T 0497/03 (Vinylidene fluoride polymer dispersion/DAIKIN) 08-08-2006

1. The appeal is admissible.

Main request

2. Sufficiency of disclosure

2.1 A European patent gives rise to objection under Article 100(b) EPC if it does not disclose the invention in a manner sufficiently clear and complete for it to be carried out by the person skilled in the art. This ground of opposition refers directly to the requirement provided by Article 83 EPC. The essence of the Respondent's arguments regarding lack of disclosure is that the skilled person does not have sufficient guidance from the patent in suit in order to arrive at the desired aqueous dispersion of a vinylidene fluoride polymer within the whole ambit of Claim 1 (see point IX above).

2.2 Since Claim 1 relates to a product defined by chemical and physical characteristics, the question to be answered is whether or not the patent specification as a whole makes this product available to the person skilled in the art. The Respondent submitted in support thereof neither evidence in the form of working experiments nor literature in the relevant technical field. The burden of proof was however upon him to substantiate his allegation (see T 270/90, OJ EPO 1993, 725, point 2.1). Already for this reason, the Respondent failed to substantiate its ground of opposition.

2.3 In lieu thereof, the Respondent argued that the presence of the non-ionic non-fluorine-containing surfactant involved in the process of preparation of these aqueous dispersions according to Claim 1 was not recited therein, whereas this presence derived necessarily of the said process.

2.4 However, this surfactant is not a feature of the claimed aqueous dispersions but merely a feature of the process for preparing them, said surfactant being used furthermore as a "trace amount" (see page 4, line 11 of the patent in suit and page 6, line 33 of the application as originally filed). A component which does not participate in the technical effect provided by the claimed product is not a technical feature of this product and does not need to be recited to render such a product sufficiently disclosed within its whole ambit under Article 83 EPC.

2.5 The Board observes that both parties and the Opposition Division agreed that the step of upconcentrating latex formed part of the common technical knowledge in the relevant field. Although the Board cannot find in the file of the opposition/appeal proceedings any literature relating to this alleged common general knowledge, the furnishing of proof of purportedly common general knowledge is, in that case, not required and such fact can be accepted by the Board (see T 534/98, point 8). However, in view of the above reason, such a finding is not relevant to the sufficiency issue.

2.6 For the above reason, the objection under Article 100(b) EPC is rejected.

3. Novelty over document (1)

3.1 The subject-matter of Claim 1 of the main request was found to be anticipated under Article 54(2) EPC in view of document (1).

3.1.1 This document discloses a method of preparing high molecular weight vinylidene fluoride polymers in aqueous emulsion. The aqueous emulsion containing the vinylidene fluoride polymer is then recovered from the reactor. Generally, this latex contains from about 10 to about 35 wt. percent polymer solids. The particle size of the polymer in the latex is in the form of small spheres in the size range of about 0.1 to about one micron, preferably 0.2 to 0.5 micron (see page 9, lines 12 to 19). The examples 1 to 5 are working examples according to this disclosure. Example 6 was carried out according to the method described in the prior art.

3.1.2 First, it is clear and not contested by the Respondent that no example discloses aqueous emulsions with all the technical features as defined in Claim 1. In particular, the Appellant repeated twice the example 3 of this disclosure. A first test submitted in the course of the examining proceedings showed that the polymer content of the latex thus obtained was 36% by weight and the average particle size of the polymer in the latex was 287 nm. A second test submitted with the statement of grounds of appeal of the same example 3 showed that the particle size of the polymer grew with the polymer content (see Figure 1). Thus, after 30 minutes of reaction time, the particle size was 150 nm and the solids content less than 10%. After about 60 minutes the particle size was 200 nm and the solids content of about 16%. After 3 hours and ten minutes, the particle size was above 350 nm and the solids content of 30% or so. Clearly, the disclosure of this document does not disclose a dispersion containing particles having an average particle size of not more than 200 nm and a solid content of not less than 30% by weight since the particle size grows as a function of the solids content. It is, therefore, not correct to ignore the latter and artificially combine the preferred range of particle size with the amount of solids content such as disclosed (see point 3.1.1 above), as if those parameters were independent from each other, since - as shown by the experiments of the Appellant - they are in fact interdependent. Such an artificial combination does not reflect the actual disclosure of document (1).

3.1.3 The Respondent submitted that if the person skilled in the art would want to prepare a dispersion having a particle size of 200 nm or less he would not conduct the emulsion polymerization up to the maximum solids content of 40% but would rather stop the emulsion polymerization at a point where the desired particle size is reached since he knew that further polymerization would only increase the particle size. To obtain the desired solids, he would simply upconcentrate the dispersion to arrive at the desired solids content of for example 40%.

3.1.4 There is indeed in document (1) a general statement that stabilized latex can be further concentrated by known techniques such as creaming or flash evaporation to obtain "lattices containing from about 40 to 60 wt. percent polymer solids" (see page 10, lines 6 to 11) and it is not contested that upconcentrating forms part of the common general knowledge (see point 2.5 above). However, the stabilized latex is not characterized with regard to the particle size. An upconcentration applied to a polymer dispersion of low solids content and having a particle size of 200 nm or less must be, therefore, regarded as speculative and not unambiguously disclosed in document (1).

3.1.5 In this context, the Board emphasises that the essential point in assessing novelty is that it is not sufficient for a finding of lack of novelty of claimed features that such features could have been derived from a prior document. In order to be novelty destroying, there must be a clear and unmistakable teaching of the claimed features in a prior art document (see T 566/01, point 4.8 and T 355/99, point 2.2.4).

3.1.6 In view of the above, document (1) does not disclose clearly and unambiguously the claimed subject-matter of Claim 1 contrary to the finding of the Opposition Division.

4. Remittal to the first instance

4.1 The Board has come to the conclusion that the subject-matter of Claim 1 of the main request complied with the requirement of novelty in respect of document (1), overcoming, therefore, the sole reason for revoking the European patent as granted. Having so decided, the Board has not taken a decision on the complete case.

4.2 Indeed, the Opponent also sought revocation of the patent in suit on the ground that the subject-matter of Claim 1 as granted lacked novelty in respect of an alleged prior use or did not involve an inventive step (see point III above). The decision of the Opposition Division is silent regarding those issues.

4.3 Regarding the prior use issue, the Board observes that the communication of the Opposition Division dated 24 October 2001 indicated that the alleged prior use was not sufficiently substantiated. However, a communication under Rule 71a EPC cannot be considered as a reason which is included the decision. The purpose of the appeal proceedings inter partes being mainly to give the losing party the possibility of challenging the decision of the Opposition Division (see G 9/91, OJ EPO 1993, 408, point 18), already for this reason, the Board finds appropriate to exercise its discretion under Article 111(1) EPC to remit the case to the first instance in order not to deprive the parties of the possibility of being heard by two instances with regard to the other issues raised in the opposition proceedings.

4.4 When dealing with the prior use issue, the Opposition Division should be aware that the Jurisprudence established by the Enlarged Board of Appeal in its decision G 1/92 (OJ EPO 1993, 277) might not be irrelevant.

An essential purpose of any technical teaching is to enable the person skilled in the art to manufacture or use a given product by applying such teaching. Where such teaching results from a product put on the market, the person skilled in the art will have to rely on his general technical knowledge to gather all information enabling him to prepare the said product. Where it is possible for the skilled person to discover the composition or the internal structure of the product and to reproduce it without undue burden, then both the product and its composition or internal structure become state of the art (see point 1.4 of G 1/92).

4.5 Furthermore, the Opposition Division had not admitted document (7) into the proceedings pursuant to Article 114(2) EPC as late-filed and not more relevant than document (1).

4.5.1 When a decision hinges upon the exercise of discretion, the reason should be given (see T 182/88, point 8). Since the Opposition Division has given in its decision the reason for disregarding the late-filed document (7), the Board considers that the non admissibility of the late-filed document under Article 114(2) EPC was within the discretion of the first instance. It is not the function of a Board of Appeal to review all the facts of the case as if it were in the place of the Opposition Division and to decide whether or not it would have exercised such discretion in the same way as the first instance. Furthermore, since the Opposition Division revoked the patent in suit for lack of novelty in view of document (1), it would have been hardly possible to find document (7) more relevant. Relevancy of document (7), in particular, for the issue of inventive step was as a matter of fact not considered in those circumstances.

4.5.2 The Board observes nonetheless that although document (7) did not form part of the opposition proceedings, the Respondent strongly challenged at the appeal stage the novelty of Claim 1 of the patent in suit over document (7). The Board exercising its own discretionary power under Article 114(1) EPC admits the newly introduced document (7) as more relevant than document (1) in the sense that this document discloses concentrated dispersions of fluorinated polymers with a high solids content obtained after an upconcentration process from dispersions of lower solids content.

4.5.3 The Board wishes to point out that this finding is in no case to be regarded as an assessment under Article 54 or 56 EPC of this admitted state of the art. It merely requires the Opposition Division to consider it in the assessment of novelty and inventive step