T 0868/02 21-09-2004

Summary of Facts and Submissions

I. Mention of the grant of European patent No. 0 629 658 in respect of European patent application No. 94 201 636.1 in the name of ENICHEM S.p.A., which had been filed on 8 June 1994 claiming an IT priority of 16 June 1993, was announced on 22. September 1999 on the basis of 19 claims, independent Claims 1 and 18 reading as follows:

"1. A rubber-reinforced vinyl aromatic (co)polymer consisting essentially of a polymeric matrix and a rubber phase dispersed and/or grafted within the polymeric matrix, wherein said rubber phase consists of a mixture of i) 20-80 wt.% of a diene rubber and ii) 80- 20. wt.% of a vinyl aromatic monomer/conjugated 1,3- diene linear block copolymer, said block copolymer having a diene content exceeding 80 wt% and, respectively, a vinyl aromatic monomer content of less than 20 wt%, with the proviso that the content of peroxy oxygen-containing material in the blend is less than 0.25 grammillimoles per 100 grams of total rubber present in the blend."

"18. A process for producing the rubber-reinforced vinyl aromatic copolymer in accordance with any one of the preceding claims, consisting of dissolving the mixture of diene rubber i) and block copolymer ii) in the monomer or monomers, possibly in the presence of an inert solvent in a quantity which can vary from 5 to 100 wt% on the mixture, then subjecting the resultant solution to polymerization, in the presence of an initiator, in two or more agitated vertical tubular plug flow reactors arranged in series, their length/diameter ratio exceeding 2 and, preferably, being between 3 and 10."

Claims 2 to 17 were dependent on Claim 1, Claim 19 was dependent on Claim 18.

Notice of Opposition requesting revocation of the patent in its entirety on the grounds of Article 100(a) and (b) EPC was filed by The Dow Chemical Company on 21. June 2000. With its letter dated 18 February 2002 the Opponent raised an additional ground of opposition under Article 100(c) EPC.

The opposition was inter alia based on documents

D1: US-A-4 524 180 and

E2: US-A-3 497 572 (cited outside the opposition period).

II. In its interlocutory decision announced orally on 28 May 2002 and issued in writing on 17 June 2002, the Opposition Division found that the patent in the form as amended according to the "second auxiliary request" met the requirements of the EPC.

This decision relates to three requests,

(a) a main request, originally submitted as "auxiliary request" with the Patentee's letter dated 24 April 2002, acquiring the status of a main request by the Patentee's abandoning of the granted version considered to contravene Article 123(2) EPC, a conclusion drawn by the Opposition Division after its admission at the oral proceedings on 28 May 2002 of the late filed ground of opposition under Article 100(c) EPC; Claim 1 of this request differing from its granted version by deletion of the disclaimer (proviso); and

(b) two requests submitted by the Patentee at the oral proceedings as "first" and "second auxiliary requests", their Claims 1 differing from the version of the afore-mentioned main request by the following amended definitions of the diene rubber i): "wherein the diene rubber is synthetic and consists of a conjugated 1,3-diene polymer containing from 4 to 6 carbon atoms" ("first auxiliary request") and "wherein the diene rubber is polybutadiene" ("second auxiliary request"), respectively.

III. The reasons of the Opposition Division's decision may be summarised as follows:

(a) Claim 1 of the main request met the requirements of Article 123(2) and (3) EPC because

(i) it no longer contained the disclaimer of granted Claim 1, which, in contravention of Article 123(2) EPC, was supported neither by the application as filed nor by document E2, and

(ii) given the lacking technical contribution of the disclaimer, its deletion did not, in accordance with the finding of G 1/93 (OJ EPO 1994, 541), extend the protection conferred by the granted patent.

(b) While the subject-matter of this request furthermore fulfilled the requirements of Article 83 EPC, it was not novel over document E2 which disclosed a blend having all features of Claim 1 of this request.

(c) By the same token the subject-matter of the "first auxiliary request" lacked novelty because in the light of the description of the opposed patent - which could not be amended without contravention of Article 123(2) EPC - the amended diene rubber definition of this request still comprised copolymers of conjugated diene and acrylonitrile.

(d) Claim 1 of the "second auxiliary request" was held to meet the requirements of Article 123(2) and (3) as well as those of Article 54 EPC.

(e) Its subject-matter was furthermore considered non-obvious over the closest prior art according to D1 because the better optical properties obtained by the selected weight ratio (diene rubber):(vinyl aromatic monomer) of the "inventive" block copolymer was not to be expected. In the Opposition Division's view, this improvement was established by the higher gloss value of 80 achieved according to Example 3 of the patent in suit as compared to the gloss value of 60 of the comparative Example (using a block copolymer according to the state of the art) submitted in Vilma Fornasari's Declaration before the USPTO dated 2 October 1995 (attached to the Applicant's letter dated 28 March 1997; hereinafter "Fornasari Declaration"); conflicting data of the Opponent (experimental reports of Mr Bouquet dated 20 June 2000 (Bouquet I) and submitted with the Opponent's submission dated 18 February 2002 (Bouquet II)) were disregarded because they had been derived, in the Opposition Division's view, from experiments using rubbers "which do not fully correspond to the rubber used in the examples of the opposed patent as well as in the Fornasari's test and in the examples of D1" (Reasons 7).

IV. On 19 August 2002 the Opponent (Appellant) lodged an appeal against the decision of the Opposition Division. The appeal fee was paid on 13 August 2002. The Statement of Grounds of Appeal was filed on 16 October 2002. A further written submission dates from 26 July 2004.

V. The arguments of the Opponent Appellant presented in the written submissions and at the oral proceedings held on 21. September 2004 may be summarized as follows:

(a) The deletion of the disclaimer "that the content of peroxy oxygen-containing material in the blend is less than 0.25 grammillimoles per 100 grams of total rubber present in the blend" from granted Claim 1 contravened Article 123(3) EPC because the patent in suit was devoid of any information permitting the conclusion that the disclaimer did not provide a technical contribution.

(b) That the disclaimer indeed provided a technical contribution was furthermore conspicuous by the novelty establishing purpose of its introduction during examination, a conclusion furthermore supported by G 1/93 (Reasons 16) according to which a limiting feature creating an inventive selection, as was the case here, was a typical example for a feature providing a technical contribution.

(c) It was by no means justified to take it for granted that, owing to the term "consisting essentially of", Claim 1 in the absence of the disclaimer excluded compositions having a content of peroxy oxygen-containing material higher than that permitted by the disclaimer.

The scope of this term was all but clear, not only with regard to the possible presence of additives, like antioxidants (used in all Examples) and mineral oil (used according to Example 5, now deleted, but still an option), but also with regard to the use of comonomers not specified in Claim 1 but envisaged in the description (paragraphs [0032] and [0033] of the specification).

(d) Furthermore, whilst it was admitted that the peroxide initiator used in the "inventive" experiments was completely consumed in the course of the polymerisation reaction, this would not rule out the subsequent addition of peroxide initiator as done according to Example 1 of document E2.

(e) After having been made aware by the Board that according to G 1/03 (OJ EPO 2004, 413, Reasons 2.5.2) the non- achievement of a desired effect which is not expressed in a claim is not a ground of insufficiency the Appellant refrained from further comments on this issue at the oral proceedings. In its written submissions the Appellant had argued that the non-attainment of the desired gloss improvement demonstrated by Bouquet I and II established that the opposed patent lacked sufficiency under Article 83 EPC.

(f) D1 was novelty destroying for the claimed subject-matter because:

(i) the alleged substantial absence of peroxy oxygen- containing material from the claimed compositions was undistinguishing: also according to D1 the residual amount of the peroxide initiator was immeasurably low;

(ii) the weight ratio ranges of diene rubber (10% to 95%) and block copolymer (5% to 95%) disclosed in D1 did not justify a recognition of novelty by "selection" of the respective "inventive" ranges (20% to 80%/80% to 20%) because not only were the latter fully within said generic prior art ranges but moreover the butadiene/block copolymer ratios exemplified in D1 (Examples 3 and 6: 50/50; Example 8: 75/25) fell squarely within said "inventive" ranges;

(iii) the only feature not prima facie clearly disclosed in D1 was the butadiene content of the block copolymer of from >80% to <100% as compared with 50% to 95% according to D1.

Considering however that (i) the overlapping area of from >80% to 95% represented one third of D1's range of 50% to 95%, (ii) that the lower limit of >80% directly abutted D1's preferred range of 65% to 80%, (iii) that the block copolymer Solprene®308 exemplified in D1 had a butadiene content of 70%, ie only 10% away from the "inventive" lower limit, and (iv) that it was established by the experimental reports Bouquet I and II that the choice of the "selected" range did not provide the desired effect of an improved gloss, the conclusion must be drawn that said "inventive" range satisfied none of the three criteria for the novelty of a selection set out in T 198/84 (OJ EPO 1985, 209) and T 279/89 of 3 July 1991 (not published in the OJ EPO).

(iv) Since block copolymers comprising ethylenically unsaturated nitrile monomer units instead of or together with monovinylidene aromatic monomers, an embodiment formally within D1's disclosure, had not been commercially available, this alternative did in practice not exist and the use of block copolymers from diene and (only) monovinylidene aromatic monomers did not therefore require any choice in that respect.

(g) Furthermore the claimed invention lacked an inventive step over D1 which was concerned with the same technical problem of providing a good balance of physical properties and gloss. Since it was shown by Bouquet I and II that the use of a block copolymer having a diene content >80% by weight did not give rise to better gloss than the use of a block copolymer having a butadiene content of 70% as exemplified in D1, and since block copolymers having a butadiene content of 90% were commercially available, their use did not require any inventivity.

(h) The Appellant objected to admitting a set of claims of a "first auxiliary request" into the appeal proceedings which was submitted by the Respondent at a point in time well into the oral proceedings because, in the face of the essentially unchanged factual situation since the filing of the opposition, there was no excuse for the lateness of this request whose admission would disadvantage the Appellant. Moreover the suggested amendment could not be seen to be related to the critical aspects of the selection invention issue and it would require intensive investigations of the Appellant to find out whether the features newly introduced into Claim 1 of this "first auxiliary request" were or were not part of the disclosure of the applicable citations.

VI. The arguments of the Respondent Patentee submitted in its letters dated 28 February 2003 and 2 August 2004 as well as at the oral proceedings may be summarised as follows:

(a) The deletion from granted Claim 1 of the disclaimer did not contravene Article 123(3) EPC because it did not provide a technical contribution. Contrary to the Appellant's contention, the disclaimer had not been introduced during examination for restoring novelty but only in order to clarify the meaning of the term "consisting essentially of".

(b) Also after deletion of the disclaimer the presence of amounts of peroxy oxygen-containing material affecting the essential characteristics of the composition remained excluded because, in conformity with the jurisprudence of the EPO (cf. T 472/88 of 10 October 1990, not published in the OJ EPO), this was guaranteed by the term "consisting essentially of". The absence of peroxide from the composition was also confirmed by the statement in E2 (column 5, lines 65 to 69) that "substantially complete decomposition of the peroxide occurs during the preparation of the composition".

(c) The Appellant's objection against the sufficiency of the disclosure of the opposed patent was inconclusive in view of its successful preparation of compositions in accordance with the disclosure of the patent.

(d) The subject-matter of the opposed patent was novel over D1 because this document did not unambiguously disclose all characteristics of the claimed compositions in the specified combinations.

In particular, it did not disclose that the amount of block copolymer in the rubber phase in the composition should be 20% to 80% by weight and that its butadiene content should be >80% by weight. Rather D1 only disclosed generic ranges: 10% to 95% by weight of polybutadiene in the rubber phase and 50% to 95% by weight of butadiene in the block copolymer.

It was therefore necessary for the skilled person to perform two choices from this generic disclosure, a situation which according to T 651/91 of 18 February 1993 (not published in the OJ EPO) established novelty.

(e) The Appellant's approach first to consider the novelty aspect of the feature concerning the amount of polybutadiene in the rubber phase and thereafter, separately, the novelty aspect of the diene content of the block copolymer was wrong. Rather these features had to be considered in combination.

(f) But even if the Appellant's approach was followed, novelty by selection of the diene content of >80% by weight must be acknowledged because this feature met the selection criteria defined in T 198/84 and T 279/89: given that the purposive character of this feature was established by Example 3 of the patent in suit and the Fornasari Declaration - which together demonstrated the gloss improvement resulting from the use of a block copolymer having a diene content of 90% by weight in lieu of only 70% by weight (gloss values: "invention": 80; "prior art": 60) - the range of overlap of 15% of the diene content (diene content of 50% to 95% according to D1, respectively, >80% according to the "invention") had to be considered narrow and the distance of 10% of the diene content exemplified in D1 (Solprene®308: cf column 10, Table I) from the "inventive" lower limit of >80% had to be considered sufficiently far removed from the known range illustrated by means of examples.

(g) The purposive character of the "inventive" selection of the diene amount of >80% by weight of the block copolymer was not affected by the Appellant's data which allegedly showed that a gloss improvement was obtained neither under polymerisation conditions and with block copolymers differing from those according to Example 3 of the patent in suit (Bouquet I) nor under identical polymerisation conditions but with non-identical block copolymers (Bouquet II).

The Appellant's so-called optimised polymerisation conditions made use of knowledge that was acquired after the effective date of the patent in suit and applied with the objective to obtain optimised gloss results; these experiments could not, therefore, be regarded to follow the teaching of the patent in suit.

Moreover the rubber starting materials (polybutadiene and block copolymer) used by the then Opponent in its experiments had to comprise an antioxidant different from that used according to the patent in suit because the antioxidant then used had in the meantime been withdrawn from the market for health reasons. This cast further doubt on the reliability of the assumption that the experiments of the Opponent Appellant had been carried out in accordance with the factual conditions applicable to the specification of the patent in suit. It rather appeared that these experiments had been purposefully designed "ex post facto".

(h) The claimed subject-matter also involved an inventive step over D1 because the experimentally established gloss improvement was not to be expected.

D1 failed to suggest that the use of block copolymers having a butadiene content in excess of that of Solprene®308 in combination with the use of particular amounts of polybutadiene rubber would be able to improve the gloss of rubber reinforced vinylaromatic (co)polymers.

(i) For the reasons set out above with respect to the purposive character of the selection of a block copolymer having a diene content >80% by weight the Patentee's results were not invalidated by the Appellant Opponent's experimental reports Bouquet I and II which showed that gloss could also be adjusted by optimisation of the polymerisation conditions, ie addition time and amount of chain transfer agent and initiator. Rather the absence of the necessity of such optimisations supported the inventivity of the claimed subject- matter.

(j) In the event that the Board should not accede to the Respondent's arguments in favour of the main request, the Respondent at the oral proceedings submitted a set of 16 claims of a "first auxiliary request" whose main claim combined the features of Claim 1 with features of Claim 7 of the main request. The Respondent argued that this request should be admitted because it represented an attempt to deal with the objections raised by further restricting the claimed invention.

VII. The Appellant requested that the decision under appeal be set aside and the patent be revoked.

The Respondent requested that the appeal be dismissed and that the patent be maintained as follows: main request: version as maintained by the Opposition Division; or alternatively on the basis of the set of Claims 1 to 16. filed as first auxiliary request during the oral proceedings.