T 0127/85 (Blasting compositions) of 1.2.1988

Summary of Facts and Submissions

I. European patent No. 19 458 was granted on 5 January 1983 with 13 claims in response to the European patent application No. 80 301 578.3 filed on 14 May 1980 claiming the priority of the earlier application of 21 May 1979. Claim 1 is worded as follows: "A cap-sensitive water-in-oil emulsion blasting composition comprising a water-immiscible liquid organic fuel as a continuous phase, an emulsified aqueous, inorganic oxidizer salt solution as a discontinuous phase, an emulsifier, and perlite as a density reducing agent in an amount sufficient to reduce the density of the composition to within the range of from 0.9 to 1.4 g/cm3 characterised in that the perlite has an average particle size ranging from 100 µm to 150 µm and is present in an amount sufficient to render the composition cap-sensitive".

II. An admissible notice of opposition was, on 26 September 1983, filed against the European patent ...

V. The Appellant emphasized in his submissions that (1) disclosed the improvement of cap sensitivity of the blasting compositions by incorporating closed cell material containing voids or hollow cavities, such as glass microbubbles, and that US-3-755 964 (5) cited in the search report explained that expanded perlite was suitable to reduce the density of the composition. Commercial grades of this material embraced the claimed range for perlite particles (cf. (3), 0-1.5 mm). The range based on average particle size was not clearly defined in the claims, since this could either be based on weight or on the number of particles of the materials. It could not, in any case, characterise the spread of the distribution.

VI. The Respondent (Proprietor of the patent) cited the Appellant's admission in a parallel case of a national application that perlite was not normally a closed cell, void containing material, and argued that according to (1) such additive would not yield sensitive explosives (cf. col. 5, lines 53-60). As to the clarity of the claims it was clear from the description that the average particle size referred to was based on weight average. Only such interpretation corresponds to the values in the examples, except one which inadvertently fell outside the scope of the claim and should therefore be deleted. ...

Reasons for the Decision

1. The appeal complies with Article 106 to 108 and Rule 64 EPC and is, therefore, admissible.

2.1. As to the question of the alleged lack of clarity of claims in consequence of the equivocality of the term "average particle size" in the claim or of an example falling outside the scope of the claim, this need not be investigated further than what is necessary to enable the assessment of the issue already at hand, i.e. the inventive step. It is the view of the Board that such objections and any consequent requests for amendments are only relevant to opposition proceedings as far as they can influence the decisions on issues under Article 100 EPC or arise in any case in relation to matter to be amended in the patent specification in consequence of such issues. This is particularly relevant to objections under Article 84 EPC.

2.2. Of the two possible interpretations of the term "average particle size", namely an average based on the weight of the particles and on the number of particles, the former appears to be consistent with all examples except the one with INSULITE where the calculated average falls just outside the stated limits. This would not be the case if one were to attribute the same importance to each particle whether large or small, and then averaged according to their numbers. Such calculation would reduce the average drastically to a figure below the range specified in the claim which would then be clearly inconsistent with the disclosure (cf. decision on the allowability of corrective amendments on a similar basis in T 13/83, "Polyisocyanurate" (OJ EPO 1984, 428)). The Board therefore accepts the interpretation of the term on the weight basis. As the true construction of the disclosure effectively removes the alleged ambiguity, there is no need to amend the claim.

2.3 The further criticism that the average for particle size could not characterise the spread of the distribution, and the term was therefore unreliable is again a matter under Article 84 EPC. Since the average size still governs the main aspect of the particle size distribution, and there was no suggestion that the absence of additional secondary statistical characteristics makes any difference on the real issue of the case the argument must be rejected as irrelevant. ...

7.1 As to the request from the Respondent to delete the example titled INSULITE from the specification, the Board considers this as unacceptable in the circumstances of the case. Some uncertainty or ambiguity, i.e. lack of clarity may arise in certain instances for a claim which is otherwise perfectly clear in language and semantic content, if an example purporting to illustrate the invention falls outside its scope. This is, however, purely a question under Article 84 EPC relevant to the prosecution of the application before grant or to the proper examination of the allowability of an amended claim contemplated after grant. Any deficiency in this respect is, however, itself no ground whatsoever for opposition under Article 100 EPC before the EPO, including self-opposition in consequence of a decision of the Enlarged Board of Appeal (G 01/84 "Opposition by the proprietor/MOBIL OIL", OJ EPO 1985, 229) by the proprietor, and cannot therefore be considered by the Board unless the uncertainty of the scope of the claim influences the outcome of legitimate issues. It could lead to an abuse of the institution of opposition proceedings if the patentee were allowed merely to tidy up and improve his disclosure by amendments not necessitated by the proper opposition grounds themselves even if the amendments were to comply with Article 123 EPC.

7.2 The requested correction of the specification cannot be construed as coming within Rule 89 EPC, either, since it cannot be considered in any case as an obvious mistake in the decision to grant the patent. This is because the original insertion of the example in the text could have also served the purpose of supporting a broader claim than that which was eventually granted. The request for the amendment cannot therefore be entertained, in the present case, for the patent under any of the provisions of the Convention.

ORDER

For these reasons, it is decided that

The appeal is rejected.