T 0445/15 01-03-2018

Reasons for the Decision

1. Admittance of documents filed during the appeal proceedings

The Board is satisfied that the documents D13-D17 were cited by the appellant in the statement setting out the grounds of appeal in order to address the findings of the decision with respect to sufficiency of disclosure (D13 and D14 relating to missing information in relation to the nuclear magnetic resonance method used to determine the overall isotacticity index) and novelty (D15 to D17 to support the applicability of the model of D2).

Documents D18-D20 of the respondents were likewise filed with the reply to the statement of grounds of appeal in direct response to the submissions made by the appellant (in particular with regard to the issues in D13 and D14).

These documents have been timely filed at the beginning of the appeal proceedings and can be seen as an appropriate reaction to the decision or the submissions of the opposing party. Moreover, it has not been rendered credible that any of these documents should have been filed at an earlier stage of the proceedings or that their filing represented an abuse of procedure.

Consequently the Board can identify no reason to make use of its power under Article 12(4) RPBA.

Documents D13-D20 are therefore in the proceedings.

As to D21, it was filed by the respondents to address technical question raised by the Board in its communication with regard to the teaching of D1 vs the teaching of the opposed patent.

In view of this, the Board finds it appropriate to make use of its discretion under Article 13(1) RPBA by admitting D21 to the proceedings.

2. Main request - admissibility - reformatio in peius

Claim 1 of the first auxiliary request before the opposition division, on the basis of which it was held that the patent could be maintained, defined the ethylene content as:

"greater than 0.3 to 0.8 wt%".

This wording therefore excluded the lower limit of 0.3 wt%, notwithstanding that the extent of the range, in particular the upper limit, was ambiguous due to the placement of the expression "greater than" before the definition of a range.

In this respect regarding the full extent of the range, the claim could have been understood as intending to define a range of greater than 0.3 and up to 0.8 wt%, as has indeed now been done in the auxiliary requests. Alternatively the claim could have been interpreted as denoting a range of values above 0.3 wt% and extending to above 0.8 wt%, or possibly even a range of values entirely above 0.8 wt%.

With the rejoinder to the statement of grounds of appeal an amended claim was submitted as claim 1 of the main request wherein the term "greater than" had been deleted, thus defining the range as "0.3 to 0.8 wt%" and hence including the amount of 0.3 wt% in the range.

The effect of the modification made is that, in contrast to the set of claims as upheld by the opposition division which excluded the lower limit of 0.3 wt%, this value is now encompassed by the claims, meaning that the scope of protection has been extended.

Since the patent proprietors are the respondents, and did not themselves file an appeal, they are primarily restricted in appeal proceedings to defending the patent within the extent in which it was maintained in the first instance proceedings (G 9/92, Reasons 16 with reference to Reasons 7 and 12 of the decision).

The main request therefore contravenes the principle of no reformatio in peius. In line with the findings of G 9/92 the presented amendments are not appropriate. For this reason the main request is not admissible.

In this respect, the Board cannot follow the additional argument of the respondents that the amendment results in the correction of an obvious error. Indeed, due to the ambiguity in the expression in claim 1 of the first auxiliary request before the opposition division, even if it is accepted that an error was present, the necessary correction was not unambiguous, so that it cannot be held that the claim would have necessarily been read by the skilled person in the manner as proposed by the respondents, resulting in the wording of the present main request. Indeed it appears that the only interpretation which could with any certainty not be discounted was that the limit of 0.3 was (intended to be) excluded from the claim - which is no longer the case in claim 1 of the main request.

3. Auxiliary request 1

3.1 Admittance

Claim 1 of this request defines the range of ethylene content as "greater than 0.3 wt% and up to 0.8 wt%", thus addressing the defect which resulted in the main request being rejected as inadmissible.

The appellant explicitly stated it had no objections to the admittance of this request to the proceedings.

On this basis the Board finds it appropriate to exercise its discretion under Article 13(1) RPBA by admitting auxiliary request 1 to the proceedings.

3.2 Novelty

D1 relates to polypropylene compositions consisting of a propylene homopolymer and a propylene/ethylene copolymer (claims 1 and 3).

According to examples 1 and 5 the compositions have 0.6 mol% of ethylene (page 10, Table 1), which corresponds to 0.4 wt%, i.e. within the range as defined in operative claim 1. The polymers of D1 are prepared using a Ziegler-Natta catalyst having a Ti solid catalyst component and an organic aluminium compound (D1, page 8, lines 27-29). Consequently, to the extent that the product-by-process feature of operative claim 1 can be regarded as characterising the subject-matter claimed, it does not provide a distinction over the disclosure of D1.

D1 does not disclose the overall isotacticity index.

In order to bridge this gap in the disclosure of D1, the appellant referred in particular to D2 which reports a method of modelling polymerisation systems consisting of a Ziegler-Natta system with external alkoxysilane donors and presented calculations based on this model.

The work of D2 is based on supported, i.e. two site, catalyst systems.

D1 does not disclose that the catalyst system thereof employs a support. Furthermore alkoxysilane donors are not present.

Thus D1 and D2 relate to different types of catalyst systems.

It is therefore not credible, and has not been shown, that the mechanism underlying the polymerisation studied in D2 would apply to the polymerisation in D1, meaning that it is cannot be assumed that the model developed in D2, and calculations based thereon would predict, even approximately, the outcome of the polymerisation of D1, let alone with the degree of precision and certainty required to establish whether there is a lack of novelty.

Due to these uncertainties the case of lack of novelty based on the application of the model of D2 to the polymerisation of D1 is not proven.

The appellant has also relied on the argument that the polymerisation processes in D1 and the patent in suit were largely identical, making it inevitable that the products would be indistinguishable.

However no evidence to support this position has been submitted. Rather this objection relies on supposition and speculation.

In view of the doubts regarding the applicability of the calculations presented to demonstrate the properties of the polymers of D1 and the absence of any evidence of the properties of the polymers of D1 in terms of the overall isotacticity index, the Board can come to no other conclusion than that the objection of lack of novelty in the light of the disclosure of examples 1 and 5 of D1 has not been proved.

The requirements of Article 54 EPC are therefore satisfied.

3.3 Inventive step.

3.3.1 The patent in suit, the technical problem

The patent is directed to propylene polymer compositions in particular suitable for producing biaxially oriented films (BOPP) (paragraph [0002]).

In paragraph [0004] it is explained that in order to meet the requirements for film production the polymer must exhibit good tensile strength and excellent high temperature stretching property. It is explained that, generally, lower isotacticity index and melting point are beneficial for film processing and forming, but that this results in reduced mechanical properties such as tensile strength and stiffness (patent, paragraph [0004], lines 21-25).

Thus, as set out in paragraph [0006] of the patent the problem addressed was to provide propylene polymer compositions for producing BOPP which can provide a better balance of high temperature stretching properties and physical properties of the film.

3.3.2 Closest prior art

Both D1 and D3 have been proposed as forming the closest prior art.

D1 is directed to modified polypropylene, a process for producing it and articles prepared therefrom (page 2, lines 3-6). According to page 2, lines 35-38, advantageous properties of highly isotactic homopolypropylene are high tensile strength, hardness and melting point, whilst balanced against these are undesirable properties such as brittleness, low impact strength and difficult processability in particular with respect to film applications regarding biaxial stretching of the polymer. D1 is directed to addressing this problem by modifying the highly isotactic polypropylene (page 2, lines 45-52, in particular 47-49) to "plan" the composition, molecular weight distribution and crystallinity. The aspects of orienting the polymer and producing a film are discussed at page 3, lines 17 and 22 and it is further stated that the modified polypropylene is especially suited for oriented film applications (page 4, lines 48, 49).

The respondents, after initially (in the written submissions) considering D1 as representing the closest prior art changed their position during the oral proceedings before the Board, and disputed that D1 and the patent addressed the same problem since the relative starting points were different. Whereas D1 was based on improving the properties of homopolypropylene, the patent in suit started from, in effect, the polymers developed according to D1. The respondents furthersubmitted that the problem to be solved with respect to D1 was to provide BOPP which had a better balance of softness and stiffness. However this is precisely the same problem as set out in D1, as follows from the statements of problem at page 2, lines 35-38 and 45-52.

Accordingly both D1 and the patent in suit address the same problem, notwithstanding that they start from different stages of development of propylene based polymers. To follow the view of the respondents regarding the relevance of D1 or the suitability thereof as closest prior art would lead to the unreasonable conclusion that any prior art document would have to be disqualified as the closest prior art if, as is normally the case, it related to an earlier stage of development of the technology in question.

D3 is directed to BOPP films based on polypropylene polymer or polymer composition (claim 1; page 1, lines 1 and 2). According to page 1, lines 14-28 the invention of D3 consisted of BOPP wherein at least one layer comprises a propylene polymer containing at least 0.8 wt% of ethylene.

Thus both D1 and D3 are directed to, if not precisely the same problem, then to a problem that is closely related to that of the patent in suit, and consequently either of these documents can be considered representative of the closest prior art.

As the Board comes to the conclusion that there is lack of inventive step starting from D1 as the closest prior art, an analysis starting from D3 is superfluous.

3.3.3 Distinguishing feature

As established above with respect to novelty, the subject-matter of operative claim 1 is distinguished from the disclosure of D1 by the specified overall isotacticity index.

3.3.4 Technical effect

The examples of the patent are divided into two parts.

In those examples relating to production of a polymer a dual loop reactor system is employed as explained in example 1.

In Table 1 two comparative examples are presented whereby comparative example 1 relates to a propylene homopolymer. Comparative example 2 employs the same catalyst system as in inventive example 3 and differs from the inventive examples 1-4 in that the component of the first stage is prepared in the presence of a 20-fold higher amount of hydrogen, resulting in a polymer with lower molecular weight (shown by the higher MFR) than that of examples 1-4. The isotacticity index is 95.5, i.e. below the minimum of the claim, whereas the ethylene content is 0.43 wt%, within the range of the claim and identical to that of inventive example 1.

The MFR of the final polymer of comparative example 2 is approximately the same as that of the inventive examples 1-4, which, as a consequence of the difference in the polymer of the first stage, confirms that also the properties of the second stage polymer of this composition are necessarily significantly different to the corresponding component of the inventive examples. Due to the difference in the constitution of the two component polymers, in particular in terms of molecular weight, comparative example 2 is not suitable to demonstrate whether any effect arises solely as a result of the isotacticity index. Nor are the examples of Table 1 suitable to demonstrate whether any effect is associated with the ethylene content.

This conclusion is not changed when taking into account the additional data provided on pages 20 and 21 of the rejoinder to the statement of grounds of appeal. These data are based on the same compositions as given in Table 1 of the patent, but report further properties.

The second set of data of the patent in suit set out in Table 2 relates to commercial products. Although certain properties are given (ethylene content, Toverall) it is not explained how, in other respects, these are similar to or differ from the inventive examples 1-4. Hence these examples cannot contribute to establishing the objective technical problem to be solved with respect to D1.

In the light of the evidence of Table 1, in association with the additional data provided in the rejoinder to the statement of grounds of appeal the objective technical problem with respect to D1 has to be formulated as the provision of further compositions for BOPP films, exhibiting a good balance of properties, in particular stiffness and flexibility.

3.3.5 Obviousness

With respect to the tacticity of the polymer and influence thereon of the underlying polymer structure, in respect of monomer placement in D1 it is stated in the passage bridging pages 3 and 4 that the chain disrupters are added to a highly isotactic polymer so as to be incorporated exclusively in the high end of the molecular weight distribution.

This is precisely the approach foreseen in the patent as set out in paragraph [0007] where it is stated that the isotacticity of the polymer having relatively lower molecular weight is increased to keep the overall isotacticity at the same level. The only way to achieve this is to have a relative increase of atacticity in the higher molecular weight portion of the polymer while using a highly isotactic homopolymer which is what D1 teaches.

Thus the patent and D1 describe qualitatively the same structure of the polymer in terms of monomer distribution and isotacticity of the homopolymer.

The respondents submitted that the definition of the overall isotacticity index (Toverall) was the result of a deeper and more differentiated understanding in respect of how not only of the total number of disrupter units (ethylene comonomer units) but also their placement within the polymer influenced the outcome in terms of the properties of the polymer.

In particular it was argued, especially with respect to the analysis provided in D21, that the mathematical treatment in D1 was incorrect or at least incomplete, failing to differentiate between the total number of molecules of disrupters and their placement within the polymer, i.e. how many instances of regions of disrupters were present regardless of the number of molecules therein.

However, regardless of the extent to which D1 was able to provide a detailed understanding or correct mathematical treatment of the structure of the polymer, as explained above, the underlying teaching of D1 and the patent regarding the location of disrupters within the polymer and the high isotacticity of the homopolymer is the same.

Even accepting that Toverall as determined according to the patent provides a more differentiated and correct (mathematical) description of the polymer than does D1 and the above conclusions with respect to novelty notwithstanding, there is no evidence that the teachings relating to the underlying structure of the polymers of D1 and the patent in suit are in fact distinguished or that the mathematical definition employed in the patent, as manifested by the definition of Toverall necessarily relates to polymers not falling under the general disclosure of D1 and is reflected by the properties of the polymer, i.e. results in a technical effect not shown by the general class of polymers of D1.

In the light of the foregoing it would appear that all that the patent provides is a more elaborate and detailed description of polymers which fall within the known group of polymers disclosed in D1. This definition or description however does not necessarily, and has not been shown to, relate to a particular subset of polymers with respect to the disclosure of D1 which subset exhibits a particular non-obvious balance of features or properties not shown by the generality of the disclosure of D1.

Consequently an inventive step has to be denied.

4. Auxiliary requests 2-7 - admittance

Auxiliary requests 2-7 differ from auxiliary requests 1, 2, 4, 6, 7, 10 and 11 as filed with the rejoinder to the statement of grounds of appeal by amendment of the definition of the range of ethylene content as in auxiliary request 1 (see above).

While this amendment is an appropriate response to a clarity objection raised by the Board (see point VIII, above) and cannot speak against the admittance of the requests (see point 3.1, above) the additional amendments were presented by the respondents at the earliest possible opportunity in appeal as a reaction to the many objections of the appellant.

On this basis, the Board finds it appropriate to exercise its discretion under Article 13(1) RPBA to admit auxiliary requests 2-7 to the proceedings.

5. Auxiliary request 2 - inventive step

Claim 1 differs from claim 1 of auxiliary request 1 by a more detailed specification of the process in the product-by-process part of the claim. In particular it is specified that the polymerisation takes place in a two-step reaction and that a molecular weight regulator is employed.

Neither of the additional features provides further differences over the process disclosed in D1.

Firstly in the examples of D1 a two reactor system is employed (page 8, lines 7 and 16, referring to a "first" reactor and a "second" reactor).

Furthermore hydrogen is present in the monomer feed (page 8, lines 7 and 17). Hydrogen serves as a molecular weight regulator. In this connection it is immaterial, as submitted by the respondents, that D1 does not identify the hydrogen as a "molecular weight regulator". This effect is inherent to the use of hydrogen in such a polymerisation.

Correspondingly the same conclusions as for the main request apply, leading to the finding that the subject matter of auxiliary request 2 does not meet the requirements of inventive step.

6. Auxiliary request 3 - inventive step

Claim 1 differs from claim 1 of auxiliary request 1 by the feature that an organic silicon compound is present as an external electron donor.

There is no evidence in the patent that the presence of an external electron donor provides any effect on the properties of the polymers. The argument of the respondents that the specific compounds identified in the patent (in paragraphs [0045] and [0048]) were novel examples of this type of component is not relevant, insofar as the claims are not limited to such specific compounds.

In view of the absence of any evidence for a technical effect detectable on the polymers arising from the incorporation of these components in the process of making the polymers which are the subject-matter of the claim, the objective problem to be (further) solved by this feature has to be formulated as the provision of further polymers based on those of D1.

The use of electron donors of the generality as claimed is known in the relevant technical field as demonstrated by D3, page 5, fifth-third lines from the bottom.

Consequently the further feature of claim 1 of auxiliary request 3 has to be seen as an obvious solution to the - further - problem indicated above, leading to the conclusion that an inventive step has to be denied.

7. Auxiliary request 4 - inventive step

Compared to auxiliary request 1, claim 1 of auxiliary request 4 differs by specifying that the melt flow rate of the propylene random copolymer is lower than that of the propylene homopolymer.

The definition of the relative melt flow rates does not introduce any additional distinguishing feature with respect to the teaching of D1 (the homopolymer representing the low end of the molecular weight distribution - see section 3.3.5, above), meaning that the conclusions as reached for auxiliary request 1 also apply to auxiliary request 4. Indeed both parties relied on the respective submissions made for auxiliary request 1 when discussing auxiliary request 4.

Auxiliary request 4 does not meet therefore the requirements of inventive step.

8. Auxiliary request 5 - inventive step

Compared to auxiliary request 1 claim 1 of auxiliary request 5 contains an additional feature, namely the definition of the xylene soluble content.

As submitted by the appellant, and not disputed by the respondents, the xylene soluble content is representative of the crystallinity, in that crystalline parts of the polymer are not soluble in xylene. Thus this feature amounts to nothing more than a further specification of what is (intended to be) represented by Toverall. There is no evidence that any technical effect is associated with the specified xylene soluble content. Furthermore it is apparent from D3, page 12, table 1 that the said xylene solubles range is conventional in this type of polymer compositions.

Consequently no inventive step can be recognised for the subject-matter of auxiliary request 5.

9. Auxiliary request 6 - inventive step

Claim 1 differs from claim 1 of auxiliary request 5 by specifying additionally the melt flow rates of the two polymer components in terms of their numerical ranges.

No additional arguments were submitted by the respondents in respect of this request.

In these circumstances the Board has no reason to come to a different conclusion in resect of inventive step, leading to the finding that the requirements are not satisfied.

10. Auxiliary request 7 - inventive step

Claim 1 corresponds to a combination of the subject-matters of claim 1 of auxiliary requests 2 and 6.

Insofar as no additional arguments were advanced by the respondents, the Board has no reason to come to any conclusion other than that the subject-matter of auxiliary request 7 likewise does not meet the requirements of inventive step.