GB2224264A

GB2224264A - Infusion or cooking bag

Info

Publication number: GB2224264A
Application number: GB8923985A
Authority: GB
Inventors: Frank Steldermann
Original assignee: Individual
Current assignee: Individual
Priority date: 1988-10-25
Filing date: 1989-10-25
Publication date: 1990-05-02
Also published as: GB8923985D0; DE8813378U1; GB8923463D0

Abstract

A filter bag, which may be filled by the user, e.g. an infusion bag for tea or coffee, a boiling bag for rice, or a spice bag, is formed by folding about lines 11, 12, 13, 18, 19 as shown in Fig. 2, threads 22, 23 being inserted beneath seam portions 20, 21, the bag subsequently being sealed at the side edges 24, 25, and the portions 20, 21 being sealed at 26 to provide a bag open at its top but closable by pulling the threads 22, 23, the ends of which are connected together, e.g. by knots 27, 28. A label 30 may be adhered to the threads 22, 23. <IMAGE>

Description

iIter particu1 & l Tnfusion ag for Beverages such as Tes or the like The invention refers to a filter bag, particularly to an infusion bag for beverages such as tea or the like, or to a boiling bag for food such as rice or the like.

Infusion bags are known e.g. for tea made of a rectangular blank of paper nonwoven which is sealed at the free longitudinal edges. A holding thread is attached to the upper edge by sealing by which the bag can be immersed into a liquid. It is further known to form a longitudinal hose of a blank which for example is filled with tea leaves, herb tea (leaves, blossoms, fruits) and to fold the hose with the ends overlapping each other and to interconnect the ends by means of a staple. The holding thread is attached by means of a staple. Such infusion bags are normally manufactured as ration packs which contents is for example sufficient for a cup. The user has no possibility to change the amount of tea. Further, such infusion bags are only offered with normal blends.

From the EP-A-O 212 561, an infusion bag for tea has become known which can be filled by the user with the desired tea blend by a certain amount. It is clear that such an infusion bag is also suited for the receipt of other substances as for example spices, rice or the like.

The known bag is made of a rectangular blank of liquid permeable paper nonwoven adapted to be sealed, the blank being folded along one edge portion for the formation of a seam into which a holding thread is inserted. Subsequently, the blank is folded about a score line extending perpendicularly to the sealed edge portion and thereafter sealed at both free edges. The ends of the holding thread exten ding beyond one end of the seam can be connected with a suitable label.

The known construction is substantially satisfactory for the desired application purposes. In particular, by the guidance of the thread a satisfactory closing effect for the upper end of the bag can be achieved. The process for the manufacturing of the known bag, however, is relatively expensive. The known bag requires that the holding thread is placed before the folding of a first portion takes place. Therefore, the thread participates with the subsequent process steps. The mechanical handling of the partially finished bag, including the thread, is relatively difficult.

When the upper edge of the bag is contracted by means of the holding thread, the main load occurs where the thread changes its direction. Since the nonwaven paper is relatively thin and easily subject to tear, it must be taken care that the load per surface unit at this location is not too high. Therefore, the holding thread must be relatively thick to reduce the surface pressure. Notwith standing it can happen that the paper tears at the most loaded location whereafter a satisfactory contraction cannot be achieved.

if scalded, the tea forms a kind of sponge within the bag having an increased volume. With the known infusion bags, the tea has no opportunity to sufficiently expand so that a relatively compact sponge is formed which prevents that sufficient water reaches all tea leaves to achieve a com- plete extraction.

The known filter bags of paper nonwoven have the further disadvantage that they are not neutral as to taste and smell, respectively. Therefore, it is already known to use paper nonwoven of non-bleached paper which is relatively expensive and limited resistant against boiling and lye.

Finally, the known paper nonwoven must be cut and sealed by separate steps.

From the DD-U-1069 an infusion bag is known having a filter material which is synthetic, resistant against boiling and lye and without smell and taste. The synthetic material is a textile fabric of synthetic fibers. Such an infusion bag, however, is relatively expensive in manu facture because it must be sewed at the lower and the side edges. The seam is made by sewing it with a synthetic thread.

The object of the invention is to improve a filter bag of the kind mentioned above such that it can be simply'manufactured and simply closed by a tension thread after being filled without being teared. A further object of the invention is to improve a filter bag which is particularly neutral as to taste and smell.

This object is attained by the features of the invention.

According to the invention, the rectangular blank for the filter bag is folded along a bottom folding line in order to overlap the wall portions. Subsequently, the both free edges of the wall portions are sealed while at the upper edge of each wall portion a seam is formed by folding an upper wall portion inwardly and sealing this wall portion.

It is further essential for the invention that two thread portions are used which are laid between the seam portions and the associated wall portions before the seam portions are sealed. The both thread portions are knotted together at least at one end.

The filter bag according to the invention has some advantages for its manufacture. The blank can be prefolded without difficulties by a corresponding apparatus in that the seam portions are folded and the wall portions are folded about the bottom folding line. Thereafter, the sealing can take place in a single step. The thread portions are inserted shortly before the sealing step. For this, they can be retained at both ends in the sealing station. After the sealing has taken place, the filter bag according to the invention is substantially ready and only a knotting of the ends of the thread at least at one end is necessary. This, however, meets no difficulties since corresponding knotting means are well known.

The knot increases the surface by which the thread engages the deflection edge in the seam when the thread portions are pulled at the other end. By this, the filter material is subject to a reduced load if compared with a smooth thread. With equal surface load, a thinner thread could be selected. Alternatively, another connection can be formed at the free ends of the thread, e.g. by welding, a clamping element of plastic material or metal, by welding it within an element of plastic material or the like.

According to an embodiment of the invention, the side walls are non-sealed in the area of the seam. By this, the bag according to the invention can be filled more simply and contracted if pulling at the thread.

According to a further embodiment of the invention, the width of the folded marginal portion forming the seam is a multiple of the thickness of the thread. According to a further embodiment of the invention, the width of the sealing seam is only a fraction of the width of the marginal portion. Finally, the width of the space receiving the thread can be a multiple of the thickness of the thread.

These features contribute to the fact that the seam area can be contracted more simply if pulling at the retaining thread. By this, it is prevented that the seam partially opens or the material tears in the area of the seam.

To meet the increase of volume by the tea an embodiment of the invention provides that the bottom is formed by two bottom portions linked to the wall portions and which are linked to each other about a folding line, the inwardly folded bottom portions being connected to the wall portions and with each other beyond the sealing seam of the wall portions by hot sealing. Thus, the bag can expand in the lower.area and form a sufficient volume. The sealing beyond the bottom portions has the advantage that no outwardly extending corners are formed upon expansion of the bag which may disturb the removal of liquid from the bag, e.g. out of a tea pot or the like.

Preferably, a label is attached to the ends of the thread portions. The label can consist of two portions adhered to each other, the ends of the thread extending between the label portions. Preferably, the label portions are formed of a blank which has a scoring line about which the label portions are linked. In order to prevent that the said ends are withdrawn from the label, the ends extending beyond the label are also knotted.

The object of the invention is further attained by a filter material of plastic nonwoven, preferably of poly propylene fiber. In an alternative solution, the filter material may consist of artificial silk.

This solution pertains on one hand filter bags which are filled and closed e.g. by a metallic staple at the manufacturer's site. The contents is for example tea, spices, rice or the like. On the other hand the solution pertains to filter bags which can be filled by the consumer. These include closable filter bags for tea, rice, spices or the like, in particular having one or two closing threads to close the opening. Particularly bags for rice or spices can be provided with a double-pull closure wherein the ends of closure threads are drawn in opposite directions to achieve a contraction of the edge of the opening. These also include non-closable filters, such as coffee filters.

A filter bag of the filter material according to the invention has no smell and no taste and an increased strength as well. Further, it can be simply manufactured with low expenses, in particular when the edges are hotsealed and/or hot-cut. The hot-sealing and hot-cutting can be carried out with a suitable sealing and cutting tool.

It can be further carried out by a combined frictional welding and frictional cutting by ultrasonic means.

Finally, according to a further embodiment of the invention, the filter material can have a surface-specific weight of 15 to 50 gum2. A range of 15 to 30 g/m2 is preferred, above all if the filter bag is used as tea infusion bag. A range of between 20 to 50 g/m2 is preferred if a boiling bag for rice is desired. For the above reason, the bag according to the invention has less weight than the inown ones.

It is understood that the bag according to the invention is above all suited for preparing tea, however, is not limited thereto. It can be used for all products where substances are extracted by water or another liquid or which are treated by water or another liquid within the bag, e.g. are boiled, as for example rice.

The invention is subsequently explained in more detail along drawings.

Fig. 1 is a plan view of a blank for a bag according to the invention.

Fig. 2 is a perspective view of a bag partially raised from a blank according to Fig. 1.

Fig. 3 is a plan view of a flat bag after being finally manufactured.

Fig. 4 is a perspective view in a larger scale of an ad hesion label just before its application.

Fig. 1 shows a blank 10 of filter material suited to be sealed, e.g. filter nonwoven paper or synthetic nonwoven.

The rectangular blank includes a center scoring line 11, scoring lines 12, 13 extending parallel thereto with a distance therefrom. The scoring lines 11 to 13 form bottom portions 14, 15. Wall portions 16, 17 are linked to the bottom portions through scoring lines 12 or 13, respectively. Seam portions 20, 21 are linked to the wall portions 16, 17 through scoring lines 18, 19.

During manufacture, the bottom portions 14, 15 are folded upwardly like a roof as can be seen in Fig. 2. Contemporarily, the wall portions 16, 17 are folded about scoring lines 12, 13 to overlap each other. Further, the seam portions 20, 21 are folded inwardly about scoring lines 18, 19. By overlapping of the portion shown in Fig. 2, they could be connected to each other subsequently by hotsealing. Prior to the folding of the seam portions 20, 21 or before the sealing step takes place two thread portions 22, 23 are placed (see Fig. 2).

In Fig. 3, individual sealing seams can be seen. Sealing seams 24, 25 interconnect the wall portions 16, 17 at the free edges thereof. In the area of the bottom, the bottom portions 14, 15 are connected to the wall portions 16, 17 beyond the seams 24, 25 through hot-sealing. Sealing seams connect seam portions 20, 21 with the wall portions 16, 17, only one thereof being shown at 26. As can be seen, the sealing seams 24, 25 terminate in front of the seam formed by the seam portions 20, 21.

If the filter material consists of a synthetic nonwoven or of artificial silk, the sealing seams 24, 25 can have a distance from the free edges of the wall portions 16, 17 because the filter bag is concurrently sealed and cut by a combined sealing or welding and cutting unit. This enables an improved guidance of the blank prior to the sealing or cutting, respectively.

The thread portions 22, 23 are knotted at both ends as shown at 27 and 28. An adhesion label 30 is connected to the thread portions 22, 23. As can be seen in Fig. 4, the label consists of two portions 31, 32 which are part of an integral blank and which are folded against each other through folding line 33. The label portions 31, 32 are interconnected by adhesion. The knot 28 prevents the thread portions 22, 23 from being pulled out of the label 30.

The folding of the blank 10, the placing of the thread portions 22, 23 and the subsequent sealing of the portions is carried out completely automatically in a suitable apparatus. The such manufactured bag shown in Fig. 3 is brought into a flat state and packed.

The upper edge portions of the seam can be manually gripped to open the bag and to fill it with a substance, e.g. with tea. Subsequently, the seam is gripped and the threaded thread portions 22, 23 are pulled in order to contract the seam so that the bag is substantially closed. An increase of volume by the filled substance can be met by an expansion of the side walls 16, 17. The bottom portions 14, 15 are partially unfolded so that a considerable enlargement of the volume takes place.

Claims

C 1 a i m 8 :

1. Infusion bag, particularly infusion bag for beverages such as tea or the like or boiling bag for food such as rice or the like wherein a flat blank of filter ma terial capable of being sealed, particularly nonwoven paper, is formed to a bag by folding and sealing the edges of the bag which is left open at the top, wherein further a seam is formed by folding and sealing the upper edges, a holding thread being inserted in the seam which extends beyond one end of the seam with two ends, characterized in that the wall portions (16, 17) are brought to a mutual overlapping by folding the blank about a bottom folding line (11, 12, 13), only the side edges of the wall portions are sealed, a separate seam is formed at the upper edge into each of which a se parate thread portion (22, 23) are inserted which ex tend beyond both ends of the respective seam, the ends of the thread portions being interconnected at least at one end, preferably by a knot (27, 28).

2. The filter bag according to claim 1, wherein the side walls (16, 17) are non-sealed in the area of the seam.

3. The filter bag according to claim 1 or 2, wherein the width of the folded edge portions (20, 21) forming the seam is a multiple of the thickness of the thread portions.

4. The filter bag according to claim 3, wherein the width of the sealing seam (26) is a fraction of the width of the edge portions (20, 21).

5. The filter bag according to claim 3 or 4, wherein the width of the space in the seam receiving the thread portions (22, 23) is a multiple of the thickness of the thread portions.

6. The filter bag according to one of the claims 1 to 5, wherein the bottom is formed by bottom portions (14, 15) linked to the respective wall portions (16, 17) through a folding line (12, 13), the inwardly folded bottom portions (14, 15) being connected to the wall portions (16, 17) by hot sealing and are interconnected at an extension of the sealing seam (24, 25) of the side walls.

7. The filter bag according to the claims 1 to 6, wherein a label (30) connected to the thread ends (22, 23) at one end of the seam consists of two label portions (31, 32) interconnected by adhesion, the thread ends coming to lie between the label portions.

8. The filter bag according to claim 7, wherein the label portions (31, 32) are interlinked at one edge.

9. The filter bag, particularly infusion bag for beverages, such as tea or the like or boiling bag for food such as rice or the like in particular according to one of the claims 1 to 8, wherein the filter material is a synthe tic nonwoven, particularly of polypropylene fibers.

10. The filter bag,particularly infusion bag for beverages, such as tea or the like or boiling bag for food such as rice or the like in particular according to one of the claims 1 to 8, wherein the filter material is an artificial silk.

11. The filter bag according to claim 9 or 10, wherein the edges are hot-sealed and/or hot-cut.

12. The filter bag according to one of the claims 9 to 11, wherein the filter material has a surface-specitic weight of 15 to SO g/m2.