T 0241/18 21-09-2020

Summary of Facts and Submissions

I. The appeal lies from the interlocutory decision of the opposition division according to which European patent number 1 668 046 could be maintained in amended form on the basis of the main request, filed with letter of 20 July 2016.

II. The patent was granted with a set of 12 claims, whereby claim 1 read as follows:

"A catalyst composition for the polymerization of propylene or mixtures of propylene and one or more copolymerizable comonomers, said catalyst composition comprising one or more Ziegler-Natta procatalyst compositions comprising one or more transition metal compounds and one or more esters of aromatic dicarboxylic acid internal electron donors; one or more aluminum containing cocatalysts; a selectivity control agent (SCA), wherein the SCA is selected from the group consisting of: dicyclopentyldimethoxysilane, di-tert-butyldimethoxysilane, methylcyclohexyldimethoxysilane, ethylcyclohexyldimethoxysilane, diphenyldimethoxysilane, diisopropyldimethoxysilane, di-n-propyldimethoxysilane, diisobutyldimethoxysilane, di-n-butyldimethoxysilane, cyclopentyltrimethoxysilane, isopropyltrimethoxysilane, n-propyltrimethoxysilane, n-propytriethoxysilane, ethyltriethoxysilane, tetramethoxysilane, tetraethoxysilane, cyclopentylpyrrolidinodimethoxysilane, bis(pyrrolidino)-dimethoxysilane, and bis(perhydroisoquinolino)dimethoxysilane; and one or more activity limiting agent (ALA) compounds, wherein the ALA is selected from the group consisting of: ethyl acetate, methyl trimethylacetate, isopropyl myristate, di-n-butyl sebacate, (poly)(alkylene glycol) mono- or diacetates, (poly)(alkylene glycol) mono- or di-myristates, (poly)(alkylene glycol) mono- or di- laurates, (poly)(alkylene glycol) mono- or di-dioleates, glyceryl tri(acetate), mixed glycerides of linoleic, oleic, palmitic and stearic acids, and mixtures thereof, wherein the total quantity of selectivity control agent employed is limited to provide a molar ratio, based on transition metal, from 0.1 to 500, said compounds and amounts being selected such that the normalized polymerization activity of the catalyst composition at a temperature from 85 to 130 °C, is less than the normalized polymerization activity of the catalyst composition in the presence of only the SCA compound at the same total molar quantity of SCA at said temperature, and/or the normalized polymerization activity of the catalyst composition at a temperature from 85°C to 130 °C is less than the normalized polymerization activity of the same catalyst composition and the SCA/ALA mixture at a lesser temperature."

Claims 2-9 were directed to preferred embodiments of the catalyst of claim 1, whereby claim 6 had the following wording:

"A catalyst composition according to any one of the preceding claims, wherein the total molar quantity of the SCA mixture based on moles of transition metal is from 1 to 50."

Independent claim 10 was directed to a polymerisation process employing the catalyst composition of claim 1 and claims 11 and 12 were directed to preferred embodiments of said process.

III. A notice of opposition against the patent was filed, invoking the grounds pursuant to Article 100(a) EPC (lack of novelty, lack of inventive step), Article 100(b) EPC and Article 100(c) EPC.

The following documents, inter alia, were relied upon by the opponent:

D1: US-A-5 432 244 (not, as erroneously stated in the decision, "US-A-5 143 244")

D3: EP-A-560 035

D4: EP-A-453 116

D5: US-A-5 414 063

D6, D7: experimental reports.

IV. The decision was based on a set of amended claims as the main request, which set of claims differed from the claims as granted by amendment of the lower limit of the numerical range claim 6 such that the claim read as follows (difference in bold):

"A catalyst composition according to any one of the preceding claims, wherein the total molar quantity of the SCA mixture based on moles of transition metal is from 1.0 to 50.".

V. According to the decision:

- The amendment of the value "1" to "1.0" in claim 6 complied with the requirements of Rule 80 EPC;

- The requirements of Article 123(2) EPC were met. In claim 6 the feature "SCA mixture" was held to have a basis in the description of the application as filed, whereby there was no indication that only a single such agent was envisaged;

- The requirements of sufficiency of disclosure were satisfied because the technical features of operative claim 1 gave enough guidance to put the claimed invention into practice. No evidence had been provided to demonstrate that said technical definition was insufficient to solve the problem as set out in paragraph [0008] of the patent, or that the results reported in the examples of the patent could not in fact be attained. The functional feature of the claim was not to be read in isolation but in the context of the specific - defined - lists of SCA and ALA in the claim;

- The subject-matter was novel because a multiple selection would be necessary from D1 in order to generate the combination of features claimed;

- The requirements of inventive step were met. Document D3 was the closest state of the art. Although it did not relate to the same problem as the patent in suit, it had the most technical features in common. The subject-matter claimed was distinguished from the disclosure of D3 by the definition of the ALA. Experimental reports D6 and D7 demonstrated that the catalyst compositions of D3 complied with the functional features of claim 1. Thus the objective problem was the provision of an alternative catalyst composition having self-extinguishing properties. There was no reason to combine the teachings of D3 and D4 in order to solve said problem. Furthermore D4 did not disclose the ALA components of interest. Nor was any pertinent teaching provided by D5.

VI. The opponent (appellant) lodged an appeal against the decision.

Together with the statement of grounds of appeal, two further documents were submitted (designated D8 and D9 by the appellant and renumbered by the Board):

D9: WO-A-95/07943

D10: US-A-4 983 562.

VII. The patent proprietor (respondent) replied to the appeal.

The set of claims as upheld by the opposition division was maintained as the main request. Sets of claims forming auxiliary requests 1 to 11 were submitted. The wording of these requests is not of relevance to the decision.

VIII. The Board issued a summons to oral proceedings.

In a communication the Board set out its preliminary view.

It was noted that the appellant had not contested the findings of the opposition division in respect of inventive step but had instead formulated an entirely new attack relying on D9 and D10.

IX. By letter of 6 August 2020 the respondent made submissions in respect of the auxiliary requests.

X. With letter of 25 August 2020 the appellant made further submissions, inter alia, on the admittance of D9 and D10 to the proceedings. An attack on inventive step relying on D3 and D4 was advanced.

XI. With letter of 15 September the respondent made observations on the preliminary opinion of the Board and the latest submissions of the appellant. In particular the admittance of the new attack on inventive step was challenged.

XII. Oral proceedings were held before the Board on 21 September 2020 with the respondent in attendance and the appellant participating via video link.

XIII. The arguments of the appellant can be summarised as follows:

(a) Admittance of D9 and D10

These documents had not been available, i.e. not in the possession of the appellant, during first instance proceedings. At that stage, the opponent had been satisfied that the attacks on novelty and inventive step were based on relevant and good documents and the preliminary opinion of the opposition division did not give any grounds to change this assessment or indicate the necessity for further documents. However the final decision came to a different conclusion. Additional searches had been carried out in order to find documents closer in terms of the problem to be solved which revealed D9 and D10.

The filing of new documents by a losing party to attempt to improve its position was a legitimate approach as held by T 927/04 of 10 May 2006, for example to provide evidence of a "missing link" in the prior art. The decision under appeal held that it was not obvious to combine D3 and D4. D9 was a more relevant document and hence could serve to reinforce the arguments made, providing said "missing link". The respondent had had sufficient opportunity to consider this document as shown by the submission of a number of auxiliary requests to take account thereof. D9 and D10 disclosed all the features of the claim and were more relevant than any of the other documents on file. Hence they should be admitted.

(b) Allowability of amendments

The definition in claim 6 of "SCA mixture" had no basis in the application as originally filed.

Even if various passages of the description indicated that more than one SCA could be present, this was in the context of a broad, generic group of SCAs. The operative claim was, as a result of amendments made during examination, directed to a much more tightly focused embodiment in which, as shown by the use of the wording "consisting of", a closed list of specific, individual SCAs was defined.

Differently from the disclosure of the ALAs, the corresponding passage of the application as originally filed relating to the closed group of SCAs did not include the wording "one or more", or "a mixture of" meaning that there was no disclosure of the possibility of members of this restricted group being present as mixtures.

Even if the claim employed a "nested comprising" structure, this could not override the correct interpretation of the wording "selected from the group consisting of" as meaning that no further component beyond those explicitly mentioned could be present, as set out for example in T 759/10 of 22 March 2012. A further defect with respect to Article 123(2) EPC was that the current wording of claim 6 linked the defined SCA compounds to the specific ALA compounds. There was no basis for such a combination in the application as originally filed.

The same situation applied to claims 7 and 8 in respect of the definition of mixtures of the ALA component.

(c) Sufficiency of disclosure

Contrary to what had been stated in the decision, it was not for the claims to provide the necessary technical guidance. Rather this was the purpose of the description. The claim relied on a combination of structural and functional features whereby the necessary result was to be achieved by selecting amounts of the SCA and ALA to get the required outcome. The patent contained only a very limited number of combinations of SCA and ALA and in limited amounts, in particular where the ALA was present in a large excess. The decision shifted the burden of trial and error testing of whether a given pair of ALA/SCA provided the required functional feature to third parties with no adequate guidance.

Furthermore the functional feature defined in the claim was exactly the same as the technical effect underlying the patent. Thus, according to the claim, the structural definitions of the SCAs/ALAs were in themselves not sufficient to solve the technical problem/satisfy the functional feature, since for each given pair the necessary amounts would still have to be selected. This was an essential feature. As shown by examples 8b, 9b and 10b, activity at 100°C progressively increased as the molar ratio SCA/ALA increased. This series stopped at the ratio 30/70. However the trend indicated that it was possible that at significantly higher ratios, still within the claims, for example SCA/ALA 70/30 or higher the claimed effect on the activity at higher temperatures would not be attained. As such higher ratios had not been shown in the patent to be effective, there was no generalisable teaching in the patent extending over the whole scope of the claims.

The patent gave only very limited guidance, which was limited to the specific examples. Thus the claim covered a large unexplored area and there were strong doubts that the effect would be attained over the whole scope of the claim. Accordingly this was a reach-through claim situation as considered in T 1063/06 (OJ EPO 2009, 516), in which the combinations satisfying the functional features had to be determined by means of a screening. Due to the absence of adequate guidance provided by the patent, the skilled person thus faced an undue burden in operating the invention over the whole scope of the claims. In this connection reference was also made to T 339/05 of 10 April 2008.

Whilst it was the task of the opponent to demonstrate, by verifiable facts, that there was insufficiency of disclosure (T 19/90, OJ EPO 1990, 476), in the situation where a patent relied on functional features, the description had to satisfy certain requirements. Such a definition would be acceptable if all possible combinations covered by the claim would result in the required effect. However in the present case the structural features relating to the amounts of the SCA/ALA would only fall within the scope of the claims if the functional features were satisfied. In this connection reference was made to decision T 1051/09 of 7 February 2012 relating to the situation where there was a lack of a generalisable teaching going beyond the specific examples.

(d) Novelty

All features of the claim were disclosed in D1, including a combination of a mixture of SCAs, which in the case of D1 corresponded to a mixture of silicon compounds and mono- or polycarboxylic acid esters. The specified ratios of SCA/Ti and of the ester and silicon compound were derivable from the composition data given in the table in column 2 of D1. D1 specifically mentioned members of the various catalyst constituents falling within the definition of the claim meaning that claim 1 did not meet the selection criteria, in particular the requirement that the selected range should be far removed from the examples of D1. Specifically according to the operative claim there were examples of internal donors (phthalates), SCA and ALA (ethyl acetate) which did not allow the claimed subject-matter to be far removed from the disclosure of D1.

Lack of novelty also existed with respect to D9.

(e) Inventive step

As stated in the decision, D3 was the closest prior art. Even if the problem defined in D3 was not the same as that in the patent there was a strong similarity, if not identity, in terms of the sought technical effects. The patent addressed the problem of reduced polymer agglomerate formation and improved process control whilst D3 was directed to avoiding fouling of the reactor and/or clogging of pipes of the reactor. Thus both the patent and D3 aimed at the same effect. Even if this effect was considered in the patent and D3 to be the result of different mechanisms, it nevertheless had its origin in the same or similar class of compounds (ALA). The skilled person seeking to reduce polymer agglomeration would consult D3 as a starting point. It would be realised that certain compounds, structurally very similar to those of the patent, affected catalyst activity and were effective in reducing reactor fouling or clogging. Since D3 disclosed the possibility of selectivity based on particle size but was silent on any other mechanism there would be no grounds for the skilled person to conclude that a temperature based mechanism would not operate in combination with the particle size. Consequently D3 would be considered as closest prior art. Experimental reports D6 and D7 showed that the catalyst compositions of D3, employing glycerol monostearate or sorbitan monooleate as ALA exhibited the required self-extinguishing properties.

No technical effect had been shown to arise from the presently defined ALAs compared to those of D3. Thus the objective technical problem was to provide alternative self-extinguishing catalyst compositions. The claimed solution was rendered obvious by D9, which was directed to the same problem as D3. Since the compounds of D3 had been shown to be effective as ALAs the skilled person would expect also the reducing agents of D9, such as ethyl acetate, to provide the same effects in terms of self-extinguishing properties and reduction of reactor fouling.

Alternatively, as submitted for the first time in the appeal proceedings with the letter of 25 August 2020, the skilled person would also have considered the combination of D3 and D4, which attack had already been advanced during the opposition proceedings.

XIV. The arguments of the respondent can be summarised as follows:

(a) Admittance of D9 and D10

Before the first instance, the appellant had based its attack on other documents. This did not mean that D9 and D10 had not been available and no evidence to this effect had been provided. Instead, as confirmed by the statements made by the appellant in particular at the oral proceedings, an active decision had been made to restrict the case during opposition proceedings to the documents then cited. Consequently D9 and D10 had to be regarded as late filed and should not be admitted. Furthermore D9 could not be seen as providing a "missing link" overcoming a deficiency in the inventive step attack raised in the first instance proceedings because it did not disclose the self-extinguishing properties of catalyst systems. Nor had it been shown that D9 and D10 were of high relevance in any other respect. On the contrary, D9 addressed a different problem to that of the patent, namely that of the presence of catalyst fines in the recycle line and for this reason could not be considered to be prima facie relevant.

(b) Allowability of amendments

The subject matter of claim 6 was disclosed at page 8, lines 31-33 of the application as filed.

The objection relating to the SCA compounds in claim 1 being in the form of a closed list was without merit. The catalyst was defined employing "nested comprising" language which permitted that more then one SCA be present as acknowledged in the decision. The objection that the term "SCA mixture" of claim 6 implied non-disclosed combinations of the explicitly listed SCAs was similarly incorrect. The claim specified that an SCA selected from a list of 18 be present. However the use of "comprising" in the preamble of the claim meant that any other SCA could also be present. The identity of these additional SCAs was not restricted in any way by the wording of claim 1. Thus the feature "SCA mixture" in claim 6 did not relate to a newly created combination of two or more of the 18 SCAs listed in claim 1.

For analogous reasons the definition of mixtures of ALA components in claims 7 and 8 was not objectionable.

(c) Sufficiency of disclosure

The appellant had advanced no evidence to support its arguments in respect of there being an undue burden in operating the invention over the whole scope of the claims, contrary to what was required according to the cited T 19/90. In this connection the findings of T 182/89 (OJ EPO 1991, 391) could also be invoked. It was also the case that no trial and error was required since the patent provided all the necessary information (with reference to T 339/05). The invoked T 1051/09 concerned the situation where the claims relied on a functional definition without any guidance. This was not the situation in the present case and no evidence had been provided to the contrary. Regarding the objection invoking examples 8-10 of the patent, the data of the patent did not allow the conclusion indicated by the appellant to be reached, and similarly no data had been advanced to support the position of the appellant.

(d) Novelty

D1 did not disclose the specific SCA/ALA mixtures in combination with a Ziegler-Natta procatalyst composition. On the contrary, as stated in the decision, a plurality of selections from several lists would be required to assemble the necessary combination of features, some of which selections would disregard the teachings of D1.

Regarding D9 and D10, to the extent that these were to be admitted, D9 related to compositions to "kill" catalysts, not to provide a catalyst system having self-extinguishing properties.

(e) Inventive step

The appellant had not challenged with the statement of grounds of appeal the findings of the opposition division that the claimed subject-matter was inventive with respect to the disclosure of D3 in combination with D4 or D5. The new attack based on D3 and D9 should not be admitted. In any case it did not lead to the conclusion urged by the appellant.

D3 did not address the problem underlying the patent in suit, namely that of providing catalyst systems having self-extinguishing properties. Instead D3 addressed the problem of selectively inhibiting the reactivity of polymer particle fines compared with that of polymer particles of average size present in the gas phase. There was no indication in D3 that the compositions thereof would provide any benefit in terms of reducing polymerisation activity at the temperature range specified in claim 1 of the patent in suit.

Experimental reports D6 and D7 were irrelevant since the results shown therein were not disclosed in D3 and would not have been evident to the skilled person.

It was not the case that the skilled person, starting from D3, would consult D9 and realise that the reducing agents thereof could be used as alternatives to compound (3) because D3 did not address the same problem as the patent in suit and there would have been no incentive to consult D9 in view of solving the problem underlying the patent in suit. Even if D9 had been consulted and it had been decided to replace compound (3) with one of the reducing agents disclosed in D9, there would have been no reason to choose any of these in preference to any of the others disclosed in D9.

The attack on inventive step based on D3 in combination with D4 had not been raised in the statement of grounds of appeal and was consequently late filed. No justification for the amendment to the case represented by submission of this attack had been advanced. Nor had it ben shown that there were any "exceptional circumstances" which would justify advancing such an attack (with reference to Article 13(2) RPBA 2020). It should not be admitted. In any case this combination of documents also did not render the claimed subject matter obvious.

XV. The appellant requested that the decision under appeal be set aside and that the patent be revoked.

XVI. The respondent requested that the appeal be dismissed (main request). In the alternative maintenance of the patent on the basis of one of the sets of claims according to auxiliary request 1 to auxiliary request 11, submitted with the rejoinder to the statement of grounds of appeal was requested.