SACHETS AND MATERIALS USED IN MANUFACTURE OF SACHETS

Abstract

A sachet has a semi-rigid layer laminated between first and second outer layers. A line of weakness formed in a mid-portion of the semi-rigid layer sequentially delineates inter-digitated finger portions of the semi-rigid layer. The first outer layer seals over and around the line of weakness. The second outer layer, optionally formed with a reservoir, is fixed to either or both of the other two layers. The sachet is flexed preferentially at the line of weakness by application of a compression force between opposite sachet edges to move at least the tips of the finger portions away from respective immediately surrounding portions of the semi-rigid layer and thereby rupture the first outer layer in the vicinity of the line of weakness and form an opening for discharge of sachet contents. A two-layered precursor web and a series of interconnected sachets are also claimed.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to New Zealand Application No. 547925, filed Jun. 14, 2006, which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. The Field of the Invention

The present invention relates to sachets used to package and dispense small predetermined quantities, e.g. single serves, of fluid or fluent materials such as liquids, creams, lotions, gels, pastes, powders, particulates, sauces, beverages, sunscreens, lubricants, paints, greases, oils, glues, resins, medicines, pharmaceuticals, etc. Such sachets can be made from multiple layers of sheet materials which are laminated together to form an enclosed reservoir. The sachets are opened by bending the sachet to rupture one or more sachet layers. The sachet contents can be discharged through the rupture, the discharge being aided by squeezing the sachet if necessary.

2. The Relevant Technology

The present invention relates to sachets and to materials prepared for use in manufacture of such sachets, and particularly relates to cuts and/or other lines of weakness that are formed in the layers of such sachets, or in web or sheet materials for use in the manufacture of such sachets. The cuts or lines of weakness are configured for facilitating rupture of at least one of the sachet layers in a controllable manner just prior to dispensing the sachet contents.

Known packages or sachets are made from layers of plastics and/or metallic foils which are laminated together to form a sealed reservoir between adjacent layers for housing the contents of the sachet. The layers are provided with weakened zones which can be preferentially ruptured to allow the contents of the package to be discharged. The contents of the sachet can be dispensed, for example by an end user at a point of use, by piercing or rupturing at least one layer and thereby creating an opening through which the reservoir contents may be expelled, for example by squeezing the sachet.

Such sachets are typically manufactured using methods and apparatus similar to those used in the printing industry where elongate webs are passed along a line of stations each performing a different function. Typically, the material to be packaged in the sachets is introduced between two webs which are sealed together continuously along their opposite edges. The webs are also sealed transversely at intervals to divide the webs into separate compartments. Individual sachets are produced by cutting the webs transversely at the transverse seals.

Typically, a layer of the sachet is ruptured by flexing the sachet. The flexing ruptures a layer at a predetermined zone, optionally defined by a line or pattern of weakness pre-formed in at least one of the layers.

Various mechanisms are known to aid in control of the rupturing and dispensing process. Typically, at least one of the webs is made from a relatively stiff or semi-rigid material which has a region that is weakened by a cut or a pattern of cuts, or other zones of weakness. When flexed, the sachet bends or folds preferentially about the weakened region, rupturing the semi-rigid material to form one or more apertures through which the contents of the sachet may be discharged by an end user at a point-of-use.

Sachets do not always readily rupture in the desired manner or location and can be resistant to rupturing without excessive force being applied. The application of force, and particularly excessive force, to open the sachet pressurizes the contents during the opening operation. This pressurization often leads to the inadvertent discharge of the contents in an uncontrolled manner. An uncontrolled discharge may occur at the desired point of rupture. Alternatively a discharge may occur at the perimeter of the sachet if the strength of the perimeter sealing is inadequate and of a lesser burst strength than that of the desired rupture point.

In this specification where reference is made to patent specifications, other external documents, or other sources of information, this is generally for the purpose of providing a context for discussing the features of the invention. Unless specifically stated otherwise, reference to such external documents is not to be construed as an admission that such documents, or such sources of information, in any jurisdiction, are prior art, or form part of the common general knowledge in the art.

U.S. Pat. No. 3,986,640 to Redmond describes a dispensing package for a flowable substance. A relatively stiff flat sheet and a flexible sheet are sealed together around their marginal edges. A flowable substance is contained between the two sheets. The relatively stiff sheet is cut through or partially cut through in an interrupted pattern forming at least one tongue and one opening when the relatively stiff sheet is bent into a V about an axis through the base of the tongue. The bending ruptures a sealant or sealing layer at the cut pattern so that the package contents can then be squeezed out through the opening. The plurality of relatively small openings formed by the interrupted pattern of cuts can impair the discharge of some packaged substances. The larger tongue of one embodiment (FIG. 1C) can impose an excessive leverage on the tongue causing it to bend and not rupture the package seal.

U.S. Pat. No. 4,236,652 to Beguhn describes a dispenser package for a flowable substance. At one side of the package, a uniaxially oriented plastic film layer is sealed over a rigid or semi-rigid layer with a single straight score or cut. The other side of the package is a relatively flexible layer. A pocket formed between the two sides contains the package contents. The package is opened by bending or folding the package about the axis of the score or cut line to rupture the rigid layer and to rupture the sealing film. The orientation of the film is used to facilitate rupturing of the film. There is no requirement for, or disclosure of, a cut or score line shaped to produce a tongue for rupturing the package during opening.

U.S. Pat. No. 4,493,574 to Redmond et al describes a dispenser package having a fault line with a protrusion. The package contains a flowable substance in a pouch in a flexible layer which is adhered to a relatively stiff sheet. The package is opened by bending the package into a “V” shape about the fault line, or cut pattern, in the relatively stiff sheet. Localised rupture of the package during opening is facilitated by providing the fault line with dimples, pyramidal shapes or other protrusions extending outwardly from the outer surface of the relatively stiff sheet. The opening of the package is localised at each protrusion and the package contents can be discharged in a highly directed stream from each opening by application of a relatively considerable pressure. However, high pressures can cause the package to burst elsewhere and inadvertently discharge the contents in an uncontrolled manner.

New Zealand Patent No. 313329 describes a sachet formed from plastics layers sandwiched together to form a reservoir. An outer semi-rigid layer has a region of weakness. An adjacent layer has an aperture adjacent the region of weakness. When the semi-rigid layer is bent, the semi-rigid layer fractures at the region of weakness. The contents of the sachet can then be dispensed upon further bending of the sachet to compress the reservoir and discharge the sachet contents through the aperture. Although this arrangement addresses some of the difficulties relating to control of the rupture and discharge, the score or region of weakness can fail prior to intended discharge of the sachet contents. Such a premature loss of seal can lead to spoiling of the sachet contents before the intended time of use.

SUMMARY OF INVENTION

One object, of at least one embodiment of the invention, is to provide a sealed sachet that overcomes some of the disadvantages of the prior art, or at least provides the public with a useful choice.

A second object, of at least one embodiment of the invention, is to provide a sachet with a sealed reservoir, the contents of which can be discharged from the reservoir in a controlled manner by first flexing the sachet to rupture a first layer sealing a discharge aperture in a second layer.

A third object, of at least one embodiment of the invention, is to provide an elongate web for use in the manufacture of sealed sachets that overcome some of the disadvantages of the prior art, or at least provide the public with a useful choice.

In a first aspect, the present invention may be broadly said to be a sachet for storing and dispensing a fluent material, the sachet comprising a lamination of first, second and third layers; wherein: the second layer is a semi-rigid layer located between the first and third layers; a line of weakness is formed in a mid-portion of the second layer; at least a portion of the line of weakness sequentially delineates inter-digitated finger portions of the second layer; the finger portions extend in respective substantially opposite directions toward first and second opposing edges of the second layer on opposite sides of the line of weakness; the first layer seals over and around the line of weakness; and the third layer is fixed to at least one of the first layer or the second layer; the sachet is adapted to flex preferentially at the line of weakness on application of a compression force between the first and second edges; the second layer is adapted to open at the line of weakness and move at least the tips of the finger portions away from respective immediately surrounding portions of the second layer by flexure of the second layer at the line of weakness; and the first layer is adapted to rupture in the vicinity of the line of weakness by movement of at least the tips of the finger portions away from respective immediately surrounding portions of the second layer to form at least one discharge opening through which contents of the sachet may be discharged.

Preferably the first and third layers are relatively flexible relative to the semi-rigid second layer. Preferably the third layer is sealed to at least part of the first layer or the second layer, at least around a peripheral region of the sachet. Preferably the line of weakness extends through the full thickness of the second layer.

Preferably at least one of the finger portions is delineated by a portion of the line of weakness that is V-shaped and comprises two substantially straight limbs which meet at an angle not equal to 180 degrees. Alternatively, at least one of the finger portions is delineated by a portion of the line of weakness that is U-shaped.

Preferably the line of weakness is offset from a mid-point between opposed edges of the second layer.

Preferably the sachet is adapted to rupture the first layer by movement of at least the tips of the finger portions away from immediately surrounding portions of the second layer on flexure of the second layer at the line of weakness without bringing the first and second edges of the second layer into contact with one another. Alternatively, the line of weakness in the second layer is a zone of weakness which lies between two relatively stronger zones of the second layer; the three zones lie on an axis of flexure about which the second layer flexes preferentially upon application of the compression force; and the two relatively stronger zones resist flexing of the second layer at the line of weakness sufficiently to prevent rupture of the first layer when the first and second edges of the second layer are brought together. Optionally, the sachet is adapted so that after initial flexure of the second layer by bringing the first and second edges of the second layer into contact with one another, the first layer is adapted to rupture when the second layer is then flexed further.

Preferably, a first line of weakness is formed in the first layer, this first line of weakness being spaced apart from, and at least approximately aligned with, the line of weakness in the second layer.

Preferably, the second layer is spaced inwardly from the peripheral edges of the sachet.

In a second aspect, the present invention may be broadly said to be an elongate web comprising a lamination of first and second layers, wherein the second layer is a semi-rigid layer; a series of lines of weakness is formed in a mid-width portion of the second layer, at least a portion of each line of weakness sequentially delineating inter-digitated finger portions of the second layer, the finger portions extending in respective substantially opposite directions toward first and second side edges of the second layer; and the first layer seals over and around each line of weakness.

Preferably, the first layer is a relatively flexible layer; and/or each line of weakness extends through the full thickness of the second layer.

Preferably, the portion of each line of weakness delineating one of the finger portions is V-shaped and comprises two substantially straight limbs which meet at an angle not equal to 180 degrees. Alternatively, the portion of each line of weakness delineating one of the finger portions is U-shaped.

Preferably, each line of weakness is offset from a longitudinal centreline of the web to be closer to one side edge of the web than to an opposing side edge. Alternatively, each line of weakness in the second layer is a zone of weakness which lies between two relatively stronger zones of the second layer and the three zones lie transversely across the web.

Preferably, a corresponding series of lines of weakness is formed in the first layer with each respective line of weakness in the first layer being spaced apart from and at least approximately aligned with a corresponding one of the lines of weakness in the first layer.

In a third aspect, the present invention may be broadly said to be a series of interconnected sachets formed by fixing an elongate web as claimed in any one of claims 20 to 30 to a third layer, wherein the third layer is elongate and is fixed to at least one of the first layer or the second layer of the web.

Preferably the series of sachets is adapted so that individual sachets each have a respective line of weakness formed in the second layer and can be separated from the series, each sachet is adapted so that when separated from the series the second layer of the separated sachet flexes preferentially at the respective line of weakness on application of a compression force to edges of the second layer of the sachet on opposite sides of the respective line of weakness in the second layer so that portions of the second layer on opposite sides of the respective line of weakness in the second layer move apart and rupture the first layer in the vicinity of the line of weakness in the second layer to form a discharge opening through which contents of the sachet may be discharged. Preferably, the third layer is a relatively flexible layer; and/or the third layer is sealed to at least part of the first layer or the second layer, at least around a peripheral region of each sachet.

The term ‘comprising’ as used in this specification means ‘consisting at least in part of’, that is to say when interpreting statements in this specification which include that term, the features, prefaced by that term in each statement, all need to be present but other features can also be present.

This 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, and any or all combinations of any two or more said parts, elements or features, and where specific integers are mentioned herein which have known equivalents in the art to which this invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth.

The invention consists in the foregoing and also envisages constructions of which the following gives examples only.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention will now be further described, by way of example only and without intending to be limiting, with reference to the accompanying drawings of which:

FIG. 1 shows a perspective view of three layers before being laminated together to form a sachet,

FIG. 1A shows a perspective view of three layers before being laminated together to form an alternative sachet in which a reservoir pouch is formed by pre-shaping the lower layer,

FIG. 2 shows a top plan view of a sachet formed by laminating together the three layers as shown in FIG. 1,

FIG. 3 is a top plan view of a sachet similar to that of FIG. 2, showing an alternative configuration of a line of weakness,

FIG. 4 shows a top plan view of another sachet, having an another configuration of the line of weakness,

FIG. 5 shows a top plan view of another sachet with a semi-rigid middle layer of reduced size,

FIG. 6 shows a top plan view of another sachet having a symmetrically shaped cut offset toward an edge of the sachet and at one end of a lateral line of weakness,

FIG. 7 shows a top plan view of an alternative to the sachet of FIG. 8 with a semi-rigid middle layer of reduced size,

FIG. 8 shows a top plan view of still another alternative sachet having a symmetrically shaped cut offset toward an edge of the sachet and at one end of a longitudinal line of weakness,

FIG. 9 shows a top plan view of an alternative to the sachet of FIG. 9 with a semi-rigid middle layer of reduced size,

FIG. 10 shows a top plan view of yet another alternative sachet having a cut that is offset toward one side edge of the sachet,

FIG. 11 shows a top plan view of another alternative sachet having an asymmetrically shaped cut placed at a mid-portion of the sachet,

FIG. 12 shows a top plan view of an alternative to the sachet of FIG. 11 with a semi-rigid middle layer of reduced size,

FIG. 13 shows a top plan view of a sachet with a first alternative non-rectangular configuration,

FIG. 14 shows a top plan view of a sachet with a second alternative non-rectangular configuration,

FIG. 15 shows a perspective view of two layers before being laminated together to form a double-layered precursor web, and

FIG. 16 shows a perspective view of three layers before being laminated together to form a series of sachets.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

It will be appreciated that sachets and preparatory or precursor materials for making the sachets can be implemented in various forms while incorporating the current invention. The following description refers to the embodiments shown in the drawings which are given, by way of example only. However, it is to be understood that the invention is not limited to the embodiments shown and may also be applied to sachets having more than the number of layers shown and described, for example.

FIGS. 1 and 1A each show three layers spaced apart from one another. The three layers are shown apart for the purposes of explanation and as may be envisaged prior to being brought together and laminated to one another to form a sachet. These views may also be envisaged as so-called ‘exploded’ views of the respective sachets.

A first sachet layer 1 optionally has a line or lines of weakness 10, 12. A second sachet layer 2 has a line or weakness or cut 20 formed in a mid-portion of the layer, i.e. inward of the periphery of the second layer. A third sachet layer 3, 3A has a reservoir 30, 30A formed in a mid-portion of the layer, i.e. inward of the periphery of the third layer.

The three layers are formed into a sachet by laminating the first, second and third layers together. The first layer 1 is sealed to one face (the upper face 21 as shown in FIGS. 1 and 1A) of the second layer 2. The third layer 3, 3A is fixed to the opposite face of the second, or intermediate, layer 2.

FIG. 2 3 shows top plan views of the three layers of the sachet of FIG. 1 when assembled together and laminated to form the sachet 4. The first and second layers are juxtaposed one above the other so that the line or lines of weakness 10, 12 in the first layer is/are aligned with, and spaced apart from, the cut 20 which is shown in FIG. 2 by a broken line. The sealing of the first layer to the upper face 21 of the second layer seals over and around the cut 20. Preferably, the first and second layers are sealed together over their whole faces.

The fixing of the third layer 3 to the lower face of the second layer 2 seals the peripheral region of the third layer, i.e. the portion of the third layer outside the reservoir 30, to a corresponding peripheral region of the second layer. The outline of the reservoir 30 is shown by a dotted line in FIG. 2.

The first and second layers of the sachet 4 are planar and the reservoir 30 of the third layer 3 houses the contents of the sachet between the second and third layers.

FIG. 1A shows the third layer 3 with the reservoir 30A formed as a pre-shaped pouch, such as by vacuum forming, before filling the reservoir and fixing the perimeter of the third layer to the perimeter of the lower face of the second layer.

In the embodiment shown in FIG. 1, the reservoir 30 is not pre-shaped. The shape of the reservoir is instead formed by the introduction of the sachet contents (not shown) when assembling the sachet. In this case, the third layer is fixed to the lower face of the second layer with sufficient fullness to accommodate the sachet contents in the reservoir space between the substantially flat second layer and the relatively looser third layer.

In one preferred embodiment, the first and third layers are relatively flexible while the second layer is semi-rigid. The second layer 2 bends in the vicinity of the cut 20 upon flexure of the sachet 4 about the line or lines of weakness 10, 12.

The second line of weakness 12 is optionally formed in the first layer 1. The second line of weakness 12 is preferably at least approximately aligned with the first line of weakness. In the sachet 4 shown in FIG. 2, the two lines of weakness 10, 12 are aligned with the cut 20 in the second layer, with the two lines of weakness being respectively located adjacent opposite ends of the cut. Each line of weakness is spaced apart from the respective adjacent outer end of the cut to leave a clear zone fully surrounding the cut 20 in the second layer where there is no cut or line of weakness formed in either layer. The first layer is sealed over the cut and is sealed to the second layer at the clear zone ensuring that the cut is completely sealed.

The line of weakness or cut 20 provided in the second layer 2 sequentially delineates inter-digitated finger portions of the second layer, the finger portions being located side by side and extending in substantially opposite directions. Adjacent fingers are delineated in part by a shared, i.e. common, portion of the line of weakness.

In the embodiments shown in FIGS. 2 and 3, there are two fingers pointing in opposite directions toward respective opposite ends of the sachet. In the embodiments shown in FIGS. 4 and 5, there are three fingers alternately pointing in opposite directions toward respective opposite ends of the sachet. In the embodiments shown in FIGS. 10, 11 and 12, there are five fingers alternately pointing in substantially opposite directions. In other options, not shown, the four, six, seven, or more fingers may be provided. In general, the inter-digitated fingers alternately extend in opposite directions, with the tips of each finger extending in its respective direction beyond the tip of at least one adjacent finger.

In one preferred embodiment of a sachet according to the invention, the lines of weakness formed in the first layer are spaced by about 2 to 3 mm from the ends of the line or weakness or cut in the underlying second layer. This provides a margin between the cut in the second layer and the line of weakness in the first layer so that the seal provided by the first layer over the cut has a sufficient width to maintain integrity of the seal prior to the sachet being flexed and opened.

In another option there is no line of weakness provided in the first layer. The cut 20 in the second layer is itself a zone of weakness about which the sachet will preferentially bend when the sachet is flexed. This option simplifies a sachet manufacturing apparatus by avoiding the need to have a manufacturing station to form a weakness in the first layer. The manufacturing station forming the cut 20 in the second layer can also form extensions to the cut to better define the zone of weakness in that second layer. The extensions to the cut can be made either part way or completely through the thickness of the second layer. At least in the latter case, where the extensions go completely through the thickness of the second layer, the first layer seals over the extensions to maintain the integrity of the sealed sachet, at least until the sachet is to be opened.

The first and second lines of weakness 10, 12 optionally extend to respective outer edges of the sachet. Each line of weakness can be made by scoring the first layer to form a line of weakness that extends partially through the thickness of the first layer.

The cut 20 in the second layer 2 preferably extends through the full thickness of the mid-portion of the second layer. Alternatively, the cut can be formed only partially through the second layer in which case, when the sachet is to be opened, the second layer is ruptured at the cut which then extends completely through the second layer to form an opening through which the contents of the reservoir can be discharged. The opening of the sachet will be discussed further below.

Each finger portion of the second layer is delineated by a portion of the line of weakness or cut 20 that follows a path deviating from a straight line. The line of weakness or cut 20 preferably has portions that are U-shaped, or V-shaped. FIG. 2 shows fingers having relatively sharply pointed tips, the fingers being delineated by lines of weakness that are V-shaped and have two substantially straight cut lines or limbs which meet an angle not equal to 180 degrees.

An alternative finger shape is shown in FIG. 3 where U-shaped line portions delineate fingers having relatively rounded tips.

The cut 20 is not limited to the shapes as shown. For example, the angle between the limbs of the V-shaped cuts may be greater or lesser than for those shown in the figures.

To open the sachet, a compression force is applied between opposite edges 42, 44 of the sachet 4 on opposite sides of the line or lines of weakness 10, 12, 20. The compression force flexes the sachet preferentially about the line or lines of weakness 10, 12 and/or about the cut 20 so that the second layer fractures at the cut 20 and portions of the second layer 2 on opposite sides of the cut 20 move apart. If the movement is sufficient it ruptures the first layer 1 in the vicinity of the cut 20 to form a discharge opening through which contents of the sachet may be discharged. When the cut fractures, the fingers are separate from one another. Alternate fingers extend as cantilevers in opposite directions.

In particular, as the sachet flexes, at least the tip of each finger portion of the second layer progressively moves away from the immediately adjacent surrounding portions of the second layer. This displacement of the finger tips ruptures the first layer 1, initially at each finger tip. As the sachet is flexed further, the initially separate rupture points in the first layer extend generally along the common portion of the line of weakness between the adjacent fingers to merge into a single enlarged discharged opening.

The sachet may be opened by folding the two parts of the sachet on opposite sides of the line or lines of weakness in either of two directions. In a first option, the sachet is opened by folding the two sachet parts to close in around the reservoir pouch. In this option, the contents in the reservoir pouch can be expelled by squeezing the reservoir between the two parts of the sachet. In a second option, the sachet is opened by bending the two sachet parts back away from the reservoir to stretch the reservoir around the outside of the bending sachet. In this option, the contents in the reservoir pouch can be expelled by tightening the reservoir in this way. The first-mentioned method of opening the sachet is preferred because the outer sealing layer is stretched around the outside of the bending sachet and is then more easily ruptured by the outward displacement of the finger tips.

If the cut 20 was formed only partially through the second layer 2, the cut ruptures completely through the full thickness of the layer when the portions of the second layer 2 on opposite sides of the cut 20 are displaced and move apart.

The cut in the second layer can be located centrally in the sachet, for example as in the sachets shown in FIGS. 1 to 5. Alternatively, the cut can be offset from a centreline of the sachet. FIGS. 6 to 9 show cuts 58, 59 that are offset from the centre of a sachet, toward one end of lines of weakness 18, 19 in the first layer of the sachet.

The line or lines of weakness can be aligned laterally across, or longitudinally along, an elongate sachet, in the first layer. For example, lines of weakness are formed in the first layer and are aligned laterally across rectangular sachets shown in FIGS. 1 to 7, and aligned longitudinally along the length of rectangular sachets shown in FIGS. 8 and 9.

FIGS. 6 to 9 show examples of sachets where cuts in the second layer are located near an edge of the sachet just inside, and clear of, the peripheral seal of the pouch in the third layer.

FIG. 6 shows a rectangular sachet with a symmetric cut 58 in the second layer. This cut 58 is offset toward an edge of the sachet, at one end of a single lateral or transverse line of weakness 18 in the first layer. There is no continuation of the line of weakness beyond the outer end of the cut which is located clear inside the peripheral seal of the pouch 30 formed by the third layer.

FIG. 8 shows a rectangular sachet with a symmetric cut 59 in the second layer. This cut 59 is offset toward an edge of the sachet, at one end of a single longitudinal line of weakness 19 in the first layer. There is no continuation of the line of weakness beyond the outer end of the cut which is located clear inside the peripheral seal of the pouch 30 formed by the third layer.

The location and shape of the cut in the intermediate layer affects the behaviour of the sachet during rupture of the sachet and delivery of the sachet contents. For example, the offset of the cut away from the centre of the semi-rigid layer, as shown in FIGS. 6 and 8, can enhance the ability of a user to open the sachet and discharge the contents of the sachet in a controlled manner.

FIGS. 10 and 11 show arrangements of offset cuts in sachets that have been found to be particularly suitable for the controlled delivery of liquids in different applications.

FIG. 10 shows a sachet 60 formed by three layers in a manner substantially as described above. A semi-rigid intermediate layer lies between upper and lower layers which are relatively flexible. The lower layer has a pouch formed therein. A perimeter portion of the lower layer surrounds the pouch and is sealed to the underside of the middle layer to form a reservoir 61 (the outline of which is shown in FIG. 10 by a dotted line) between the second and third layers.

In the sachet shown in FIG. 10, the middle layer has a continuous cut 62 (shown by a broken line in FIG. 10). The cut has a central zig-zag portion that is flanked by two straight-line portions. The two straight-line portions are aligned with one another and are aligned mid-way between peaks of the zig-zag portion. The cut 62 is generally symmetrical about the two aligned straight line portions and also about an axis of symmetry that is parallel to two of the outer side edges 63, 64 of the sachet. The cut 62 is offset toward one side of the sachet; i.e. the cut 62 is nearer to outer side edge 63 than to the opposite outer side edge 64. Advantageously, the outermost end of the cut 62 is located inward of, but close to, the seal between the middle and lower layers at the perimeter portion of the lower layer surrounding the reservoir 61.

The cut 62 extends at least partially through the thickness of the middle semi-rigid layer to form a line of weakness across the sachet. The cut 62 may be continuous along its length or it may be formed by a series of cuts, or indentations or perforations. The upper layer seals over and around the cut 62. In one option, not shown in FIG. 10, one or more score lines are provided across at least part of the upper sealing layer to augment the line of weakness provided by the cut 62. In the un-opened sachet, these score lines do not extend completely through the thickness of the upper sealing layer.

When pressure is applied at opposing ends 65, 66 of the sachet, the sachet bends preferentially about the line of weakness provided by the cut 62 (and the optional score lines, if present). The sachet bends more readily in the vicinity of the cut. When pressure is applied at opposing ends 65, 66 of the sachet shown in FIG. 10, the sachet will tend to bend more acutely at side edge 63 than at side edge 64.

The position at which the bending pressure is applied affects the differential in bending angles across the sachet. For example, when the pressure applied at opposing ends 65, 66 of the sachet shown in FIG. 10 is applied nearer side edge 63 than side edge 64, the sachet will tend to bend even more acutely at side edge 63 than at side edge 64.

The sachet may be opened by bending the sachet generally about the line of weakness formed by the cut 62 by application of pressure to the opposite ends 65, 66 of the sachet. As the two ends of the sachet are brought toward one another, the volume of the reservoir 61 is reduced. As noted above, the sachet may be opened by closing the two ends of the sachet around the reservoir pouch which is squeezed between the two sachet ends, or by bending the two ends back to tighten the reservoir pouch around the outside of the bending sachet.

When opening the sachet, the pressure applied to the opposite ends 65, 66 of the sachet is advantageously applied adjacent the two corners of the sachet at opposite ends of the side edge 63. When the pressure is applied near these two corners, the sachet bends more acutely in the vicinity of the middle zone of the side edge 63 than in the vicinity of the middle zone of side edge 64. This differential in the bending angles causes fluent contents in the sachet reservoir to move away from the more acute bending in the vicinity of the cut 62 and toward the side edge 64. In a preferred sachet, this bending of the sachet moves the reservoir contents away from the vicinity of the cut 62 before the bending is sufficiently acute to rupture the upper sealing layer. This reduces the likelihood that the sachet contents will squirt out in an uncontrolled manner when the sealing layer ruptures.

In a preferred arrangement, the sachet shown in FIG. 10 is opened by bending one end of the side edge 63 of the sachet back through about 150 degrees relative to the other end of that side edge so there is an acute angle of about 30 degrees between the two ends. At this point the finger portions of the second layer are displaced sufficiently from respective surrounding portions to begin rupture of the upper sealing layer before the pressure in the reservoir builds up, allowing controlled delivery of the reservoir contents. In this case, the sachet is adapted to rupture the first layer without bringing the opposite ends of the sachet into contact with one another. The sachet may be adapted to do this by selection of the thickness and/or strength of the first layer, and/or the sharpness of the finger tips, and/or the shape or dimensions of the fingers, for example.

The more acute bending in the vicinity of the cut 62 (nearer side edge 63) ruptures the upper layer of the sachet while the less acute bending at the other side of the sachet (nearer side edge 64) leaves the sachet contents relatively unpressurised. The sachet contents can then be pressurised and delivered from the ruptured reservoir in a controlled manner by gradually increasing the pressure applied to the corners of the sachet to bend the sachet even further.

FIG. 11 shows a sachet 70 that is particularly suitable for direct oral ingestion of the sachet contents. The sachet 70 is formed by three layers in a manner substantially as described above. A semi-rigid intermediate layer lies between upper and lower layers which are relatively flexible. The lower layer has a pouch formed therein. A perimeter portion of the lower layer surrounds the pouch and is sealed to the underside of the middle layer to form a reservoir 71 (the outline of which is shown in FIG. 11 by a dotted line) between the second and third layers.

In the sachet shown in FIG. 11, the middle layer has a continuous cut 72 (shown by a broken line in FIG. 11). The cut has a central zig-zag portion that is flanked by two aligned straight-line portions. The two straight-line portions are aligned with one another but are offset to one side of the zig-zag portion. The cut 72 is symmetrical about an axis of symmetry that is parallel to, and about midway between, opposed outer side edges 73, 74 of the sachet. The outermost ends of the cut 72 are each spaced inward from respective sides of the reservoir 71.

The cut 72 extends at least partially through the thickness of the middle semi-rigid layer to form a line of weakness across the sachet. The cut 72 may be continuous along its length or it may be formed by a series of cuts, or indentations or perforations. The upper layer seals over and around the cut 72. In one option, not shown in FIG. 11, one or more score lines are provided across at least part of the upper sealing layer to augment the line of weakness provided by the cut 72. In the un-opened sachet, these score lines do not extend completely through the thickness of the upper sealing layer.

When pressure is applied at opposing ends 75, 76 of the sachet, the sachet bends preferentially about the line of weakness provided by the cut 72 (and the optional score lines, if present). When the sachet is bent and the opposite end edges 71, 75 are brought together, the relatively stronger un-cut zones of the semi-rigid middle layer lying along the line of weakness at each end of the cut 72 resist bending of the sachet so that the sachet does not crease along the line of weakness, but instead tends to bend in a smooth curve having a radius of curvature that is too large to displace the fingers sufficiently to rupture the sealing layer.

The middle zone of the sachet (midway between the two end edges 75, 76) bends through less than about 150 degrees and does not form a tightly defined crease line. This is due, at least in part, because the line of weakness does not extend across the full width of the sachet. The portions of the semi-rigid middle layer on either side of the cut 72 are therefore brought to an angle, greater than about 30 degrees in a preferred embodiment, which does not displace the finger portions of the second layer sufficiently to rupture the upper sealing layer. When thus bent, the sachet can then be opened by a user by closing these two portions on either side of the cut 72 to an angle of less than about 30 degrees. This can be done by nipping those two portions of the sachet between the user's teeth, thereby reducing the radius of curvature to displace the finger portions sufficiently to rupture the upper sealing layer. The contents of the sachet can then be discharged directly into the mouth.

The cost of a sachet can be lowered by reducing the amount of material used to manufacture a sachet. The semi-rigid middle layer, being relatively thick and/or dense, accounts for a significant part of the material content, and therefore the cost, of the sachet. In one approach to reduce the cost of the sachet, relatively thin upper and lower layers having similar dimensions envelop the semi-rigid middle layer which has a lesser length or breadth than that of the upper and lower layers.

FIGS. 5, 7, 9 and 12 each show sachets in which the area of the semi-rigid middle or second sachet layer 2A (the outline of which is shown in these figures by broken lines) is less than that of the two outer sachet layers. In the sachets shown in FIGS. 5, 7 and 9, the semi-rigid middle layer 2A has a length which spans across the full dimension of the sachet, from one outer edge to the other, while having a width that is substantially less than the corresponding dimension of the other two sachet layers. For example, in FIG. 5, the semi-rigid layer 2A spans from one end edge of the sachet to the opposite end edge, while not extending across the full width of the sachet. The semi-rigid layer is laminated between the first and third layers at the peripheral edge of the sachet at each end of the sachet.

In the sachet variations shown in FIGS. 5, 7, 9 and 12, the lower face of the upper layer is sealed to the upper face of the semi-rigid middle layer 2A, preferably over the full upper face of the semi-rigid layer, but at least over and around the cut 50, 58, 59, 72 in the semi-rigid layer.

The semi-rigid middle layer of reduced area can be positioned to one side, i.e. adjacent three of the four outer side edges of a rectangular sachet, as seen in the sachet variations shown in FIGS. 7 and 9. Alternatively, the semi-rigid layer can be spaced apart from two opposite side edges of the rectangular sachet, as shown in the sachet variations of FIG. 5.

The size of the semi-rigid layer can be further reduced, when compared to the size of the first and third layers, as seen in the sachet variation shown in FIG. 12. In this case, the semi-rigid layer 2A is spaced inwardly from each peripheral edge 73, 74, 75, 76 of the sachet. The semi-rigid layer 2A has a line of weakness, such as cut 72, and is sealed to the underside of the first layer, at least around the line of weakness.

In another option, not shown, only one end of the semi-rigid second layer is laminated between the first and third outer layers.

In effect, the semi-rigid layer acts as a tool which is attached to a relatively flexible outer wall of the sachet. An external indication of where the tool is located, and how it is to be operated, may be printed on at least one outer face of the sachet. The tool can be bent about a line of weakness to rupture the sachet wall layer for delivery of the sachet contents.

The sachets are conveniently shaped to maximise sachet size while minimising waste in materials used to manufacture the sachets. A convenient sachet shape is rectangular as shown in FIGS. 1 to 12. However, other sachet shapes, for example triangular or D-shaped sachets, are envisaged. Furthermore, the lines of weakness do not have to be aligned substantially parallel to a peripheral edge of the sachet as in the examples shown in FIGS. 1 to 12.

FIGS. 13 and 14 show examples of some alternative sachets configurations. FIG. 13 shows a sachet that is generally hexagonal, having a shape derived from a square with two opposite corners 81, 82 truncated. This sachet has a line of weakness 83 that is aligned diagonally across the square between the two non-truncated corners 84, 85. The sachet may be opened by applying a compression force to the two opposed truncated corners 81, 82. The semi-rigid middle layer 86 may extend between the two truncated corners and may have a width that is less than the corresponding diagonal dimension across the sachet between the two non-truncated corners. The perimeters of the two outer sachet layers and the ends of the semi-rigid middle layer are laminated together around the outer edge of the reservoir 87.

FIG. 14 shows a sachet which has two peripheral edges 91, 92 that converge. A line of weakness 93 in a semi-rigid middle layer 94 is aligned between the two converging edges which, in the example shown, are symmetrically arranged on either side of the line of weakness. The sachet may have a shape derived from a triangle with two truncated corners 95, 96, as shown in FIG. 14, or may be more closely triangular. A similar shaped sachet, not shown, has two curved sides that depend from a straight side to provide a D-shape. With a perpendicular line of weakness mid-way along the straight side, this package can be advantageously opened by applying a compression force at the two corners at the ends of the straight side.

Sachets of different shapes can be used to indicate types or applications of sachet contents. For example, it is particularly desirable to clearly differentiate sachets containing materials that are intended for human consumption, such as by oral ingestion, from those containing materials intended for external use only, or for other uses such as domestic, industrial, agricultural or horticultural uses, for example.

Sachets as described above can be manufactured by first forming an elongate web comprising a lamination of two web layers. A series of lines of weakness or cuts (for example, each being a cut 20 as described above) is formed in a mid-width portion of the second web layer. The web layers are sealed face to face so that the first layer seals over and around each cut.

FIG. 15 shows a perspective view of two layers 101, 102 before being laminated together to form such an elongate double-layered web. This double-layered web is used a precursor for forming a series of sachets when the precursor web is laminated with a third layer.

A series of lines of weakness 110 (for example, each line being a line of weakness 10 as described above with reference to FIG. 1) are formed in the first or upper web layer 101 of FIG. 15. A corresponding series of lines of weakness 120 (for example, each being a line of weakness 20 as described above with reference to FIG. 1) are formed in the second or lower web layer 102. The upper web layer 101 and the lower web layer 102 are laminated together so that the lines of weakness 110 in the upper layer are spaced apart from, and at least approximately aligned with, a corresponding line of weakness 120 in the lower layer.

The upper web layer 101 is a relatively flexible layer, such as a plastics film. The lower web layer 102 is a semi-rigid layer which, in the finished sachet, bends preferentially in the vicinity of the aligned lines of weakness upon flexure of the sachet about the lines of weakness.

A second series of lines of weakness can be formed in the first web layer, with each line of weakness of the second series being spaced apart from and at least approximately aligned with a respective one of the cuts in the second web layer so that corresponding lines of weakness of the first and second series are at least approximately aligned with one another and with the corresponding cut, and are respectively located adjacent opposite ends of the corresponding cut, and each line of weakness is spaced apart from the respective adjacent end of the corresponding cut. Preferably, each line of weakness extends to one or other outer edge of the web. The lines of weakness can be score lines which extend partially through the thickness of the first web layer.

Each line of weakness or cut in the second web layer can extend through the full thickness of the layer. Each line of weakness in the second layer follows a path which deviates from a straight line, with a portion of each line sequentially delineating inter-digitated finger portions of the second layer. These fingers extend in respective substantially opposite directions towards first and second side edges of the second web layer. For example, each of these line portions can be a U-shaped cut or a V-shaped cut comprising two substantially straight limbs which meet an angle not equal to 180 degrees, each V-shape or U-shape outlining one of the fingers.

Each line of weakness in the second web layer may be offset from a longitudinal centreline of the web to be closer to one outer side edge of the web than to an opposing outer side edge. Each cut may be a zone of weakness lying between two relatively stronger zones, the three zones lying in line across the width of the web.

FIG. 16 shows a perspective view of three layers 101, 102, 103 before being laminated together to form a triple-layered web. This triple-layered web is an elongate series of connected sachets. The triple-layered web can be formed by laminating the bottom layer 103 to the double-layered precursor web discussed above with reference to FIG. 15 which may be manufactured prior to use in a sachet loading machine.

A series of interconnected sachets can be formed by sealing the two-layered web described above to a third elongate layer.

In a preferred arrangement, a series of pouches 130 is formed in a mid-width portion of the third or bottom layer 103. The third layer is sealed to the lower face of the second layer along each longitudinal edge of the web to provide a series of reservoirs for housing the contents of respective sachets. The material intended as sachet contents can then be introduced between the longitudinally sealed second and third layers. The second and third layers are then sealed together transversely across the web at spaced locations corresponding to gaps between the pouches.

The sachets can be produced as an interconnected series of sachets which is formed, loaded with sachets contents, sealed, and separated into individual sachets or into groups of sachets. A series of transverse lines of weakness 140, 150 160 may be provided in respective web layers 101, 102, 103 to allow the interconnected sachets to be separated from one another.

The second layer is semi-rigid and substantially flat or planar over the length of each sachet. However, it is to be understood that although the second layer is substantially flat or planar, the double-layered precursor web may be wound into a roll for ease of handling long web lengths.

The web or layer material can be any material known to be suitable for the manufacture of sachets and such like containers. Typical web materials include plastics (for example, polyethylene, polyethylene terephthalate, or polyethylene terephthalate glycol), metallic films, and paper or similar materials derived from wood fibre, either plain or treated with waxes or similar coatings. Other materials suitable for making sachets in accordance with the invention are biodegradable plastics, for example plastics based on cornstarch, soya and/or potato, and polylactic acids (PLAs), the latter being suitable as a biodegradable replacement for polyethylene terephthalates (PETs).

The foregoing describes the invention with reference to a preferred embodiment. Alterations and modifications as will be obvious to those skilled in the art are intended to be incorporated within the scope of the invention as defined in the accompanying claims. For example, when sachets are produced as groups of joined sachets, the joined sachets may be intended to remain together in use, such as when two or more different materials are contained in respective sachets of two or more grouped sachets, e.g. for simultaneous dispensing such as may be required in a two-part resin formulation. Alternatively the joined sachets may be joined in a manner allowing easy separation, for example at point of sale, or just prior to use.

The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims

1. A sachet for storing and dispensing a fluent material, the sachet comprising:

a lamination of first, second and third layers;

wherein: the second layer is a semi-rigid layer located between the first and third layers;

a line of weakness is formed in a mid-portion of the second layer;

at least a portion of the line of weakness sequentially delineates inter-digitated finger portions of the second layer; the finger portions extend in respective substantially opposite directions toward first and second opposing edges of the second layer on opposite sides of the line of weakness;

the first layer seals over and around the line of weakness; and the third layer is fixed to at least one of the first layer or the second layer;

the sachet is adapted to flex preferentially at the line of weakness on application of a compression force between the first and second edges;

the second layer is adapted to open at the line of weakness and move at least the tips of the finger portions away from respective immediately surrounding portions of the second layer by flexure of the second layer at the line of weakness; and

the first layer is adapted to rupture in the vicinity of the line of weakness by movement of at least the tips of the finger portions away from respective immediately surrounding portions of the second layer to form at least one discharge opening through which contents of the sachet may be discharged.

2. A sachet as claimed in claim 1, wherein the first and third layers are relatively flexible relative to the semi-rigid second layer.

3. A sachet as claimed in claim 1, wherein the third layer is sealed to at least part of the first layer or the second layer, at least around a peripheral region of the sachet.

4. A sachet as claimed in claim 1, wherein the line of weakness extends through the full thickness of the second layer.

5. A sachet as claimed in claim 1, wherein at least one of the finger portions is delineated by a portion of the line of weakness that is V-shaped and comprises two substantially straight limbs which meet at an angle not equal to 180 degrees.

6. A sachet as claimed in claim 1, wherein at least one of the finger portions is delineated by a portion of the line of weakness that is U-shaped.

7. A sachet as claimed in claim 1, wherein the line of weakness is offset from a X mid-point between opposed edges of the second layer.

8. A sachet as claimed in claim 1, wherein the sachet is adapted to rupture the first layer by movement of at least the tips of the finger portions away from immediately surrounding portions of the second layer on flexure of the second layer at the line of weakness without bringing the first and second edges of the second layer into contact with one another.

9. A sachet as claimed in claim 1, wherein the line of weakness in the second layer is a zone of weakness which lies between two relatively stronger zones of the second layer; the three zones lie on an axis of flexure about which the second layer flexes preferentially upon application of the compression force; and the two relatively stronger zones resist flexing of the second layer at the line of weakness sufficiently to prevent rupture of the first layer when the first and second edges of the second layer are brought together.

10. A sachet as claimed in claim 9, wherein the sachet is adapted so that after initial flexure of the second layer by bringing the first and second edges of the second layer into contact with one another, the first layer is adapted to rupture when the second layer is then flexed further.

11. A sachet as claimed in claim 1, wherein a first line of weakness is formed in the first layer, this first line of weakness being spaced apart from, and at least approximately aligned with, the line of weakness in the second layer.

12. A sachet as claimed in claim 1, wherein the second layer is spaced inwardly from the peripheral edges of the sachet.

13. An elongate web comprising:

a lamination of first and second layers, wherein the second layer is a semi-rigid layer;

a series of lines of weakness is formed in a mid-width portion of the second layer, at least a portion of each line of weakness sequentially delineating inter-digitated finger portions of the second layer, the finger portions extending in respective substantially opposite directions; and the first layer seals over and around each line of weakness.

14. An elongate web as claimed in claim 13, wherein the first layer is a relatively flexible layer.

15. An elongate web as claimed in claim 13, wherein each line of weakness extends through the full thickness of the second layer.

16. An elongate web as claimed in claim 13, wherein the portion of each line of weakness delineating one of the finger portions is V-shaped and comprises two substantially straight limbs which meet at an angle not equal to 180 degrees.

17. An elongate web as claimed in claim 13, wherein the portion of each line of weakness delineating one of the finger portions is U-shaped.

18. An elongate web as claimed in claim 13, wherein each line of weakness is offset from a longitudinal centreline of the web to be closer to one side edge of the web than to an opposing side edge.

19. An elongate web as claimed in claim 13, wherein each line of weakness in the second layer is a zone of weakness which lies between two relatively stronger zones of the second layer and the three zones lie transversely across the web.

20. An elongate web as claimed in claim 13, wherein a corresponding series of lines of weakness is formed in the first layer with each respective line of weakness in the first layer being spaced apart from and at least approximately aligned with a corresponding one of the lines of weakness in the first layer.

21. A series of interconnected sachets formed by fixing an elongate web as claimed in claim 13 to a third layer, wherein the third layer is elongate and is fixed to at least one of the first layer or the second layer of the web.

22. A series of interconnected sachets as claimed in claim 21, wherein the series of sachets is adapted so that individual sachets each have a respective line of weakness formed in the second layer and can be separated from the series, each sachet is adapted so that when separated from the series the second layer of the separated sachet flexes preferentially at the respective line of weakness on application of a compression force to edges of the second layer of the sachet on opposite sides of the respective line of weakness in the second layer so that portions of the second layer on opposite sides of the respective line of weakness in the second layer move apart and rupture the first layer in the vicinity of the line of weakness in the second layer to form a discharge opening through which contents of the sachet may be discharged.

23. A series of interconnected sachets as claimed in claim 22, wherein the third layer is a relatively flexible layer.

24. A series of interconnected sachets as claimed in claim 22, wherein the third layer is sealed to at least part of the first layer or the second layer, at least around a peripheral region of each sachet.