T 0845/95 13-05-1997

1. The appeal complies with the formal requirements of Articles 106 and 108 and Rules 1(1) and 64 EPC. It is therefore admissible.

2. Background to the claimed invention; state of the art

2.1. Containers for liquid products which have been formed by folding and sealing together the edges of a paperboard blank are to be found on supermarket shelves and in household larders everywhere. The paperboard blank is conventionally a laminate comprising inner and outer layers of polyethylene or the like. Under the application of appropriate temperatures and pressure two of these layers will form a mechanical bond which is also liquid-tight. This operation is known as "heat-sealing". The blanks for forming the containers are generally delivered to the packaging plant in a flat condition and are provided with fold lines along which the blank is folded and sealed to form the finished container. Initially the blank will be folded and sealed along a longitudinal seam to form a tube; bottom panels are then folded in and sealed to close the bottom of the tube; the partially formed container is then filled with the product to be packaged; finally top panels are folded together and sealed to close the container. The top closure end of the package is conventionally of gable-top form (with a ridge-roof- like configuration) or of the block type (with ears folded down over the sides of the container). In both cases the actual seal at the closure end of the container takes the form of a sealing fin. With a "gable-top" container the fin is the same width as the container and, as a result of the folded-in top sides of the blank, will generally be of four blank thicknesses. With a "block" container the sealing fin comprises only two blank thicknesses and after completion of the container lies substantially flat on its top surface and ears.

Most consumers will also have had experience of opening this type of container without the assistance of kitchen tools and also, perhaps, of spilling some of the contents while doing so. Three prior art proposals for facilitating the opening of a container of this type are found in documents E1 to E3, which are considered in more detail below.

2.2. Document E2, published in 1963, relates to a gable-top container in which certain areas of the edge zone of the blank which on forming the container will constitute its sealing fin are coated with a polysiloxane material that resists the formation of a permanent seal between these areas as the container is closed. This therefore facilitates the opening out of one end of the closure by opposed thumb pressure and then snapping out of the roof and end panels of the blank to form a pouring spout. According to the respondents containers of the type disclosed in document E2 are still in widespread use today.

2.3. Document E3, published in 1969, proposes a gable-top container in which the sealing fin is provided with a line of weakness along which it can be torn to remove an uppermost strip thereof which is preferably half as long as the fin. The fin is not heat-sealed over its whole area but only along a relatively narrow line which lies above the line of weakness. Once the strip has been torn off, it is easy to separate the top panels of the blank to form a spout in the manner described above in the reference to document E2.

2.4. Document E1, published in 1982, relates to a blank for a block-type container which has a line of weakness provided in the sealing fin extending across approximately half of its width. The facing areas of the fin-forming areas of the blank beneath the line of weakness remain substantially unsealed as the container is formed. After the corresponding ear of the container has been lifted, the upper strip of the fin above the line of weakness can be readily torn off to define a pouring spout.

3. The claimed invention (main request)

Claim 1 of the main request is in very general terms and extends to blanks for forming both "gable-top" and "block" type containers, amongst others. Indeed, although the finished forms of the closures are quite distinct, the general pattern of fold lines required in the respective blanks is virtually identical. This well-known pattern, which is not specified in the claim, includes longitudinal fold lines which effectively divide the transverse running, fin-forming, edge zone into a number of panels. In comparison with claim 1 as granted, claim 1 of the main request requires that a seal inhibiting composition is provided on "adjoining surfaces" of the edge zone. Taken by itself that statement is not particularly clear. However, in the light of the description, it can be understood as meaning that the seal inhibiting composition is provided on at least two surfaces of the edge zone which adjoin each other at a longitudinal fold line.

In the course of the appeal proceedings, the appellants have referred to the passage at lines 49 to 53, column 3, of the patent specification according to which pretreatment of appropriate portions of the blank "reduces" their "sealing capacity" and seek to have the term "seal inhibiting composition" as used in claim 1 understood in a corresponding way, i.e. as a "seal reducing" but not "seal preventing" composition. The Board cannot accept that proposition. As a matter of language the term "inhibiting" clearly extends to both preventing and reducing something. That view is supported by the patent specification itself at lines 1 to 5, column 4, where it is stated that the pretreatment may involve the covering of the plastics layer with a coating "inhibiting or weakening" the seal, consisting for example of a polysiloxane material (i.e. the same as proposed in document E2).

4. Novelty and inventive step (main request)

4.1. In the opinion of the Board the fold lines in the fin-forming edge zone of the blank shown in figures 4 and 5 of document E2 cannot be equated to a "line of weakness" in the sense this is used in the contested patent, i.e. a line along which the material of the blank is weakened with the purpose of facilitating tearing of the blank. Thus the subject-matter of claim 1 according to the main request is novel with respect to the disclosure of document E2.

4.2. The most appropriate starting point for the evaluation of inventive step is the blank disclosed in document E1, since of the three cited prior art documents this is the only one which relates to a container having a sealing fin the layers of which, in a manner corresponding to the container described in the contested patent, are heat-sealed together over their whole extent except for the area lying below a line of weakness provided in the fin.

Document E1 does not disclose how in practical terms the heat-sealing of that area below the line of weakness is to be avoided. In view of the technical considerations involved, a modification of the heating means (hot air jets) conventionally used to heat the edge zone of the blank before closing jaws complete the seal would be very problematic. The person skilled in the art knows however from document E2 that heat-sealing in relatively precisely bounded areas of the blank can be achieved by applying a coating of a seal-inhibiting composition to those areas. It would therefore be obvious for him to apply such a coating to the whole of the area of the fin-forming edge zone of the blank of document E1 which is not to be sealed. Since that area extends over two longitudinal fold lines of the blank, it is inevitable that the seal inhibiting composition would then be provided on "adjoining surfaces" of the blank as required by claim 1.

In support of their view that the subject-matter of claim 1 involves an inventive step, the appellants relied especially on the relative age of documents E2 and E3 and as a corollary thereto that the appellants had satisfied a long-felt need for a container which could be readily opened but was nevertheless fluid-tight. In the latter respect it would seem however that the proposal of document E2 is still being used commercially today, which would point against any urgent need for a replacement. Furthermore, as regards the age of the citations, it must be noted that the closest state of the art, document E1, was published only a relatively short time (less than four years) before the priority date of the contested patent.

Having regard to the above the Board has come to the conclusion that the subject-matter of claim 1 according to the main request lacks inventive step (Article 56 EPC).

5. Auxiliary request

It belongs to the established case law of the Boards of Appeal that the admission of amended claims into appeal proceedings, particularly when the amendments are first submitted at oral proceedings, is at the discretion of the Boards, see for example T 95/83 (OJ EPO 1985, 75) and T 153/85 (OJ EPO 1988, 1). The factors which need to be taken into account when exercising this discretion include whether the amended documents are clearly allowable, firstly in the sense of conforming with the formal requirements of the EPC and secondly in the sense of having at least a reasonable prospect of removing the outstanding substantive objections against the documents previously on file.

In the present case a feature has been added to the preamble of the claim, namely that the blank is "rectangular", which is not clearly derivable from the original disclosure. It is indeed said there that the blank is "substantially rectangular" but since its bottom edge is not shown and particularly since it is well-known that this bottom edge may be formed with flaps etc. for facilitating forming the bottom closure, it is not clear that the blank is "rectangular" in the strict sense that the appellants intend. Furthermore, the feature added to the characterising clause of the claim that the line of weakness "is formed along a line between and parallel with a top line and a foot line of said fin" is also clearly disclosed in document E1, so that it is difficult to see how this feature could have any bearing on the evaluation of inventive step.

The Board therefore comes to the conclusion that the auxiliary request of the appellants is inadmissible and accordingly rejects it.

6. Costs

According to Article 104(1) EPC each party to the proceedings shall normally pay its own costs. A different apportionment of costs incurred during taking of evidence or in oral proceedings may be ordered for reasons of equity.

In the present case the respondents have based their request for costs on the fact that the appellants introduced for the first time at the appeal stage the aspect of the alleged "seal reducing" rather than "seal preventing" nature of the seal inhibiting composition. That aspect made up however only a minor part of their written statement of grounds and addressing that question at the oral proceedings did not involve the respondents in any extra costs.

The Board can therefore see nothing in the circumstances of the present case which could justify an award of costs.