Special receptacle or package – Laminate sheet packet
Reexamination Certificate
1999-05-21
2003-01-07
Luong, Shian (Department: 3728)
Special receptacle or package
Laminate sheet packet
C206S438000, C206S447000
Reexamination Certificate
active
06502697
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a container for anaerobic products in particular anaerobic sealants and adhesives, in particular liquid products. Anaerobic adhesives and sealants cure, set-up or polymerise in the absence of oxygen (air).
BACKGROUND OF THE INVENTION
The term anaerobic products as used here refers to formulations which cure, set-up or polymerise in the absence of air.
EP 0 352 143 describes an anaerobic liquid acylate sealant composition. U.S. Pat. No. 4,180 640 (Loctite) describes a hardenable adhesive and sealing composition. U.S. Pat. No. 3,218,305 (Krieble) discloses an anaerobic sealant composition. U.S. Pat. No. 2,895,950 and U.S. Pat. No. 3,046,262 (Krieble) also disclose anaerobic compositions. The products described in these specifications are examples of the type of product that may be stored in the container of the invention.
Containers or packages for storing anaerobic adhesive and sealant products are known. Typically such containers may be constructed from plastic, having substantially rigid walls, and capable of holding a number of liters of anaerobic product. Larger containers with pouring spouts are suitable only for low viscosity products. High viscosity products are not-easily decanted. It is known to provide semi-rigid plastic containers for such products. High viscosity products may be dispensed from containers by manual squeezing.
Rigid and semi-rigid containers are used with automatic dispensing machines. They do not readily conform to the shape of the dispenser and thus can create pockets of trapped (and therefore undispensing) products in the dispensing machine. High viscosity products tend to adhere to the walls of the container even if the container is pressurised, leaving a substantial amount of product within the container which is then wasted, or has otherwise to be removed from the container. A further disadvantage of such containers is the shelf life of products and particularly of anaerobic products placed in such containers if the container is filled beyond a certain level. Containers for anaerobic products are ordinarily left with a headspace above the level of liquid in the container. Typically 30% to 60% of the internal volume of the container is left unfilled with anaerobic product, depending on the rigidity of the side wall of the container in order to give a sufficient shelf-life. This allows a sufficient volume of air (oxygen) to remain within the container to help stabilise the anaerobic product. There exists however a conflict between the necessity to seal in the product on the one hand and to allow air (oxygen) to permeate through the product on the other. Such containers when filled or nearly full do not provide commercially acceptable shelf life for anaerobic products, as there is not sufficient air (oxygen) present in the container, nor does sufficient air permeate into the container. There is therefore substantial wastage of packaging materials and higher costs due to the partial filling of containers with this product.
Containers made from air-permeable material allow air through their walls etc. This air may replace air in the headspace or may permeate into the product within the container. However in order to ensure stability of anaerobic products permeation into the headspace alone is not sufficient to ensure adequate shelf-life. The air must permeate through the product also to ensure curing, setting up or polymerisation of the product does not occur. The area where curing, setting up or polymerisation is most likely to first occur is at the centre of the mass of product. Thus even with an air permeable container, and headspace of air in the container, curing or setting up or polymerisation may take place prematurely giving the product a shorter than desired shelf-life. The problem of curing or setting up is exacerbated by elevated storage temperatures. It is known to refrigerate, for example at temperatures of 2-8° C., certain anaerobic products which are sensitive to polymerisation, curing or setting up (particularly those of high viscosity) in order to prevent premature curing. Temperatures greater than about 28-30° C. cause even more rapid curing or setting up of anaerobic products.
An example of one of such containers is commonly referred to as a “cubitainer” [commercially available from Dynopack Ltd. in the U.K.]. The name stems from its cubic shape. The container is constructed from a typically translucent plastic constructed from low density polyethylene/ethylene vinyl acetate (LLDPE/EVA) copolymer mixed with linear low density polyethylene (LLDPE) with a wall thickness of about 160 &mgr;m to 180 &mgr;m. A nozzle with a threaded cap is fitted at the centre of the top wall of the container. Typically the cubitainer has a 3 liter internal volume, which is used to hold 1 liter or 2 liters, of an anaerobic adhesive. The less anaerobic adhesive placed in the cubitainer the greater the shelf-life of the adhesive.
The cubitainer has a continuous welded seam which runs about the outside of the container. The seam runs along one side of the base wall, then diagonally across a first side wall, then across one side of the top wall and then diagonally down a second side wall opposite the first side wall to meet the base wall to form a continuous seam about the container.
The container is relatively rigid, though its contents can be dispensed manually by squeezing the walls of the container to some extent. However, users of the cubitainer have noticed that substantial amounts of medium to high viscosity product remain in the container despite manual pressure, causing them to resort to cutting open the container to remove the contents. The cubitainer is packaged within an external paperboard carton which prevents physical damage to the plastic walls and allows stacking. The oxygen permeability of the cubitainer at 20° C. and 350 &mgr;m wall thickness is about (546 cm
3
/m
2
.day.atm) 553 cm
3
/m
2
.day.bar.
When partially full the cubitainer provides a storage means for anaerobic containers which gives the product an excellent shelf life. However as stated above partially filled containers are wasteful of materials and energy. It is of course possible to fill the cubitainer completely, but in practice it has not been filled as this would compromise the shelf-life of the product. Furthermore the cubitainer is suitable only for low to medium viscosity products, not for medium to high viscosity products due to their “difficult to pour” nature. High viscosity products have been traditionally sold in “bucket with lid” containers i.e. a very wide mouthed container (and thus large) to allow the product to be removed manually from the container.
The containers described above are all “stand-alone” containers i.e. the rigidity of the side-walls is sufficient to allow the container to stand without falling over or deforming to any appreciable extent under internal pressure from its contents. To make a stand-alone container it is necessary to conform to a base area:height ratio which makes the container stable when standing. The cubitainer described above is packaged in a paperboard carton to protect it from damage during transport, storage and the like. The cubitainer is a stand-alone container, its cubic shape and relatively rigid side walls allowing it to stand on its base.
Another form of container used for high viscosity anaerobic products is a cartridge having a nozzle and a built-in piston from which product is dispensed by a dispensing gun etc. No headspace is left in the cartridge. This severely limits the shelf-life of the product. Furthermore the amounts placed in these cartridges are relatively small, of the order of 300 ml to 800 ml. Larger volumes would result in an even shorter shelf-life of the product.
A collapsible container is known from EP-A-0172711 which is suitable for use with medicaments or other liquids which must be preserved from contamination. Likewise EP-A-0590465 relates to a composite film barrier for packaging oxygen-sensitive products. These containers are int
Bryan Hilary E.
Crampton Alan T.
Gordon Fergal A.
Bauman Steven C.
Loctite (R&D) Limited
Luong Shian
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