WO2004018770A1

WO2004018770A1 - Beverage package

Info

Publication number: WO2004018770A1
Application number: PCT/GB2003/003589
Authority: WO
Inventors: Christopher Jowsey
Original assignee: J R Crompton Limited
Priority date: 2002-08-22
Filing date: 2003-08-15
Publication date: 2004-03-04
Also published as: GB0219600D0; AU2003269093A1

Abstract

The present invention relates to a novel type of beverage infusion package which possesses good wet strength and resistance to bursting. The beverage infusion package may be of the heat seal or non-heat seal type and is formed from cellulosic material containing at least 65 % by weight wood pulp.

Description

BEVERAGE PACKAGE

The present invention relates to a novel type of beverage infusion package which possesses good wet strength and resistance to bursting. The present invention also relates to porous, fibrous web materials for use in producing such packages. It is also possible to apply printing and/or a relief pattern to the package of the present invention. More particularly, the invention relates to tea bags which can be manufactured from paper containing a large percentage of wood pulp.

Beverage infusion packages such as tea bags comprise a particulate beverage precursor material, e.g. tea leaves, in a bag, sachet, pouch or the like (all conveniently refeπed to herein as a bag) of a porous, fibrous cellulosic material. This material typically has a weight of 10 to 30gm^"2 and is often refeπed to as "tissue" or "tissue paper". The paper maybe of the "heat seal" or "non-heat seal" type.

The present invention is concerned with the production of both heat-seal and non- heat seal tea bags using papers containing a high percentage of wood pulp.

Heat seal paper comprises a web of one or more layers. The single layer heat sealed paper contains cellulosic and thermoplastic fibres. In cases of webs having two or more layers, one layer contains cellulosic fibres and the other layer incorporates thermoplastic fibres which are to form the basis of the heat seal. In another arrangement the inner (structural) layer comprises both cellulosic fibres and thermoplastic fibres. The entrained thermoplastic fibres provide a stronger heat seal between two webs of the tissue paper because the thermoplastic forming the heat seal is an integral part of the structural layer. The second (outer) layer is an insulating layer of material whose primary function is to protect the rollers of the processing machinery from the thermoplastic-containing structural layer during processing.

Non-heat seal paper usually comprises a web of material which is a single layer of cellulosic fibres. Conventionally, both the heat seal paper and the non-heat seal paper are produced from cellulosic fibres produced from mixtures of well known paper-making fibres which may include both wood and non-wood materials such as manila hemp, sisal, jute, bleached and un-bleached softwood and hardwood species, and sometimes compatible synthetic fibres such as viscose rayon and spun bonded rayon. The web of paper material is typically manufactured by wet laid processes which are well known. The paper material is generally treated with classic wet and dry strength chemical enhancing products such as carboxymefhyl cellulose (CMC), polyamide epichlorohydrin and melamine formaldehyde.

Coffee filters have previously been produced having a cellulosic fibre content which is 100% wood pulp. However, these products are very heavy grammage paper, typically greater than 50 gmf² and these materials act as a filter paper by allowing direct exposure of hot or boiling water with the solid beverage so that the filtrate passes through the paper due to gravity. These materials are open and are not formed into packages. If such a paper were to be made into a sealed product such as a beverage infusion package, the package simply would not function as the material is unable to allow the effective passage of liquid across it in the absence of, for example, gravitational force pulling liquid through the paper. These materials would not be able to be processed on machines into beverage infusion packages.

It is generally the case that paper suitable for the production of tea bags contains around 70% of abaca or manila (which may include approximately 10% of sisal or jute.) A small quantity of wood pulp, typically about 30% by weight of the cellulosic material, is added as a filler. However, traditionally, it is important to ensure that the wood pulp is only present in a relatively small proportion, usually not greater than 20% by weight, in order not to detract significantly from the strength of the bag, and in particular from the properties of the bag when wet.

United Kingdom patent no. 1091073 describes a heat sealable paper and a process of manufacturing the same. This patent describes the production of a heat sealable paper from a liquid dispersion of non-toxic and tasteless thermoplastic fibres having a melting point between 100°C and 240°C and non-thermoplastic cellulosic fibres. One significant disadvantage with existing paper used in the production of tea bags is the cost of the raw materials. Materials such as abaca, manila, sisal and jute all cost in the region of £1500 per ton at cuπent market rates. Similarly, synthetic fibres such as rayon are expensive to produce. This maybe contrasted with a cost of around £350 per ton for wood pulp.

Wood pulp differs from the above fibres in tending to be of much shorter length, with wood pulp typically being only half the length or less of fibres such as manila. In approximate numeric terms a manila fibre would typically be around an average of 4.5mm long whereas a wood pulp fibre of the type incorporated into a tea bag would typically be an average of 2.0mm. It is therefore widely appreciated in the art that increasing the amount of wood pulp present in the tissue paper leads to a substantial decrease in the strength of any package formed and in particular in the wet strength of the paper. The reduction in strength appears to decrease in linear relation to the increasing wood pulp content.

Another problem with prior art tea bags, particularly of the non-heat sealed type, is that they are prone to bursting because the crimp which serves to seal the bag is unable to cope with gas pressure when introduced to boiling water. This problem is exacerbated with increasing trend of users to introduce the bag into cold water and then apply microwave heating. This heating regiment is much more aggressive and increases the failure rate of tea bags and causes loss of the contents with the effect being most noticeable in non-heat seal tea bags.

It is therefore an object of the present invention to produce a paper which is useful in the manufacture of beverage infusion packages such as tea bags. More particularly, it is intended that the paper should be capable of use in both heat seal and non-heat seal packages. It is a further aim that the paper should have good wet and dry strength and be resistant to bursting.

It is also an aim of the present invention to provide a beverage infusion package such as a tea bag which retains its structural integrity and which is not subject to bursting. It is thus desired that the resulting package has a good crimp strength once sealed to form a closed package. It is thus an aim of the present invention to provide a paper which can be used in the production of a non-heat sealed package eg a tea bag having a high crimp strength and a resistance to failure. It is also desired that a heat sealed package should be similarly strong and resistant to failure. It is a further object of the invention to provide a package and paper for the production of a package which is easy to process and economical to produce. Another aim is to produce a package formed from paper which is free from unnecessary additives.

The present invention satisfies some or all of the above objects.

Surprisingly, we have found that it is possible to incorporate relatively high proportions of wood pulp into paper whilst maintaining or improving the wet strength of the paper. The paper can thus be used to produce beverage infusion packages which have good wet and dry strength. We have also found that it is not necessary to include dry strength additives, in particular carboxymethyl cellulose (CMC) in the paper. The paper of the present invention has good dry strength in its own right without CMC being added.

The reasons underlying this surprising finding are not understood although it is postulated that the shorter flatter ribbon-like fibres contained within the wood pulp result in the fibres laying together well. The increased surface area of the fibres may also lead to improved contact bonding between the fibres when folded. It is speculated that this may result in an improved strength in the paper both before and after crimping in a non heat- sealed bag. The resulting crimped product thus has improved strength and is less likely to fail due to pressure on exposure to boiling water.

According to a first aspect of the present invention, there is provided a beverage infusion package formed from a web of porous, fibrous, cellulosic material, wherein the cellulosic material contains at least 65% by weight wood pulp, the package having a closure seam produced by a mechanical compression action without heat sealing. Normally, the web consists of a single layer of material. The non-heat sealed paper of the present invention may also be produced by a dual layer process as described in our earlier patent no EP 0842043.

We have found that the incorporation of at least 65% wood pulp in the cellulosic material leads to an improved strength in the mechanical seam both when dry and when wet. The mechanical seam may be produced by conventional methods such as applying a mechanical compressive force using a toothed wheel to folded over edges of the web in a process conventionally known as crimping.

The paper web generally has a grammage of 9 to 40 gm^"2 and more typically in the range of 10 to 20gm^"2. It is prefeπed that the material has a grammage of from 10 to 15gmf² from the point of view of producing a package which has good dry and wet strength and which allows effective infusion of water into the package.

From the point of view of ensuring good dry and wet strengths, it is essential that the wood pulp comprises at least 65% by weight of the cellulosic material. More preferably, the cellulosic material comprises at least 80% by weight wood pulp as this leads to a significantly improved wet strength. It is further prefeπed that the wood pulp comprises at least 90% by weight of the cellulosic material because this provides both good wet strength and ensures a strong mechanical seal when crimped. It is even possible for the paper web to be produced from cellulosic material containing 100%) wood pulp.

In an embodiment the beverage infusion package may be a tea bag or a coffee bag/pouch/pod. Preferably, the package is adapted for use as a tea bag containing traditional or herbal tea. The package will contain from 2 to 4 g of the infusion product such as tea, and typically around 3 g.

According to a second aspect of the present invention, there is provided a beverage infusion package formed from a web of porous, fibrous, cellulosic material, wherein the porous material includes thermoplastic fibres, and wherein the cellulosic material comprises at least 65% by weight of wood pulp. The heat seal is formed when two paper webs which may be of the same or different composition containing thermoplastic fibres are brought together in the presence of heat.

In a prefeπed embodiment, the web of porous material comprises a structural layer containing cellulosic material and thermoplastic fibres, and an insulating layer which is formed of cellulosic fibres. For the avoidance of doubt, in this embodiment, the cellulosic component of the structural layer must contain at least 65% by weight of wood pulp in order to ensure adequate strength in the package. The proportions of cellulosic material and thermoplastics material are within conventional ranges.

Examples of suitable fheπnoplastics which maybe used are polypropylene, polyester, polyamide 6, polyamide 66, polyamide 11, polyamide 12 and high density polyethylene. Blocked or random co-polymers or ter polymers of polypropylene and ethylene may also be used. Other suitable polymers include modified polyethylene copolymers, copolymers of vinyl chloride and vinyl acetate, polyethylene, polylactic acid, fibrils, bi-component fibres. Thermoplastic materials known as synthetic wood pulp or fibrils would also be suitable.

The thermoplastic fibres will preferably have a thickness of 0.5 to 6.0 denier although the best results are generally achieved with fibres in the 2 to 4 denier range.

The length of the thermoplastic fibres may be from 0.5mm to 12mm but preferably are in the range of 3 to 6mm in order to ensure compatibility with the wood pulp fibres.

The thermoplastic fibres in the web are preferably fused or thermally bonded together at a temperature greater than the crystalline melt temperature of the thermoplastic fibres. This assists in ensuring the structural integrity of the web.

In either aspect of the present invention, the balance of the cellulosic material (if any) may be of natural origin and/or synthetic material. Natural materials which are suitable include abaca, manila, sisal, jute and hemp. Suitable synthetic materials include rayon.

In principle, the wood pulp used in the present invention may be of any origin and may be hardwood or softwood. The important feature is that the pulp is capable of developing good strength at low levels of refining. Any wood pulp that has sufficient strength such that the paper web can be formed and processed at the desired weight ranges without rupture can be used in the package or web of the present invention. It is also important that the wood pulp retains porosity after refining. Usually, there is a conflict between increasing the degree of refining to develop strength and reducing the porosity of the resultant web as a consequence of increased refining. Refining is a conventional process applied to wood pulps and thus will not be described here.

We have found that certain wood pulps are advantageous. Specifically Northern Bleached Softwood Kraft (NBSK), black spruce pulp from British Columbia, Catawba pulp derived from Southern USA pine pulp and harmac pulp derived from coastal British Columbia western red cedar pulp. Other suitable pulps include Canadian pulps such as Miramichi newbrite (Newcastle New Brunswick NBSK), Squamish (British Columbia western red cedar pulp), Howe sound (coastal British Columbia NBSK), and Donahue St Felicien (NBSK from Quebec). Scandinavian pulps such at Botinia pine and Wisapine from Finland and Norland from Sweden are also suitable. Hardwood pulps such as Encel (Eucalyptus pulp from Spain), Caucas Betula (Birch pulp from Finland), Chesapeake (mixed hardwood from the USA), and Jari (Amazonian Eucalyptus pulp) can also be used particularly when blended softwoods to achieve the required properties. The key properties for the wood pulp are tensile breaking length, tear strength, porosity and bulk after refining.

Conventional additives such as wet and dry strength agents, sizing agents and fillers may be incorporated in the paper as required to give the paper desired properties. Thus wet strength agents, preferably in an amount of not more than 10% by weight, such as melamine formaldehyde and polyamide epichlorohydrin can be added. We have found that the use of melamine formaldehyde imparts particularly good properties. This is particularly important in the case of a non-heat sealed package because it is important that the crimp remains intact during use. Traditionally crimp strength has been enhanced by adding thermoplastic materials to the paper even though the package is not heat sealed. This improves the crimp strength but has processing and cost disadvantages. However, the non-heat sealed package of the present invention does not require the addition of thermoplastic in order to enhance strength, although it is possible to incorporate thermoplastic material in the non-heat seal paper of the present invention used to form a non-heat sealed package should it be desired.

The manufacturing process for the paper is conventional and thus will not be described here in detail. Briefly, the process involves dispersion of the fibrous material in water followed by mechanical treatment of the fibres (refining) in order to enhance the cross bonding between fibres. The next stage involves blending the fibrous components together and the addition of any necessary dry or wet strength chemicals. The liquid dispersion of fibre (stock) is then cleaned in hydra-cyclones to remove dense contrary material. The dilute stock is then screened. Finally, the paper web is formed by metering the very dilute stock onto an endless mesh (wire). The water is drained away and the wet web is carried forward to the drier part of the paper-making machine. The resulting wet paper web is dried by hot air and contact with steam heated cylinders or other drying methods and optional surface treatment of the paper surface is then performed. It is at this stage that functional chemicals such as sizing agents are added. Further drying, including curing of wet strength resins and thermal bonding of any thermoplastic component is then effected. The final stages of the process involve moisture coπection with water or steam spray, calendaring to control the thickness or smooth the paper surface, and reeling the continuous web onto a roll.

The manufacture of beverage packages such as tea bags from the paper of this invention is achieved in the case of non-heat sealed paper by folding, crimping and stapling as described in our earlier patent No WO01/41610.

In the case of heat sealable papers, two webs of paper are placed together with their thermally active surfaces facing one another and then compressed between heated rollers. Ultrasonic or other suitable methods of sealing thermoplastic surfaces may also be used. The design of the roller surface controls the pattern of the heat seal obtained, e.g. round, square, pyramidal etc. The key variables are the temperature of the heated rollers, the pressure applied, the speed of the web, the condition of the rollers and the choice and quantity of thermoplastic material within the construction of the tea bag paper. However optimisation of appropriate heat sealing processing parameters for a given paper is entirely within the contemplation of the skilled person.

A problem with prior art beverage packages of the non-heat sealed type is that frequently they are required to be coated with latex in order to facilitate processing of the paper during the manufacture of the package. Such packages have the disadvantage that they float because latex is hydrophobic and infusion performance is reduced. In order to overcome this, these prior art packages frequently contain further additives in order to make them sink and restore infusion performance. The non-heat sealed packages of the present invention do not require a latex coating and thus maintain good infusion performance without additional treatment steps. For specific applications latex coatings may be of use and this may be incorporated with the package of the invention. There is also the advantage that the non-heat sealed packages of the present invention do not contain a cocktail of additives and are thus simpler and more economical to manufacture. Since the inclusion of additives is also generally seen as undesirable there are environmental and health benefits associated with the packages of the present invention.

The non-heat sealed paper described in the first aspect of the invention may also incorporate thermoplastic fibres which may preferably be fused or thermally bonded together as above. The thermoplastic fibres may be amorphous or partially crystalline. We have found that the incorporation of these fibres also produces a significant enliancement in the mechanical seam integrity ie in the crimp strength.

It is envisaged that the papers of the present invention may find uses other than simply in beverage packages such as tea and coffee bags. Thus, it is believed that a strong lightweight wood pulp containing paper could be used in a number of alternative beverage packages or beverage filtration products. In another aspect of the present invention there is provided use of a web of porous, fibrous, cellulosic material, wherein the cellulosic material in the web contains at least 65%> by weight wood pulp in the manufacture of a beverage infusion package.

In a further aspect of the present invention, there is provided the use of a web of porous, fibrous, cellulosic material, wherein the web includes cellulosic fibres and thermoplastic fibres and wherein the cellulosic material in the web comprises at least 65% by weight wood pulp, in the manufacture of a beverage infusion package.

In a further aspect of the present invention there is provided a web of porous fibrous cellulosic material, the web comprising at least a structural layer and an insulating layer, wherein the structural layer includes cellulosic fibres containing at least 65% by weight wood pulp and thermoplastic, and the insulating layer includes cellulosic fibres but does not contain thermoplastic, and wherein the web has a grammage of from 9 to 40 gm^"2.

In a further aspect of the present invention there is provided a web of porous fibrous cellulosic material, the web comprising a structural layer and a bonding layer, wherein the structural layer includes cellulosic fibres containing at least 65% by weight wood pulp and optionally thermoplastic, and the bonding layer includes cellulosic fibres and thermoplastic, and wherein the web has a grammage of from 9 to 40 gm^"2.

In a further aspect of the present invention there is provided a web formed of porous fibrous cellulosic material, the web comprising at least one layer comprising cellulosic fibres and optionally thermoplastic, wherein the cellulosic fibres contain at least 65%o by weight wood pulp, and wherein the web has a grammage of from 9 to 40 gm^"2.

In an embodiment, the web may be produced to allow sealing on both sides of the paper for beverage infusion packages for machines that require sealing on both sides of the web.

Beverage infusion packages such as tea bags may be produced from the paper of the present invention by conventional processes. Thus, the bag is produced by folding, crimping and stapling as described in our earlier patent No WO01/41610. Thus, the processing steps described in that patent are directly applicable to the materials described in the present invention.

A heat sealed package may be produced in the manner described in our earlier patent No WO98/36128 and the processes described therein are directly applicable to the materials of the present invention. The paper and beverage packages of the present invention may thus be manufactured and processed in a conventional manner to packages made from conventional papers.

Likewise, the paper used to make the beverage packages of the present invention may be embossed with a pattern in the manner described in our earlier patent No GB 2286159 and the processes described in that patent are directly applicable to the paper of the present invention.

The beverage packages of the present invention have the further advantage that printing may be applied to the package either for the purpose of decoration or for the purpose of identification despite the relatively high porosity of the paper. The printed beverage packages according to one embodiment of the present invention are specially designed so that the ink remains on the package. An ink approved for use in contact with food is used. In a further embodiment of the present invention the beverage package (either a heat sealed package or a non-heat sealed package) includes a printed region which remains visible after exposure to hot or boiling water.

The present invention will now be illustrated with reference to the following examples of beverage infusion packages which can be produced according to the invention.

EXAMPLE 1 - Heat Seal Package

A heat sealed package can be produced from a two layer paper web having a grammage of 16.5 gm^"2. The total moisture content of the package is 5.5% and the top (insulating) layer has a grammage of 4.5 gm^"2 and comprises of 100% wood pulp. The base (structural) layer has a grammage of 12.0 gm^"2 which is comprised of 7.5 gm^"2 of cellulosic material which consists of 100% wood pulp and 4.5 gm^"2 of polypropylene. The wood pulp is 50% Harmac K10 and 50% Catawba. Melamine formaldehyde is added as a wet strength agent in such an amount that not more than 3% by weight is retained in the product. The package had excellent wet strength and resistance to bursting.

EXAMPLE 2 - Non-Heat Sealed Product

A non-heat sealed package was produced from a web of paper comprising a single layer having a grammage of 13.0 gm^"2. The moisture content was 7.3% by weight and the balance of the material was cellulosic fibre derived from 100% wood pulp. The wood pulp was a single variety of wood pulp (Canfor NSBK). Melamine formaldehyde was added as a wet strength agent in such an amount that not more than 3% by weight was retained in the paper. The package had excellent wet strength and resistance to bursting.

EXAMPLES 3 and 4

Packages were prepared exactly as described in Examples 1 and 2 above, except that the melamine formaldehyde was replaced by polyamide epichlorohydrin as the wet strength agent such that not more than 1.5% by weight of polyamide epichlorohydrin is retained in the product. The product has excellent wet strength and resistance to bursting.

In summary, the beverage package of the present invention provides a number of advantages. Thus, it is possible to avoid using synthetic fibres when designing a package having a high crimp strength. Likewise, it is possible to avoid adding latex and related additives to retain the integrity of the crimp. The beverage package thus becomes biodegradable due to the absence of synthetic fibres and latex or related additives and this is an important advantage. Finally, the beverage packages are simple and economical to manufacture and are essentially free of synthetic fibres or unnecessary chemical additives whilst maintaining good wet and dry strength.

Claims

CLALMS

1. A beverage infusion package formed from a web of porous, fibrous, cellulosic material, wherein the cellulosic material contains at least 65% by weight wood pulp, the packaging having a closure seam produced by a mechanical compression action without heat sealing.

2. A beverage infusion packaged formed from a web of porous fibrous cellulosic material, wherein the porous material includes thermoplastic fibres, and wherein the cellulosic material comprises at least 65% by weight of wood pulp.

3. A package as claimed in claim 1 or 2, wherein the cellulosic material comprises at least 80% by weight wood pulp.

4. A package as claimed in claim 1, 2 or 3, wherein the cellulosic material comprises at least 90% by weight wood pulp.

5. A package as claimed in any preceding claim, wherein the web has a grammage of from 9 to 40 gm^"2.

6. A web as claimed in claim 5, wherein the grammage is from 10 to 20 gm^"2.

7. A package as claimed in claim 2, or any claim dependent thereon, wherein the thermoplastic is selected from polyester, polyamide 6, polyamide 66, polyamide 11, polyamide 12, high density polyethylene, modified polyethylene copolymers, copolymers of vinyl chloride and vinyl acetate, polyethylene, polylactic acid, fibrils, bi-component fibres, thermoplastic materials known as synthetic wood pulp or fibrils.

8. A package as claimed in claim 2 or any claim dependent thereon, wherein the thermoplastic fibres have a thickness of 0.5 to 6.0 denier.

9. A package as claimed in claim 1, wherein the web further includes thermoplastics fibre.

10. A package as claimed in claim 9, wherein the thermoplastics is selected from polyester, polyamide 6, polyamide 66, polyamide 11, polyamide 12 and high density polyethylene, and blocked or random copolymers or terpolymers of propylene and ethyl ene.

11. A package as claimed in any preceding claim, wherein the wood pulp has sufficient strength such that the paper web can be formed and processed at the desired weight ranges without rupture.

12. A package as claimed in any preceding claim, wherein the wood pulp is selected from Northern Bleached Softwood Kraft (NBSK), Black Spruce pulp, Catawba pulp, Harmac pulp, Miramichi Newbrite, Squamish pulp, Howe Sound pulp, and Donahue St Felicien, Botnia Pine, Wisapine, Eucalyptus pulp, Caucas Betula, Chesapeake, and Jari pulp.

13. A package as claimed in any preceding claim, wherein the wood pulp is a blend of softwoods and/or hardwoods.

14. A package as claimed in any preceding claim, further including melamine formaldehyde and/or polyamide epichlorohydrin as a wet strength agent, preferably in an amount of not more than 10% by weight.

15. A package as claimed in any preceding claim, further including one or more wet strength agents, sizing agents or fillers.

16. A package as claimed in claim 1 , wherein the web is produced by a dual layer process as described in EP 0842043.

17. A package as claimed in any preceding claim, wherein the package includes a region printed with ink approved for use in contact with food.

18. A beverage product comprising a package according to claim 1 which has been sealed and contains a beverage infusion.

19. A beverage product comprising the package of claim 2 which has been sealed and contains a beverage infusion.

20. A paper web formed from porous fibrous cellulosic material, wherein the cellulosic material contains at least 65% by weight wood pulp, the web having a grammage of from 9 to 40 gm^"2.

21. A paper web formed from porous fibrous cellulosic material, the web comprising a structural layer and a bonding layer, wherein the structural layer includes cellulosic fibres containing at least 65%> by weight wood pulp and optionally thermoplastic, and the bonding layer includes cellulosic fibres and thermoplastic, and wherein the web has a grammage of from 9 to 40 gm^"2.

22. A paper web formed from porous fibrous cellulosic material, the web comprising at least one layer comprising cellulosic fibres and optionally thermoplastic, wherein the cellulosic fibres contain at least 65 % by weight wood pulp, and wherein the web has a grammage of from 9 to 40 gm^"2.

23. A paper web formed from porous fibrous cellulosic material, the web comprising at least a structural layer and an insulating layer, wherein the structural layer includes cellulosic fibres containing at least 65% by weight wood pulp and thermoplastic, and the insulating layer includes cellulosic fibres but does not contain thermoplastic, and wherein the web has a grammage of from 9 to 40 gm^"2.

24. A paper web as claimed in claim 20, 21, 22 or 23, wherein the cellulosic material contains at least 80% by weight wood pulp.

25. A web as claimed in any of claims 20 to 24 further containing melamine formaldehyde in an amount of not more than 10% by weight, or polyamide epichlorohydrin in an amount of not more than 10% by weight.

26. Use of a web of porous fibrous cellulosic material wherein the cellulosic material contains at least 65% by weight wood pulp in the manufacture of a beverage infusion package as claimed in claim 1 or any claim dependent thereon.

27. Use of a web of porous fibrous cellulosic material, wherein the porous material includes thermoplastic fibres and wherein the cellulosic material comprises at least 65% by weight wood pulp, in the manufacture of a beverage infusion package as claimed in claim 2 or any claim dependent thereon.