EP0746515B1

EP0746515B1 - Disposable filter bag for the preparation of extraction drinks such as tea

Info

Publication number: EP0746515B1
Application number: EP95910454A
Authority: EP
Inventors: Erling Vangedal-Nielsen
Original assignee: Unigreen International AS
Current assignee: Unigreen International AS
Priority date: 1994-02-23
Filing date: 1995-02-20
Publication date: 1999-12-15
Anticipated expiration: 2015-02-20
Also published as: DK172116B1; AU1754795A; ATE187700T1; DE69513953T2; FI963301A0; NO963515L; FI963301A; DK22194A; DE69513953D1; EP0746515A1; GB2286816B; GB9503651D0; WO1995023100A1; NO963515D0; GB2286816A

Abstract

A disposable filter bag (1) for the preparation of extraction drinks such as tea comprises an upper part (2) constituting a holder component (3) and a lower pant (4) constituting an extraction chamber (5) for containing the material (10) to be extracted. The parts (2) and (4) are integrally made and are connected to each other in an area (6) around a common central axis (7) of the holder component (3) and of the extraction chamber (5) and the holder component (3) on each side of the central axis is provided with a suspension means (8) which comprises a suspension area (9) intended during the extraction to rest on the rim of the container in which the extraction takes place which suspension area (9) is produced so that it is able to receive container rims of different dimensions. <IMAGE>

Description

The present invention relates to a disposable filter bag to be used in the preparation of extraction drinks, such as tea, and in particular a disposable filter bag which is especially suitable for the preparation of one single portion of tea directly in a cup or a mug.

During several years, disposable tea filter bags of the kind comprising a bag made from paper material and being prefilled with tea leaves and which tea filter bag is connected to a holder component, made from a piece of cardboard or as part of an envelope, through a string fixated by means of a staple, have been extensively used in the preparation of tea, not least in the preparation of tea in small quantities such as the preparation of one single portion directly in a cup or a mug.

However, the manufacture of such disposable filter bags is costly as in addition to the production of the tea filter bag and the filling of tea into the bag it comprises fixating a piece of cardboard or the like to a string, closing the tea filter bag by folding and fixating the string, which is provided with a piece of cardboard, to the closed tea filter bag by means of a staple. A further disadvantage of such tea filter bags is that they are not very environmentally desirable.

Disposable filter bags made from two sheets of a fiber material as e.g. heat sealed filter paper which is sealed along their edges for containing a portion of tea leaves have been suggested for substituting the above mentioned tea filter bags. In the sealed edge areas, a cut or a weakening line is made enabling partly detachment of a part of the sealed edge areas from the filter bag for the formation of a holder component for handling of the bag. Examples of this prior art is described in US patent No. 2,413,686 and French patent No. 1,327,192.

It has furthermore been suggested to provide tea filter bags with a special fixation means to be placed around the spout of a teapot or the handle of a cup.

US patent No. 3,899,599 thus describes the assembly of a tea filter bag in which the tea filter bag proper is confined between two sheets which may be used for fixating the bag to the spout of a teapot by means of a number of cuts. Moreover, it is illustrated how the bag may be brought to hang on the edge of a mug, which way of hanging is considered to be very unstable. Anyway, this US patent relates to an assembly which may be considered very expensive to produce.

WO 93/15974 shows a disposable filter bag manufactured by means of two sheets of filter paper which are sealed together around a material to be extracted and in which assembly an edge area is cut for the formation of a loop formed handle to be placed around the handle of a cup. This assembly suffers from the drawback that it is applicable for cups or mugs, only, the handle size, handle form and handle position of which fit with the dimensions of the loop formed tea bag handle.

The present invention provides a disposable filter bag to be used for the preparation of extraction drinks in containers of different dimensions, especially in cups and mugs of different dimensions and without considering the design and position of a handle, if any, of the container, the disposable filter bag in accordance with the present invention being meant for hanging on the edge of the container during extraction and furthermore being designed in a manner enabling it to be hung on container edges of different dimensions, especially cups or mugs having different rim configurations.

Thus, the present invention relates to a disposable filter bag as specified in claim 1.

When in the following expressions such as "upper" and "lower", "upwards" and "downwards" etc. are being used these expressions have to be apprehended in relation to the position of the filter bag when it is positioned in a hanging position on the edge of a container with the suspension areas resting against the rim of the container.

The disposable filter bag according to the present invention is inexpensive to produce as it may be produced from two sheets of material joined together for producing of the extraction chamber for containing the material which is to be extracted, the extraction chamber being either totally closed around a suitable quantity of extractable material or being upwardly open for later filling by an extractable material to be chosen by the user. The surrounding part of the two sheets of material may be joined totally or partly as desired.

As examples of suitable materials for manufacturing of disposable filter bags according to the present invention various kinds of paper material may be mentioned, including paper material mixed with other fibrous materials than cellulose, such as thermoplastics fibers, various kinds of plastics materials, including non-woven or melt-blown plastics or polymeric material. Also coated materials such as paper coated by latex or plastics materials may be used. Perforated plastics foils are also applicable. A heat sealable paper material is presently preferred. Usually, the paper material has a grammage of 10 to 50 g/m², e.g. a grammage of 12.5 to 25 g/m² and perferably a grammage of 12.5 g/m² to 16.5 g/m², such as a preferred grammage of 12.5 g/m² provided the paper material is joined together in an embossing or printing process, and a grammage of 16.5 g/m² provided the paper material is joined together in a heat sealing process. Such paper materials are available on the market bearing the trade mark Tea Bag Paper and Heatsealable Tea Bag Paper from the German company Papierfabrik Schoeller & Hoesch GmbH, D-7562 Gernsbach, Germany. Another preferred material is a polypropylene materiale, especially a non-woven, point by point heat seable polypropylene material. Such a material is available on the market bearing the trade mark Holmestra Non-Woven® from the company Fiberweb Sweden AB, Box 193, S-601 Norrköping, Sweden. The material is available in various grammages and usually a material having a grammage of from 10 to 100 g/m² will be used, e.g. a grammage of from 20 to 80 g/m² and especially from 25 to 60 g/m².

The material sheets used must be characterized by being able to substantially retaining the extractable material in the extraction chamber, but being able to allow the liquid used for the extraction to pass to such an extent that the desired extraction can take place. It is to be understood that the extraction chamber defining material sheets are able jointly to substantially retain the extractable material in the chamber, but allow the liquid necessary for the extraction to pass to such an extent that the extraction desired can take place. Thus, it would be possible to leave e.g. one of the material sheets impermeable or substantially impermeable for the extraction liquid, provided that the second material sheet is sufficiently porous for allowing the desired extraction to take place and at the same time is in all essentials able to retain the extractable material in the chamber. Thus, one of the material sheets may be produced from a continuous foil, e.g. a foil made from thermoplastics material, such as polypropylene. Furthermore, one of the material sheets or both of them may be designed with one part being permeable for the extraction liquid as well as a second part being unimpermeable for the liquid.

For joining the material sheets any suitable joining technique may be utilized, such as welding, glueing, printing and/or embossing as the joining technique is to be chosen in consideration of the nature of the material sheets. Cold sealing as well as heat sealing techniques are applicable, and a rotation technique suchs as rotation heat sealing/cutting is just as applicable as a more discontinuously effective technique, such as flush heat welding or cutting.

The disposable filter bag according to the present invention comprises an upper part constituting a holder component and a lower part constituting an extraction chamber for containing the material to be extracted. The upper part and the lower part are integrally made and are connected to each other in an area around a common central axis of the holder component and of the extraction chamber. On each side of the central axis, the holder component is provided with a suspension means. Each of these suspension means comprises a suspension area intended to rest on the rim of the extraction container. These suspensions areas are designed in a manner enabling them to receive edges of different dimensions. This suspension by means of two suspension means, one of each side of the central axis and each being provided with a suspension area designed in a way enabling them to receive container rims of different dimensions, causes the disposable filter bag according to the present invention to rest safely on the rim of e.g. cups and mugs of different designs during the extraction.

In order to save materials the disposable filter bag according to the present invention is typically of rectangular configuration, but principally it may be produced in other configurations, e.g. having a circular extraction chamber. In consideration of the balance when hanging the bag on the rim of a container, the bag may usually in all essentials be symmetrical around the central part.

The suspension means will typically be produced by means of cuts or weakening lines made in the bag material, the cut or weakening lines being produced simultaneously with the bag being cut from continuously conveyed and joined material sheets.

The cutting may take place in any suitable manner, but typically it will be made by blanking. The blanking may be made coldly or during influence of heat. By blanking during influence of heat, a joined welding of the material sheets in the blanking area is simultaneouly obtained if the material sheets comprise a sufficient quantity of thermoplastics material.

It is an essential feature of the disposable filter bag according to the present invention that the suspension areas in each of the suspension means are designed in a manner so as to enable receipt of container rims of different dimensions. This feature may be obtained by producing the suspension area by means of an upwardly to convex cutting in the holder component. This upwardly convex cutting may be of many different configurations and may be of an angular or an annular configuration. The cutting may e.g. take the configuration of an upward triangle top, an upwardly section of a rectangle, a trapezium, a circle, an ellipse, an oval or similar. Moreover, the cutting may constitute a closed configuration, e.g. a circle or an oval, so that a figure of this configuration is cut in the holder component. A similar effect is obtained when the suspension area forms a star-like cut in the holder component. The cutting may also have the same shape as the upper part of a shepherd's stick. The shepherd's stick-shaped cutting as well as other kinds of cuttings may have its free end turned towards the central axis or against it. It is of vital importance that the upwardly convex part of the cutting comprises a good surface of contact for the container rim.

Usually, curved cuttings are preferred since they do not constitute a natural point for an unintended breach of the holder component.

In one embodiment of the disposalble filter bag according to the present invention, the suspension means are made in the upper part of the bag. However, the suspension means may also extend from the upper part of the bag and further down into the lower part of the bag on both sides of the extraction chamber. For instance, the suspension means may extend downwardly along one third or one fourth of the sides of the extraction chamber as a couple of downwardly projecting flaps. The flaps may be of different configurations, but may e.g. be made by means of a cutting or weakening line extending from the edge of the bag and discontinuing in a distance from the central axis and causing the upper part of the extraction chamber and the lower part of the bag defining this part of the extraction chamber to get a curved configuration as a couple of rounded shoulders.

In the above description, the disposable filter bag according to the present invention is described with special reference to a simple bag produced by joining two material sheets together. The disposable filter bag according to the present invention may, however, be produced as a so-called twofold bag.

Traditional twofold bags are produced from one hose length of e.g. filter paper which, after having been filled up with for instance tea, is bent together in the middle so that its free ends reach one another and are thereafter folded once and closed by a staple and provided with a string and a holder component flap. A disposable filter bag according to the present invention and produced as a twofold bag is produced correspondingly by means of a hose filled up with material to be extracted, but after bending of the hose, the two ends of the hose are joined together for the formation of an upper part consisting of four layers and constituting a holder component as described above. Due to its four layers, this holder component is of course characterized by being of increased strength and rigidity.

Also in other embodiments of the disposable filter bag according to the present invention, the holder component may be made more rigid by adding one further material sheet. The holder component may also be made more rigid by embossing of a suitable pattern, e.g. by embossing of slots or ribs for strengthening in the desired direction.

The holder component may also be provided with some kind of characteristic for identification of the product and/or the manufacturer. Such a characteristic may be made by means of embossing or blanking in connection with the manufacturing procedure, by printing on the finished bag or by printing on the material sheet before manufacturing the bag. Of course, it is also possible to provide the holder component with a characteristic by sticking a label or the like which will make the holder component more rigid, as well.

The holder component may, moreover, be provided with means for reducing the wick effect, e.g. by means of a water repellant ribbon to be welded into the assembly and which may further serve the purpose of reinforcing the holder component in cross direction. The means for reducing the wick effect may also comprise transverse welding lines or cutting lines. The wick effect may also be reduced by increasing the temperature during welding of the holder component.

In the following the present invention will be described further with reference to the drawing in which

Fig. 1 is a view of an embodiment of the disposable filter bag according to the present invention in which the suspension means is provided in the upper part of the bag and the extraction chamber is a closed chamber containing material to be extracted,

Fig. 2 is a view of another embodiment of the disposable filter bag according to the present invention in which the suspension means extends from the upper part of the bag and further down in the lower part of the bag on each sides of the extraction chamber and the extraction chamber is a closed chamber containing material to be extracted,

Fig. 3 is a view of yet another embodiment of the disposable filter bag according to the present invention in which the bag is made as a twofold bag, the suspension means is made in the upper part of the bag and the extraction chamber is a closed chamber containing the material to be extracted,

Fig. 4-10 are schematic views of different embodiments of the holder component, and

Fig. 11 illustrates a disposable filter bag according to Fig. 2 in a hanging position on the rim of a mug before filling of boiling water.

Fig. 1 illustrates a presently preferred embodiment of the disposable filter bag according to the present invention designated by the reference numeral 1. The bag comprises an upper part 2 constituting a holder component 3 and a lower part 4 constituting an extraction chamber 5. The filter bag is produced from two

material sheets

11, 12 of a paper material mixed with thermoplastics fibers for the formation of a heat weldable filter paper with a grammage of 16.5 g/m². Between the two material sheets 11, 12 a portion of tea leaves 10 is situated as shown in the lowermost lefthand corner of the bag in which a part of the material sheet 11 is removed for purposes of illustration. The upper part 2 of the filter bag as well as the side edges of the lower part are joined for defining the extraction chamber 5. It is evident that the upper part 2 of the filter bag and its lower part 4 are integrally made and connected to each other in an area 6 around the common central axis 7 of the holder component 3 and the extraction chamber 5. On each side of the central axis the holder component 3 is provided with a suspension means 8. The suspension means 8 is produced by means of cuttings for weakening lines 13 made in the bag material. Over an upward section, the cuttings or the weakening lines 13 have an upwardly convex course each of the cuttings or weakening lines 13 ending upwardly in an annular cut 17 in the holder component. These annular cuts 17 constitute suspension areas 9 intended to rest during the extraction on the edge of the container in which the extraction is to take place, e.g. on the rim of a cup or a mug, and will typically be of a diameter in the range of 3-8 mm, e.g. approx. 5 mm. When being hung on the rim of e.g. a mug, the disposal filter bag 1 is positioned with the lower part including the extraction chamber 5 which contains the tea leaves hanging down into the mug with the suspension areas 9 resting on the rim of the mug and the downwardly projecting flaps of the suspension means 8 positioned against the exterior of the mug. The special design of the suspension areas 9 causes the disposable filter bag 1 to hang safely on edges of dimensions of ordinary occurance. In the upper part of the bag, perpendicular slots or ribs are made by embossing which causes the upper part of the bag to be more rigid in the cross direction. However, in an area 24 the slots or ribs are omitted e.g. for esthetic reasons, in order to provide a special holder component area or in order to provide an area intended to be printed with a logo or the like.

If instead an increase of the rigidity in the cross direction is desired it is of course also possible to produce the upper part of the bag with horizontal slots or ribs. By embossing of horizontal slots or ribs in the joining area along the horizontal upper edge of the extraction chamber, a further increase of the advantageous supporting effect already provided by the joining along this horizontal upper edge in the cross direction may be obtained. Also a combination of horizontal and vertical slots or ribs or other embossing patterns are applicable. Even the joining proper of the two material sheets provides an increased rigidity.

Fig. 2 illustrates another embodiment of the disposable filter bag 1. This embodiment is different from the one shown i Fig. 1 in that the suspension means 8 extends from the upper part of the bag 2 and further down into the lower part 4 of the bag on each side of the extraction chamber. The upper part of the extraction chamber is also rounded upwardly so that the configurations of the suspension means 8 and the extraction chamber 5 are adjusted to each other. Further, it is evident how the lower edge of the bag is not in this case formed by a fold, but by a joining. Like in the embodiment shown in Fig. 1, the suspension areas 9 are formed by annular cuttings in the holder component 3, but the cuts or weakening lines 13 end up somewhere else in the annular curve so that the suspension means 8 forms an upward projection 19 immediately below the suspension area 9. These upward projections 19 serve the purpose of being able to engage with an outward edge, e.g. of a mug and thereby contribute to further fixation of the filter bag during the extraction. Like in the embodiment shown in Fig. 1, the holder component 3 is provided with embossed slots or ribs in cross direction, but in the present embodiment the slots or ribs continue in the side seams of the lower part of the bag.

Fig. 3 illustrates a disposable filter bag 1 produced as a so-called twofold bag. In this bag, the extraction chamber 5 is made by a hose of filter paper which is filled with tea leaves (not shown) and folded in the centre, so that the two free ends of the hose abut on one another. Thereafter, these two free ends are welded or embossed together for the formation of the upper part 2 of the bag with the holder component 3 which thus comprises four layers of joined filter paper. The suspension means 8 is made by means of cuts for weakening lines 13 which over an upward section are upwardly convex so that an upwardly convex cut 16 is provided in the holder component which cut is of almost the same configuration as the upper part of a shepherd's stick. The holder component 3 of the bag is provided with characteristics 20 which may be made by embossing, blanking or printing. In the embodiment illustrated, the suspension means converge downwardly towards the central axis of the bag, and in this area a water repellant ribbon 21 is welded into the assembly which water repellant ribbon partly serves the purpose of breaking the wick effect of the paper material and partly serves the purpose of strengthening and supporting the area in which the suspension means converge towards the central axis. The mutual distance between the converging projections of the suspension means 8 is relatively short, of the range of 5 to 10 mm, and therefore it contributes to further ensure fixation of the filter bag to a cup or to a mug by engaging with the handle of the cup or the mug.

Further embodiments of the holder component are illustrated schematically in Fig. 4-10. In the embodiment of the filter bag shown in Fig. 4, the cuts or weakening lines 13 have a curved course 14 during a section so that a kind of barbs are provided contributing to prevent the bag from sliding down from the rim of the container. A corresponding effect is obtained by the embodiment shown in Fig. 5 in which the cuts or weakening lines 13 are transversely provided with small cuts 15.

Fig. 6 illustrates an embodiment of a filter bag in which the suspension areas are formed by star-shaped cuts 17 in the holder component. These star-formed cuts 18 have the double function of being able to receive container edges of different dimensions and at the same time being able to engage with any container edge.

In the embodiment shown in Fig. 7, a scale 22 is provided on the upper part of the bag for indication of infusion time, as the distance reached by the liquied in the upper part of the bag indicates the infusion time.

Fig. 8 illustrates that the upward cutting or weakening lines may just as well have an inward as an outward bending as shown in some of the other figures.

In fig. 9, a cut 23 is made in the holder component which cut may be utilized for grasping the bag either during the preparation of an extraction drink or during the manufacture of the bag proper. The cut may be of various configurations, a circular cut being suitable for suspension of the bag on a punch during the process of production. An oval cut like the one shown in the figure is suitable for grasping the bag in connection with use of the bag and would furthermore be able to provide a certain breach of the wick effect. In this embodiment, the cuts or the weakening lines 13 are of a softly outward configuration.

Fig. 10 illustrates a cutting line 21 provided for breach of the wick effect.

Fig. 11 illustrates a mug 50 with a filter bag 1 of the embodiment shown i Fig. 2 hanging on the edge 51 of a mug with the extraction chamber 5 hanging down into the mug and with the suspension means 8 (not shown) protruding beyond the rim of the mug on its reverse side (not shown) with the suspension areas 9 resting against the edge 51 of the mug 50. In the condition shown water has not yet been poured into the mug. When hot water is poured into the mug, the extraction chamber 5 will swing out from the inside of the mug and float in the water or turn tilted between the opposite sides of the mug so that the extraction may take place freely.

At the same time, the suspension means 8 is pressed against the exterior of the mug and contributes to fixate the filter bag against the edge of the mug. Gradually, as the water is absorbed by the part of the holder component situated between the suspension areas and the extraction chamber, this part of the filter bag adheres to the inside of the mug above the surface of the liquid and serves the purpose of further fixating the bag. When the desired extraction has taken place the filter bag is removed from the extract by grasping around the holder component.

In the above description, the invention is described by means of preferred embodiments of the invention, but it will be understood that different modifications and amendments can be made within the scope of the attached patent claims.

Claims

A disposable filter bag (1) for preparation of extraction drinks, such as tea, in a container (50) having a rim (51), said disposable filter bag (1) comprising an upper part (2) forming a bolder component (3) and a lower part (4) forming an extraction chamber (5) for containing material (10) to be extracted, the upper part (2) and the lower part (4) being integrally made from a common web of material (11, 12) and connected to one another in an area (6) around a common central axis (7) of the holder component (3) and of the extraction chamber (5),
characterised in that

the holder component (3) on each side of the central axis (7) is provided with cuts or weakening lines (13) each extending from an edge of the bag and ending at a distance form the central axis (7), such that a couple of downwardly projecting suspension means (8) in the form of a flap on each side of the axis (7) are formed in the upper part (2) of the bag,

and in that each suspension means (8) comprises a container rim receiving area (9) intended during the extraction to rest on and receive the rim (51) of the container (50), said rim receiving area (9) being adapted to receive container rims (51) of different dimensions.
A disposable filter bag according to Claim 1, in which the container rim receiving area (9) is made by an upwardly convex cut (16) in the holder component, the cut (16) being connected to a corresponding cut or weakening line (13) for the suspension means (8).
A disposable filter bag according to Claim 1, in which the container rim receiving area (9) is made by an annular or oval cut (17) in the holder component, the cut (17) being connected to a corresponding cut or weakening line (13) for the suspension means (8).
A disposable filter bag according to Claim 1, in which the container rim receiving area (9) is made by a star-shaped cut (18) in the holder component, the cut (18) being connected to a corresponding cut or weakening line (13) for the suspension means (8).
A disposable filter bag according to one or more of the preceding Claims, in which the cuts or weakening lines (13) extend upwardly convex over an upward section.
A disposable filter bag according to one or more of the preceding Claims, wherein the common web of material of the disposable filter bag is produced by means of joining at least two material webs (11, 12) together.
A disposable filter bag according to Claim 6, in which at least one of the material webs (11, 12) is made from a paper material such as a paper material mixed with thermoplastic fiber or porous plastics material or polymeric material, such as a perforated plastics foil or a non-woven polymeric material such as a scattered heat sealed, non-woven polypropylene material.
A disposable filter bag according to Claim 6 or 7, in which the joining is made by welding, gluing and/or embossing.
A disposable filter bag according to one or more of the preceding Claims, which disposable filter bag has the form of a twofold bag.
A disposable filter bag according to one or more of the preceding Claims, in which the suspension means converge downwardly towards the central axis (7).
A disposable filter bag according to one or more of the preceding Claims, in which the suspension means form an upward projection (19) immediately below the container rim receiving area.
A disposable filter bag according to one or more of the preceding Claims, which disposable filter bag is of a substantially rectangular configuration.
A disposable filter bag according to one or more of the preceding Claims, in which the extraction chamber (5) is upwardly open.
A disposable filter bag according to one or more of Claims 1-12, in which the extraction chamber (5) is a closed chamber containing material (10) to be extracted.
A disposable filter bag according to one or more of the preceding Claims, in which the holder component (3) is reinforced by embossing.
A disposable filter bag according to one or more of the preceding Claims, in which the holder component (3) is reinforced by adding a further material web.
A disposable filter bag according to one or more of the preceding Claims, in which the holder component (3) is provided with a characteristic (20), preferably by embossing, blanking or printing.
A disposable filter bag according to one or more of the preceding Claims, in which the holder component (3) is provided with means (21) for reduction of the wick effect.
A disposable filter bag according to Claim 18, in which the means (21) for reduction of the wick effect are transverse welding lines, cutting lines, cuttings or inserted welded ribbons.
A disposable filter bag according to one or more of the preceding Claims, in which the cuts or the weakening lines (13) have a section with a curved course (14) or are provided with small transverse cuts (15).
A disposable filter bag according to one or more of the preceding claims, which disposable filter bag is substantially symmetrical around the central axis (7).