T 1186/05 06-12-2007

1. The appeal is admissible.

2. Submissions not filed in due time.

2.1 The Appellant with its Statement setting out the Grounds of Appeal filed the further documents D11 - D14 and E9 - E12 and the Respondent with letter dated 21 April 2006 filed declaration B with further experimental results.

2.2 In the Board's judgement the filing of these new pieces of evidence by the respective parties cannot be considered as a tactical abuse of the proceedings. The submissions were made at the due stage of the appeal proceedings with regard to Art. 10a (RPBA) (1) a) and b) and the other party had enough time to take them into consideration.

2.3 The documents and exhibits filed by the Appellant aim mainly to support its previous arguments and to establish the skilled person's general common knowledge. The experimental report filed by the Respondent was filed in response to the objections raised by the Appellant in the Grounds of Appeal concerning the significance of the experimental examples in the patent, and to demonstrate that the problem had been solved over the whole area claimed.

2.4 Accordingly in application of Art. 10(4) RPBA the Board decides to admit these submissions into the proceedings.

MAIN REQUEST

3. Novelty (Article 54 (3) EPC).

3.1 Claim 1 of the patent in suit is essentially directed to a multilayer film capable of withstanding heat sterilization at 121ºC comprising:

(a) an interior layer comprising a homogeneous ethylene/alpha-olefin copolymer having a density from 0.89 to 0.92 grams per cubic centimetre or a blend of two or more homogeneous ethylene/alpha-olefin copolymers having a density from 0.89 to 0.92 grams per cubic centimetre;

(b) a first exterior layer as defined in the claim; and

(c) a second exterior layer, also as defined in the claim.

3.2 The novelty of Claim 1 of the main request has been contested by the Appellant having regard to the disclosure of D1. D1 was filed on 16 November 1994 and published on 26 May 1995, after the priority date of the present patent. D1 entered the European regional phase as European application 95902620.4 and it is therefore to be considered as state of the art in accordance with Article 54(3) EPC.

3.3 D1 discloses multiple layer polymer films which may be fabricated into medical grade articles such as containers or bags for storing medical solutions (see page 5, lines 6 - 11). D1 describes films comprising a skin layer, a radio frequency susceptible layer and a core layer interposed between said layers, the core layer including an ultra low density polyethylene (see Claims 8 to 11).

The films having the reference numbers "Figure 2", "Figure 4" and "Figure 6 to Figure 9" (see pages 19 - 23) include as one of the components of the core layer 40% of "Mitsui TafmerTM ULDPE". These films anticipate the subject-matter of Claim 1 of the main request, which is therefore not novel.

3.4 It is not disputed that the skin layer and the radio frequency susceptible layer of the films according to these Figures of D1 correspond to the exterior layers of features (b) and (c) of the claimed films. These exterior layers are therefore not a distinguishing feature over the disclosure of D1.

3.5 In order to justify the novelty of the subject-matter of Claim 1, the Respondent argued essentially that TafmerTM A - 4085 was not explicitly mentioned in the Figures of D1 and that another TafmerTM product could have been used, these other products having densities varying from 0.865 to 0.885 g/cm**(3) (see E9 under "1. Samples"). In any case TafmerTM A-4085 was mentioned in D1 not in relation to the core layer but in relation to the radio frequency susceptible layer, and its density value, 0.885 grams per cubic centimetre, was outside the claimed range of 0.89 to 0.92 grams per cubic centimetre.

3.6 The Board notes, however, that even if in Figures 2, 4, and 6 to 9 of D1 the low density polyethylene used in the core layer is referred to unspecifically as "Mitsui TafmerTM ULDPE", it is evident for the skilled person from reading D1 that this "Mitsui TafmerTM ULDPE" can only be TafmerTM A - 4085.

3.6.1 The core layer in D1 consists of three components, the second component being an ultra low density polyethylene ("ULDPE") (see page 6, lines 24 - 32). Suitable types of ULDPE are discussed in more detail on pages 9 and 10 in relation to the radio frequency susceptible layer. They are said to include ultra low density polyethylenes commercially available and sold under the trademark TafmerTM (Mitsui Petrochemical Co.) with the product designation A - 4085 (page 9, lines 23 - 25, the reference to "485" being a typing mistake) which is then mentioned as one of the preferred components (page 10, lines 29 - 30, now without the typing mistake).

3.6.2 The film of Figure 2 is described in detail on page 12, line 33 to page 13, line 20. The second component of the layer is said to be chosen to confer flexibility on the core layer and preferably is ULDPE or polybutene-1 (page 13, lines 8 - 13 and page 19, Figure 2 film). It is clear for the skilled person that the Mitsui TafmerTM ULDPE mentioned in Figure 2 as an ingredient of the core layer and of the RF layer can only be the TafmerTM A - 4085 because it is the only TafmerTM polymer specifically disclosed in D1.

3.6.3 TafmerTM A - 4085 has a density of 0.885 grams per cubic centimetre which, when rounded off according to standard mathematical rules, results in a value of 0.89 grams per cubic centimetre, that is to say within the range covered by Claim 1 of the patent in suit.

3.6.4 The Board cannot accept the argument of the Respondent that the value 0.885 could also be rounded down to 0.88 and thus outside the claimed range. The mathematical conventions for rounding values wherein the last digit is 5 (or more) require that the value be increased, or rounded up, resulting in a value of 0.89 in the present case.

3.6.5 For the definition of the density range the Respondent has chosen to use only two decimal places. This implies that a comparison with the prior art identifying three decimal places can only be made if the prior art values are also reduced to two decimals, that is to say rounded. The skilled person reading D1 would thus be obliged to round the disclosed value up to 0.89 for comparison (see decision T 0708/05 of 14 February 2007, not published in OJ EPO, under point 3 of the Reasons).

It is noted also that polyolefin densities are usually indicated with the accuracy of three decimal places, with the consequence that where only two decimal places are indicated, as in present Claim 1, this implies that rounding has already occurred. It is of interest in this context that the respective densities disclosed in the original application (and maintained in the granted specification) are preceded by the qualification "about".

3.6.6 The above finding is not in contradiction with decision T 74/98 cited by the Respondent. In that case the Board considered that rounding up to the next integer (thus matching the lower limit of the claimed "inventive" range) of a component's molar percentage having two decimal places, calculated by conversion from its weight proportion, was not justified because (i) this would lead to a broadening of the claimed range and (ii) by reconversion of the rounded molar percentage to the corresponding weight proportion, would also imply a modification of the latter, ie would alter the true meaning of this specific disclosure. The factual situation of that case is quite different from the present one in that according to T 74/98 a real gap existed between the calculated molar percentage and the claimed lower limit while according to the present case rounding up is required to enable comparing two density values, each one reflecting a "true" density value having three (or more) decimal places, but expressed to a different degree of accuracy, ie one having three the other one having only two decimal places. Thus, the rounding exercise does not bridge a real gap but puts the claimed and the prior art density values on the same level by using the mathematical rule existing for that purpose. This exercise has no impact on the density value as disclosed in the prior art document.

3.7 For these reasons the subject-matter of Claim 1 according to the main request lacks novelty having regard to the disclosure of document D1.

AUXILIARY REQUEST 1

4. Novelty (Article 54 EPC).

4.1 The subject-matter of Claim 1 of auxiliary request 1 has been limited to density values of 0.90 to 0.92 g/cm**(3). The films of D1 discussed above using polyethylene having a density of 0.885 g/cm**(3) no longer fall inside the claimed range. The subject-matter of Claim 1 is therefore clearly novel.

As the novelty of this subject-matter was also acknowledged by the Appellant no further comments are needed.

5. Inventive step (Article 56 EPC).

5.1 Closest prior art.

5.1.1 The patent in suit relates to multilayer films which are suitable for the packaging and administration of medical solutions in the form of flexible pouches.

According to the introductory section of the specification, these pouches must meet a number of performance criteria, including collapsibility, optical clarity and transparency, high-temperature heat-resistance, and sufficient mechanical strength. These medical pouches must be able to endure heat sterilization without deterioration (see [0001] - [0004]). Heat sterilization of medical pouches is carried out typically in an autoclave at about 121ºC for periods of 15 to 30 minutes (see [0005]). Pouches made from highly plasticized polyvinyl chloride are known but they show some drawbacks (see [0007] - [0008]) and alternatives to these PVC pouches are sought.

5.1.2 From the documents cited by the Appellant only documents D2 and D11 disclose films suitable for medical solution pouches. These documents disclose PVC-free medical pouches made from multilayer films including in their interior layer a heterogeneous ethylene/alpha-olefin copolymer (see D2 Claims 1 and 5, and also examples 5 and 6) and D11 (Claims 1 and 12, and also example 8).

The disclosure of these documents represents the closest prior art.

5.2 The objective problem to be solved and its solution.

5.2.1 A drawback of the pouches of D2 and/or D11 is that during heat sterilization the steam which is used to heat the pouches penetrates into the film from which the pouch has been formed. When the sterilization process is completed and the pouch is allowed to cool, some of the steam in the film condenses and remains trapped inside the film, giving the pouch a hazy, cloudy appearance which can make it difficult to inspect the medical solution contained in the pouch.

5.2.2 The technical problem to be solved by the patent in relation to said prior art can thus be formulated as the provision of a multilayer film for the manufacture of medical solution pouches having improved optical properties after the pouch has been heat-sterilized.

5.2.3 This problem is solved by the films according to Claim 1 having an interior layer of the film comprising a homogeneous ethylene/alpha-olefin copolymer having a density from 0.90 to 0.92 grams per cubic centimetre or a blend of two or more homogeneous ethylene/alpha-olefin copolymers.

5.2.4 The results in the specification of the patent and the further experimental evidence supplied by the Respondent (Declaration B) demonstrate that by replacing the heterogeneous ethylene/alpha-olefin copolymers used in D2 and/or D11 by homogeneous ethylene/alpha-olefin copolymers improved optical properties after heat sterilization are achieved.

Thus, examples 1 to 3 in the patent show that pouches made from the claimed films have better optical properties (haze, clarity and gloss) than the comparative film of example 4 (which corresponds to the film of example 8 of D11) having a heterogeneous ethylene/alpha-olefin copolymer.

Declaration B filed by the Respondent during the appeal proceedings further demonstrates the superior optical properties after heat-sterilization of the films having an interior core layer formed from a homogeneous ethylene/alpha-olefin copolymer.

A comparison of the pre- and post-sterilization optical properties of films comprising homogeneous or heterogeneous ethylene/alpha-olefin copolymers shows that, while the pre-sterilization optical properties are similar for both the inventive and the comparative films, the films of the invention exhibited improved post-sterilization optical properties. The optical properties of the comparative films, particularly haze and gloss, degraded much more than those of the claimed films so that all post-sterilization optical properties of the inventive films are superior to those of the comparative films (see Declaration B, Tables 1, 2 and 3).

5.2.5 The Appellant did not dispute such improvement but doubted that the experimental evidence provided by the Respondent was sufficient to show that said problem was credibly solved across the whole scope of the claims. In particular, it criticized the fact that there was no mention of the amount of homogenous ethylene/alpha-olefin copolymer used in the claims and that it was doubtful that the presence of very low amounts of the homogeneous ethylene/alpha-olefin copolymer would result in improved post-sterilization optical properties.

5.2.6 The Board cannot agree with this argument of the Appellant. The results in the declaration B of the Respondent show that the improvement in post-sterilization optical properties is also achieved when lowering the proportion of the homogeneous ethylene/alpha-olefin copolymer in the core layer. The films of Tables 4, 5 and 6 using 15%, 25%, 50%, 75% and 100% of homogeneous ethylene/alpha-olefin copolymer in the core layer exhibit in all cases improved post-sterilization optical properties when compared with a film having only heterogeneous ethylene/alpha-olefin copolymer in the core layer. These results show an improvement in post-sterilization optical properties with increasing homogeneous ethylene/alpha-olefin content in the core layer.

The Appellant (who has the burden of proof) has not adduced any experimental evidence showing that an embodiment covered by the claims did not show the required improved post-sterilization optical properties. Insofar as very small amounts of homogeneous ethylene/alpha-olefin copolymers are within the claimed subject-matter, it is noted that the present invention is based on the use of homogeneous ethylene/alpha-olefin copolymers as replacement of the known heterogeneous ethylene/alpha-olefin copolymers and it is clear for the skilled person that a certain amount should be used in order to obtain the desired effect. This amount can be determined by the skilled person on the basis of the information in the specification.

5.3 Obviousness.

5.3.1 It remains to be decided whether, in view of the available prior art documents, it would have been obvious for the skilled person to solve this technical problem by the means claimed, namely by using a homogeneous ethylene/alpha-olefin copolymer.

5.3.2 There is no hint to this solution in the above mentioned prior art documents D2 or D11 as they do not mention the possible use of homogeneous ethylene/alpha-olefin copolymers.

5.3.3 There is also no suggestion of this solution in the other documents cited by the Appellant. These documents are mainly directed to the use of homogeneous ethylene/alpha-olefin copolymers in lieu of heterogeneous ethylene/alpha-olefin copolymers in a variety of films. Films incorporating said homogeneous copolymers are said to generally exhibit improved physical and optical properties as compared to films of heterogeneous copolymers (see, for instance, D7, page 4, lines 4 - 5). However, none of these documents mentions post-sterilization optical properties at all and for these reasons cannot give a hint to its use in the now claimed films.

In particular D7, on which the Appellant mainly relied, is directed to heat-shrinkable, thermoplastic films (see title). The films of D7 have been oriented by stretching at elevated temperature followed by quickly quenching to retain the films stretched dimensions (see page 5, lines 8 - 16) and are therefore not capable of withstanding heat sterilization, since they would return to their original unstretched dimensions when heated. The skilled person does not find any hint in this document suggesting the use of homogeneous ethylene/alpha-olefin copolymers in order to improve the post-heat sterilization optical properties of medical solution pouches.

5.3.4 The Appellant argued further that it would have been obvious for the skilled person to try the homogeneous ethylene/alpha-olefin copolymers in order to improve the optical properties of the films per se (before sterilization). The fact that by this measure the post-sterilization properties of the films were also improved would merely be a bonus effect which could not justify an inventive step.

Apart from the fact that the Board cannot see any objective reason to ignore the very problem of the claimed subject-matter already set out in the application as filed, it furthermore accepts the Respondent's argument advanced during the oral proceedings, namely that the lower melting point range of about 60 - 110ºC, i.e. below the steam-sterilization temperature, of the homogeneous ethylene/alpha-olefin copolymers would certainly not encourage the skilled person to use such copolymers for the intended purpose. The assertion of the Appellant that it would anyway have been obvious to try out these new copolymers can only be made with the knowledge of the invention.

5.3.5 Insofar as the Appellant relied on D7 as closest prior art, the Board notes that this document is not an appropriate starting point for the assessment of inventive step as it does not relate to medical solution pouches and as the films therein disclosed are not suitable for resisting steam-sterilization (see above 5.3.3).

5.3.6 Hence, the Board considers that, in the light of the cited prior art, it would not have been obvious to a person skilled in the art to replace the heterogeneous ethylene/alpha-olefin copolymer used in D2 or D11 by the homogeneous ethylene/alpha-olefin copolymers now used in order to solve the above-mentioned problem. The subject-matter of Claim 1 of the auxiliary request 1 thus involves an inventive step within the meaning of Article 56 EPC.

5.3.7 Dependent Claims 2 to 7 and Claim 8, which relates to pouches comprising the films of said claims, also satisfy the requirements of Article 56 EPC.

6. As the claims of the auxiliary request 1 of the Respondent fulfil the requirements of the EPC, there is no need for the Board to deal with the auxiliary requests 2 to 6.