Small Differences from Prior Art Can Be Inventive

In Lonza NZ Limited v Koppers Performance Chemicals New Zealand 2020 NZIPOPAT 4 the Assistant Commissioner confirmed that close prior art is not sufficient for a finding of obviousness.

The decision concerns a divisional patent application of Lonza’s that was filed in February 2015 but which has an antedated complete specification filing date of 22nd June 2011, being the international filing date of the PCT application from which it derives, and so qualifies as a patent application under the Patents Act 1953.

The patent application relates to a fungicidal composition and methods for its use for glue-line treatment of wood products, where the composition contains the known fungicides triadimefon and cyproconazole as the active ingredients in a respective weight ratio limited to be within the range from 6:1 to 20:1. While the active ingredients are known fungicides novelty was asserted in respect of the synergistic effect of combining the active ingredients within the claimed ratios. The composition is formulated to be added to the glue shortly before it is used to glue wood products at the glue line in amounts that are not detrimental to the properties of the glue but continue to be fungicidally effective against a broad spectrum of fungi, and the synergistic effect assists in satisfying those constraints.

The PCT application from which it derives had a wider ratio of triadimefon to cyproconazole: namely a weight ratio limited to be within the range from 1:1 to 20:1. However, the application in question was limited to the 6:1 to 20:1 range on account of a prior patent (now in Lonza’s name) disclosing compositions where triadimefon is combined with cyproconazole in a molar ratio within the range from 5:1 to 1:3. Koppers alleged that Lonza’s patent application lacks novelty and is obvious in light of the earlier patent and the US application from which it derives.

The Assistant Commissioner noted that the difference between the weight ratios and molar ratios was negligible on account of triadimefon and cyproconazole having very similar molecular weights and that the prior art did not specifically teach application rates for the triadimefon cyproconazole combination. Koppers first argued that the difference between the prior art 5:1 ratio and the 6:1 ratio is mathematically trivial. However the Assistant Commissioner found that the existence of a mathematically trivial difference is irrelevant as the key question in applying the General Tire [1972] RPC 457 test for anticipation is whether the skilled person following the prior art would inevitably produce a composition within the claimed weight ratios. The Assistant Commissioner held that the skilled person would not diverge from the range stated in the prior art as they would want to obtain a composition with known fungicidal properties.

Koppers next argued that the only difference between the prior art and Lonza’s application is the ratio and that the closeness of the ratio ranges means that the application claims subject matter that is obvious. However, the Assistant Commissioner criticized this argument for not taking into account the differences between the tests for novelty and obviousness, stating that being nearly not novel in the sense that it is very close to the 5:1 ratio disclosed in the prior art does not imply that the claims are obvious because they are only not novel by a small degree. In contrast to the findings of the Delegate in the related Australian proceedings the Assistant Commissioner found that the application rates for the triadimefon cyproconazole combination is part of claimed monopoly and so constitutes another difference from the prior art.

However, even without that other difference, the Assistant Commissioner still found that obviousness was not established. Koppers had argued that there was no material difference between the 5:1 ratio and the 6:1 ratio as the PCT application disclosed no difference in synergy for those ratios. The Assistant Commissioner held that it didn’t follow from this that it would be obvious for the skilled person to investigate nearby ratios such as 6:1, especially as there was nothing presented regarding why the skilled person would be motivated to do so. Even if Koppers had established the obviousness of 6:1 Lonza could have amended without affecting its monopoly in its commercial product which has a ratio of 10:1.

Koppers further attempted to establish obviousness from the prior art in combination with their assertion that it was common knowledge for the person skilled in the art to test azole pair combinations for fungicidal effectiveness across a range of ratios from 20:1 to 1:20. Lonza sought to counter this with expert evidence to the effect that the increased synergistic effect as the ratios increased from 6:1 to 20:1 were unexpected. Koppers’ experts cast doubt on the statistical basis of that claim, but the Assistant Commissioner gave Lonza the benefit of the doubt (given that the 1953 Act applies). Nonetheless, irrespective of the asserted increased synergy, the Assistant Commissioner rejected Koppers' common knowledge claim. Firstly, the Assistant Commissioner cast doubt on whether the experience of one of Koppers’ experts in testing a range of ratios was common practice or more akin to privileged and confidentially held company information. Secondly the expert had not been aware of the use of triadimefon as a wood preservative until close to the priority date and only gave an example of an azole-azole combination in a 1:1 ratio. Thirdly, the expert’s experience related to the fungicidal treatment of whole wood products rather than glue-line treatment and it was known that effectiveness in treating the former did not necessarily imply effectiveness in treating the latter. Instead the Assistant Commissioner accepted the evidence of other experts who stated that it was common knowledge for the person skilled in the art to test azole pair combinations for fungicidal effectiveness across a range of ratios from 3:1 to 1:3. The Assistant Commissioner also noted that it was known that cyproconazole is far more effective as a fungicide than triadimefon and so it would be counter-intuitive for the skilled person to think that further diluting cyproconazole with triadimefon would give improved results. Given these doubts the Assistant Commissioner held that obviousness had not been established.

Author: Quinn Miller

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