T 570/08 – Abnormality

When the patent proprietor and the opponents file contradictory experimental results, will the patent proprietor be given the benefit of doubt? Not always, as the present decision shows.

Claim 1 of the main request read:

A fuel composition comprising a major amount of a diesel fuel oil containing not more than 0.05% by weight of sulphur and having a 95% distillation point of not greater than 350°C, and from 150 to 500 ppm (active ingredient) by weight, per weight of fuel oil, of an additive composition comprising (a) an ashless dispersant comprising an acylated nitrogen compound and (b) a monocarboxylic acid of general formula

R’(COOH)

wherein R’ represents an alkyl group or alkenyl group having 10 to 30 carbon atoms; wherein the ratio of (a):(b), on a weight:weight basis, is in the range of from greater than 1:4 to 2 1; and wherein the acylated nitrogen compound comprises a hydrocarbyl-substituted succinimide or succinamide prepared by reacting a poly(isobutylene)-substituted succinic anhydride acylating agent wherein the poly(isobutylene)-substituent has between 30 and 400 carbon atoms with a mixture of ethylene polyamines having 3 to 7 amino nitrogen atoms per ethylene polyamine and 1 to 6 ethylene groups.

The Board considered D31 to be the closest prior art and pursued:

[1.1.2] The problem according to the patent-in-suit vis-à-vis D31 is the provision of a low sulphur fuel composition comprising an additive composition with improved low temperature solubility while exhibiting good lubricity performance.

[1.1.3] The composition of Claim 1 represents the proposed solution to this problem.

[1.1.4] The Opponents argued that the problem has not been solved over the entire range claimed.

Opponent 4’s comparative tests of 23 May 2008 show in test runs 9 and 10 that the addition of 250 ppm detergent 3 (a dispersant defined as compound (a) in Claim 1 of the patent-in-suit) to 250 ppm behenic acid (which corresponds to compound (b)) results in an increase of sediment level, i.e. a decrease of solubility. The Proprietor did not dispute the results but regarded them as an “abnormality”.

Opponent 5’s tests of 22 December 2008 show that the addition of a dispersant (a) to oleic acid does not lead to any improvement in wear scar after 28/29 days at -30°C and that the addition of dispersant (a) to TOFA b after 27 days at -30ºC even leads to an increase in wear scar.

These results are in contrast to Proprietor’s tests of 27 March 2002, 14 September 2007 and 20 May 2008. However in the latter tests the fuel has either not been defined as a low sulphur diesel containing not more than 0,05% by weight of sulphur or they do not specify the compounds (a) and (b) exactly as defined in Claim 1 of the main request.

Even when assuming that these tests meet the requirements defined in Claim 1 of the main request, the Board would still be confronted with several sets of tests of the parties leading to contradicting results. Therefore it cannot be concluded that improved lubrification and solubility of the additive is achieved in low sulphur diesel fuel, at least not for all combinations claimed.

Proprietor’s argument that the burden of proof would still be on the Opponent’s side is not valid, as results have been provided by the Opponents which cast doubts on the effect allegedly achieved by the present invention. However, the Proprietor could not convincingly eliminate these doubts.

Therefore, since an effect has not been proven, the objective problem has to be re-formulated as the provision of low sulphur diesel fuel compositions comprising an additive composition with alternative low temperature solubility while exhibiting good lubricity performance.

The patent was finally revoked for lack of inventive step.

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