T 0334/03 23-01-2004

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

2. Late filed documents

It may be convenient to recall at this juncture that Documents D3 to D5 were filed by the appellant for the first time with the statement of grounds of appeal and were, therefore, late filed. At the oral proceedings, the appellant withdrew its request for their introduction into the proceedings (see point VI, above). Consequently, D3 to D5 do not belong to the factual framework of the case which is the subject of the present appeal.

3. Interpretation of Claim 1 (main request)

3.1. Claim 1 as granted is in the form of a use claim. In particular, it is directed to the use of a specified amount of graphite having a specific average particle diameter as laser sensitive pigment in thermoplastic polyester resin compositions which are suitable to be marked with laser light.

3.2. It has been stated in decision G 6/88 (supra) that there are basically two different types of claim, namely a claim to a physical entity (eg product, apparatus) and a claim to a physical activity (eg method, process, use) (point 2.2 of the reasons) and that the technical features of a claim to an activity are the physical steps which define such activity (point 2.5 of the reasons). Thus, in the present case, the decisive question is which physical steps are required by the activity (use) referred to in Claim 1.

3.3. As pointed out above, Claim 1 as granted is directed to the use of a specified amount and form of graphite as laser sensitive pigment in thermoplastic polyester resin compositions. In effect, that use claim is directed to the use of a physical entity (graphite) to produce a product (thermoplastic polyester resin composition) which requires the physical step of incorporating the graphite into a thermoplastic polyester resin. This activity is notionally equivalent to a process for producing a thermoplastic resin composition including the step of using graphite. Apart from this, no further physical step forms part of the claimed activity. The resulting composition contains graphite and is, as required in Claim 1, suitable to be marked with laser light. Neither the term "as laser sensitive pigment" nor the term "suitable to be marked with laser light" requires an activity involving the application of laser light. Moreover, these terms refer to an intended use of the resulting composition and are therefore not apt to further limit the claim. In other words, laser marking is not a physical step of the activity claimed in Claim 1 and, hence, not a technical feature of the claim.

3.4. On the other hand, the respondent interpreted Claim 1 as encompassing laser marking as a mandatory technical feature whereby its only justification for this interpretation was that laser marking was at least hinted at by the wording chosen in Claim 1.

3.5. If the board were to follow the interpretation of the respondent that Claim 1 include a laser marking step, Claim 1 as granted would not define the matter for which protection is sought in terms of the technical features of the invention (Article 84 in combination with Rule 29(1) EPC). Since such an objection against a granted claim is not possible at the opposition and the opposition appeal stage, respectively, the board has to interpret the claim in its broadest meaning for the assessment of novelty and inventive step. Consequently, Claim 1 is interpreted as being directed to the use of graphite in the production of a thermoplastic polyester resin composition which is suitable for laser marking whereby laser marking as such is not a limiting technical feature of the claim.

4. Novelty (main request)

4.1. In the present case, the only ground of opposition was inventive step. However, in view of the broad interpretation of Claim 1 (point 3, above), the board deems it appropriate to confirm that the claimed subject-matter is novel over D1 and D2 even in this broad interpretation.

4.2. D1 discloses a process for marking high molecular weight organic material containing at least one radiation-sensitive additive that effects a change in colour which process comprises utilising a laser beam, and using as additive at least an inorganic and/or organic pigment and/or a polymer- soluble dye (Claim 1). The markings obtained by this process are - inter alia - of high contrast, easily legible and have good edge definition (page 10, last paragraph; page 11, 2nd paragraph). Graphite is mentioned as a possible radiation- sensitive additive amongst an extensive list of possible examples of varying inorganic pigments (paragraph bridging pages 3 and 4). The particle size of the pigments, and in particular of the graphite, is not disclosed. Polyester resin is mentioned - inter alia - as a suitable high molecular weight organic material (Claims 5 and 6). The amount of the colour-forming additive is in the range of 0.001 to 10 wt.% based on the high molecular weight organic material, preferably in the range of 0.01 to 3 wt.% (page 5, fourth paragraph). However, the use of a polyester resin in combination with graphite, let alone with graphite in the amount and form (average particle diameter) as required in the patent in suit, is not disclosed in D1. Furthermore, none of the examples using a polyester resin (Examples 2, 5 to 8, 16 to 21 and 24 to 26) contains graphite as a laser sensitive additive. Thus, the subject-matter claimed in the patent in suit is novel over D1.

4.3. D2 discloses in Claim 1 a composition containing a thermoplastic high molecular weight organic material, 0.001 to 3.0% by weight of graphite, relative to the high-molecular weight organic material, and one or more pigments or polymer- soluble dyes. It has been found that in the dyeing of plastics with a pigment or dye the addition of graphite provides homogeneous, evenly glistening and novel shades of colour. With regard to the nature of the graphite, crystalline graphite having a particle diameter of less than 100 µm is preferred (page 2, last paragraph). Linear polyester resin is mentioned - inter alia - as a suitable high molecular weight organic material (Claim 3, page 1, last paragraph). However, the combination of a polyester resin in combination with graphite in the amount and form (average particle diameter) as required in the patent in suit, is not directly and unambiguously derivable from D2. Furthermore, none of the examples of D2 uses a polyester resin. Thus, the subject- matter claimed in the patent in suit is also novel over D2.

5. Problem and solution

5.1. It follows from the above analysis of the wording of Claim 1 (point 3.3) that the patent in suit is concerned with a process for producing a thermoplastic polyester resin composition including the step of using graphite. The compositions obtained according to this process exhibit a high contrast in the marking with a YAG laser or a CO2 laser and permit the marking of fine lines or precise prints (page 2, lines 31 to 32).

5.2. Such a process is known from D1 which discloses technical effects, purpose and intended use most similar to the claimed invention (see point 4.2, above). Hence, in accordance with the opposition division and the respondent, the board regards this document as representing the closest state of the art. D2 cannot adequately fulfil this function, since, as rightly submitted by the respondent, it is not concerned with laser marking at all.

5.3. It also is clear from the above analysis (see point 4.2, above) that the processes of both the patent in suit and the closest prior art provide compositions with good laser marking properties. Thus, the salient point in the present case is whether or not the process of Claim 1 of the patent in suit yields a product which has improved properties, as argued by the respondent. The outcome of this issue is important because in this step of the problem solution approach the technical effect(s), if any, that the patent in suit provides over the closest prior art are taken into account when formulating the objective technical problem. When evaluating the technical effect(s) of a process, the character of the product resulting from this process has to be taken into account since the effect of a process manifests itself in the result, ie in the product in chemical cases (see eg T 119/82, OJ EPO 1984, 217, point 11 of the reasons).

5.4. All examples in the patent in suit, ie Examples 1 to 6 (polyester resin and graphite) and Comparative Examples 1 to 4 (polyester resin and carbon black), were prepared according to the general teaching of D1 which equally mentions both graphite and carbon black as a laser sensitive additives for thermoplastic resins. It is immediately evident from the data in Tables 1, 2, 4 and 5 in the patent in suit, that the use of graphite in the polyester resin improves the marking properties of the composition with respect to the contrast ratio of background luminance (BL) to characteristic luminance (CL), the etching depth and the foamability. The foamability is related to the phenomenon in which graphite contained in a moulded article absorbs laser light to generate heat, and the polymer around it is thermally decomposed and foamed to form the marking. Therefore, compared with D1, the objective technical problem to be solved by the patent in suit has to be seen in the provision of a thermoplastic resin composition with improved laser marking properties.

5.5. As regards the appellant's objection that the average particle diameter of the graphite did not contribute to the solution of the relevant technical problem and could therefore not be taken into account when assessing the inventive step of the claimed subject-matter (see point VI(c), above), the data in Table 3 of the patent in suit demonstrate, as pointed out by the respondent, that the average particle diameter of the graphite influences the contrast ratio CL:BL, a property which has been taken into account when formulating the objective technical problem (point 5.4, above). Since, furthermore, the respondent resiled from its written statement at the oral proceedings and the appellant has not in fact shown that this parameter is a superfluous feature, the board finds it credible that all the claimed features provide an effective solution of the stated problem arising from D1.

6. Inventive step

6.1. For the assessment of inventive step, it is necessary to consider whether the skilled person, in possession of the technical teaching according to D1, would have expected that the laser marking properties of thermoplastic resins could be enhanced by using a combination of a polyester resin and graphite, whereby the graphite has a particle size and is used in an amount as defined in Claim 1 of the patent in suit.

6.2. In D1 itself, there is no suggestion as to how the laser marking properties of the thermoplastic compositions might be further improved, let alone a hint to the combination of a polyester resin and a specific graphite as a more promising variant within the general teaching of D1. Consequently, the disclosure of D1 itself offers no hint to the solution of the relevant technical problem.

6.3. As to the disclosure of D2, there is no reason why the skilled person should consider this teaching as relevant to the solution of the technical problem in the first place, since it does not relate to laser marking of polymeric compositions. Thus, there can be no pointer to the solution of the technical problem in the teaching of D2, either.

6.4. With its approach pursued at the oral proceedings that the claimed subject-matter was not novel over D2 and therefore not inventive (see point VI(b), above), the appellant avoided the introduction of novelty as a new ground of opposition, presumably relying on the finding in point 7.2 of G 7/95 (OJ EPO 1996, 626) where it has been held that "if the closest prior art document destroys the novelty of the claimed subject- matter, such subject-matter obviously cannot involve an inventive step". This approach proceeds on the assumption that the combination of polyester resin and specific graphite (including the amount thereof) is disclosed in D2. Since, however, D2 does not clearly and unambiguously disclose this specific combination (see point 4.3, above), ie a general disclosure does not take away the novelty of a specific disclosure, the basis assumption of the appellant's approach is not correct. Thus, the present case is different from G 6/88 (supra) which dealt with a claim to the new use of a known compound. Consequently, this approach must fail.

6.5. In view of the above, it is evident that the subject- matter of Claim 1 of the main request, and by the same token, that of dependent Claims 2 and 3, does not arise in an obvious way from documents D1 and D2. Hence, the subject-matter of Claims 1 to 3 as granted involves an inventive step.

7. Because the respondent succeeded on the main request, there was no need to consider the introduction of the auxiliary request into the proceedings.