TECHNICAL FIELD

The present invention relates to improvements in and relating to packaging and machines therefor. In particular, protective wrap type packaging made from paper products and machines and methods for the manufacture thereof.

BACKGROUND ART

Protective packaging is in considerable demand with an increasing volume of goods being transported around the world.

Expanded polystyrene (EPS) is a common form of protective packaging used. EPS has the properties of being very light, impact absorbing and relatively cheap to produce. These are all desirable qualities of protective packaging.

However, EPS (and other similar materials) have problems associated with them.

Firstly, most foams and polymers used in packaging tend to be environmentally unfriendly. Their manufacture requires the use of undesirable chemicals.

Furthermore, these materials can be difficult to dispose of as often they are not biodegradable and produce undesirable fumes when burned.

Another problem with the use of EPS and plastics materials is that they are largely inflexible. This means that to be effective for irregular shaped products, the polystyrene has to be moulded to a particular shape that accommodates that product. The requirement to produce customised moulds can be expensive, and time consuming.

However, inflexible packaging is suitable for regular shaped products. Thus boards whether made out of foam, corrugated paperboard, plastics or pulp can be used to fashion cartons and other containers.

Corrugated paperboard is considerably more eco-friendly than polystyrene and plastics material when used in protective packaging. However, as this is substantially rigid, due to the flutes formed by the corrugated sheet material - it can only be used for regular shaped products, or in conjunction with a moulded insert such as polystyrene with the inherent problems discussed previously.

Thus, corrugated board is likewise not suitable for irregular shaped products due to its rigidity.

One material which is suitable for irregular shaped objects is Bubble Wrap. Bubble Wrap is made from plastics material and has a number of the problems identified previously. However, it can be readily formed around objects. Unfortunately, Bubble Wrap does not have the impact resistance of more solid materials such as corrugated board and polystyrene foam. In addition Bubble Wrap is prone to tearing on sharp objects.

Therefore, it would be desirable if there could be provided a packaging material which is more eco-friendly than plastic Bubble Wrap, yet is sufficiently flexible or bendable to effectively wrap around irregular objects, robust, light weight and is relatively inexpensive to produce. Ideally, the cost of manufacture should not be too dissimilar to the cost of manufacture of Bubble Wrap.

Previously the applicant has addressed some of these issues in WO 2011/059347. However, whilst this is a satisfactory solution, it would be useful if there could be an alternative solution which can be manufactured more cheaply and simply.

There is a need in the art for elongate objects of an indeterminate length exceeding around 3m to be more easily and efficiently wrapped by single face paperboard. For example, aluminium tubes or extrusions which are longer than 2m in length, cannot be uniformly wrapped by single face paperboard without: cutting the single face paperboard and wrapping in two or more discrete sections.

Previously the Applicant had thought that simply spiralling the single face around an elongate object, exceeding 3m in length, might be a way to wrap it. However, spiralling the single face paperboard around the length of the object has subsequently been found problematic, due to the rigidity imparted to the single face, by the flutes along the axis of the flutes; causing puckering.

It is an object of the present invention to address the foregoing problems or at least to provide the public with a useful choice.

All references, including any patents or patent applications cited in this specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. The discussion of the references states what their authors assert, and the applicants reserve the right to challenge the accuracy and pertinency of the cited documents. It will be clearly understood that, although a number of prior art publications are referred to herein, this reference does not constitute an admission that any of these documents form part of the common general knowledge in the art, in New Zealand or in any other country.

Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise", "comprising", and the like, are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense, that is to say, in the sense of "including, but not limited to".

Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only.

SUMMARY OF THE INVENTION

The present invention in general terms is directed towards single face paperboard suitable for protective packaging of items, which can be of indeterminate length. This packaging being capable of being wrapped around irregular shaped objects along either or both the longitudinal and/or transverse axes of the laminate due to a series of intersecting creases being formed over the single face paperboard, which enable bending/folding of the laminate across the longitudinal axes of the flutes.

According to a first aspect of the present invention there is provided an apparatus for making single face paperboard which includes: a single facing unit which has located downstream; a first roller which includes a plurality of spaced apart creasing discs positioned around which have a circumferential-axis substantially orthogonal to the rotational axis of the first roller; at least one further roller which includes: a) a plurality of spaced apart circumferential rails which have their circumferential- axis at an angle of substantially 20-70 degrees to the rotational axis of the second roller towards the LHS thereof; and/ or b) a plurality of spaced apart circumferential rails which have their circumferential- axis at an angle of substantially 20-70 degrees to the rotational axis of the second roller towards the RHS thereof; wherein said rollers all have an associated nip roller positioned on the other side of the single face paperboard to that of the first, second and third rollers; wherein said rollers all have their respective creasing rollers/circumferential rails positioned to crease the flutes of the single face paperboard as it passes said rollers.

According to a second aspect of the present invention there is provided a single face paperboard which includes: a plurality of transversely spaced apart creases which orthogonally intersect the longitudinal axis of each of the flutes; a plurality of transversely spaced apart creases which intersect the longitudinal axis of each of the flutes at an angle of substantially 20-70 degrees towards the RHS thereof; a plurality of transversely spaced apart creases which intersect the longitudinal axis of each of the flutes at an angle of substantially 20-70 degrees towards the LHS thereof.

According to a third aspect of the present invention there is provided a single face paperboard which includes: a plurality of transversely spaced apart creases which substantially orthogonally intersect the longitudinal axis of each of the flutes; wherein a distance Y by which each crease is separated from an adjacent crease is calculated by the formula:

Y = flute height x 5.

According to a fourth aspect of the present invention there is provided an apparatus for making single face paperboard which includes: a single facing unit which has located downstream; a first roller which includes a plurality of transversely spaced apart circumferential creasing discs which have their circumferential-axis substantially orthogonal to the rotational axis of the first roller; wherein said first roller has an associated nip roller positioned on the other side of the single face paperboard to that of the first roller; wherein in use, the creasing discs press a crease tip into the single face paperboard to crease the flutes as single face paperboard passes said roller, in a direction substantially orthogonal to the flutes; and wherein a distance Y by which each crease tip is separated from an adjacent crease tip is calculated by the formula:

Y = flute height x 5.

According to a fifth aspect of the present invention there is provided a single face paperboard which includes: a plurality of transversely spaced apart creases which substantially orthogonally intersect the longitudinal axis of each of the flutes; a plurality of transversely spaced apart creases which intersect the longitudinal axis of each of the flutes at an angle of substantially 20-70 degrees towards the RHS thereof; a plurality of transversely spaced apart creases which intersect the longitudinal axis of each of the flutes at an angle of substantially 20-70 degrees towards the LHS thereof; wherein a distance Y by which each crease is separated from an adjacently parallel crease is calculated by the formula:

Y = flute height x 12.5.

According to a sixth aspect of the present invention there is provided an apparatus for making single face paperboard which includes; a single facing unit which has located downstream: a first roller which includes a plurality of transversely spaced apart creasing discs which have their circumferential-axis substantially orthogonal to the rotational axis of the first roller; at least one further roller which includes: a plurality of spaced apart circumferential rails which have their circumferential- axis at an angle of substantially 20-70 degrees to the rotational axis of the second roller towards the LHS thereof; and/or a third roller which includes a plurality of spaced apart circumferential rails which have their circumferential- axis at an angle of substantially 20-70 degrees to the rotational axis of the second roller towards the RHS thereof; wherein said rollers all have an associated nip roller positioned on the other side of the single face paperboard to that of the first, roller; wherein a distance Y by which each rail on said first second and third rollers is separated from an adjacent rail is calculated by the formula:

Y = flute height x 12.5.

According to a seventh aspect of the present invention there is provided a roller for creasing single face paper board wherein the outer surface of the roller includes: at least one circumferential rail projecting therefrom, and/or a plurality of creasing discs; the rail/creasing discs when viewed in cross section having a creasing tip formed from left and right sides which are outwardly sloped and a top section connecting the left and right sides, wherein the top section has a length of substantially 2- 3mm and wherein the height of the creasing tip, is substantially equal to the height of the flutes, on the single face to be creased.

In one preferred embodiment, the circumferential rail is helical in nature.

According to an eighth aspect of the present invention there is provided a single face paperboard which includes: a plurality of transversely spaced apart creases which orthogonally intersect the longitudinal axis of each of the flutes; wherein a distance Z by which the creases are separated from one another within substantially 100mm of at least one outer edge of the single face is at least half the distance Y by which the other creases are separated from one another. According to a ninth aspect of the present invention there is provided a method of

manufacturing single face paperboard which includes the step of: a) forming a plurality of transversely spaced apart creases which substantially orthogonally intersect the longitudinal axis of each of the flutes; wherein a distance Y by which each crease is separated from an adjacently parallel crease is calculated by the formula:

Y = flute height x 12.5.

According to a 10 ^th aspect of the present invention there is provided a method of manufacturing single face paperboard substantially as described above which includes the additional steps of: b) forming a plurality of transversely spaced apart creases which intersect the longitudinal axis of each of the flutes at an angle of substantially 20-70 degrees towards the RHS thereof; c) a plurality of transversely spaced apart creases which intersect the longitudinal axis of each of the flutes at an angle of substantially 20-70 degrees towards the LHS thereof.

According to an 11 ^th aspect of the present invention there is provided a method of

manufacturing single face paperboard which includes the step of: a) forming a plurality of transversely spaced apart creases which intersect the longitudinal axis of each of the flutes at an angle of substantially 20-70 degrees with respect to the longitudinal axis of each flute.

According to a 12 ^th aspect of the present invention there is provided a single face paperboard which includes: a liner sheet bonded to a fluted sheet, wherein the liner sheet extends on at least one side edge beyond the edge of the fluted sheet; and a plurality of transversely spaced apart creases that substantially orthogonally intersect the longitudinal axis of each of the flutes.

Preferably, the liner sheet extends a distance of at least substantially 100mm from the edge of the fluted medium. According to a 13 aspect of the present invention there is provided a single face paperboard which includes a liner sheet substantially as described above, wherein within substantially 100mm of each outer edge of the fluted sheet, the creases are separated from one another, a distance Z, which is at least half the distance Y, by which the other creases are separated from one another.

According to an 14 ^th aspect of the present invention there is provided a method of

manufacturing single face paperboard characterised by the step of forming a series of spaced apart creases which intersect the longitudinal axis of the flutes on the single face paperboard.

According to a 15 ^th of the present invention there is provided a single face paperboard which includes a series of creases along the length thereof which intersect the longitudinal axis of the flutes to enable folding or bending across said axis.

According to a 16 ^th aspect of the present invention there is provided a singe face paperboard which includes a plurality of transversely spaced apart creases which substantially orthogonally intersect the longitudinal axis of each of the flutes.

According to a 17 ^th aspect of the present invention there is provided a singe face paperboard which includes a plurality of transversely spaced apart creases which intersect the longitudinal axis of each of the flutes at an angle of substantially 20-70 degrees.

According to a 18 ^th aspect of the present invention there is provided a singe face paperboard which includes: a plurality of transversely spaced apart creases which substantially orthogonally intersect the longitudinal axis of each of the flutes; a plurality of transversely spaced apart creases which intersect the longitudinal axis of each of the flutes at a non-orthogonal angle towards the RHS thereof; a plurality of transversely spaced apart creases which intersect the longitudinal axis of each of the flutes at a non-orthogonal angle towards the LHS thereof. BRIEF DESCRIPTION OF THE DRAWINGS

Further aspects of the present invention will become apparent from the ensuing description which is given by way of example only and with reference to the accompanying drawings in which:

Figure 1 shows a schematic plan view of single face paperboard in accordance with one preferred embodiment of the present invention;

Figure 2 shows a close up view of a corner section of the single face paperboard of Figure

1 together with and end on view of the corner section;

Figure 3 shows an end on view of the section of single face paperboard of Figure 2 in a flexed state along one axis;

Figure 4 shows a schematic plan view of an apparatus for making single face paperboard in accordance with one preferred embodiment of the present invention; and

Figure 5 shows a perspective view of an alternate creasing roller for use in an apparatus for making single face paperboard as shown in Figure 4 which can replace rollers 105 and 107;

Figure 6a shows a schematic transverse cross sectional view of conventional "uncreased" single face paperboard;

Figure 6b shows a schematic transverse cross sectional view of a preferred embodiment of single face paperboard according to one aspect of the present invention wherein the flutes of the single face are intersected by a series of orthogonal creases spaced apart a distance Y;

Figure 7 shows a schematic plan view of a preferred embodiment of single face

paperboard according to a further aspect of the present invention wherein the flutes are intersected by spaced apart longitudinal creases and 45 degree angled RHS and LHS spaced apart creases all parallel creases being spaced apart a distance Y;

Figure 8 shows a side view of a roller assembly for use in an apparatus making single face paperboard suitable for longitudinally wrapping around an elongate object; shows a crease disc used on the creasing roller shown in Figure 8; shows an enlarged view of the crease tip of the crease disc shown in Figure 9 shows an enlarged view of the right hand end of the creasing roller in Figure 8. shows a schematic plan view of single face paper board made by the creasing roller of Figure 8 which has longitudinal creases and has one edge including additional creases to facilitate wrapping around long thin objects; shows a schematic plan view of a single face paperboard which has the liner sheet over extending past the edge of the fluted sheet; shows a schematic plan view of single face paper board which has spaced parallel angled creases which enable this embodiment of single face to be spirally wrapped around an elongate object, and also has one edge which includes liner sheet extending beyond the edge of the flutes to facilitate wrapping around long thin objects; shows a schematic plan view of single face paperboard with parallel creases which are orthogonal to the longitudinal axes of the flutes according to another aspect of the present invention; and shows a schematic plan view of single view of single face paperboard which incorporates the orthogonal creases and edge elements of Figures 12 and 13.

BEST MODES FOR CARRYING OUT THE INVENTION

With respect to the Figures 1 -3 there is provided a single face paperboard 1 which is formed to have: a plurality of spaced apart longitudinal creases 2 which orthogonally intersect the longitudinal axes of the flutes 3; a plurality of spaced apart creases 4 which intersect the longitudinal axes of the flutes 3 at an angle of substantially 45 degrees towards the RHS thereof; a plurality of spaced apart creases 5 which intersect the longitudinal axes of each of the flutes at an angle of substantially 45 degrees towards the LHS thereof. In Figure 4 there is shown an apparatus 100 for forming the single face paperboard according to one aspect of the present invention.

The apparatus 100 has a single facing unit 101 which produces single face paperboard 102 in the direction indicated by arrow R. Preferably the single facing unit 101 produces the single face paperboard via a cold process.

It will be appreciated in some embodiment this intermediate form of the paperboard 102 in apparatus 100 may be an end product and rollers 105 and 107 would not be required.

The single face paperboard 102 shortly after exiting the single facing unit 101 passes between a first roller 103 and associated nip roller (not shown). The first roller 103 has a plurality of circumferential rails 104 thereon which, in use, crease the flutes of the single face paperboard to create longitudinal creases 1040 therein (as depicted in Figure 4). This intermediate form of creased paperboard is indicated by reference numeral 02' and will now simply be referred to as longitudinal creased single face paperboard.

The single face creased paperboard 102' now passes between a second roller 105 and associated nip roller (not shown). The second roller 05 has a plurality of rails 106 thereon which have their circumferential- axis at an angle of substantially 45 degrees to the rotational axis of the second roller towards the LHS. This penultimate intermediate form of creased paperboard is indicated by reference numeral 102" and will now be simply referred to as double creased paperboard. The roller 105 forms LHS creases 1050.

The double creased paperboard 102" now passes between a third roller 107 and associated nip roller (not shown). The third roller 107 has a plurality of rails 108 thereon which have their circumferential-axis at angle of substantially 45 degrees to the rotational axis towards the RHS. The resulting tri-creased form of paperboard is the end product of the apparatus 100 and constitutes one form of improved single face paperboard 200 of the present invention. The roller 107 forms the RHS angled creases 1080.

With respect to Figure 5 there is shown a creasing roller 200 which has four pairs A-D of rails 201 thereon, each pair of rails being in the form of a double helix. In each pair, one rail has a clockwise spiral and the other rail of the double helix has an anticlockwise spiral. In Figure 6a there is shown a partial end on view of a conventional "uncreased" sheet of single face 300, having a fluted sheet 301 and a liner sheet 302. The ridge of the flute is depicted by the line indicated by reference numeral 310. With respect to Figure 6b there is shown the single face paperboard of Figure 6a, after it has been of creased according the present invention. As can be seen creases 303, running across the flutes, have a base section 304 which connects the outwardly sloped left and right walls 305 and 306. The angle at which the creases 303 intersect the longitudinal axes of the flutes is 90 degrees. The fluted sheet 301 has creases 303 which are spaced apart a distance Y. The distance Y is calculated from a flute height of 4mm multiplied by 5 to give a distance of 20mm by which the adjacent creases are separated from one another.

With respect to Figure 7 there is shown a sheet of single face 400 withthe fluted sheet 401 being topmost and the liner sheet not being visible. The fluted sheet 401 has: a plurality of spaced apart longitudinal creases 402 - orthogonally intersecting the axes of the flutes 410 - and which are all separated a distance Y from one another; a plurality of spaced apart creases 403 which intersect the longitudinal axes of the flutes at an angle of substantially 45 degrees towards the RHS thereof and which are all separated a distance Y from one another; a plurality of spaced apart creases 404 which intersect the longitudinal axes of each of the flutes at an angle of substantially 45 degrees towards the LHS thereof and which are all separated a distance Y from one another.

The distance Y is calculated from the flute height of 4mm multiplied by 12.5 to give a distance of 50mm by which the adjacent creases are separated from one another.

In relation to Figure 8 there is shown a roller assembly 500 which has a creasing roller 501 and a nip roller 502. Figures 9 and 10 show greater detail the shape of the creasing discs 503 which form the creasing roller 501. The creasing discs 503 have a crease tip 550 formed from an outwardly sloped left wall 504L and outwardly sloped right wall 504R connected via a flat top section 505 which forms a crease tip which is substantially 3mm wide. As shown in Figures 8 and 11 the roller 500 has the space between each crease tip determined by a distance Y, as per the formula discussed in relation to Figure 6. The exception being the rightmost group of edge crease discs 510 which are separated by a distance Z which is half that of distance Y. The distance Y is calculated from the flute height of 4mm multiplied by 5 to give a distance of 20mm by which the adjacent creases are separated from one another.

The roller assembly 500 in use produces single face paper board 700 having creases 701 spaced apart either a distance Y, or proximate the left edge a distance Z - as shown in Figure 12. The creases 701 intersecting at 90 degrees the longitudinal axis of flutes 702. The shorter distance Z compromises flute integrity, in order to facilitate, easier folding of the paperboard, to initially wind it around a thin elongate object. The distance Y is calculated from the flute height of 2.5mm multiplied by 5 to give a distance of 12.5mm by which the adjacent creases are separated from one another.

In Figure 13 there is shown a single face paperboard 800 which has longitudinal creases 801 which orthogonally intersect the longitudinal axis of the flutes 802. In addition, the single face paperboard 800 also has a liner sheet extending beyond edge 803 of the fluted paper sheet to which it is bonded, to form a flat edge section 804. The flat section 804 provided by the over extended liner sheet, facilitates easier folding of the paperboard, to initially wind it, around a thin elongate object. The distance Y is calculated from the flute height of 5mm multiplied by 5 to give a distance of 25mm by which the adjacent creases are separated from one another.

In Figure 14 there is shown single face paperboard 900 which has spaced apart diagonal creases 901 which intersect the flutes 902 and enable this form of single face to be spirally wound around elongate objects. The distance Y is calculated from the flute height of 4mm multiplied by 5 to give a distance of 20mm by which the adjacent creases are separated from one another.

In Figure 15 there is shown single face paperboard 1000 which has spaced apart longitudinal creases 1001 which orthogonally intersect the flutes 1002 and enable this form of single face to wrap around elongate objects along the longitudinal axis of the single face paperboard. The longitudinal creases 1001 are separated from one another a distance Y. The distance Y is calculated from the flute height of 3.5mm multiplied by 5 to give a distance of 17.5mm by which the adjacent creases are separated from one another.

In Figure 16 there is shown single face paperboard 1 100 which has a first set of spaced apart longitudinal creases 1101 which orthogonally intersect the flutes 1 102 and are separated from one another a distance Y. The single face paperboard 1101 also has a second set of spaced apart longitudinal creases 1103 which orthogonally intersect the flutes 1102 and are separated from one another a distance Z. Distance Z is half that of distance Y. The distance Y is calculated from the flute height of 2.2mm multiplied by 5 to give a distance of 11 mm by which the adjacent creases are separated from one another. ALTERNATE WAYS FOR IMPLEMENTING THE INVENTION

The paperboard may come in a variety of different forms without limiting the scope of the present invention.

The angle that the creases bisect the longitudinal axes of the flutes may be substantially orthogonal or substantially between 20 - 70 degrees.

In preferred embodiments non-orthogonally angled creases may have an angle of substantially between 40 - 50 degrees with respect to the longitudinal axes of the flutes.

Most preferably the non-orthogonally angled creases may have an angle of substantially 45 degrees with respect to the longitudinal axes of the flutes.

In one embodiment which enables the single face to be spiralled around an elongate object there is a series of parallel spaced apart creases which have an angle of substantially 30-45 degrees with respect to the longitudinal axis of the flutes.

The creases may be formed in a variety of different ways without departing from the scope of the present invention.

Thus, it will be appreciated that creases may be formed by any suitable method of pressing a line across the flutes of single face paperboard as part of a continuous process.

In one embodiment the creases may be formed by a series aligned but spaced apart rotating discs which all have a common axis of rotation so as to collectively form a roller.

In another preferred embodiment the LHS and RHS angled creases may be formed by a roller including two helical intersecting rails thereon.

In some iterations of the present invention there may be three sets of rollers employed to crease the single face.

The creases enable the paperboard to bend or flex against the longitudinal axes of the flutes.

The number of creases and/or spacing apart of the creases dictates the amount of curvature that can be imparted to the paperboard along the axis in which the flutes extend. Thus, if the flutes generally extend in the transverse direction with respect to the longitudinal axis of the single face paperboard, the creases enable the paperboard to be curved about the longitudinal axis of the paperboard. The number of creases depends on the degree of flexibility one wishes to impart to the single face paperboard. The more creases the more effective curvature that can be introduced to the paperboard.

During single face production the axes of the flutes extend transversely with respect to the direction in which the board is being produced as a continuous length.

When creating the present invention there are two competing objectives which need to be taken into account when considering the number, and spacing, of the creases: first, having a sufficient number of creases in order to create single face paperboard which can be folded about multiple axes so as to closely conform to the surface shape of an object ; and second, at the same time as trying to achieve the above objective, not having too many creases, such that the structural integrity (and hence protective ability) of the flutes becomes compromised, due to undue flattening thereof.

An exception to the second objective occurs when it is necessary to have an embodiment of single face which is suitable for wrapping thin objects. In this instance, to enable the edge of the single face to start to roll (i.e. fold or wrap) around a thin object, which may have a width smaller than distance Y: the creases, located in an edge region, which say extends 100mm inwardly from at least one edge of the single face, may be more closely spaced than distance Y, Y which otherwise governs the spacing of the creases located in central regions (i.e. non-edge regions).

Otherwise the single face will not efficiently fold along its length, and will resist folding making capture of the elongate object within the fold problematic. Increasing the fold ability (wrap ability) along the edge, even at the cost of flute integrity, facilitates the wrapping of said objects, and the integrity of the non-edge flutes, which is maintained, still acts to protect the object once fully wrapped.

The inventor has also found that the profile of the crease can also facilitate bending.

The inventor has found the optimum crease shape is in the form of channel having outwardly splayed walls on either side of a base section.

In one exemplary example the internal angle of each wall may be substantially 45 degrees with respect to the planar sheet of the single face liner sheet. In other embodiments the internal angle of the walls may be any angle selected from within the range of substantially 45 -60 degrees.

In one exemplary example the base section may span a distance of substantially 2 - 3mm between each of the walls.

The entire disclosures of all applications, patents and publications cited above and below, if any, are herein incorporated by reference.

Reference to any prior art in this specification is not, and should not be taken as, an

acknowledgement or any form of suggestion that that prior art forms part of the common general knowledge in the field of endeavour in any country in the world.

The invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, in any or all combinations of two or more of said parts, elements or features.

Where in the foregoing description reference has been made to integers or components having known equivalents thereof, those integers are herein incorporated as if individually set forth.

It should be noted that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the invention and without diminishing its attendant advantages. It is therefore intended that such changes and modifications be included within the present invention.

Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope thereof as defined in the appended claims.