EP0936997A1 - Solvent pack with aseptically sealed snap cover and preform for producing this pack - Google Patents

Abstract

A package for flowable media and a snap lid which package and snap lid are both made from thermoplastic material, in which a collar-shaped head of the package surrounds a pouring aperture of the package, which collar-shaped head has a retaining ring on its outside, an inside annular surface, and an upper end having an edge with a snap catch, which upper end can be closed using the snap lid. The snap lid has a closing wall from which an annular sealing lip projects towards an inside of the package, and can be brought into contact with an inside surface of the edge in sealing engagement. The closing wall is provided with an outside catch for snap engagement with a snap catch of the edge of the head. The head of the package widens outwards and upwards at its edge, and both the inner surface of this edge and an outer surface of the sealing lip on the snap lid are curved convexly relative to each other. The invention also includes preforms for making the package of the invention.

Description

 Plasticizer pack with aseptically tight snap lid and preform for the production of this pack

The invention relates to a plastic packaging with a snap lid, both of which are made of thermoplastic, in which the collar-shaped head encloses a pouring opening, the outside has a retaining ring, the inside has an approximately annular inner surface, and at the top at the free end has an edge with a snap catch and can be closed by the snap lid , from the closure wall of which an annular sealing lip protrudes from the inside of the pack and can be brought into sealing engagement with the inner surface of the edge and which has an outer catch for snap engagement with the edge of the head.

The invention also relates to an injection-molded preform for producing a plastic packaging made of thermoplastic, in which the collar-shaped head encloses a pouring opening, on the outside a retaining ring, on the inside an approximately annular inner surface and at the top at the free end has an edge with a snap catch.

Injection molded preforms made from plastic, in particular from polyethylene terephthalate (PET), are known. A distinction is made between preforms and the resulting packs, e.g. B. bottles, three different areas, namely the bottle head, the body and the bottom. The bottle head is often formed with a thread and with sealing surfaces. The later inflated and filled bottle is then closed with a screw cap. For aseptic closures, the screw caps either have sealing inserts, such as B. foils, or the screw caps are formed with special sealing lips that seal on the cylindrical inside of the bottle head or on the bottle rim.

Snap closures made of plastic are also known, which also seal on the inside of the bottle mouth. These snaps are z. B. used in still mineral waters. Known snap caps of this type have an external snap edge with an internal wedge seal. The inside of the cylindrical head of the preform or the bottle has no curvature along the cylinder axis.

Although this gives you a seal against liquids, such as. B. water or the like, with a low capillary action, but not a tightness against methyl alcohol or z. B. helium. Helium is one of the smallest chemical elements particularly good as a measuring medium for leak tests. If you want an aseptically sealed closure on a plastic packaging, you can use such measuring methods.

The object of the invention is to provide an eluent pack of the type mentioned, the head of which can be aseptically sealed with the snap lid; and the creation of an injection-molded preform, as also described above, from which a package of the type mentioned can be produced, the head on the preform not being changed during the production process of the package.

According to the invention, the object is achieved for the superplasticizer pack in that the head of the pack expands radially outward and upward at its edge and both the inner surface of this edge and the outer surface of the sealing lip on the snap cover in the direction of view of each of these two surfaces are convexly curved. First of all, it should be explained that the pouring opening and thus the head of the pack is arranged on the side of the pack opposite the stand base, namely “above”. The free end of the head is therefore at the top, where the mentioned edge with the snap catch is arranged. At this upper free end, the pouring opening can be closed by the aforementioned snap lid, which essentially has the shape of an inverted U in cross-section, the web connecting the two free legs of the U being the projection onto the closure wall. In accordance with the generally circular configuration of the pouring opening, the closure wall is a flat, round disk, which is preferably essentially flat. An outer ring adjoins its annular outer circumference via a curvature, which ensures that the edge of the head is enclosed. The outer ring can be set weakly against the edge of the head, e.g. B. at an angle of 5 to 10 °, preferably about 20 °. At the outer lower end of the outer ring, a locking device is attached, which if necessary provides a catch on the head of the pack to hold the snap lid on the head.

Such a snap lid is clamped onto the edge of the pack and can be snapped particularly well at the free end by the head of the pack expanding outwards and upwards. The diameter of the edge at the upper free end of the packing head is therefore larger on average than the diameter of the pouring opening.

This radial expansion of the edge outwards and upwards provides an inner surface of this edge. Looking at this, the curvature is convex.

If you look at the snap lid and look at the inside of its closure wall, then one recognizes the ring-shaped sealing lip protruding from the closure wall against the viewing direction, namely inwards. Their diameter is matched with respect to the center of the snap lid to the outer surface of the widening edge of the packing head. The edge and the sealing lip should namely be brought into mutual sealing engagement with one another. The outer surface of the sealing lip plays a role, and according to the invention it is curved so that it appears convexly curved when viewed obliquely from the outside on the outer surface of the sealing lip. The curvature of the inner surface of the edge on the head and the curvature of the outer surface of the sealing lip on the snap cover are therefore curved towards one another. These two surfaces come to rest on one another when the snap cover is closed, and the convex curvatures result in a sealing line according to the teaching of the invention. In other words, the two curved lines touch at one point in cross section along the pouring opening. This point is the projection of the line that extends along the sealing lip or along the edge of the head. This line contact allows the aseptically tight closing of the head with the snap lid described.

Bacteria and spores are generally much larger than helium atoms and can therefore pass a helium-tight seal less than helium atoms. In order to define the aseptic tightness according to the invention, two criteria have been defined: the first criterion demands the tightness against helium. The second criterion for an aseptically sealed closure requires that the sealing surfaces can be sterilized. An aseptically tight closure in the sense of the teaching according to the invention is therefore a closure which is at least tight against methyl alcohol, preferably even dichloro against helium. This condition is guaranteed by the solution according to the invention.

It is particularly advantageous if the sealing surfaces of the aseptically sealed closure can also be easily sterilized. That is u. a. is particularly well guaranteed if the surfaces of both the top edge and the snap cover facing the interior of the pouring opening have surfaces that are as smooth as possible. According to the invention, it is ensured that the surfaces facing the interior of the pack have no or almost no undercuts. The sterilization processes then work particularly well. The person skilled in the art understands that a rim which widens radially outwards and upwards on the one hand and a snap cover with a sealing lip which projects downwards on the other hand enable smooth surfaces without undercuts.

The tightness between the head of the package and the snap lid is checked in the case of the invention by two different mechanisms, the following macrological Seal and micrological seal are called. It may already be sufficient if the micrological seal has been measured and reached in order to describe the sealing of a packing head of the type described here with a snap lid as aseptic.

With the micrological seal, care is taken to ensure that as much compressive stress as possible is concentrated at one point and thus reliably sealed aseptically at this point or on the corresponding line of maximum compressive stress. According to the invention, series of tests were carried out which have shown that a high stress concentration on only one line of the sealing surface, as described above, leads to better sealing properties than the distribution of the contact forces over several contact lines. Due to the convex curvatures of the sealing surfaces lying on top of one another, this stress concentration is advantageously achieved on a single line.

In an advantageous further embodiment of the invention, the snap cover has on its inside a ring-shaped snap notch which surrounds the sealing lip and extends over the edge of the head, and the thickness of the snap cover is smaller in the direction outside and above the snap notch than in the area of the outer catch. Where the closure wall of the snap cover ends on the outside and merges into the described outer ring due to a curvature, there is the snap notch on the inside, which can reach over the edge of the head when the snap cover has been pressed onto the head of the pack. It is precisely in this transition area between the upper closure wall and the lateral outer ring of the snap cover that the material thickness is reduced according to the invention so that it is less than the material thickness in the area of the outer catch, which - without the head of the pack in between - lies opposite the outer surface of the sealing lip. In the area of this outer catch and / or in the area of the sealing lip, according to the invention the wall thickness is selected to be larger than in the transition area described above. Where the material thickness is greater, the snap lid has greater rigidity. If, according to the invention, the material thickness is reduced in the area outside and above the snap notch, ie in the wall outside the snap notch, there is less rigidity and a line around which, as about an axis, the outer ring of the snap cover relative to it Closing wall can be bent. Again in cross-section along the pouring opening, this bend line represents the point about which the outer ring can rotate. In other words, according to the invention, a vertical section in the vertical section creates a point of rotation in the transition region between the closure wall and the outer ring of the snap cover, by means of which there are possibilities for compensating for shape defects in the parts to be sealingly engaged, as was previously unknown in conventional closures. As a result, according to the invention, the second tightness criterion can also be met, in that, in addition to the micrological tightness, there is also the macrological tightness. The macrological tightness compensates for larger defects in the shape of the snap lid or the packing head, e.g. B. Out of roundness, delay. Between the sealing lip formed on the closure wall of the snap cover on the one hand and the outer catch of the snap cover formed on the outer ring at the top, there is the compensating rotational line (a rotation point in vertical section), which gives both the sealing lip and the outer catch sufficient leeway in order to avoid the possible dimensional errors mentioned of the snap lid and the packing head. Since the snap cover is made of relatively soft plastic and the large material thicknesses in the area of the outer catch and also in the area of the sealing lip lead to a relatively rigid behavior, the tapering of the material in the area described above results in the rotation line. In addition to compensating for dimensional errors, the macrological seal also has the function of providing suitable tensile and compressive forces for the secure fit of the snap-on lid on the packing head and for the contact pressure of the sealing lip.

It is also advantageous according to the invention if, in cross section along the pouring opening, the radius of curvature of the inner surface of the edge of the packing head decreases from the inside of the packing towards the free end, preferably reduced from infinity to 0.5 mm. Proceeding from the uncurved cylinder wall facing the interior of the packing, which therefore has an infinitely large radius of curvature, the sealing properties have proven to be very favorable if the radius of curvature decreases towards the free end. It is similarly favorable if, according to the invention, the cross-section along the pouring opening of the radius of curvature of the outer surface of the sealing lip on the snap cover is in the range from 0.2 mm to 2 mm. The area with the greatest curvature is therefore on the surface, where it has a radius of curvature of only 0.2 mm; while the area of the weakest curvature has a radius of preferably about 2 mm. According to the invention it is further provided that the convexly curved inner surface in the region of the head edge and the convexly curved outer surface of the sealing lip have a low roughness for a high surface quality and are designed without raised parts. The manufacturing tools for casting the preforms when bottles are blown from them often have parting lines that are in parting lines. The resulting workpiece then sometimes has beads, small ribs or knobs that form as raised parts. According to the invention, the production tool is to be designed in such a way that such parting planes, insofar as they are necessary on the tool at all, do not come to lie in the oppositely curved surfaces mentioned. This gives you smooth Sealing surfaces and optimal tightness. The tools for producing these convexly curved surfaces can preferably be polished to a high gloss. This results in a high surface quality, which further improves the tightness.

In order to obtain a good and reliable seal, it is also advantageous if, according to the invention, the snap cover consists of a softer thermoplastic than the head of the pack, preferably of amorphous polypropylene. If the plasticizer is blown from a preform, it is useful if this preform z. B. consists of PET, APET, PETG.

The object of creating an injection molded preform, with the head of which an aseptically tight closure can be achieved by means of a snap cover of the type mentioned above, is achieved according to the invention in that the head of the preform widens radially outwards and upwards at its edge and the inner surface this edge is convexly curved in the direction of view of this. The purpose of the manufacture and configuration of the preform according to the invention is ultimately also the manufacture of a plasticizer packaging and its aseptically tight closure with a snap lid. However, no reference needs to be made to the snap lid before the superplasticizer pack itself is made, and yet it is expedient to take the measures mentioned in order to then achieve the same advantages as in connection with the finished superplasticizer package. Reference is therefore made to the explanations of the corresponding design of the superplasticizer package, which also apply to the preform. Ultimately, the design and arrangement of the snap cover then also play an important role, so that a corresponding applicability should also exist for the preform.

Similarly, reference is made to the above explanations regarding the shaping of the radii of curvature and surface roughness if it is noted for the injection molded preform that according to the invention in cross section along the pouring opening the radius of curvature of the inner surface of the edge of the head of the preform from the inside of the Preform decreases towards the free end, preferably decreases from infinity to 0.5 mm. The same is true in the advantageous embodiment of the injection molded preform, wherein according to the invention, the convex ^'curved inner surface in the region of the head edge for a high surface quality has a low roughness and is formed with no raised portions.

Like the plasticiser itself, the injection molded preform made of polyethylene ephthalate (PET).

The snap cover, on the other hand, to which reference is made only indirectly in connection with the injection-molded preform, namely via the manufacture of the plasticizer pack of the type mentioned at the outset, can be produced from the following materials:

PP random copolymer type 3300 MC from BASF,

PP random block copolymer type NX 40036 from BASF,

PE metallocenes type Luflex 1712SX from BASF,

LDPE type 1200MN18 from ELFATO,

LDPE type 1700MN18 from ELFATO and

PP Moplen EP-C57MA from Montel.

With the head shaped according to the invention both of the preform and of the plasticizer pack of the type described above, the use of material for packs which can be sealed aseptically can advantageously be reduced. By dispensing with a thread, the wall thickness of the head can also be made thinner. Compared to a conventional preform with a threaded head that weighs approximately 50 g, 6 g of PET can be saved in the preform according to the invention.

Another advantage of the preform head shaped according to the invention is the functional division into the macrological seal and the micrological seal. This reliably compensates for large error tolerances that can occur when the package is molded. Because the contact point or the contact line of the micrological seal on the curved inner surface of the packing head can migrate over a wide range both in the axial and in the radial direction, large error tolerances can also be reliably compensated for. A typical order of magnitude of the fault tolerance, which occurs with a packing head outer diameter of 34 mm, is +/- 0.1-0.2 mm.

The packages formed with the packing head according to the invention can be filled with drinks with a low carbon dioxide content. The internal pressure of a filled package, e.g. B. a PET bottle, is advantageously in the range of 1 bar - 4 bar.

Further advantages, features and possible uses of the present invention result from the following description of preferred exemplary embodiments in conjunction with the attached drawings. Show it: FIG. 1 broken and enlarged a cross-sectional view along the pouring opening, only the hinge-side end of the snap-on lid drawn onto the head of the pack being shown in sealing engagement being shown,

Figure 2 is an eluent pack with the head designed according to the invention and

Snap lid, the package is shown here as a PET bottle,

3 shows a broken-off and enlarged part of the packing head with a snap-on lid according to detail III in FIG. 2 and

FIG. 4 shows an injection-molded preform which has the same configuration in the upper region as is shown enlarged in FIGS. 1 and 3 for the finished-blown bottle.

The superplasticizer pack 1 shown in FIG. 2, here a PET bottle, has a collar-shaped head 3 closed at its upper end with a snap cover 2. This surrounds a pouring opening 4. The cross-sectional views of the figures are taken through the longitudinal central axis 5 of the plasticizer pack 1 or the injection-molded preform 6 according to FIG. 4. The pouring opening 4 is surrounded by the annular inner surface 7 arranged on the inside of the head 3. In the lower region of the pouring opening 4, namely towards the interior of the package 1 or the preform 6, this can be designed essentially in the form of a cylinder jacket. For the sake of simplicity, the shape of this inner surface 7 is almost cylindrical-shell-shaped in the schematic representation of FIG. 1, while this inner surface 7 in the embodiments according to FIGS. H. the area of the head 3, narrowing frustoconically to about half the height (line 8); and then, seen further upward in the direction of arrow 9, above the central height 8 is designed to expand slightly frustoconically. At the free upper end 10 of the head 3 - in relation to what has just been described - a radially outward and upward widening edge 11 is formed to form a snap catch 12. The inner surface 13 of this edge 11 is consequently curved upwards and outwards. If one looks obliquely from above onto this inner surface 13 of the edge 11 in the direction of the normal according to arrow 14 (FIG. 1), the curvature appears convex.

The head 3 of the pack 1 or of the preform 6 is provided on the outside below the edge 11 with a catch 15 which, as a projection, delimits an outer groove 16 towards the top. The latter is limited at the bottom by an outwardly projecting retaining ring 17. The same conditions are found both on the head 3 of the plasticizer 1 and on the head 3 of the preform 6. A locking device 18 of the snap cover 2 engages in the annular outer groove 16 of the head 3, which runs perpendicular to the longitudinal central axis 5. This closure lock 18 forms a visual protection for the consumer when the pack is filled and closed, which indicates the first opening of the pack by breaking predetermined points 19 of the closure lock 18 when the snap lid is opened for the first time.

Apart from this locking device 18, the snap-on lid 2 generally has the shape of a cup, which is clamped onto the head 3 with the opening facing downward in the cross section of a U. The snap cover 2 then has the essentially flat closure wall 20 at the top. This is adjoined on the outside by an approximately cylindrical jacket-shaped outer ring 21 which is hinged in relation to the opening handle 22, the hinge being partially formed only by the predetermined breaking points 19 and not playing a special role. After repeated opening, the predetermined breaking point 19 will also break in this area opposite the handle 22, so that the snap lid 2 can then be loosely removed after opening again.

From the closure wall 20 of the snap cover 2, an annular sealing lip 23 protrudes toward the inside of the pack 1. The radially outer surface 24 of this sealing lip 23 is curved radially outward from the center. The cross section shown in the cross-sectional representations (along the pouring opening 4 or the longitudinal central axis 5) shows a curvature which, according to FIGS. 1 to 3, is opposite to the curvature of the inner surface 13 of the edge 11. So there are opposite curvatures. If you look in the direction of arrow 25 (against arrow 14) in the direction of the normal to this curved, curved surface 24 of the sealing lip 23, then it appears convex. The surfaces 13 and 24 are therefore oppositely convex curved surfaces. These two touch in the illustration of FIGS. 1 to 3 at a point 26 which is an annular line 26 in the three-dimensional body.

In the transition area between the closure wall 20 and the outer ring 21, the snap cover 2 is provided with a snap notch 27. Radially outwards, diagonally upwards, the material of the snap cover 2 is formed with a thickness d that is smaller than the thickness of the closure wall 20, with the result that an annular rotation line 28 results in the snap cover 2, which is shown in FIG. 1 as a point is shown. This point of rotation or line of rotation 28 is an element of the macrological seal described above. The snap notch 27, in cooperation with an outer catch 29, which is configured in the form of a bead underneath and provided on the inside of the outer ring 21, and the snap catch 12 of the head 3 secure closure of the snap lid 2 on the head 3. The imaginary force arrow 30 schematically shows in FIG. 1 the closing force with which the two curved surfaces 13 and 24 are pressed against one another at the point of contact (line 26). These sealing surfaces 13 and 24 are always convex to one another. This always results in exactly the defined contact point (line 26) for the above-mentioned micrological seal. This line 26 can move on the curved sealing surfaces 13 and 24 and thus compensate for dimensional inaccuracies due to manufacturing errors due to thermal expansion. The filled packs are often exposed to different temperatures during transport and storage. Sometimes the packages are in the blazing sun, other times in a cold room. The new snap lock offers with its micrological seal, in particular that the support line 26 can migrate on the curved inner surface 13 of the edge 11 and thus compensate for thermal expansion, increased security against leaks. Likewise, increased security against leaks is made possible, which can result from the manufacturing tolerances of the preforms 6, as shown in FIG. 4, the snap lid 2 or the package 1 (PET bottle) formed by blisters. Leakages caused by vibrations are also avoided in this way.

FIG. 4 shows a blow parison 6 with the new head 3. The inner surface 13 on the edge 11 is formed with a highly polished injection molding tool. Such tools can be made in particular in such a way that in the area of this inner surface 13, which forms the curved sealing surface of the head 3, there are no parting planes.

Claims

Patent claims 1. plasticizer pack (1) with snap lid (2), both of which are made of thermoplastic, in which the collar-shaped head (3) encloses a pouring opening (4), on the outside a retaining ring (17), on the inside an approximately annular inner surface (7), has at the top at the free end (10) an edge (11) with a snap catch (12) and can be closed by means of the snap cover (2), from the closure wall (20) of which an annular sealing lip (23) protrudes from the inside of the package (1) and can be brought into sealing engagement with the inner surface (13) of the edge (11) and has an outer catch (29) for snap engagement with the edge (11) of the head (3), characterized in that the head (3) the pack (1) at its edge (11) extends radially outwards and upwards and both the inner surface (13) of this edge (11) and the outer surface (24) of the sealing lip (23) on the snap cover (2) in the viewing direction (14, 25) are convexly curved on them. 2. Pack according to claim 1, characterized in that the snap cover (2) on its inside has a sealing lip (23), annular, over the edge (11) of the head (3) engaging snap notch (27) and that the thickness (d) of the snap cover (2) in the direction outside and above the snap notch (27) is smaller than in the area of the outer catch (29). 3. Pack according to claim 1 or 2, characterized in that in cross section along the pouring opening (4) the radius of curvature of the inner surface (13) of the edge (11) of the packing head (3) from the inside of the packing (1) to the outside to the outside End (10) decreases, preferably decreases from infinity to 0.5 mm. 4. Pack according to one of claims 1 to 3, characterized in that in cross section along the pouring opening (4) the radius of curvature of the outer surface (24) of the sealing lip (23) on the snap cover (2) in the range from 0.2 mm to 2 mm lies. 5. Pack according to one of claims 1 to 4, characterized in that the convexly curved inner surface (13) in the region of the head edge (3) and the convexly curved outer surface (24) of the sealing lip (23) for a high surface quality have a low roughness and are designed without raised parts. 6. Pack according to one of claims 1 to 5, characterized in that the snap lid (2) consists of a softer thermoplastic plastic than the head (3) of the pack (1), preferably of amorphous polypropylene. 7. Injection-molded preform (6) for producing a plasticizer (1) made of thermoplastic, in which the collar-shaped head (3) encloses a pouring opening (4), on the outside a retaining ring (17), on the inside an approximately annular inner surface (7) and above at the free end (10) has an edge (11) with a snap catch (12), characterized in that the head (3) of the preform (6) at its edge (11) widens radially outwards and upwards and the inner surface (13) of this edge (11) is convex in the viewing direction (14, 25). 8. Preform according to claim 7, characterized in that in cross section along the pouring opening (4) the radius of curvature of the inner surface (13) of the edge (11) of the head (3) of the preform (6) from the inside of the preform (6) outside decreases towards the free end (10), preferably decreases from infinity to 0.5 mm. 9. Preform according to claim 7 or 8, characterized in that the convexly curved inner surface (13) in the region of the head edge (3) has a low roughness for a high surface quality and is formed without raised parts. 10. Preform according to one of claims 7 to 9, characterized in that it is formed from polyethylene terephthalate (PET).