T 1834/11 (Core-shell powder particles/VALSPAR) 16-10-2013

1. The appeal is admissible.

2. Procedural matters

2.1 The ground for opposition under Article 100(c) EPC was raised for the first time during the oral proceedings before the opposition division by the respondent. In exercising its discretion under Article 114(2) EPC, the opposition division decided to admit this late-filed ground into the proceedings.

2.2 This decision was challenged by the appellant, who argued that the opposition division had not exercised its discretion correctly. In support, the appellant referred to point 4.2.4 of the reasons for the decision, which states "Therefore, the opposition ground under Arts. 100(c) and 123(2) EPC is not relevant in the present case". According to the appellant, the opposition division had no reason to admit a ground which was filed at such a late stage without justification and which, in addition, it did not consider to be relevant. This ground should, therefore, not be considered in the appeal proceedings.

2.3 The board is not convinced by the appellant's arguments.

The statement to which the appellant referred is part of point 4.2 of the contested decision entitled "Reasoning", which deals with the allowability of the newly raised ground for opposition under Article 100(c) EPC, i.e. with the question whether or not this ground prejudiced the maintenance of the patent in suit. The question of its admission into the proceedings is discussed in point 4.1 of the contested decision entitled "Admissibility". In point 4.1.1 the opposition division summarised the appellant's arguments as to why the new ground was not prima facie relevant. Apparently, the opposition division was not convinced by these arguments. It considered this ground to be relevant for the opposition proceedings and, accordingly, decided to admit it into the proceedings (point 4.1.2 of the contested decision). In view of the fact that the term "liquid carrier" cannot be found in the passages cited by the appellant, thus requiring a more detailed examination, the opposition division had good reasons to consider this ground as (prima facie) relevant and to allow it into the proceedings, notwithstanding the fact that, ultimately, it did not follow the respondent's argument and considered Article 100(c) EPC to be complied with.

The board concedes that the wording the opposition division used in its statement in point 4.2.4 is rather unfortunate and misleading. The board is, however, convinced that in view of the separate decision on the admissibility in point 4.1 and taking into account the first part of the statement in point 4.2.4 that the "opposed patent fulfills the requirements of Article 123(2) EPC", the proper understanding of the opposition division's statement is that the opposition division considered that the ground of opposition under Article 100(c) EPC did not prejudice the maintenance of the patent in suit.

2.4 The board, therefore, sees no indication that the opposition division has exercised its discretion to admit the late-filed ground for opposition under Article 100(c) EPC into the proceedings in a wrong or unreasonable way and, consequently, sees no reason to overrule the decision of the first instance in this respect (G 7/93 OJ EPO 775, point 2.6 of the reasons).

Main request (claims as granted)

3. Amendments

3.1 According to the respondent, the term "liquid carrier" in claim 1 as granted was nowhere to be found in the application as originally filed, which only mentioned the general term "carrier". The liquid carriers referred to on page 7, lines 9 to 17 were merely examples. Furthermore, the last paragraph of the same page referred to solid dispersions, which means that at least in these cases the carrier can also be solid. The term "liquid carrier" therefore constituted an intermediate generalisation which had no basis in the application as originally filed.

3.2 The board is not convinced by the respondent's arguments.

Support for the use of a carrier in the presently claimed method was uncontested. On page 7, lines 9 to 17 of the application as filed suitable carriers are mentioned, which are all liquids (for example water, organic solvents or mixtures thereof, in particular water, aliphatic solvents such as "Mineral spirits", "VM&P Naphtha", hexane, heptane and octane). There is no mention of suitable "solid carriers". Furthermore, in the last paragraph of the same page it is stated that "The dispersion may be a liquid, slurry, gel, paste or solid, though liquids are generally preferred" (emphasis added by the board). The respondent's arguments that this cannot support the fact that a liquid carrier is used, since liquidity could be the result of the dispersing aid, is not considered convincing in view of the fact that dispersing aids are not mentioned in this context, and in view of the preceding paragraphs referring to suitable carriers which are all liquids. Furthermore, this last paragraph continues on page 8, lines 3 to 4 with the explanation that solid pre-dispersed pigments (pigment dispersion) can be transformed into a liquid dispersion by mixing with a suitable carrier, which speaks against the respondent's arguments that the dispersing agent provides the liquidity. Furthermore, as pointed out by the appellant, on page 7, line 22 the dispersing agent is soluble in the carrier, which also supports the fact that the carrier is a liquid. Other indications that the carrier is a liquid are that the carrier is removed (see page 12, lines 9-10), as pointed out by the appellant, which preferably takes place by drying (see page 10, line 22).

The board also concurs with the appellant that the carrier being a solid is not a technically meaningful interpretation in view of the aim of the invention to coat the base powder particles with a colourant.

3.3 For the aforementioned reasons, the board concludes that the ground for opposition pursuant to Article 100(c) EPC does not prejudice the maintenance of the patent on the basis of the main request.

4. Sufficiency of disclosure (Article 100(b) EPC)

4.1 Claim 1 is directed to the preparation of a free flowing powder from a base powder comprising a thermosetting binder and a stable colourant dispersion. The colourant dispersion comprises a pigment with a median particle size of 0.04 to 1 microns or a dye in a liquid carrier and the mixing of the base powder and the colourant dispersion is performed below 40**(o)C (see point II above).

Claim 11 is directed to a composition comprising a core-shell particle with the core particle comprising a thermosetting binder and the shell comprising a dye or a pigment particle and a dispersing aid. The pigment particle has a median particle size of 0.4 to 1 microns and the dispersing aid comprises one or more surfactants, monomers, polymers and oligomers (see point II above).

4.2 With respect to the alleged insufficiency of disclosure, the respondent essentially argued that the median pigment particle size in claims 1 and 11 was not sufficiently defined to enable the skilled person to carry out the invention without undue burden, since the type of median particle size (for example volume, surface area, number) was not specified and no information was available as to which method was used for the determination of the particle size. According to the respondent, no standard method existed and the various methods available to the skilled person yielded different results. Moreover, the respondent argued that even for a single method, like laser diffraction, sample shape, sample preparation and data analysis had an essential influence on value and type of the particle size. In support of its assertions, the respondent relied on a number of documents, including documents (2), (12), (17) (18), (20) or (21). Furthermore, it referred to decision T 914/01.

4.3 The board does not dispute the fact that various types of, and measurement methods for, median particle sizes exist or that depending on the circumstances different results may be obtained using different methods. It can also not be denied that the patent in suit does not contain explicit information as to the type of median particle size or the method for its measurement. However, it is the board's conviction that the respondent's objections in this respect concern the question whether the claimed invention is correctly defined in accordance with Article 84 EPC, i.e. whether the scope of the claims is clear. Since Article 84 EPC is not a ground for opposition, deficiencies under this article are not to be considered in the examination of the present main request, which corresponds to the claims as granted.

4.4 The board accepts that the lack of a clear definition of a parameter (in particular if a newly formulated and therefore unfamiliar parameter is used and no method for its measurement is defined) may well lead to an objection of insufficiency of disclosure. However, the board is convinced that this does not apply in the present case for the following reasons:

4.4.1 The present invention is not concerned with the preparation of pigment particles but relates to the preparation of powder coating compositions (paragraphs [0001] and [0011], claim 1). This is achieved by mixing colourants (dye or pigment dispersions in a liquid carrier) and optionally other ingredients with the base powder. The colourant, once added to the base powder, forms a coating layer (shell) on the surface of the base powder particles (core) (paragraph [0045], claim 11). According to the patent in suit, covering the base powder particle with a colourant comprising shell instead of distributing the colourant throughout the base powder particle has certain advantages (see patent in suit, paragraphs [0002] to [0010] and [0049]).

4.4.2 The patent in suit contains a considerable number of examples illustrating the claimed subject-matter and provides further detailed information on the selection of suitable base powders (paragraphs [0017] to [0022]), suitable carriers (paragraph [0028]) and the mixing and treatment steps for obtaining the free flowing powder (paragraphs [0037] to [0042]). This was not contested by the respondent. Suitable pigments according to the patent in suit are readily available commercial products (paragraph [0025]) with typical particles sizes falling well within the presently claimed range (paragraph [0026]). This was also not disputed by the respondent. Furthermore, the patent in suit indicates that, if the colourant is a pigment, the number of pigment particles should be much higher than the number of base powder particles and their size much smaller (paragraphs [0044] and [0045]).

4.4.3 The board also notes that there is no indication in the patent in suit that a particular particle size belongs to the core of the invention. What is essential - and here the board concurs with the appellant - is the formation of a colourant layer on the surface of the base powder particles. Information as to how this can be achieved is clearly derivable from the patent in suit (see point 4.4.2 above). Hence, the skilled person has no difficulties in putting the invention into practice. No undue experimentation and no particle size measurement are required. With regard to the particle size, the skilled person relies on the specification provided by the supplier.

4.4.4 The respondent has provided no experimental evidence showing that by using these commercially available products (irrespective of how their size was measured), the skilled person is unable to prepare the base powder particles surrounded by the colourant-comprising shell. Relying on the aforementioned documents, the respondent has merely shown that the measurement method used for the determination of a particle size, including sample shape, sample preparation and data analysis, may have an influence on the actual value of that parameter, i.e. it has shown that an ambiguity exists due to the lack of information concerning the method for particle size measurement, but not that the claimed subject-matter is not workable or that undue burden is associated with achieving the benefits of the claimed invention.

4.4.5 Notwithstanding the lack of experimental evidence, the board also notes that claim 1 refers to a rather broad range for the median particle size. Thus, even if, as argued by the respondent with reference to document (18), the particle size measured with two different methods can be up to three times higher (or lower), such a particle size would still be mainly within the claimed range, considering the typical particle size of suitable pigments (paragraph [0026] of the patent in suit). The accuracy of measurement techniques takes effect mainly at the edges of the claimed range, which according to established jurisprudence of the boards of appeal is not sufficient to support an objection of insufficiency of disclosure (T 482/09, see point 2.1 of the reasons, T 608/07, point 2.5.2 of the reasons, T 593/09, points 4.1.4 and 4.1.5 of the reasons). Moreover, as indicated in paragraph [0026] of the patent in suit, particles sizes of 0.01 to 4.0 microns are apparently equally suitable in the present invention.

4.4.6 Furthermore, in the present case, the fact that the skilled person has no clear information as to the type of the median particle size does not mean that he cannot carry out the invention. It merely requires that he take into account every technically meaningful interpretation of this feature in the context of the invention.

4.4.7 In the board's opinion, decision T 914/01 cannot support the respondent's objection of insufficiency either, since the cases are not comparable. In the decision T 914/01 the support for a catalyst system was defined by a number of unusual parameters. At least for one of these parameters no standard measurement method existed. Furthermore, there was no evidence that the support was commercially available and the method for its production was not sufficiently described for the skilled person to obtain the support with the desired properties without carrying out a research programme.

4.5 In view of the above, the board concludes that the patent in suit provides sufficient information for the skilled person to carry out the invention. The ground for opposition according to Article 100(b) EPC does therefore not prejudice the maintenance of the patent on the basis of the main request.

5. Remittal

5.1 In the decision under appeal the opposition division revoked the patent solely on the ground of lack of sufficiency of disclosure. It did not decide on the other grounds of opposition relied on by the respondent, that is lack of novelty and inventive step. It did, however, present comments on novelty with respect to claim 11 in an "obiter dictum", which it emphasised was not part of the decision.

5.2 The board notes that lack of novelty as a ground of opposition was not discussed with the parties during the oral proceedings before, and not decided by, the opposition division. The board is therefore of the opinion that lack of novelty of claim 11 as a ground for opposition had not been the subject of a complete and final examination before the opposition division. The obiter dictum merely represents the preliminary opinion of the opposition division on the subject-matter of claim 11 of the main request. In addition, the board notes that the division has not yet decided on the objections of lack of novelty and inventive step raised against claim 1 of the main request.

5.3 In view of the above, the board was not convinced by the respondent's argument that the case was "ready for decision" and that for reasons of procedural economy the board should come to a final decision in the present case.

5.4 In these circumstances, the board considers it appropriate to exercise its discretionary power pursuant to Article 111(1) EPC in the appellant's favour and remit the case to the department for further prosecution.

5.5 Having come to the conclusion that the main request complies with the requirements of Article 100(b) and (c) EPC and having decided to remit the case, there is no need for the board to decide on auxiliary requests 1 to 6.