IE921692A1 - Container sealing - Google Patents
Container sealingInfo
- Publication number
- IE921692A1 IE921692A1 IE169292A IE921692A IE921692A1 IE 921692 A1 IE921692 A1 IE 921692A1 IE 169292 A IE169292 A IE 169292A IE 921692 A IE921692 A IE 921692A IE 921692 A1 IE921692 A1 IE 921692A1
- Authority
- IE
- Ireland
- Prior art keywords
- closure member
- container
- sealant
- container body
- composition
- Prior art date
Links
- 238000007789 sealing Methods 0.000 title claims description 14
- 239000000565 sealant Substances 0.000 claims abstract description 21
- 239000000203 mixture Substances 0.000 claims abstract description 12
- 238000010438 heat treatment Methods 0.000 claims abstract description 7
- 229910052751 metal Inorganic materials 0.000 claims description 16
- 239000002184 metal Substances 0.000 claims description 16
- 239000004743 Polypropylene Substances 0.000 claims description 15
- -1 polypropylene Polymers 0.000 claims description 15
- 229920001155 polypropylene Polymers 0.000 claims description 14
- 239000004033 plastic Substances 0.000 claims description 11
- 229920003023 plastic Polymers 0.000 claims description 11
- 238000004826 seaming Methods 0.000 claims description 7
- 238000000034 method Methods 0.000 claims description 4
- 230000003213 activating effect Effects 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 claims description 2
- 229910052782 aluminium Inorganic materials 0.000 description 10
- 239000004411 aluminium Substances 0.000 description 10
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 10
- 239000004922 lacquer Substances 0.000 description 9
- 239000000463 material Substances 0.000 description 9
- 230000006698 induction Effects 0.000 description 5
- 238000012360 testing method Methods 0.000 description 5
- 238000003466 welding Methods 0.000 description 5
- 229910000831 Steel Inorganic materials 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000010959 steel Substances 0.000 description 3
- 239000004593 Epoxy Substances 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 230000032798 delamination Effects 0.000 description 2
- 239000006260 foam Substances 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 229920003313 Bynel® Polymers 0.000 description 1
- 229920003354 Modic® Polymers 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 230000000721 bacterilogical effect Effects 0.000 description 1
- 235000013361 beverage Nutrition 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 238000009924 canning Methods 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 238000002788 crimping Methods 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 239000003822 epoxy resin Substances 0.000 description 1
- QHZOMAXECYYXGP-UHFFFAOYSA-N ethene;prop-2-enoic acid Chemical class C=C.OC(=O)C=C QHZOMAXECYYXGP-UHFFFAOYSA-N 0.000 description 1
- 230000004927 fusion Effects 0.000 description 1
- LNEPOXFFQSENCJ-UHFFFAOYSA-N haloperidol Chemical compound C1CC(O)(C=2C=CC(Cl)=CC=2)CCN1CCCC(=O)C1=CC=C(F)C=C1 LNEPOXFFQSENCJ-UHFFFAOYSA-N 0.000 description 1
- 239000012775 heat-sealing material Substances 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 229920000554 ionomer Polymers 0.000 description 1
- 238000003475 lamination Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 229920001200 poly(ethylene-vinyl acetate) Polymers 0.000 description 1
- 229920001748 polybutylene Polymers 0.000 description 1
- 229920000647 polyepoxide Polymers 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 239000004810 polytetrafluoroethylene Substances 0.000 description 1
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 239000012812 sealant material Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
- 230000037303 wrinkles Effects 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
- B65D77/00—Packages formed by enclosing articles or materials in preformed containers, e.g. boxes, cartons, sacks or bags
- B65D77/10—Container closures formed after filling
- B65D77/20—Container closures formed after filling by applying separate lids or covers, i.e. flexible membrane or foil-like covers
- B65D77/2024—Container closures formed after filling by applying separate lids or covers, i.e. flexible membrane or foil-like covers the cover being welded or adhered to the container
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D51/00—Making hollow objects
- B21D51/16—Making hollow objects characterised by the use of the objects
- B21D51/38—Making inlet or outlet arrangements of cans, tins, baths, bottles, or other vessels; Making can ends; Making closures
- B21D51/44—Making closures, e.g. caps
- B21D51/46—Placing sealings or sealing material
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Lining Or Joining Of Plastics Or The Like (AREA)
- Closures For Containers (AREA)
- Rigid Containers With Two Or More Constituent Elements (AREA)
Abstract
A sealed container comprises a container body, an end closure member and a sealant therebetween, in which the sealant is bonded to the body and to the closure member by a bond having a peel/bond strength (as herein defined) of at least 30 Newtons. A strong bond of this type can be obtained by providing an end closure member which carried a composition that can be activated indirectly, e.g. by induction-heating, to form a sealant bonded to the closure member and also to the container body.
Description
CONTAINER SEALING This invention relates to the sealing of containers, and in particular to the material that is used to provide a seal between a container body and an end closure, as well as to a process for forming a seal.
Much research has gone into the problem of providing a secure seal between containers and corresponding end closures. A seal must be formed between these two components after the container is filled with, say, a beverage or microwavable food. It is of course important to ensure that the contents of the sealed container do not leak out, and also to prevent bacteriological or other contamination of the contents from the ambient atmosphere.
The container may be of metal or plastic material. The closure member is usually of metal. It will often include a ring-pull or other frangible portion, in order to allow ready access to the contents. ?.o It is conventional to crimp or otherwise form the end closure onto a flange at the open end of the container, and to provide a sealant composition between the two components. Metal cans formed in this way are described in, for example, US-A-3403813, PS23018 - 2 US-A-3774560, US-A-3882763 and US-A-4089283; reference to these specifications will show various forms, and procedures for forming, container-closure seals.
In US-A-3403813, the sealant is atactic amorphous polypropylene; it states that this material has viscosity characteristics such that it provides a permanently tacky sealant between the can end and can body. In US-A-3774560, an expandable foam seam-sealing compound is used, which expands, on heating, to fill voids that may be present in the seam area.
Despite these various proposals, sealed containers of the type described suffer from various disadvantages. Firstly, it is difficult to fill all the voids that may be formed during sealing, especially when the two components are respectively of metal and plastics. Secondly, the compressive force that is applied when bringing the two components into contact leads to the possibility of buckling of 20 relatively weak containers, e.g. of plastics.
Thirdly, the stress imposed by the forming of the respective components at the area of sealing means that multi-layer plastics materials may delaminate during seaming, when the curl overlap between 25 container and closure takes place.
According to a first aspect of the present invention, in a sealed container comprising a container body, an end closure member and a sealant therebetween, the sealant is bonded to the body and to 30 the closure member by a bond having a peel/bond strength of at least 30, e.g. up to 50, 75, 100 or more, Newtons, by a flat seal peel test which involves flat-sealing a 15 mm wide strip of coated aluminium to a 15 mm wide strip of polypropylene, as used in a PS23018 - 3 container; the samples are then peeled apart at an angle of 180° and at a speed of 100 mm/min.
According to a second aspect of the present invention, an end closure member, of the type suitable for sealing to a container body, carries a composition that can be activated indirectly to form a sealant bonded to the closure member and also to a container body.
According to a third aspect of the present 1° invention, a method for producing a sealed container comprises seaming a container body and an end closure member with an indirectly-activatable composition therebetween, and activating the composition so that it forms bonds to the closure member and to the 15 container body.
The present invention is based on the utility of a strong bond between the container body and the sealant, and between the sealant and the end closure. This is in contrast to the previous use of materials 20 which have various properties but are designed primarily to prevent the passage of contaminants in and/or contents out. Further, by contrast with the known system of treating a sealant composition to foam it in situ, the present invention can involve the use 25 of an activatable material to form the desired bond. The effect of the strong bond is to provide several important advantages to products and processes of the present invention. Firstly, the burst strength of the sealed container is enhanced. Secondly, the 30 fact that a strong bond can be formed with plastics material indirectly means that little compressive force is needed when bringing the components together; the system is therefore as useful for plastics as metal containers. Thirdly, the sealant fixes the 35 relative positions of the components in the sealed PS23018 - 4 container and resists the forces that are built in during crimping; this is a particular advantage when using plastics laminates that are liable to delaminate. By creating a weld between the materials, the strength of the finished seam will be increased even if delamination has taken place during seaming. Unlike unsealed containers, further delamination will be restricted and therefore a much stronger and higher integrity container will result.
In general terms, the nature of the container body and closure member may be conventional. The container will usually be provided with a flange at its open end, to facilitate the contact between the components. The closure member may be formed with a ring-pull or other frangible portion.
The components may be combined in conventional manner, e.g. using chucks and rolls to press the components together. A hermetic joint is formed by interlocking the edges to both the closure and container components. The joint is generally produced in two operations, a sealing compound having already been introduced between the other components, e.g. by forming a layer thereof on the closure member. The first operation forms a metal/plastic or metal/metal curl/overlap, while the second operation flattens them to produce the required seam. This operation may be followed, if necessary or desired, by activation of the sealant, e.g. by induction heating, to a temperature of, say, 150 to 200‘C.
Examples of sealant materials than can be used in the invention include the following: Polymers that can be extruded onto aluminium or steel sheet: these include polypropylene, polyethylene and polybutylene; Morprime-based systems; PS23018 - 5 Polyolefinic resins: these are mainly modified ethylene acrylates (trade names include Admer, Modic and Bynel); PE-CTFE; PE-TFE; PTFE; EVA; MAA; EAA; Ionomers; and Modylene P/A (carboxylic acid-modified PP).
By way of example, the invention will be described below in connection with a plastics or polypropylene container and a metal or aluminium end closure, although steel is an alternative metal, and of course the invention is applicable to metal container-metal end systems.
As already indicated, a Morprime/polypropylene or other material can be applied to one of the metal or plastics components, and most suitably to a metal closure member. It can be applied as a lacquer, by way of replacement for a conventional epoxy lacquer.
A primary aim of the lacquer is to provide a, say, polypropylene/aluminium weld in the area of the double seam, and to provide protection of aluminium from attack by acids, e.g. in the container contents.
A suitable lacquer may comprise a dispersion of modified polypropylene or other polymer in a blend of high boiling solvents. The polypropylene can be blended with epoxy resins to provide excellent adhesion to aluminium and steel and can be used to make high strength laminations to polypropylene.
The sealant may be applied in an overall coating process. Alternatively, the sealant may be applied selectively. For example, a heat-sealing material may PS23018 - 6 be applied only to the flange overlap area on the aluminium or other closure member.
In either case, bonding between a polypropylene flange and an aluminium end can be formed indirectly.
For example, fusion is created by passing the seamed container through an induction field. The energy can be focused on the area of overlap by coil design, causing the aluminium to heat, and resulting in the lacquer melting and fusing to the polypropylene.
Conventional contact heating systems or ultrasonics could create the same effect as induction sealing. An important advantage of induction sealing is that the time taken to create the bond is very short, and will therefore not significantly affect 15 existing canning line speeds. Other suitable heating systems include sonic welding, induction welding, radio-frequency welding, conduction welding, spin-welding and impulse sealing.
In addition to the advantages described above, 20 the present invention may allow greater potential for the reduction of problems associated with reverse seam wrinkles. It may also provide wider seaming operating windows. All these advantages and effects can be achieved without any significant reduction of 25 conventional double-seaming line speeds with a heat-sealing system.
The following Example illustrates the invention.
Example 30 Aluminium sheet was hand-coated with a Morprime lacquer. The Morprime lacquer basically consists of an epoxy lacquer containing a polypropylene suspension. The lacquer was applied as a thin film and cured to the surface in an oven.
PS23018 - 7 The sheets were converted to ends and seamed onto 30 cm. diameter containers, and induction-sealed using a system supplied by Stanelco.
For testing, the containers were split into two 5 groups. One group was tested without retorting, and the other group was retorted at 121*C and then tested. The containers were tested by assessing their burst strength. The burst test involves introducing compressed air into the container in a controlled 10 manner, and recording the pressure needed to rupture the pack’s seal.
The results of the burst tests are given below: Unretorted Containers Conventional double-seamed Induction- sealed 1st OP seam only very low 193 kPa 2nd OP seam 131 kPa 234 kPa Retorted Containers Conventional double-seamed Induction- sealed 1st OP seam only very low 213 kPa 2nd OP seam 124 kPa 207 kPa These results show that the induction-sealed containers not only possess a burst strength twice that of conventionally-seamed containers, but also possess equivalent bond strengths when only seamed with the first operation (OP) seaming roll.
PS23018 IE 921693 - 8 In the flat seal peel test described above results of 30-40 Newtons have been obtained by operation in accordance with the invention.
Claims (6)
1. A sealed container comprising a container body, an end closure member and a sealant therebetween, in which the sealant is bonded to the body and to the closure member by a bond having a peel/bond 5 strength (as herein defined) of at least 30 Newtons.
2. A container according to claim 1, in which the container body and the end closure member are each of metal. io
3. A container according to claim 1, in which the container body is of plastics and the end closure member is of metal.
4. A container according to claim 1, 2 or 3, in which the sealant comprises polypropylene. 15 5. An end closure member, of the type suitable for sealing to a container body, which carried a composition that can be activated indirectly to form a sealant bonded to the closure member and also to a container body. ?o 6. A member according to claim 5, in which the sealant comprises polypropylene. 7. A member according to claim 5 to 6, in which the composition can be activated by induction-heating. PS23018 - 10 8. A method for producing a sealed container, which comprises seaming a container body and an end closure member with an indirectly-activatable composition therebetween, and activating the
5. Composition so that it forms bonds to the closure member and to the container body.
6. 9. A method according to claim 8, in which the composition is activated by induction-heating.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB919111873A GB9111873D0 (en) | 1991-06-03 | 1991-06-03 | Container sealing |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| IE921692A1 true IE921692A1 (en) | 1992-12-16 |
Family
ID=10695986
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| IE169292A IE921692A1 (en) | 1991-06-03 | 1992-07-01 | Container sealing |
Country Status (7)
| Country | Link |
|---|---|
| EP (1) | EP0518411A1 (en) |
| JP (1) | JPH05213360A (en) |
| AU (1) | AU1720892A (en) |
| CA (1) | CA2070255A1 (en) |
| GB (1) | GB9111873D0 (en) |
| IE (1) | IE921692A1 (en) |
| ZA (1) | ZA923837B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4239894A1 (en) * | 1992-11-29 | 1994-06-01 | Ucb Transpac Nv | Gastight vacuum pack for coffee, cocoa, nuts, etc - comprises inner and outer envelopes laminated together with adhesive in such a way that delamination occurs when pack is opened |
| ES2377333T3 (en) | 2006-12-20 | 2012-03-26 | Selig Sealing Products, Inc. | Stratified |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2994455A (en) * | 1959-08-05 | 1961-08-01 | Gen Mills Inc | Metallic containers |
| GB2064468B (en) * | 1979-12-08 | 1984-10-10 | Metal Box Co Ltd | Container seams |
| US4526290A (en) * | 1983-10-19 | 1985-07-02 | Ball Corporation | Flanged container |
-
1991
- 1991-06-03 GB GB919111873A patent/GB9111873D0/en active Pending
-
1992
- 1992-05-26 ZA ZA923837A patent/ZA923837B/en unknown
- 1992-05-27 AU AU17208/92A patent/AU1720892A/en not_active Abandoned
- 1992-06-01 EP EP92201560A patent/EP0518411A1/en not_active Withdrawn
- 1992-06-01 JP JP4163326A patent/JPH05213360A/en active Pending
- 1992-06-02 CA CA002070255A patent/CA2070255A1/en not_active Abandoned
- 1992-07-01 IE IE169292A patent/IE921692A1/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| CA2070255A1 (en) | 1992-12-04 |
| AU1720892A (en) | 1992-12-10 |
| JPH05213360A (en) | 1993-08-24 |
| GB9111873D0 (en) | 1991-07-24 |
| EP0518411A1 (en) | 1992-12-16 |
| ZA923837B (en) | 1993-11-26 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FC9A | Application refused sect. 31(1) |