AU630149B2

AU630149B2 - Container closure with internal-pressure limiter

Info

Publication number: AU630149B2
Application number: AU49005/90A
Authority: AU
Inventors: Bernd Hackmann; Jurgen Kopp; Dieter Peissl
Original assignee: Unilever PLC
Current assignee: Unilever PLC
Priority date: 1989-02-06
Filing date: 1990-02-01
Publication date: 1992-10-22
Anticipated expiration: 2010-02-01
Also published as: BR9000501A; AU4900590A; JPH02269666A; ES2042091T3; ES2042091T5; JP2742315B2; EP0382146A1; EP0382146B1; DE59001635D1; EP0382146B2; DE3903509C2; ZA90867B; DE3903509A1

Description

r i i 1 AUS

PATENTS

TRALIA

63m 149 Form ACT 1952 COMPLETE SPECIFICATION

(ORIGINAL)

FOR OFFICE USE Short Title: Int. Cl: Application Number: Lodged: Complete Specification-Lodged: Accepted: Lapsed: Published: Priority: Related Art: TO BE COMPLETED BY APPLICANT Name of Applicant: Address of Applicant: tr i

*I

a 5 4a I;a*o UNILEVER PLC UNILEVER HOUSE

BLACKFRIARS

LONDON EC4

ENGLAND

Actual Inventor: Address for Service: GRIFFITH HACK CO., 601 St. Kilda Road, Melbourne, Victoria 3004, Australia.

Complete Specification for the invention entitled: CONTAINER CLOSURE WITH INTERNAL-PRESSURE LIMITER.

The following statement is a full description of this invention including the best method of performing it known to me:- 2 The present invention relates to a container closure with an internal-pressure limiter in accordance with the preamble to Patent Claim 1. Containers with internal-pressure limiters are utilised in various connections, for example in the case of plastic bottles having contents which readily evolve gas, but which can only be subjected to relatively low internal pressures.

If the internal pressure rises due to heating or shaking during transport, the gas must be released. Bottles which could be cited as an example are those containing bleaching agents which have a tendency to liberate gas and where the bottles should not be subjected to any appreciable internal pressure.

00 o o o known from the British Patent GB-A 2 026 994 in which the upper 0 0. rim of the neck of the container serves as the seating for an o0 0 00 annular valve on which a rubber disc is mounted to act as the 000 valve body which can lift up away from the neck of the container against spring-loading provided by a metal disc and the metal screw cap of the container, so that the evolved gas can pass 0000 through the gap between the rim of the container and the rubber 000°0 disc and then escape to the atmosphere through a lateral slot 00.0 o in the metal cap. The threshold limiting pressure is dependent 00 upon the width of the screw-on container closure.

oo In connection with a container in which it is not pressure relief 0. but the expelling of the contents because of excess pressure due 0 2t to external compression of the container which is to be achieved, it is known, from the American Patent US-A 3 319 836, Fig. 4, that a valve body consisting of two combined rigid plates can be forced against the annular valve seating by the use of metal springs. The resultant valve is entirely contained within the container closure. As a variation of this, in accordance with the Patent US-A 3 319 836, Fig. 1, in agreement with the construction according to the preamble to Patent Claim 1, instead of the metal springs, it is possible to utilise a sponge body which forces the plates against the valve seating and this sponge material in itself is sufficiently permeable to the liquid which is to be 3 expelled, so that it can escape from the upper side of the cap.

A similar type of construction, known from the German Utility Model Specification DE-GM 85 34 913, is contained in the closure member of a maintenance-free automobile battery. The valve body in this instance is plunger-like and engages with a funnelshaped valve seating, and the valve closure surface is a narrow annular surface and, optionally, it may only be a circular m.ine of a tangential contact.

Lastly, it is known from the Patent US-A 4 089 434 that it is 0 possible to release the gras by means of a sealing disk inserted between the container cap and the upper rim of the container o 0 neck, said sealing disk consisting of sponge material laminated 9090 with foil on both sides and having, on the upper side, ridges which, even when the disk is very strongly compressed, give rise 15 to sites of moderate compression in the region of the ridges, making possible the local lifting up of the disk from the annular valve seating and thus allowing the gas to escape around the screw thread in the container cap.

Containers for those types of liquid which belong amongst the goods for daily consumption are generally mass-produced at lowt I cost. Container caps with metal springs and even only with metal plates increase the cost of production. On the other hand, pressure limitation with the aid of conventional sealing disks which are forced away from the rim of the container neck by excess pressure to allow gas to escape around the screw thread cannot easily be adjusted to a precise pressure-limit threshold and are thus only useful for the relief of higher pressures.

Compared with this, the objective of the present invention is to provide a container closure with an internal-pressure lmiter which is simple to manufacture and which is effectual when subjected to low internal pressures. This is made possible by the characteristic features set out in Claim 1. The sponge material body laminated with foil which acts as the valve-spring 4 aggregate, can be manufactured in continuous strips from which the inserts required for the individual container caps can be stamped out. The placing of these laminated disk units in the individual caps is a simple operation because there is no spring body on the one hand, and no valve body on the other hand, to be mounted separately in the container cap. The container closures can thus be manufactured by cheap mass-production methods which lead, in particular, to the construction referred to in Claims 2 and 3. The entire construction of the closure is especially suitable for the limitation of internal pressure because the escaping gas can readily permeate the compressed t sponge material, whereas the liquid in the container is r substantially completely retained thereby. Close-fitting of the perimeter of the sponge material in the cap does not detract from the effect. If there is no excess internal pressure to lift the foil away from the rim of the container neck, the sealing is very good because a relatively wide valve seating is available which results in good contact with the foil and makes any inadvertent defective contact at a small localised spot unimportant, because this spot would generally be surrounded on all sides by the foil in good contact with the valve seating.

The internal-pressure threshold, even when it is very low, can thus be established to a certain degree in advance, because in a general fashion the valve seating is formed on a portion of the cap, so that the compression of the sponge material is not dependent upon the depth of the cap being applied to the container and, in the case of a rotary closure (screw cap), neither the neck of the container nor other similar structural parts come into frictional contact with the foil, so that there is no twisting of the sponge material attached to the foil to cause wrinkling of the foil and interfere with its good sealing contact.

The measures described in Claims 4 and 5 provide concrete details of the teachings of the present invention, and the measure described in Claim 6 results in the closure fulfilling its purpose in an excellent fashion and prevents the escape of liquid from the container, even if it is lying on its side.

The construction described in Claims 8 and 9 is especially expedient and can be easily fabricated. The measure according to Claim 10 replaces the single valve opening present in normal cases with a plurality of valve openings, by which means the through-flow surface can be enlarged without the foil covered sponge body bulging out.

According to Claims 11 and 12, various characteristic features of the valve performance can be determined in advance by the S0 °°16 employment of very simple constructional operations.

0 S Additional advantages, developments and details of preferred 4c00 S embodiments of the present invention are set out in the following ti description, with reference to the accompanying drawings, in which: Fig. 1 is a half side-elevation and half section of a container closure in accordance with the present invention, mounted on the neck of a container; Fig. 2 is a section through a sponge body as used in the container closure shown in Fig. 1, in the relaxed condition; Fig. 3 is a cross-section through a modified form of embodiment in the operational state when gas is being released; Fig. 4 and 5 are cross-sections through additional modified fam of embodiment.

Fig. 1 depicts a form of embodiment of a closure cap 3, consisting of synthetic plastics material, mounted on the neck 1 of a container into which a pouring spout 2 has been inserted. The closure cap is mounted on the neck 1 of the container by means of a screw thread or bayonet connection 4. The closure cap is attached to a security ring 6 which remains in position around the neck of the container when the cap is removed by tearing away the webs 5, the integrity of which indicates that the original contents of the filled container have not been tampered with.

The container to which the depicted container closure belongs is made of synthetic plastics material for holding a laundry bleaching agent. These agents have a tendency to liberate gases which could lead to distension of the plastic container. For this reason the closure cap 3 is furnished with a relief valve 11 for limitation of the internal pressure. An opening 12 for the escape of gas from inside the container cap is provided in the upper wall of the cap. The region in which the opening 12 is located, eccentrically in the depicted example of embodiment, S is surrounded by an annular flange 13 which projects downwards into the container and a cover 14 is pushed on over this annular flange. This cover 14 has a substantially cylindrical portion in the form of two flanges 15 and 16 into which the annular flange 13 can be pushed with a tight fit. Because of the presence of radial projections or grooves in the walls of the annular flanges 13 and 15, they undergo elastic deformation when the cover 14 is pushed on into position where it is firmly held in place. The elastic deformation is made possible by the physical properties of the synthetic plastics material used for the fabrication of these components. In the disk-shape base 17 of the cover 14 there is a central hole 18 to provide an opening for the escape of gas. The inner surface 19 of the base 17is flat and smooth and the inner surface of 20 of the inner annular flange 16 of the cover 14 is cylindrical and smooth. The radial length ratio between the opening 18 and the surface 19 is between 1 and 1 4, resulting in a surface-area ratio between 1 19 and 1 24.

A sponge body 25 is inserted in the space defined by the pushed on cap 14 and the adjacent regions of the closure cap 3, and the sponge is laminated with polyethylene foil 26 which has a circular perimeter 27. The polyethylene foil 26 covers the entire inner surface 19 of the base 17 and the central hole 18. The sponge body is depicted in the relaxed condition in Fig. 2, whereas it is shown in the compressed condition in the section 7 in Fig. 1. Here the sponge body is compressed to 1/5 of its original relaxed thickness. This substantial compression results in the foil 26 being pressed down against the surface 19 with a considerable amount of force where it exerts a sealing effect which is adequate to withstand moderate pressures, including the hydraulic pressure exerted on it by the liquid contents of the container if it happens to be tipped onto its side.

The sponge portion of the sponge body 25 consists of a material with a degree of porosity sufficient to allow the gas, which is S permeation by the liquid takes place at a very much slower rate.

Any possible entry of foreign bodies and foreign materials into the valve space 11 from the outside is also prevented by the sponge body Polyamide is also suitable as the material for use as the foil.

Polyether foam material, with an average raw density of 72 kilograms per cubic metre, a pore count of 20 to 25 per centimetre and a compression hardness (per ISO 3386) of 32 kPa, is preferred for use as the sponge portion of the sponge body Fig. 3 which depicts only the upper part of a closure cap, relates to a form of embodiment in which there is a plurality of holes in the disk-shaped base 17 of the cover cap 14 instead S of the single central hole 18. These holes are distributed over Sthe inner surface 19 but they are all kept at a minimum distance away from the annular flange 16 and thus away from the perimeter of the sponge body 25. In the top wall of the closure cap 3 there are several gas-escape openings 12 present, with two of said openings being shown in the cross-section. In accordance with another form of embodiment (not depicted) the gas-escape openings and the holes can be implemented as a sieve or grid.

Fig. 1 shows the closvre in the absence of excess pressure and Fig. 3 depicts the situation where excess pressure within the container leads to escape of the gas. First of all, the foil in I I j- \Ic\J S ~3fF\ oR the region of the holes 28 is forced up away from theXsurface 19 and, as the pressure increases, it is forced up further away from the holes over more of the surface. The upward curvature causes the circular perimeter of the foil 26 to be drawn inwards away from the annular flange 16. The escaping gas, in the form bubbles or in a continuous stream, finally reaches the perimeter of the foil and enters into the annular space 30 which has developed between the sponge body 25 and the inner surface of the annular flange 16. From there the gas permeates through the compressed sponge body 25 and passes out through the gas-escape openings 12.

o 0 Fig. 4 is an illustration, corresponding to that shown in Fig. 3, *000 Sof a form of embodiment in which the underside of the cover cap 14, instead of the flat disc shape, has a flattened conicallyconfigured base 32, in the downwardly-directed apex of which the central hole 18 is located. The cylindrical sponge body 25, with the polyethylene foil covering its lower surface, assumes here a very blunt-pointed shape, so that the surface pressure exerted by it is greater in the peripheral zone than in the vicinity of the central hole 18. As the internal pressure increases, the foil 26 is forced up gradually from the centre towards the outside of the surface 19 until the gas reaches the perimeter and escapes to the atmosphere as described previously. As the pressure in the container falls, the foil subsides evenly back from the outside 26 towards the centre of the surface to re-establish the seal.

0 Fig. 5 is an illusbration, corresponding to that shown in Fig. 4, of a form of embodiment in which the underside of the cover cap 14 has a slightly hollowed conically-configured base 32' with an upwardly-directed apex. In this situation, the sponge body is most strongly compressed immediately above the central hole 18 and less strongly compressed around the peripheral zone. A gas pressure which can force the foil 26 up from the hole 18 will therefore be relieved by gas bubbles escaping in pulses between the foil 26 and the surface 19.

Claims

2. The container closure according to Claim i, wherein the sponge body is disk-shaped and its underside circular surface is covered with a foil and its peripheral zone is in contact with a surface region forming the annular seating for the valve.
3. The container closure according to Claim 2, wherein the foil is peripherally in contact with the inner surface of the wall of the closure cap.
4. The container closure according to any one of Claims 1 to 3, wherein the flexible foil consists of polyethylene or polyamide. The container closure according to any one of 4 %L1AA Claims 1 to 4, wherein the sponge body consists of porous s/I 1 synthetic plastics material foam which, in the direction towards the foil is compressed to between 1/6 and 1/4 of the thickness which it has in the relaxed condition.
6. The container closure according to Claim wherein the pr.ous synthetic plastics material foam is a polyether foam material with an average raw density of 72 kilograms per cubic metre, a pore count of 20 to 25 per centimetre and a compression hardness [per ISO 33863 of 32 kPa.
7. The container closure according to any one of Claims 1 to 6, wherein the opening present in the valve seating is surrounded in every radial direction by the foil in contact with a valve seating, the width of which is one- and-a-half times as great as greatest transverse dimension of the pressure relief opening. i 4 r
8. The container closure according to any one of 20 Claims 1 to 7, wherein the space in which the sponge body is accommodated is defined by a top wall of the closure cap, by a cylindrical flange which projects inward from the top wall of the cap and by a disc which forms the valve seating attached to said cylindrical flange and which contains the pressure relief opening.
9. The container closure according to Claim 8, wherein the disk is configured as a cap and is clipped onto the cylindrical flange with a snap fit. The container closure according to any one of Claims 1 to 9, wherein the valve seating includes a grid plate which has a plurality of pressure relief openings covered by the foil. 4 0 11
11. Claims 1 surface.
12. Claims 1 surface. The container to 10, wherein The container to 10, wherein closure according to any one of the valve seating has a flat closure according to any one of the valve seating has jinical DATED THIS 26TH DAY OF AUGUST 1992 UNILEVER PLC By Its Patent Attorneys GRIFFITH HACK CO Fellows Institute of Patent Attorneys of Australia