T 0714/00 06-08-2002

I. Mention of the grant of European patent No. 0 574 054 in respect of European patent application No. 93 201 347.7 in the name of ENICHEM S.p.A., which had been filed on 11 May 1993 claiming an IT priority of 21 May 1992, was announced on 5 March 1997 on the basis of 20 claims, independent Claim 1 reading as follows:

"1. A flame-retardant, halogen-free, thermoplastic composition, classifiable under V0 rating according to the UL 94 V test, comprising: a halogen-free impact resistant vinyl aromatic copolymer, consisting of a vinyl aromatic monomer, an acrylic monomer and a rubber; a halogen-free aromatic polycarbonate, and red phosphorus"

Claims 2 to 20 were dependent on Claim 1.

II. Notice of Opposition requesting revocation of the patent in its entirety on the grounds of Art. 100(a) EPC was filed by Teijin Chemicals Ltd. on 1 December 1997.

The opposition was i.a. based on documents

D1: JP-A-48 85642 (partial translation),

D3: JP-A-61 192643 (partial translation),

D4: JP-A-4 106142 (partial translation),

D5: US-A-5 061 745, and

D6: JP-A-62 25179 (partial translation).

III. By its interlocutory decision orally announced on 18. May 2000 and issued in writing on 14 June 2000, the Opposition Division rejected the opposition and found that the patent as amended met the requirements of the EPC.

IV. The decision was based on a set of 15 claims of the then main request, Claim 1 reading as follows:

"1. A flame-retardant, halogen-free, thermoplastic composition, classifiable under V0 rating according to the UL 94 V test, comprising:

(A) from 70 to 5 parts by weight of an impact-resistant, halogen-free vinyl aromatic copolymer consisting of a vinyl aromatic monomer, an acrylic monomer and a rubber;

(B) from 30 to 95 parts by weight of a halogen-free aromatic polycarbonate;

(C) from 1 to 30 parts by weight, with respect to 100 parts by weight of the mixture of the two (A) + (B) resins, of a grafted polymer consisting of an elastomeric core having a glass transition temperature of the second order lower than 10 C and containing chains of vinyl aromatic monomers grafted thereon;

(D1) from 0.1 to 2.1 parts by weight with respect to 100 parts by weight of (A) + (B), of red phosphorus;

(D2) from 0 to 15 parts by weight with respect to 100 parts by weight of (A) + (B), of a phosphorus containing organic compound of the formula:

FORMULA

wherein R1, R2 and R3 are, independently from each other, an alkyl radical containing from 1 to 8 carbon atoms or an aryl radical or an optionally alkyl substituted aryl radical containing from 6 to 20 carbon atoms, and n represents 0 or 1;

(E) optionally, an anti-dripping agent."

Claims 2 to 15 of this request were dependent on Claim 1.

V. That decision essentially held that

(i) the subject-matter of Claim 1 did not extend beyond the content of the original disclosure in that

(i-1) the range of 1 to 30 parts by weight of grafted polymer component C was supported by Claim 17 and by the statement on page 6, lines 24 to 25 of the patent as granted, and

(i-2) the range of from 0.1 to 2.1 of parts by weight of red phosphorus (component D1) was fairly based, with respect to the lower limit of this range, on granted Claim 2 and, with respect to the upper limit, on the specifically exemplified value of 2.1 of worked Example 4; the generalisation of the latter value was admissible in view of the totality of the worked Examples which all achieved, without the use of halogen-containing flame retardants, the required V0 rating and also showed that an enhanced impact resistance could be achieved with low amounts of red phosphorus and independent from any specific combination of components A, B and C as well as independent from any specific amount of the organic phosphorus compound D2;

(ii) the claimed subject-matter was novel and

(iii) non-obvious over document D1, which differed from the claimed compositions by the absence of a grafted polymer component C, by the use of higher amounts of red phosphorus (component D1) and by the possible addition of halogen-containing flame retardants, because none of the further citations could, in combination with D1, suggest the solution of the existing technical problem, namely the provision of flame-retardant (i.e. V0 rating according to UL 94 V), impact-resistant thermoplastic compositions which were free of halogen:

(iii-1) D3 failed to teach the use of red phosphorus in the claimed amounts,

(iii-2) the compositions of D4 did not comprise polycarbonate, red phosphorus and an organic phosphorus compound in the required amounts,

(iii-3) the compositions of D5 did not comprise an impact resistant vinyl aromatic copolymer (component A) nor red phosphorus (component D1), and

(iii-4) the compositions of D6 did not comprise a flame retardant.

VI. On 11 July 2000 the Opponent (Appellant) lodged an appeal against the interlocutory decision of the Opposition Division and paid the appeal fee on the same day. The Statement of Grounds of Appeal was submitted on 13 September 2000.

VII. The Respondent (Proprietor of the patent) defended the opposed patent on the basis of a main and three auxiliary requests filed with the letter dated 20 June 2002 (main and first auxiliary request) and at the oral proceedings held on 6 August 2002 (second and third auxiliary request).

(i) Claim 1 of the main request differs from the version of Claim 1 underlying the decision under appeal (cf. point IV) by

- the replacement in the definition of component A of the term "an acrylic monomer" by "acrylonitrile", and

- by a minor rearrangement of the definition of component C as well as by addition of the underlined passage in the following quotation:

"(C) from 1 to 30 parts by weight ... of a grafted polymer consisting of an elastomeric core ... and grafted thereon chains of vinyl aromatic monomers and a methacrylate selected from methyl methacrylate and 1,3-butylene glycol dimethacrylate".

(ii) Claim 1 of the first auxiliary request differed from Claim 1 of this main request by the following changes in the ranges of amounts of the respective components:

- component A: "from 5 to 30 parts by weight",

- component B: "from 70 to 95 parts by weight",

- component C: "from 1 to 10 parts by weight", and

- component D2: "from 5 to 15 parts by weight".

(iii) Claim 1 of the second auxiliary request differs from the Claim 1 of the first auxiliary request by the restriction of the definition of component D2 to triphenylphosphate.

(iv) Claim 1 of the third auxiliary request differs from Claim 1 of the second auxiliary request by the further restriction of

- component A to "an impact-resistant, halogen-free vinyl aromatic copolymer consisting of 67.5 % by weight of styrene, 10.5. % by weight of polybutadiene rubber and 22. % by weight of acrylonitrile";

- component B to "a halogen-free aromatic polycarbonate consisting of Sinvet(R)(PC) polycarbonate"; and of

- component C to "a grafted polymer consisting of 60 % by weight of a core of polybutadiene rubber on which chains of styrene-methylmethacrylate copolymer (ratio 1:1) are grafted in an amount of 40%".

VIII. The arguments presented by the Appellant may be summarized as follows:

(i) Objections under Article 123 EPC

Claim 1, main request

(i-1) Apart from features of original Claims 2, 3 and 17. this claim comprised amended ranges of amounts of the red phosphorus component D1 ("0.1 to 2.1 parts by weight") and of the grafted polymer component C ("1 to 30 parts by weight").

(i-2) There was no support in the original application for the value of red phosphorus of 2.1. parts by weight because the only basis therefor in Example 4 of the patent specification did not lend itself to a generalisation to the quantitative and qualitative definitions of the further components of this claim.

(i-3) In particular, this generalisation was not in line with the criteria of T 201/83 (OJ EPO 1984, 481) in that this value was closely associated with the values of the other components of the composition as could be inferred from the statement on page 3, lines 24 to 28 of the patent specification: "The amounts of red phosphorus and, optionally, of the phosphorus containing organic compound ... are, generally, correlated with those of the polycarbonate (B), in that these amounts are inversely proportional to those of the polycarbonate. Generally, it is preferred that the quantities of the total phosphorus, given by the sum of the red phosphorus both in the free status and in the combined form, be not higher than 10 parts by weight with respect to 100 parts by weight of the mixture of the two (A) and (B) resins."

(i-4) From that it followed, for example, that, differently from the situation of T 201/83, the choice of the concentration of one component (here D1) affected the concentration of the other component (here D2), since both had the same function of being a flame retardant.

(i-5) Furthermore, contrary to the situation of T 201/83, the red phosphorus value of 2.1 parts by weight lay in the middle of the exemplified values and did not, therefore, suggest itself as limiting value of an amended range of amounts.

(i-6) A further obstacle to a generalisation of the red phosphorus value of Example 4 was the importance for the properties of the resultant composition of the weight ratio acrylonitrile-butadiene-styrene copolymer (ABS) to polycarbonate (PC) of 30/70 of this example because a change of this ratio must have an impact on the amounts of the flame retardants D1 and D2 for the desired V0 flame retardancy.

(i-7) Moreover, contrary to the broad definition of the polymeric components A, B, C and D2 according to Claim 1, Example 4 made use of a specific combination of polymer components A (a specific ABS), B (a specific polycarbonate), C (a specific graft copolymer) and D2 (a specific organic phosphorus compound) and it was therefore not justified to transfer the amount of 2.1 of red phosphorus according to this example to the much broader definitions of Claim 1.

(i-8) The amendment of the value of red phosphorus to 2.1. parts by weight, thus, contravened Article 123(2) EPC.

(i-9) Likewise, the feature of the range of "1 to 30 parts by weight" of the grafted polymer component C in Claim 1 of the main request did not meet the requirements of Article 123(2) EPC because all worked examples used 5 parts by weight of component C, and because the patent in suit only referred to ranges "from 0 to 30 parts by weight" (page 6, line 24 and Claim 7) and "from 1 to 10 parts by weight" (page 6, line 24 and Claim 17). However, this objection was not further elaborated by the Appellant at the oral proceedings.

Claims 1, first and second auxiliary request

(i-10) Though, as compared with Claim 1 of the main request, these claims comprised considerably restricted ranges of amounts of components A, B, C and D2, the objections against the admissibility of the upper limit of 2.1 parts by weight of red phosphorus raised with regard to the main request remained essentially the same.

(ii) Admissibility of the third auxiliary request

In the Appellant's view, this request should not be admitted into the appeal proceedings because it was filed at a very late stage and was not clearly allowable: the chemical composition of the polycarbonate component B, which was identified in Claim 1 by reference only to the trademark SINVET(R), was unclear and could not be ascertained from the available evidence.

(iii) Objections under Article 54 EPC

In that respect the Appellant referred to its submissions of 1 December 1997 and 17 February 1999 before the first instance and maintained its assertion that the claimed subject-matter was anticipated by the disclosure of document D1.

(iv) Objections under Article 56 EPC

(iv-1) Since D1 only differed from the claimed subject-matter by the lack of a grafted polymer component C, the only problem that objectively could be formulated vis-à-vis this document was that referred to on page 3, lines 18 to 21 of the patent specification, i.e. an improvement of the weld strength. The problem which was considered by the decision under appeal ("to obtain a flame retardant and impact resistant thermoplastic composition having a V0 rating which is free of halogen") could not be accepted because there was no evidence of any improvement over D1 with respect to flame retardancy or impact resistance which was due to the addition of the grafted polymer component C.

(iv-2) The solution of the afore-mentioned technical problem by the addition of a grafted polymer component C was, however, obvious in the light of D6 which contained exactly this teaching.

(iv-3) Furthermore, the presence of an inventive step should also be denied for the subject-matter of Claim 1 of the main request on the basis of the test report attached to the Appellant's submission dated 16 March 2000 which showed that the required V0 value could not be obtained with compositions containing as the only flame retardant 0.15 % by weight of red phosphorus.

IX. The Respondent's arguments as presented in its written submissions dated 30 January 2001 and 20 June 2002 (in response to the Rapporteur's communication dated 5. April 2002) and at the oral proceedings may be summarised as follows:

(i) Objections under Article 123(2) EPC

Main request, first and second auxiliary requests

(i-1) The condition of decision T 201/83, namely that the generalisation of an individual experimental value was admissible provided that a skilled person could have readily recognised that it was not closely associated to the other features of the example, was met for the value of 2.1 parts by weight of red phosphorus according to Example 4 because

(i-1.1) the reference on page 3, lines 24 to 28 of the patent specification to a total amount of phosphorus of lower than 10 parts by weight only related to a preferred feature of the invention and not to a compulsory requirement, and

(i-1.2) because said decision did not, in fact, require that the components of the example from which the individual value was taken must have different functions.

(i-2) Furthermore, it could be concluded from the examples in the patent in suit that the amounts of the red phosphorus component D1 and of the organic phosphorus component D2 could be varied independently from one another. This was particularly clear from the influence of the amounts of the triphenyl phosphate on the Vicat and MFI values according to Examples 1 and 3 which both used the same amounts of red phosphorus.

(i-3) In spite of the variation of the amounts of red phosphorus, the same phenomenon was also apparent from Examples 7 to 10. These examples furthermore demonstrated an increase of the Izod values with decreasing amounts of red phosphorus.

(i-4) Since the specific polymeric components A, B and C as well as the specific organic phosphorus compound (triphenyl phosphate) used according to Example 4 were only representative examples of the broader definitions in the respective Claims 1, the discrepancy between the chemical species of Example 4 and the broader wording of these claims did not constitute an obstacle to the incorporation into Claim 1 of the value of 2.1 parts by weight of the amount of red phosphorus.

(i-5) Similarly, the amendment in Claim 1 of the main request of the range of component C to "1 to 30 parts by weight" was fully supported by the original specification, e.g. Claim 17 and page 6, line 24.

(i-6) Consequently, the Claims 1 of all requests met the requirements of Article 123(2) EPC.

(ii) Admissibility of the third auxiliary request

This request should be considered admissible because it was clearly supported by the statements on page 7, lines 39 to 46 of the patent specification.

(iii) Article 54 EPC

The subject-matter of present Claim 1 was novel over D1 because the compositions of this document did not comprise a grafted polymer component C.

(iv) Article 56 EPC

(iv-1) The problem underlying the present subject-matter resided in the provision of compositions having improved flame resistance while maintaining good mechanical properties, and especially high impact strength, and avoiding the use of any halogen compound. This problem was solved by the use of specific amounts of red phosphorus, optionally together with a phosphorus compound, as well as by the presence of a component C which provided particular mechanical properties.

(iv-2) The worked examples of D1 (Examples 9 to 12 and 14. to 16) showed that ABS/polycarbonate blends could only achieve a SE0 rating in the presence of at least 4 % by weight of red phosphorus or, if less red phosphorus was used, in the additional presence of sufficient amounts of a halogen-containing flame retardant (cf. Example 6: 2 % red phosphorus plus 5 % of decachlorodiphenylcarbonate).

(iv-3) However, for a number of reasons (corrosion of metallic parts, development of toxic flue gas, substantial decrease of impact strength, elongation and aging resistance) the patent in suit (cf. page 2, lines 28 to 32) wanted to avoid the presence of halogen-containing flame retardants.

(iv-4) Document D6 did not lend itself to a combination with D1; but even if these documents could be combined the resulting product would be different in that, in the case of the presence of less than 4 % by weight of red phosphorus, it must also contain a halogen-containing flame retardant.

(iv-5) The Appellant's contention that an inventive step should be denied for the claimed subject-matter on the basis of its test report of 16 March 2000 which showed that the required V0 value could not be obtained with compositions only containing 0.15 % by weight of red phosphorus was, in the Respondent's view, not conclusive because its was sufficient under the EPC that the desired technical effect of a claimed invention was, substantially obtained over the whole claimed range.

X. The Appellant requested that the decision under appeal be set aside and that the European patent No. 574 054 be revoked.

The Respondent requested that the appeal be dismissed and that the patent be maintained on the basis of Claims 1 to 14 (main request) or Claims 1 to 13 (first auxiliary request), respectively filed on 21 June 2002, or Claims 1 to 12 (second auxiliary request) or Claims 1 to 4 (third auxiliary request), respectively submitted at the oral proceedings.