A CLOSURE DEVICE FOR A CONTAINER

Abstract: A container is sealed by the use of a cover. In the applied position of the cover there is an annular sealing bead between the container and the cover, said sealing bead being secured to both the container and the cover and being adapted to absorb mechanical shear between the two parts produced by an outer mechanical force.

Description: A closure device for a container The invention concerns a closure device for a container provided with a cover, preferably for storage and transport of liquid materials, in particular dangerous liquids, such as wood preservation compositions, lacquers and paint. The increasing demands made on the protection of the environment, on the safety of the individuals working with dangerous liquids, and the like, result in greater demands on the package in which the materials are supplied, transported and stored. The term "dangerous liquids" covers many different materials which, when handled wrongly, can constitute a risk to the individual working with the materials and the surroundings in the form of fire hazards, etc. Therefore, e.g. containers and covers having a cooperating closure device have been developed. Here the cover is adapted to be mounted on the container so that an annular material portion on the cover is caused to engage the container. This annular portion may moreover have an annular bead, so that the diameter of the cover at the bead is slightly greater than the adjacent diameter of the container. This results in sealing of the container, but this seal cannot survive even modest mechanical impacts, e.g. in the form of a drop from a low height. It has been attempted to compensate this drawback by increasing the mechanical coupling between cover and container, by moreover providing the coupling with separate clips or an annular band. This improves the resistance to mechanical impact to some degree, but even small deformations of the contact area between container and cover will still cause leaks. Simultaneously, it has become more difficult to remove the cover from the container, since the clips are first to be removed, or the annular band is to be broken. The object of the invention is therefore to provide a closure device for a container of the type defined in the opening paragraph, said container with closure device being capable of surviving even a significant deformation of both container and cover without this resulting in leaks. Of course, this must not increase the consumption of materials or impede the working operations signifi¬ cantly. Further, when the contents are to be used, it must of course be possible to open the container without special tools being needed. This object is achieved as stated in the characterizing portion of claim 1, there being provided an annular bead of a deformable material between the cover and the container body, said deformable material being adapted to absdrb, through deformation, the impact to which the container is subjected. As stated in claim 2, the sealing areas on both the container and the cover may advantageously be provided with annular beads, adhesive being applied to at least one of the beads. This provides good adhesion between container and cover. With some types of adhesive, it may be expedient to apply it to both sealing areas, as stated in claim 3. Claim 4 states how, in a preferred embodiment, the bead consists of a plastics material, which, as stated in claim 5, can be received in an annular channel, thereby giving the container an unprecedented resistance to outer mechanical impacts. As stated in claim 4, the sealing area may be provided with roughnesses e.g. in the form of burrs or scratches, thereby improving the adhesion of the plastics material to the sealing area. Since it must be possible later to remove the cover from the container, the adhesive may be applied as stated in claim 7. When the closure devise is constructed as stated in claim 8, the bead of the deformable material and the adhesive do not have to be resistant to the contents of the container. The feature stated in claim 9 contribute to enhancing the size of the deformation which the closure device can absorb before a mechanical impact results in a leak. The invention will be explained more fully below in connection with preferred embodiments and with reference to the drawing, in which fig. 1 is a perspective view of a container with a closure device according to the invention, fig. 2 is a sectional view of the closure device shown in fig. 1 along the line 2-2, fig. 3 shows the closure device of fig. 2, the cover and the container being separated, fig. 4 shows an alternative embodiment of a closure device according to the invention, and fig. 5 shows a further alternative of the closure device according to the invention. Fig. 1 shows a container 10 with which the closure device of the invention can be used. The container 10 is shown to be cylindrical, but nothing prevents the closure device from being used on containers with other shapes, e.g. with a square or rectangular cross-section, if this is considered expedient owing to better space utilization during transport. The container 10 may advantageously be sligthly frustoconical, so that empty container bodies can be stacked before being filled with the contents. The container 10 comprises a cover 18 and a container body 16 with a bottom (not shown); in this example the container as a whole is made of sheet metal with a thickness of the order of 0.25 mm, and is shaped in a known manner, e.g. by means of rolling and beading. The container body 16 may moreover have a handle 12, which is pivotally attached to two holders 15, which are fixed to the container body 16 through soldering, spot-welding or the like. The container 10 is closed by mounting of the cover 18. Figs. 2 and 3 are sectional views of the closure device on the container 10. Disregarding the handle 12, 15, the container 10 may in this case be regarded as being substantially rotational-symmetrical. The cover 18 is produced by punching a circular disk from a metal sheet which, e.g. for paint pots, will typically have a thickness of between 0.15 mm and 0.50 mm. The disk moulded so that the cover comprises a central, substantially plate-shaped part 22, which is outwardly defined by an annular channel 21 through an annular part. The outer side of this channel is provided with an annular elevation 22 in the radial direction of the cover 18 by moulding. As will be mentioned later, this elevation 22 serves as part of a primary seal upon application of the cover 18 on the container body 16. The sheet material then extends upwardly and is bent outwardly in the radial direction of the cover 18 and is then bent again, so that the rim of the disk-shaped sheet material forms an annular channel 23. As will appear later from the description, this channel 23 serves as a basis for the application of a deformable sealing material. In this case the container body 16 consists of a sub- stantially cylindrical shell 30 which terminates upwardly in a cylindrical part 32 through a shoulder 31, whose function is to increase the diameter of the container body from the shell 30 to the cylindrical part 32. The upper rim of the cylindrical part forms part of a joint 33, where the container body 16 is secured to a rim 34, it being possible to effect the joining e.g. by beading. The rim 34 extends downwardly from the joint 33 and forms a shoulder part 35, which continues in a bent part 36 and terminates in an outwardly extending flange 37 adapted to retain the sealing agent like the channel 23. In the preferred embodiment, the sealing agent is a PVC plastics material which is applied to the cover in the area adjoining the channel 23 and extending a distance downwardly from the channel toward to the elevation 22. Correspondingly, this sealing material is applied to the rim in the area around the shoulder part 35 and below the outwardly extending flange 37. The sealing agent is heated together with the cover 18 and the rim 34 to a suitable temperature so as to cure and assume a soft, but still firm and coherent state. An additive has been added in advance to the sealing agent so as to release nitrogen in a gas form when heated additionally. This results in small blisters in the beads 40 and 41 on the cover 18 and the rim 34, respectively. A number of products of this type are commercially avaiable, where the material is blistered deformably and partly elastically after cooling. In the preferred embodiment, an adhesive, which may e.g. be a vinyl acetate acrylic dispersion glue, is applied to the sealing bead 40 and a portion of the outer wall of the cover from said bead down toward the elevation 22. Owing to stacking of the containers prior to use it is expedient that the adhesive is applied to the cover, since, otherwise, it may be difficult to destack empty containers when these are to be filled with their contents. When the container is to be closed, the cover 18 is pressed down over the rim 34 of the container in a known manner, which is shown in fig. 3. It is noted that the elevation 22 is adapted to grip below the bent part 36 or in an annular groove in the part 36. In preferred embodiment, the elevation 22 thus serves as a primary seal of the pot. The closure device of the invention thus serves as a secondary seal, the binder fixing the two sealing beads 40, 41 with respect to each other, and these beads 40, 41 are fixed to the cover 18 and the rim 34, respectively, partly through the adhesion of the acrylic material to the metal faces and partly through the mechanical retention obtained through the channel 23 and "the outwardly extending flange 37. The bent part 35 may be shaped so as to provide a channel between the walls to receive the sealing agent. This improves the retention of the sealing bead 41. It is often desired to limit the extent of the adhesive applied to the cover, such that just the sealing bead 40 is covered, since, otherwise, it may be difficult to remove the cover when the container is to be opened. As appears from figs. 2 and 3, the sealing beads 40, 41 are pressed together when the cover is applied. A blow to the shell of the continer in the vicinity of the rim area will cause the parts of the container to be deformed, and shear may occur so that the primary seal no longer keeps tight, but the two sealing beads 40, 41 are capable of absorbing a not insignificant shear force through the mutual fixing and the adhesion to the cover 18 and the rim 34, respectively. By simple means and more effectively, a container with the disclosed closure device of the invention is capable of providing the sealing function which has otherwise required a locking ring. Fig. 4 shows an alternative embodiment of a closure device according to the invention, the container body similarly having a shell 130, a shoulder 131, a cylindrical part 132 and a joint 133. The cover still has a central plate- shaped part 120, which, like before continues outwardly in an annular channel 121 upwardly provided with an engage¬ ment face 124 which, in the assembly, is adapted to retain the cover in a mechanically stable position by engagement with an annular stiff bead 138 provided by bending. The rim 134 on the container body 16 is formed with a sealing bead 141 which, like in the embodiment described above, may be secured mechanically by suitable bending of the sheet metal forming the rim 134. Owing to stacking, the outer wall portion of the channel 121 facing the bead will he provided with a suitable adhesive. As will be seen, the sealing now forms the primary seal, while the secondary seal is provided by the engagement face 124 and the annular ring 138. It will be appreciated that when using a sealing bead 141 of a PVC plastics material it is necessary that this plastics material is resistant to the contents of the container. It will likewise be appreciated that it is necessary that the adhesive can ensure sufficient adhesion to the metal sheet with which the bead 141 is in contact. Instead of using an adhesive in this case, it may be expedient to provide a container closure machine with a heat source which is caused to contact the metal parts surrounding the PVC material. The sealing bead can hereby be heated locally, so that it is first cured and then blistered to assume suitable properties. The sealing bead 141 can thus obtain the necessary adhesion through heating without additional adhesive being needed. Fig. 5 shows a third embodiment where a sealing bead 240 is provided in an annular channel 223 on the cover. The rim on the container body has an engagement face 239, the bead 240 being adapted to be fixed to the engagement face 239 by means of either heating or application of an adhesive upon mounting of the cover. The cover is moreover provided with an annular elevation 224 in a radial direction in the outer wall of the channel 221. When the cover is applied to the container body, the elevation 224 is adapted to be received in a complementary annular groove 238 in the container rim. The elevation 224 and the groove 228 will hereby form a primary seal, while the bead 240 and the engagement face 239 form the secondary seal. When a deformable and elastic material is provided between the cover 18 and the container body 16, the advantage is achieved that this material will be capable of absorbing shear in the engagement faces between the cover 18 and the container body 16 to a great extent. As shown, the cover may advantageously also have an annular channel 21, 121, 221 which additionally makes the cover resilient, thereby positively intensifying the effect of the sealing bead 40, 41, 141, 241. The invention has been described with reference to a container of sheet metal, but nothing prevents the same advantages from being achieved with a container of plastics material, optionally fibre-reinforced. However, also other materials may be considered. The bead has been described as being a PVC material, but other materials can be used since such a sealing material is merely to be secured to the container body 16 and the cover 18 and to exhibit suitable properties with respect to deformability and elasticity. Even though a container with a sealing bead according to the invention is capable of surviving strong mechanical outer impacts, removal of the cover 18 presents no problem in relation to the prior art when the contents of the container are to be used.

Claims: P a t e n t C l a i m s: 1. A closure device for sealing a container by application of a cover which has an annular sealing area adapted to engage a likewise annular sealing area on the container upon application of the cover, c h a r a c t e r i z e d in that at least one of the two sealing areas is provided with an annular bead of a deformable material, and that adhesive is moreover applied to at least one of the sealing areas so that, in the applied position of the cover, adhesive is present between the bead and the adjacent part of the other sealing area to fix the bead with respect to said area. 2. A closure device according to claim 1, c h a r a c t e r i z e d in that both sealing areas are provided with annular beads of a deformable material. 3. A closure device according to claim 1 or 2, c h a r a c t e r i z e d in that adhesive is applied to both sealing areas. 4. A closure device according to claims 1-3, c h a r a c t e r i z e d in that an annular bead in a closing area is a compound made of a blistered plastics material which is fixed to the sealing area by adhesion. 5. A closure device according to claim 4, c h a r a c t e r i z e d in that respective sealing areas have an annular edge forming a channel to receive part of the blistered plastics material. 6. A closure device according to claim 4, c h a r a c t e r i z e d in that the sealing area is provided with roughnesses. 7. A closure device according to claims 1-6, c h a r a c t e r i z e d in that adhesive is applied to the sealing areas substantially only on the engagement faces formed by the beads. 8. A closure device according to claims 1-7, c h a r a c t e r i z e d in that the seal formed by the deformable bead is a secondary seal, and that the cover moreover has an annular area adapted to form a primary seal with the container. 9. A closure device according to claims 1-8, c h a r a c t e r i z e d in that the cover moreover has an annular, resilient channel along the rim.

Inventors: SEBBELOV LARS ERIK, SEBBELOV, LARS, ERIK
Applicants: BALTIC METALVAREFAB, METALVAREFABRIKEN BALTIC A/S
Application year: 1991
Main classification: B65D53
IPC codes: B65D43