T 0309/94 19-03-1997

1. The appeal is admissible.

2. The Board, as the Examining Division already did, considers the subject-matter of both versions of Claim 1 to be new since a copolymer of N-acrylamido-o-benzenedicarboxylic acid with (meth)acrylamide is not disclosed in the cited prior art.

3. The application in suit concerns water soluble copolymers containing (meth)acrylamide benzene dicarboxylic acid units, more specifically units wherein the COOX groups are in ortho-position in relation to each other, useful in water treatment, to eliminate and/or recover metals or to inhibit incrustations (column 1, ll.46-50).

3.1. Polymers also useful as water treatment agents and antistats are described in D2, which the Board considers to represent the closest state of the art. These polymers are homopolymers or copolymers of diesters of N-acrylyliminodiacetic acid as well as the corresponding polymers, in which the ester groups have been converted into carboxylic groups by saponification and acidification (column 1, lines 30 to 52).

3.2. In the light of this disclosure the technical problem underlying the application in suit may thus be seen in the provision of further water soluble polymers suitable for the same applications.

3.3. According to the application in suit this problem is said to be solved by copolymers containing units (I) derived from N-methacryloyl-3-aminophthalic acid or metal salts thereof, and units (II) derived from (meth)acrylamide, the molar ratio between units (I) and units (II) varying between 1:99 and 99:1, as specified in claim 1 of the two sets of claims.

3.4. In view of the information provided in the application in suit as well as the two examples in the Statement of Grounds of Appeal (page 2, paragraph 3 to page 3, paragraph 3), which illustrate the suitability of the copolymers as claimed in the water treatment, in particular as chelating agents for the recovery of metals, the Board is satisfied that the above problem is effectively solved.

4. It remains to be decided whether the claimed subject-matter was obvious to a person skilled in the art having regard to the teaching of D1 and D2.

4.1. Although D2 is a broad disclosure encompassing several embodiments, there is no mention of copolymers containing either units (I) or units (II), let alone a combination thereof.

4.1.1. Whatever the comonomer used in the preparation of the polymers of D2, it is evident that the units which are basically responsible for the general properties of these polymers derive from diesters of N-acrylyliminodiacetic acid, since homopolymers are explicitly envisaged. These units must thus be regarded as the essential feature of the polymers described in D2. In the absence in D2 of any alternative to these diesters this document cannot provide any guidance for the solution of the technical problem, which means that unit (I) in the application in suit must be regarded as non obvious with respect to this disclosure.

4.1.2. In all the embodiments directed to the preparation of copolymers, e.g. embodiments D, E, F and G, the only comonomers mentioned are acrylic acid, methyl acrylate, methyl methacrylate, vinylpyridine, N-vinylpyrrolidone, styrene, acrylonitrile and vinyl acetate (embodiment E: column 4, lines 43 to 46; embodiment F: column 4, line 74 to column 5, line 1; column 8, Table 1). This is also apparent from the formulae of the recurrent units in the case of copolymers (embodiment D: column 3, line 70 to column 4, line 15; embodiment G: column 5, lines 53 to 68), wherein the various meanings of Z correspond exactly to the above comonomers. The above list of eight comonomers would thus be interpreted by a skilled person as exhaustive, who would have consequently no incentive to consider extending this specific teaching to further comonomers, in particular to acrylamide or methacylamide. It follows that unit (II) in the application in suit must also be regarded as non obvious with respect to D2.

4.1.3. Consequently, D2 cannot provide any incentive to consider a solution along the line of a combination of units (I) and (II) as required in the application in suit.

4.2. D1 describes cation exchangers obtained by copolymerising N-methacryloyl-4-aminophthalic acid with hexahydro-1,3,5-triacryloyl-1,3,5-triazine. The latter being a trifunctional compound, the resulting copolymer must be a cross-linked, therefore solid product. Infrared spectroscopy and potentiometric titration reveal the presence in the copolymer of dicarboxylic acid units which correspond to unit (I) in the application in suit. No further comonomer is envisaged, which means that, even if the skilled person carried out routine experiments within the framework of D1 in order to explore the ion-exchanging activity provided by this specific dicarboxylic acid unit, copolymers comprising units derived additionally from acrylamide or methacrylamide would not be considered.

For this reason already D1 cannot lead to copolymers with the terms of the application in suit.

4.3. Even a combination of D1 and D2 would not lead to copolymers as claimed, since neither mentions the possibility to incorporate units derived from acrylamide or methacrylamide (units (II) in the application in suit) into the copolymers.

In fact, it is doubtful whether a skilled person would even contemplate such a combination. Firstly, there are differences in structure between the copolymers according to D1 and D2 which militate against it. Concerning D2, both the various recurring units of the copolymers according to Embodiments D to G and the method of preparation in the absence of any polyfunctional monomer, either by the use of high energy ionizing radiation or by the use of free radical initiating substances (column 6, lines 24 to 27), clearly indicate a linear structure of these copolymers. By contrast, as stated above, the copolymers obtained in D1 must be regarded as having a cross-linked structure. Secondly, it is far from evident that the mere reference to exchange capacity in D1 should be interpreted as meaning that these cationic exchangers would be suitable in the water treatment as chelating agents for the recovery of metals and that, consequently, a skilled person would regard the particular dicarboxylic acid unit as a promising feature for the solution of the technical problem. In view of these differences in terms of structure and properties, thus, a combination of D1 and D2 in the Board's view can only be made by hindsight.

4.4. All these considerations apply to the products (set of claims A) as well as to the process for preparing them (set of claims B), since both are characterized by the same combination of features, so that the claimed subject-matter in both cases involves an inventive step.

5. Claim 1 of the two sets of claims being allowable, the same applies to the respective dependent claims 2 to 7, which are directed to preferred embodiments of the copolymers respectively process as defined in claim 1 and whose patentability is supported by that of the respective main claim.

6. Procedural matters

In accordance with Rule 67 EPC, reimbursement of an appeal fee shall be ordered when the Board deems an appeal to be allowable and "if such reimbursement is equitable by reason of substantial procedural violation". Since the Board deems the appeal to be allowable (see above) it needs to be decided whether the above requirement is met.

The information given by the Examining Division in its last communication before the decision (see item III above) was that the chelating properties were due to a particular 7-membered ring structure and that, in the case of a restriction to such compounds, it seemed that an inventive step could be acknowledged. The Board regards this as a clear hint of the Examining Division to the Appellant that a positive decision, e.g. a grant of a patent could be expected if claims restricted in that sense were filed. Together with his reply to that communication the Appellant filed indeed two sets of claims amended in that sense as well as a description amended accordingly. Without any further information, however, the Examining Division deviated from the impression given to the Appellant and issued a decision of refusal of the application (Article 97(1) EPC), depriving the Appellant of any chance to present counter-arguments. The Board considers this to be a completely unacceptable conduct misleading the Appellant and depriving him of the opportunity to comment pursuant to the requirements of Article 113(1) EPC. The Board therefore holds that a substantial procedural violation of Article 113 EPC has occurred justifying the reimbursement of the appeal fee under Rule 67 EPC.