sup.3CFU/gram (colony-forming units per gram).

[0049] When the polymer granulate contaminated with spores of the bacillus atrophaeus is extruded using the above described static mixer devices 31, with the total length of the extruder device 19 remaining unchanged compared with the reference tests, a deactivation of the contaminant through said encapsulation was obtained which was improved by a factor of 50-170. In the case of the use of spores of the bacillus subtilis, an increased effect compared with the reference was obtained with an inactivation factor of on average 100.

[0050] When, in an additional or alternative manner, the contaminated polymer granulate is introduced with a hose head 33 with an oval sleeve 67 in accordance with the design according to FIGS. 3a to 3c, an inactivation of the used spores is in turn obtained which is improved by a factor of 70-230. Further tests were also realized with spores of the bacillus megaterium CDC 684, which are larger compared with the spores of the bacillus atrophaeus and of the rather spherical bacillus sphaericus ATCC 4525 with an average length-to-diameter ratio of ca. 1.27, and with spores of the bacillus stearothermophilus ATCC 12980. The latter have almost double the diameter compared with the spores of the bacillus subtilis. In all tests significantly improved inactivations of the respective spores were obtained compared with the respective reference.

[0051] All of the above-mentioned methods according to the invention together with the device according to the invention for minimizing the microbiological contamination have the advantage that it is not an empty container or even an already filled container 11 that is to be sterilized, as is described in the prior art, instead solely the already plasticized polymer suffices as a mechanism of inactivation by encapsulation, and there is no equivalent of this in the prior art.

[0052] When producing multilayer containers according to the BFS method, as described for example in document DE 103 47 908 A1, it may be sufficient to use the respective described devices according to the invention solely for the polymer granulate which forms the inner surface of the container 11.