T 1476/08 – Seriously Contemplating

This appeal was against the refusal of an application by the Examining Division.

Claim 1 of the main request before the Board read:

A glass comprising:

wherein the glass has at least one of the following properties:

(a) a log 10 viscosity temperature of at least 1280°F (694°C) and

(b) a liquidus temperature of at least 2350°F (1288°C).

The Board found this claim not to be novel over document D4:

[1.1] D4 (claim 1) discloses a crystallisable glass comprising approximatively in wt%:

with the mol ratio of Al2O3/R2O being between about 1 and about 1.35, R2O being an alkali metal oxide.

In its examples 5, 6 and 7, D4 discloses the following specific glasses compositions (in wt.%):

[1.2] The appellant argued that the disclosure of D4 did not anticipate the subject-matter of claim 1 because iron and (CaO and/or MgO) were absent from the above glass compositions. Further, the amount of ZrO2 was higher in the glasses of D4 than in the subject-matter of claim 1 at issue.

[1.3] The board cannot follow this argumentation because the raw materials used in the preparation of glasses always contain iron and alkaline earths as impurities and in view of the very small values of the lower limits (0.05 and 0.04, respectively) of the ranges defined in claim 1 regarding iron and (CaO + MgO), the board is convinced that the glasses known from D4 also contain such low amounts of iron and of (CaO + MgO).

[1.4] With respect to ZrO2, it is true that in the examples of D4 the amount of ZrO2 is disclosed to be 1.6%, i.e. above the upper limit of 1.5% defined in claim 1 at issue.

It is however established jurisprudence that the teaching of a piece of prior art is not limited to the specific examples disclosed therein. In this context, it is observed that D4 further discloses (claim 1) the amount of ZrO2 in terms of the total amount of ZrO2 and TiO2 in the glass, which is defined to be between 2.0 and 3.6% wt.

Considering that the examples in document D4 represent preferred embodiments of the above disclosure in claim 1 of D4, the board judges that the skilled reader of D4 would seriously contemplate (in the sense of e.g. decisions T 440/04 [4.3.2]; T 666/89) applying the broader disclosure in claim 1 of D4 to the production of other specific glass compositions close to those in the examples of D4, in particular in view of the lower limit of 2.0% wt. as regards the sum of (ZrO2 + TiO2) defined in claim 1 of D4. The skilled reader of D4 would thus seriously contemplate preparing glass compositions with a lightly lower amount of ZrO2 than in the examples of D4 (wherein the amount of ZrO2 is 1.6%), namely an amount of ZrO2 falling directly and unambiguously within the terms of claim 1 at issue, for instance 1.5% wt.

The board observes that D4 does not explicitly disclose the log 10 viscosity temperature or the liquidus temperature of the glass compositions in D4. Owing to their composition which – as explained above – reads on the wording of claim 1 at issue, at least one of these parameters should inevitably be fulfilled as a direct consequence of the chemical composition of the glasses. The board invited the appellant to comment on this issue and if the need arises, to provide evidence to the contrary, e.g. by reworking the glass compositions in D4. The appellant neither commented on this issue, nor did it provide any kind of evidence in this sense.

It follows from the above considerations that the subject-matter of claim 1 of this request lacks the requirements of A 54(1) and (2) EPC 1973 in the light of the disclosure of D4.

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