EP0912420B1 - Container with pressure compensation holes - Google Patents

Abstract

PCT No. PCT/DE97/01348 Sec. 371 Date Dec. 30, 1998 Sec. 102(e) Date Dec. 30, 1998 PCT Filed Jun. 27, 1997 PCT Pub. No. WO98/01366 PCT Pub. Date Jan. 15, 1998The receptacle is produced in a coextrusion-type blow molding process and consists of a stiff outer receptacle and an easily deformable inner bag which are made from respectively different thermoplastic materials that do not form a welded joint with one another. The bottom weld seam of the inner bag is clamped in a closed bottom web of the outer receptacle. The pressure compensating openings are offset by about 90 DEG with respect to the plane passing through the bottom weld seam and the longitudinal center axis of the receptacle, whereby the inner bag is only contracted at two sides when the receptacle contents is discharged. The negative pressure prevailing inside the inner bag is thereby reduced.

Description

The invention relates to a coextrusion blow molding process Container consisting of an essentially rigid Outer container and an easily deformable inner bag each different, no welded connection to each other incoming thermoplastic, with a container opening and at least two pressure equalization openings in the wall of the outer container for pressure equalization in the space between the outer container and the inner bag when the inner bag contracts, when squeezing excess material on the ground the blow mold of the inner bag is closed by a bottom weld seam and this bottom weld in the also closed Bottom of the outer container is jammed.

Such a container is described in DE 41 39 555 C2. In this known container is at the bottom of the outer container an outwardly projecting web is formed, in which the Closing the blow mold material of the outer container merged because the material of the inner bag a damming effect in the area of the above web from the Pinch edge retracts inwards. This gets material of the outer container over part of the amount of the above Bridges in contact with each other, creating a closed Weld seam is created. The bottom weld seam of the inner bag is anchored in the adjoining area of the web. The jetty can an approximately kite-shaped cross-sectional shape, for example have, but also other, for example curved cross-sectional shapes of the web to a welded bottom seam of the Can lead outer container. Too much details of the manufacture of the known container is on DE 41 39 555 C2 directed.

The bottom weld seam of the inner bag can also be applied to others Be attached to the bottom of the outer container, for example using a suitable slide in the blow mold.

In the previously known container, the pressure equalization openings formed on the outer container in that the tubular Blank when closing the blow mold in the shoulder area is squeezed, here the material without training protruding web is squeezed smoothly, so that the two Material layers of the outer container do not come into contact with each other because this is due to the double layer between them of the inner bag is prevented. With this arise at the previously known container in the shoulder area two unwelded Seams on the outer container that extend from the shoulder area extend to the neck area.

These pressure equalization openings on both sides lie in the circumferential direction of the container viewed in places that match the Intersection points of the bottom weld seam with the peripheral seam of the Align container. In other words, these pressure equalization openings are located in the circumferential direction on the cutting lines through the central longitudinal axis of the container and the bottom seam going plane with the peripheral wall of the container.

If at the top of intersections of the floor weld with the peripheral wall is spoken, this also includes the case that the bottom weld does not cover the entire diameter of the container extends, in this case the intersection points formed by a line extending the bottom weld are.

When dispensing the container contents, for example by means of a Pump reduces the volume of the inner bag and it kicks in to equalize air from the surroundings of the container in the Space between inner bag and outer container. there there is always a certain negative pressure in the container which Maintains contraction of the inner bag.

In the case of the known container, the inner bag pulls in Horizontal section, i.e. in one to the longitudinal axis of the container vertical plane essentially star-shaped together when the Container content is spread. This means that the Inner bags on four essentially opposite each other in pairs Detach from the outer container, namely in the circumferential direction seen - at the pressure equalization openings and at the for this purpose circumferential areas offset by 90o. With increasing Contraction increases the four detached Areas, so that roughly the above-mentioned star shape arises.

This contraction on four sides of the inner bag means that a relatively large negative pressure in the inner bag occurs - and of course regardless of the fact that by the Pressure equalization openings ambient air in the space between the outer container and inner bag - in other words, a relatively large collapse force is required to cause this star-shaped contraction and then to maintain.

However, the greater the vacuum inside the inner bag, the greater it is permeation through the wall of the inner bag and the risk of leakage. The quality of the container contents can be impaired by the permeation, while if there is a leak due to air entering the bag The pump may become inoperative or the contents of the tank may leak.

EP 0 550 772 A discloses a container which is used for storing a Serves liquid from which components evaporate, even when the bottle is tightly closed. This can be, for example, oxygen, which escapes through the container wall, creating a vacuum in the bottle arises.

So that the outer layer of the container is not deformed by the negative pressure, air enters the space between the outer layer and the inner layer. If the inner layer is closed by a bottom weld seam on both sides of a web of the outer layer is covered, the air passes through the overlapped Area of the inner layer and the outer layer, which creates the inner layer can separate from the outer layer, so that only the inner layer is contracted and deformed while the outer layer through the Vacuum is not deformed.

The inner layer should contract in a certain shape. This certain shape is caused by the fact that one or more adhesive strips be arranged between the outer layer and the inner layer, the result have that in their areas the inner layer firmly with the outer layer stays connected.

The present invention has for its object a container considered in such a way that the vacuum is reduced, which in the inner bag occurs after the filling substance has been released.

This object is achieved according to the invention by the features of patent claim 1 solved.

Advantageous developments of the invention are in the subclaims characterized.

In the container according to the invention are - in the circumferential direction of the container considered - at least one on each side of the bottom weld Pressure equalization opening formed in the outer container, all Pressure equalization openings opposite the intersections of the bottom weld (or its extension) are offset with the peripheral wall of the outer container. It is preferred that the pressure equalization openings by about 900 to the Intersections are staggered, although the invention is not there is limited.

This ensures that the inner bag is no longer attached to four around 900 areas offset from each other from the outer container, but forms it a so-called "dog bone shape" during the contraction of the inner bag in which the inner bag is only on two opposite areas of the wall of the outer container lifts off, its center around 90o offset from the above-mentioned intersection points. that is, the inner bag is compressed increasingly flatter on both sides, where the central axis of the compressed cross-sectional shape approximately with the pinched bottom seam of the inner bag coincides.

This no longer from four, but from two sides Contraction of the inner bag has the consequence that the negative pressure in the inner bag against detachment on more than two Areas is significantly reduced. Both are reduced Collapse force that pulls the bag into the "dog bone shape" as well as the negative pressure that sustains this shape receives.

As a result, the permeation into the inner bag is reduced, the risk of leakage decreases and the residual amount in the Inner bag is reduced, which is not removable.

It is understood that the two-sided Contraction of the inner bag is not only caused by this can be that exactly around 90o to the intersections mentioned offset pressure equalization openings are formed. This can rather, for example, in a particular case the material of the inner bag and its wall thickness dependent circumferential area, which is opposite the intersection points is offset, for example by two in Pressure compensation openings spaced apart from one another in the circumferential direction, the pair by about 80o each Intersections can be offset.

It is essential that the pressure compensation openings in the Containers according to the invention no longer seen in the circumferential direction in the narrower area of the intersection of the bottom weld with the peripheral wall, but if possible in a 90o offset area, so that the inner bag at least at the initial contraction no longer in the intersection area replaces. This circumferential range is preferably around 45o to 135o to the intersection.

As I said, the negative pressure can otherwise be the same Minimize boundary conditions by having two diametrically opposed ones Pressure equalization openings arranged on one level are at right angles to that through the bottom seam and the Longitudinal central axis of the container extending plane.

Of course, several pressure equalization openings can also be used spaced one above the other on each side of the Bottom weld seam should be formed.

These pressure equalization openings can be made through elongated incisions be formed in the wall of the outer container by this for example with a knife, punching tool or with a Lasers are cut into the wall, leaving one remaining inner wall section then by applying a compressive force can be torn open. This can be the case with a container whose outer wall has a wall thickness of approx. 0.7 to 0.9 mm has to be accomplished in such a way that with a a crescent-shaped incision on a circular guided knife is generated, the wall down to a remaining safety wall thickness cut by approx. 0.2 mm, which ensures that despite the tolerances that occur, the inner bag cannot be damaged. Then, for example a stamp so strong against the outside wall on one side of the cut that the remaining wall section bursts. In a similar way, a pressure equalization opening be formed with a punch or with a laser.

The pressure equalization openings can also be punctiform Bores or punctures are formed in the wall of the outer container be, the injection needle provided with a central bore may be in connection with a source of print media stands. If the puncture needle penetrates the wall of the outer container, at the moment of the passage from the wall of the Outer container is the pressure medium, for example can be air, water or a gel, so firmly against the Inner bag pressed so that it withdraws, so that the inner bag cannot be damaged by the injection needle.

Very small, capillary-like openings are sufficient to equalize the pressure, to the desired ones in the manner described above Places of the outer container can be formed.

The container according to the invention can be seen as a so-called Be wide-necked containers because of the pressure equalization openings not just in the shoulder area, but anywhere of the outer container can be formed.

Fig. 1

einen Vertikalschnitt durch einen im Coextrusionsblasen hergestellten Behälter der betrachteten Art;

Fig. 2

eine perspektivische Ansicht eines bekannten Behälters mit offenen Schulternähten;

Fig. 3

einen Horizontalschnitt durch den Behälter gemäß Fig. 2 oberhalb der eingeklemmten Bodennaht des Innenbeutels in einem Zustand, in dem sich der Innenbeutel zusammengezogen hat;

Fig. 4

eine perspektivische Ansicht eines erfindungsgemäßen Behälters in einer Fig. 2 entsprechenden Darstellung und

Fig. 5

einen Horizontalschnitt durch den Behälter gemäß Fig. 4 in einer der Fig. 3 entsprechenden Darstellung.

The invention is described below with reference to the drawing. Show:

Fig. 1

a vertical section through a container produced in the coextrusion blow molding of the type under consideration;

Fig. 2

a perspective view of a known container with open shoulder seams;

Fig. 3

a horizontal section through the container of Figure 2 above the pinched bottom seam of the inner bag in a state in which the inner bag has contracted.

Fig. 4

a perspective view of a container according to the invention in a Fig. 2 corresponding representation and

Fig. 5

a horizontal section through the container of FIG. 4 in a representation corresponding to FIG. 3.

The container 1 shown in Fig. 1 contains a container neck 2 and a shoulder section 3. At the container opening 4 can a pump for dispensing the container contents is attached, without the invention being limited to this. The container can also be designed as a squeeze bottle in which the container wall squeezed by hand to dispense the contents of the container and the container can also be a so-called wide-neck container be without shoulder section.

At the bottom of the container is preferred due to the closure of the Blow mold - a protruding, cross-sectionally dragon-shaped Web 5 formed, in the lower area in the figure touch the material layers of the outer container 6 (see FIG. 3), since the two squeezed out in the mold cavity of the web Material layers of the inner bag 7 a little bit of have withdrawn the separation point upwards. The one during the squeezing process formed weld seam of the inner bag is in the clamped upper area of the web 5 and thus in the axial Direction kept.

Fig. 2 shows a known container in which the delivery of the container contents required pressure equalization in the space between the outer container and the inner bag open shoulder seams 8 of the outer container 6 is carried out by a smooth, seamless squeezing of the blow mold in this Area are formed.

The open shoulder seams 8 lie in the vertical plane 9 through the axis of the web 5 and the central longitudinal axis 10 of the container runs. The intersection of this level 9 with the The peripheral wall of the outer container 6 are shown in FIG Reference number 11 denotes.

The inner bag is released as the contents of the container are released 7 in four growing areas of the Inner wall of the outer container, at the intersection 11 surrounding areas 12, on which - in the circumferential direction seen the air inlet to the pressure equalization and at areas offset by about 90 ° for this purpose. This has result in a star-like contraction form of the inner container educated.

The contraction of the inner container 7 from four sides requires a relatively large collapse force, the one also relatively large negative pressure in the inner bag with which this form of contraction is maintained becomes. The result is a relatively large permeation, Leakage of the inner bag 7 and a proportionate large remaining amount that cannot be removed from the inner bag is.

FIG. 4 shows a representation corresponding to FIG. 2 a container according to the invention 1. This container contains no open shoulder seams to equalize pressure, but to Level 9 or the position of the open shoulder seams 8 according to FIG. 2 positions offset by an angle α of 90 ° each two pressure equalization openings 14, which are purely schematic in FIG are marked.

Since there are no pressure equalization openings in the area of the intersection points 11 are provided, dissolves when the contents of the container are dispensed the inner bag 7 not from the inner wall of the outer container 6 from, i.e. there are no contraction sections 12 of the Star-shaped contraction according to FIG. 3. The inner bag 7 pulls only from two sides, this area being different increasingly spreads around the pressure equalization openings 14 and is identified in FIG. 5 by the reference number 15. A so-called "dog bone shape" is increasingly forming the inner bag contraction out.

This contraction of the inner bag, which occurs only from two sides has the consequence that they have a lower collapse which also requires a lower vacuum to maintain corresponds to the form of contraction. The result is lower permeation, also a reduced risk of Leakage and a smaller residual amount that cannot be discharged is.

It is emphasized that the contraction occurs only from two sides can of course not only be caused by the fact that the pressure equalization openings exactly 90o to the intersections 11 are offset. It is important that in the closer circumferential area to the intersections 11 no pressure equalization openings are located that detach the inner bag 7th cause of the wall of the outer container 6 in this area can. The bilateral contraction can of course also be done cause that on both sides of the pressure equalization openings 14 further pressure equalization openings are formed, but a sufficient circumferential distance from the intersection 11 must comply.

Claims (5)

1. A container (1) produced in a coextrusion blowing process comprising a substantially rigid outer container and a readily deformable inner bag (7) of different thermoplastic plastic materials, which do not enter into a welded connection with one another, with a container opening (4) with at least two pressure compensation openings (14) in the wall of the outer container (6) for pressure compensation in the gap between the outer container (6) and the inner bag (7) on contraction of the inner bag, whereby for the purpose of squeezing out excess material on the base of the blow mould, the inner bag (7) is sealed by a bottom seam weld (5) and this bottom seam weld (5) is clamped in a bottom seam weld (5), which is also sealed, of the outer container (6), characterised in that at least one pressure compensation opening (14) is formed on both sides of the bottom seam weld (5) and that all the pressure compensation openings (14) are formed at positions on the outer container (6) which are substantially offset in the peripheral direction with respect to the intersection points (11) of the bottom seam weld (5) with the peripheral wall of the outer container (6) so that when the container content is delivered, the inner bag (7) contracts only from two sides.
2. A container as claimed in Claim 1 characterised in that at least one respective pressure compensation opening (14) is formed offset by about 90° from the intersection points (11).
3. A container as claimed in one of Claims 1 or 2, characterised in that at least two respective pressure compensation openings (14) are formed spaced apart and situated above one another offset by about 90° from the intersection, points (11).
4. A container as claimed in one of Claims 1 to 3, characterised in that the pressure compensation openings (14) are formed by elongate cuts into the wall of the outer container (6).
5. A container as claimed in one of Claims 1 to 3, characterised in that the pressure compensation openings (14) are formed by punctiform bores or perforations in the wall of the outer container (6).

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