Friday, 19 August 2011

T 967/08 – D-ISO-lation

Most patent drafters are well aware that when you characterise an invention by parameters which have to be measured, it is necessary to unambiguously define the measurement method. When the inventor provides a well documented measurement standard, such as an ISO or ASTM standard, everything looks fine. But is it? Not necessarily, as the present decision shows.

The decision deals with an appeal against the refusal of the application under consideration by the Examining Division.

Claim 1 before the Board read:
A process for the Direct Synthesis of trialkoxysilane of formula HSi(OR)3 wherein R is an alkyl group containing from 1 to 6 carbon atoms using a member selected from the group consisting of nanosized copper, nanosized copper oxides, nanosized copper chlorides, other nanosized copper salts, and mixtures thereof, having an average particle size in a range from 0.1 to 100 nanometers, as sources of catalytic copper, said process comprising:
(a) forming a reaction mixture comprising a thermally stable solvent, silicon metal, a catalytically effective amount of said nanosized copper catalyst precursor;
(b) agitating and heating this mixture to form copper-activated silicon in situ and injecting into said reaction mixture an alcohol to react with said copper-activated silicon to produce said trialkoxysilane; and
(c) recovering said trialkoxysilane from the reaction product. (my emphasis)
[2.1] The Board mentioned in its communication that document D4 stated the following […]:
“The general description of an average particle size within a powder is thus dependent upon both the type of size distributions and the method of calculation from moments of the particle size mean.”
The appellant did not provide any evidence for its statement that the values of average particle sizes determined by different methods were similar.

Moreover, it is known that these values may differ considerably. Reference is made to T 1819/07, where the following is stated under point 3.2 of the reasons:
“... average particle sizes (more precisely: mean particle diameters) such as the arithmetic mean diameter (or count mean diameter) ð, the volume or mass mean diameter ðv and the mean surface area diameter ðs are among the most commonly used quantities for describing the average diameter of a particle population (...). The values of the average particle sizes ð, ðv, and ðs differ for any particle size distribution (...). …

Hence, there are different methods for determining the average particle size yielding values for the same particle distribution and these generally differ, under particular conditions by one or two orders of magnitude.”
[2.2] The appellant referred to the first complete sentence in the right-hand column on page 13 of document D4 which reads as follows:
“Equations for the calculations of average particle sizes or average particle diameters from a given particle size distribution are defined in ISO 9276-2(39) to give a unique definition of average size, derived from the moments of a size distribution.”
The respective standard D7 does not, however, give one definition of average particle size but rather provides equations for calculating the different kinds of averages (see document D7, third page (page 1 of ISO 9276-2:2001), namely the arithmetic averages (chapter 5.1), weighted averages (chapter 5.2) and further average particle diameters (Annex B); see page 5, fourth to second line from the bottom, which refer to length, surface and volume averages).

[2.3] For these reasons the Board concludes that
  • the person skilled in the art would equally consider several methods when determining average particles sizes, and
  • these different methods yield considerably different values.
Claim 1 refers to a range of average particle sizes without indicating which type of average is to be taken or by which method it is to be determined.

Hence, for a given particle size distribution, the average particle size determined by one method may be within the range indicated in claim 1 whereas it may be outside said range when determined by another method. Therefore, this feature is unclear.

[2.4] “A claim comprising an unclear technical feature, ... entails doubts as to the subject-matter covered by that claim. This applies all the more if the unclear feature is essential with respect to the invention in the sense that it is designed for delimiting the subject-matter claimed from the prior art, thereby giving rise to uncertainty as to whether or not the subject-matter claimed is anticipated.” (T 728/98 [3.1]).

The latter applies to the feature “average particle size” in the present case […].

[2.5] For these reasons claim 1 of the main request and of auxiliary request II is unclear.

So when you cite a standard, it might be a good idea to actually have a look at it. ;-)

To read the whole decision, click here. The file wrapper can be found here.