T 0290/88 04-12-1990

1. The appeal complies with Articles 106 to 108 and Rules 1(1) and 64 EPC; it is, therefore, admissible.

2. Formal allowability of the amendments

2.1. Current Claim 1 comprises the features of the independent method Claim 5 as granted and its dependent Claim 7. All of the features of the preamble of Claim 1 as granted, which by virtue of the reference in Claim 5 to Claim 1 were implicitly present in Claim 5, have also been taken up into the preamble of current Claim 1. With respect to the features of the characterising clause of Claim 1 as granted these appear in clarified or limited form as characterising features of current Claim 1. Thus, the definition of the material of the thermoplastic layer which forms the inside surface of the packages in terms of the difference in its melting temperature to that of polypropylene has been replaced by the statement that this material is polyethylene. The reference to the melting temperature difference, therefore, became redundant, the melting temperatures of polyethylene and polypropylene being well established, and has been deleted. Further, the range of "thicknesses" (more accurately the weight per unit area) for the polypropylene layer has been limited to 5 to 10 g/m2, the minimum value of 5 g/m2 corresponding to that stated in granted Claim 1 and the maximum value of 10 g/m2 corresponding to the preferred value stated in the original description. (It is accepted by both parties that these values correspond to a true thickness of 5.5 to 11.1 µm).

Dependent Claims 2 and 3 derive from Claims 3 and 4, respectively 8 as granted.

There is, therefore, no objection to the current claims under Article 123(3) EPC.

2.2. In the opinion of the Board that part of the original disclosure describing in detail, with respect to the embodiment of Figure 2, the prevailing conditions under which the polypropylene layer is extruded on to the polyethylene layer would be interpreted by the skilled man as also applying to the essentially equivalent embodiment of Figure 5. That these features are, therefore, also present in the embodiment of Figure 5 is implicit and accordingly current Claim 1, which contains a combination of these features with other features that are only applicable to the embodiment of Figure 5, does not offend against Article 123(2) EPC as alleged by the Appellants. Moreover, this combination of features is explicitly claimed in original Claim 8 when referred back to original Claim 6 (after replacement of the stated value of 140°C by the value of 150°C mentioned on page 6, paragraph 1 of the original description in the same context).

2.3. The amendments made to the description in comparison with that originally filed consist essentially in an evaluation of the most relevant state of the art and an adaptation to the terms of the new claims.

2.4. In conclusion, the Board finds no formal objections to the documents forming the basis of the Respondents' request.

3. Sufficiency of disclosure

3.1. The first line of the Appellants' attack under this heading relates to the cooling roller which contacts the polyethylene layer shortly after it is extruded, possibly acting as a source of contamination. In the opinion of the Board the skilled man would, if as the result of routine quality control tests it was established that the necessary degree of sterility was not being obtained, quickly identify the cooling roller as the only possible source of the contamination and could, on the basis of his common general knowledge and without the application of any inventive skill, take appropriate measures, such as shielding the roller, to eliminate this source. It belongs to the well established jurisprudence of the Boards of Appeal that the common general knowledge of the skilled man reading the specification of the contested patent has to be taken into account when determining the question of sufficiency of disclosure.

3.2. With regard to the question as to whether the method described and claimed in the contested patent leads to a packing material with the necessary sterile qualities, or whether the extreme thinness of the polypropylene coating would prevent this functioning properly, the Board is faced with contrary assertions from the parties the divergences between which the Board is unable to resolve on the strength of its own specialised knowledge. It is true that under Article 114(1) EPC the European Patent Office, in proceedings before it, examines the facts of its own motion and is not restricted in this examination to the facts, evidence and arguments provided by the parties and the relief sought. But if the European Patent Office is unable to establish the facts of its own motion, it is the party whose argument rests on these alleged facts who loses thereby. (See Decision T 219/83, OJ EPO 1986, 211, point 12).

In the present situation the Board is of the opinion that it would not have been beyond the means or competence of the Appellants to have obtained samples of what is after all a product that has been sold in large quantities and have tested it to provide substantiation for their assertions. In the absence of such evidence, the Appellants' assertions can only be treated as an unproven assertion that cannot lead to a finding that the claimed invention has not been disclosed in a manner sufficiently clear and concise for it to be carried out by a person skilled in the art.

3.3. The situation with regard to the question of the temperature reached by the contact zone of the polyethylene layer as the polypropylene layer is extruded onto it is similar but somewhat different insofar as the Board itself has doubts as to whether the contact zone of the polyethylene layer could in fact be brought to a temperature of at least 150°C for a time sufficient for this to have any significant sterilizing effect as is suggested by the description of the patent specification. Current Claim 1, however, merely requires that at some point, for an unspecified length of time, the contact zone reaches 150°C and makes no mention of any sterilizing effect. The number of imponderables surrounding the estimation of the temperature actually reached by the contact zone are so numerous that the Board cannot with any conviction say that the requirement of Claim 1 in this respect cannot be met. Accordingly, this line of attack on the sufficiency of disclosure also fails.

3.4. The Board, therefore, comes to the conclusion that also the ground of opposition under Article 100(b) EPC is no bar to the maintenance of the patent in the amended form as requested.

4. State of the art The closest state of the art is that shown in document (D1) which relates to a sterile packing material of the form-fill-seal type, methods and apparatus for producing this material and apparatus for forming the material into packages. According to this prior art, the sterility of the layer of the packing material that is to form the inside surface of the package is preserved by a coating that is peeled off shortly before the material is formed into a package, filled and sealed. It is suggested to use thermoplastic materials for both the sterile layer and the coating but no specific materials are mentioned. The sterility of the thermoplastic layer may be achieved by extruding it or by a separate heat treatment step.

Documents (D4), (D5), (D6), (D7), (D9), (D10) and (D13) all relate to the "Neutral Aseptic System" of packaging developed by the Appellants. This system utilises a packing material comprised essentially of a polypropylene base layer and a peelable polyethylene cover layer, the contacting surfaces of the two layers being sterile. After separation of the layers the polypropylene base layer is deep drawn to form beaker-like containers, which after filling with the product are covered and closed by the polyethylene layer. The sterile packaging system of document (D2) is similar in some respects but in this case the cover layer is of metal foil and is not bonded to the base layer.

Document (D3) of the Respondents relates to a conventional form-fill-seal packing material of which the layer forming the inside surface of the packages is comprised of polyethylene or polypropylene, but without a thermoplastic protective layer. Document (D14) relates to a method of sterilizing such a form-fill-seal packing material and forming it into packages.

Documents (D8), (D11), (D12), (D15), (D16), (D18) and (D19) have all been cited to show what thicknesses of polyethylene or polypropylene coatings or films were conventional in the packaging art or known generally, whereas document (D17) is concerned with general considerations involved when extrusion coating with thin polyolefin films.

Document (D20) is not prepublished and need not, therefore, be considered further.

5. Novelty The method according to Claim 1 is distinguished from the closest state of the art according to document (D1), on which the preamble of the claim is based, by the features of its characterising clause. Since the novelty of the subject-matter of Claim 1 is no longer in dispute, further explanations in this respect can be dispensed with.

6. Inventive step

6.1. The characterising features of Claim 1 can be divided into two groups, those concerned with the choice of materials for the thermoplastic layer that forms the inside surface of the packages and for the thin thermoplastic coating, as well as the thickness of this coating, and those relating to the way in which the thermoplastic layer and the thermoplastic coating are formed and brought together.

All of these features contribute to the solution of the technical problem involved, which is to develop a method for producing a cost-effective sterile form-fill-seal packing material that is reliably protected from recontamination until it is used to form packages, and from which the protective coating layer can be readily removed.

6.2. The Board holds the view, in essential agreement with the arguments developed by the Appellants on this point, that the features of the first group identified above do not in themselves make a sufficient contribution to the state of the art to justify an inventive step.

In particular, the skilled man wishing to put into effect the teachings of document (D1), which does not mention suitable thermoplastic materials for the layers involved, will have to look for a suitable material pairing to give the desired results. He could not have failed to have been aware of the widely publicised "Neutral Aseptic System" of the Appellants as exemplified in, for example, documents (D4) and (D13). In the latter document it is stated that polyethylene/polypropylene material pairing has been chosen since these two materials adhere poorly to each other.

It is well known that form-fill-seal packing material is generally provided with a polyethylene layer on that surface that will form the inside of the package, see for example document (D3). When considering ways of providing a sterile material of this type, in accordance with the teachings of document (D1) it would, therefore, be obvious, having regard to the clear indication in document (D13), to choose polypropylene for the thin coating layer.

Concerning the issue of the obviousness of choosing a coating having a thickness as claimed, it is to be noted that in the packing material made according to Claim 1, the polypropylene coating is essentially a waste product so that the skilled man will endeavour to keep this as thin as is practically possible having regard to the fact that it must be strong enough to allow it to be peeled from the polyethylene layer. He also knows from document (D17) that the adhesion of an extrusion coated polyolefin layer decreases as this layer becomes thinner, which in view of the requirement for good peelability gives him another incentive to reduce the thickness of the polypropylene coating. It is also true that the top end of the range of thicknesses given in Claim 1, i.e. approximately 11 µm, is not so significantly different from the minimum thickness values for polypropylene films known in the art (document (D15) for example suggests a minimum of approximately 13 µm) that the skilled man could not have arrived at a thickness within the range claimed by virtue of routine experimentation. On the other hand, there is some merit in the Respondents' argument that a skilled person would be discouraged from choosing such a thin layer in a case where it has to be peeled from the laminate without leaving any debris whatsoever on the remaining inside forming layer. The doubts expressed by the Appellants concerning sufficient disclosure in respect of peelability in one piece also appear to point in this direction (see point VII, last paragraph above). The Board, however, takes the view that these considerations are not sufficient to justify the existence of an inventive step in themselves.

6.3. With regard to the second group of characterising features, the only state of the art that is of any relevance is document (D1).

This document specifically exemplifies three main alternatives for producing a laminated sterile packing material. In the first, the layers of the laminate are preformed webs which are heat sterilized in a sterilization chamber and then laminated together by pressure welding. In the second, the first layer is a preformed web which is heat sterilized in a sterilization chamber and then roller coated with the second layer. In the third, the two layers are co-extruded. In this latter embodiment no sterilization chamber as such is required since the layers leave the extruder in a sterile condition. It is also suggested in general and somewhat obscure terms that at least one of the two layers may be extruded and deposited on the other layer at a temperature close to that of extrusion (page 7, last paragraph of D1).

The Board cannot see in this suggestion a clear teaching to the skilled man to extrude sequentially the first (polyethylene) layer and then to deposit by extrusion on this layer the peelable (polypropylene) coating, the contact zone of the polyethylene layer being protected by a sterile gas between the two extrusion operations by means of a hood, as is required by current Claim 1. Instead, it seems much more likely, since this suggestion is made immediately after the description of the second main alternative mentioned above, that the skilled man would simply understand it as referring to the possibility of replacing the roller coating operation by extrusion coating, i.e. the base layer would still be preformed and require separate sterilization.

Document (D1) in fact teaches clearly how this separate sterilization step can be eliminated by extruding both layers, but solely in the context of co-extrusion, which, since this did not require the maintenance of a sterile environment between separate extrusion operations, would appear, at least in this respect, advantageous over the method actually proposed in the contested patent. The skilled man would, therefore, have no incentive to depart from the specific teachings of document (D1) in this regard.

Furthermore, it would appear that it is the use of sequential extrusion as specified in Claim 1, in combination with the particular materials chosen, that results in the good peelability of the protective coating despite its extreme thinness.

6.4. The Board, therefore, comes to the conclusion that the subject-matter of current Claim 1 cannot be derived in an obvious manner from the state of the art and must accordingly be seen as involving an inventive step, Articles 52(1) and 56 EPC.

This claim, together with its dependent Claims 2 and 3 and the revised description, can, therefore, form the basis for maintaining the patent in amended form.