T 0641/99 16-07-2002

1. The appeal is admissible.

2. Procedural Matters

2.1. During the oral proceedings, the Appellant submitted the said "Sheet of data" to further support its case. These data were based on Annexes 1/1 to 2/4 which had been submitted together with the Statement of Grounds of Appeal. Since, in the sheet, only information which had been already in the file was presented in a different form, it was admitted by the Board to the discussion.

2.2. In the course of the presentation of its case with respect to inventive step, the Respondent referred to Document D6 which had been cited in the Notice of Opposition filed on 1 October 1997 (pages 9 and 10 of the letter; viz. Example 1 of the document).

The only additional references to this document are found in the reply to the Notice of Opposition, dated 3. July 1998 (page 3), wherein the Patentee argued that D1 neither anticipated nor made obvious the claimed subject-matter and continued that this finding would also apply to a number of combinations of citations, including inter alia "D6 + D2 and D6 + D3", and in the decision under appeal (page 4), wherein reference was made to "D6 EP-B 450924: improvement of absorbents by surface treatment with a polyhydric alcohol."

This document did not play any role in the further proceedings before the Opposition Division or during the written proceedings before the Board.

D6 was published on 16 October 1996, ie after both the priority date and the filing date of the patent in suit. Consequently, it does not belong to the state of the art to be taken into account for the consideration of inventive step.

After having discussed this fact with the parties in the oral proceedings and after deliberation, the Board decided to take D6a, the basic patent application of D6, ex officio into consideration (Article 114(1) EPC).

The Respondent had referred to decision T 185/88 (above) to support its request that D6a should automatically replace D6 in the proceedings.

Decision T 185/88 deals, however, with a completely different situation. In that case, the first question dealt with in the decision was the admissibility of an opposition in view of the fact that the only document cited (a German patent specification DE-PS-...) was late-published and did therefore not qualify as a proof for lack of patentability. It was found, however, that the front page of the DE-PS (C-document) contained a clear reference to the date on which the corresponding unexamined application (as DE-OS, ie the A-document) had been laid open to public inspection, which preceded the priority date of the contested patent, and that it was immediately apparent that the corresponding unexamined application should have been cited, since in the Notice of Opposition reference had been made to the "previously published document DE-PS..." which was "discussed in the contested patent" and on examination it could be seen that the contested patent mentioned document DE-OS of the same number, i.e. the previously published A-document. (point 2.2 of the reasons).

The Board in that case was prepared, under the circumstances, to consider the content of an earlier A-document corresponding to the cited C-document evidently to avoid an opposition being thrown out as inadmissible on the basis of a clerical error. The Board in the present case does not, however, see that such a measure amounts to a finding that an opponent has the automatic right, at any stage of opposition or opposition appeal proceedings, to replace a document in the proceedings by another document to which it refers, but which itself is not in the proceedings, particularly where, in the present case, there is no ameliorating indirect reference in the Notice of Opposition to the relevant earlier document. On the contrary, it was evidently the intention of the Opponent to rely on the C-document and only on the C-document.

Thus, the situation corresponds rather to that in T 38/96 of 11 May 1999 (not published in OJ EPO), wherein late filed document D26 was the A-document corresponding to D1 which had been cited in due time, but published too late to be taken into consideration. However, the content of D26 was prior art pursuant to Articles 54(3) and (4) EPC and the document was therefore admitted to the proceedings (Article 114 EPC; point 2 of the reasons).

The Board therefore exercised its discretion in a manner favourable to the Respondent in the present case.

2.3. In view of the resulting change of the situation for the Appellant, however, the Board admitted the new auxiliary requests ("Hilfsantrag 1" and "Hilfsantrag 2") referred to in section IX, above, to the proceedings, since these were made in response to the objection based on the new document.

2.4. With its letter dated 17 June 2002, the Appellant had submitted two publications

D14 Römpp, 10th edition, 1998, page 2549 and

D15 "Modern Superabsorbent Polymer Technology" F.L. Buchholz, A.T. Graham, John Wiley & Sons, 1998, pages 87 to 93,

both of which had been published only after the effective date of the patent in suit. Therefore, they are not considered sufficiently relevant to be taken into account by the Board. Hence, they are disregarded (Articles 114(1) and (2) EPC).

3. Amendments (Articles 123(2) and (3) EPC)

The limitation of the independent claims in both auxiliary requests to the use of "organic carbonates, polyquaternary amines or polyvalent metal compounds" and "organic carbonates", respectively, as surface crosslinking agents clearly complies with Article 123(3) EPC as it results in a restriction in the scope of the claim.

These amendments are supported by the application as filed (Claims 10 and 23 and page 13, lines 5 and 4 from below; patent in suit: Claims 10 and 23, page 6, lines 2/3) and, consequently, also meet the requirements of Article 123(2) EPC.

The claims in both auxiliary requests are based on Claims 1 to 9, 12 to 22 and 25 to 28, as granted. Due to the deletion of Claims 10, 11, 23 and 24 of the granted version, the subsequent claims were renumbered and the references to preceding claims contained therein were amended accordingly (see section IX, above). They also comply with the requirements of Articles 123(2) and (3) EPC.

4. Novelty

The Respondent conceded novelty of the claims defining the method of making the superabsorbent polymer (independent Claim 14 of the main request, independent Claims 12 of both auxiliary requests) in admitting that neither of D1 nor D10 disclosed step (d).

Since independent Claim 27 of the main request and independent Claims 23 of both auxiliary requests, respectively, differ from the above independent method claims only in the presence of additional feature (i), this is also true for these claims.

With respect to the product claims defining the product in terms of a process, the question of novelty must be examined under two aspects: (i) which of the process features as defined in steps (a) to (h) are identically disclosed in the prior art relied upon by the Respondent and (ii) whether the individual process steps are manifest in the properties of the product so that the product was made available to the public by the said prior art.

In the case where a prior art document fails explicitly to disclose something falling within the claim, availability in the sense of Article 54 may still be established if the inevitable outcome of what is literally or explicitly disclosed falls within the ambit of the claim.

4.1. According to the decision under appeal, D1, D2, D4 and D10 were of particular relevance, but none of these documents was deemed to anticipate any product or method claim of the patent in suit. In the appeal proceedings, the Respondent maintained that the disclosures of both D1 and D10 took away novelty of the product claims. This point of view has mainly been based on the argument that steps (d) and (e) would not affect the structure of the final product.

In view of these facts and arguments, the Board does not see any reason to deviate from the findings in the decision under appeal with respect to novelty over the documents D2 and D4 and focuses, therefore, on the remaining two documents D1 and D10.

4.2. D1 provides "a method of improving the water-absorbent properties of a water-absorbent resin characterised in that it comprises surface treating the water-absorbent resin with a sufficient amount of a polyquaternary amine substantially to increase the water absorption of said water-absorbent resin". Such resins have found wide uses in a variety of applications including sanitary and hygienic goods (page 2, lines 7 to 9 and 43. to 46).

4.2.1. The process for preparing the known solid water-absorbent resins of D1 includes the steps of preparing an aqueous monomer solution of (A) acrylic acid (neutralised 70 to 100 mol %), (B) optionally styrene and/or methyl methacrylate and (C) a water-miscible to water-soluble polyvinyl monomer in a combined concentration of (A), (B) and (C) of at least 30% by weight; initiating polymerisation of the monomers in such a way that, during polymerisation, the exothermic heat of reaction is substantially the only heat energy used to accomplish polymerisation and cross-linking and to drive off sufficient water to obtain a solid crosslinked resin having a water content of 15% by weight or less; and thereafter surface treating the said resin with a polyquaternary amine (independent process Claim 6; page 2, line 53 to page 3, line 4).

4.2.2. On page 6, line 12 to page 7, line 6, the process is further specified by way of example: An aqueous solution is at first prepared by combining acrylic acid with potassium and ammonium hydroxides, ammonium carbonate and a crosslinking agent. In the solution, the degree of neutralisation is in the range of about 70. to 90%. According to the Appellant, the disclosure on page 6 of D1 means that the acrylic acid in the monomer solution is neutralised by the above hydroxides and carbonate to a degree of 72% and that the total water content of the reaction mixture amounts to about 13%.

To this aqueous solution maintained at 70°C, which may additionally contain an organic solvent having a boiling point of 40 to 150°C, an azo initiator is then added and the mixture is poured onto and spread over a travelling endless belt in the form of a thin layer. After about 30 seconds, the mixture starts to polymerise, and the exothermic reaction is complete in about one minute. During the reaction, the temperature rises to a maximum of about 130°C which is sufficient to evaporate any water or solvent initially present in the reaction mixture. The polymer is allowed to complete curing for about 30 minutes at ambient temperature, allowing water and solvent to evaporate, to give a dry solid strip of polymer having a water content of less than 15%. The Respondent argued that, under these reaction conditions, the carbonate would still act as a blowing agent together with the evaporating water because it was less reactive towards the acid than the two hydroxides. This argument was strongly disputed by the Appellant.

The strip is then pulverised into a powder which is then contacted and surface treated by evenly spraying a polyquaternary amine in methanolic solution over the powder. Thereafter the surface-treated powder is evenly distributed throughout the product (page 7, lines 1 to 4).

In the document, particular emphasis is repeatedly put on the fact that the exothermic heat of reaction is the only non-ambient energy source to drive water away from the resin to form the said crosslinked resin polymer having a water content sufficiently low to be powdered without intermediate drying step (Claim 6; page 3, lines 1 to 3 and 31; page 6, lines 52 to 57; page 10, lines 46 to 48; page 11, lines 1 to 4 and 15 to 17).

4.2.3. It follows that D1 does not disclose the chopping or grinding of a microporous hydrogel before the drying step as admitted by the Respondent.

4.2.4. Furthermore, there is no explicit reason for supposing that D1 discloses a microcellular product, since the document does not mention such a product, but refers to a dry solid strip, nor does it refer to the use of a blowing agent.

4.2.5. The submission by the Respondent, that the ammonium carbonate ingredient referred to under the heading "Chemicals" on page 6 of D1 must necessarily function as a blowing agent, so that the resulting product would inevitably be microcellular, was strongly disputed by the Appellant on the basis that, whilst evolution of gas from a chemical blowing agent is irreversible and the gas evolved therefrom remains evenly distributed in the forming polymer, water evaporation, as required in the polymerisation in D1, is an equilibrium process of evaporation at hot and re-condensation at cooler spots within the polymerisation mixture. Moreover, such a repeated evaporation and re-condensation of water removes any carbon dioxide from the mixture, regardless of whether it is formed during the initial neutralisation of the monomers or during the following polymerisation step, and thus prevents a microporous structure from being formed. Hence, the structure of the resulting solid water-insoluble polymer in D1 which required the removal of the water during the polymerisation is different from that in the patent in suit and a microporous structure cannot be formed therefrom during the further steps of the process.

The Board sees no reason to reject this perception of the progress of the process exemplified in D1, since the Respondent neither showed that it had any inconsistency with the relevant disclosure of D1, nor supplied any evidence of its own which would support another conclusion. The onus of proof at this stage lay with the Respondent, however, which it has not discharged.

Consequently, it is held that D1 does not make available a microcellular polymer as defined in Claim 1 of the main or first or second auxiliary requests.

4.2.6. In other words, the novelty objection based on D1 must fail. It follows that D1 does not anticipate the subject-matter claimed in the independent claims of the patent in suit according to the main, first or second auxiliary requests.

4.3. Document D10 discloses a powdery, water-swellable, crosslinked polymer, capable of absorbing aqueous fluids (in particular body-fluids), the polymer being formed from unsaturated at least partially neutralised acid-functional monomers, whereby the polymer is characterised by an absorption capacity of at least 12. g of a 0.9% sodium chloride solution per gram of polymer under a load of 60 g/cm2.

The document also discloses a process for the preparation of this polymer by polymerising acid group-containing monomers and a crosslinking agent in the presence of a blowing agent on the basis of carbon dioxide, thereby forming a hydrogel, drying the resulting polymer and treating its surface with 0.01 to 10% by weight, relative to the water absorbent resin, of at least one surface crosslinking agent (such as glycerol, polyalkylene glycols, polyamines and/or alkylene carbonates) at elevated temperatures (Claim 6).

The particle shape may be irregular, as originating from drying and comminuting steps. The sequence of comminution and drying steps and the particle sizes resulting therefrom were disputed between the parties. Whilst the Respondent based its arguments on the examples and comparative examples, the Appellant referred mainly to the paragraph bridging pages 7 and 8.

At the bottom of page 7, reference is made to drying and comminution; the examples refer to comminution, drying, grinding and sieving (eg page 11, comparative Examples 1 and 2; page 13, Examples 2 to 10). According to Claim 8, grinding is carried out after the drying step. The particle size is, in general, in the range of 20. to 3000 um, preferably between 50 and 1000 um.

4.3.1. Evidently, this size refers to the polymer after having been dried and optionally ground (see Claims 7 to 9; page 8, lines 2/3 and the examples), which was not contested by the Respondent. This means that D10 is silent about the size of the gel pieces after the comminution, if any, before drying.

4.3.2. Apart from the missing size of the gel pieces before drying, it must be noted that "Zerkleinerung" (comminution) means any physical activity reducing the size of the product. Therefore, it encompasses not only "chopping" and "grinding", but also "cutting". This means, however, that these terms do not have the identical meaning as regards the activity carried out. Furthermore, it is evident that the shapes and sizes of the gel pieces resulting from these different activities are not inevitably the same, let alone comply with their definition in the claims under consideration.

4.3.3. Thus, D10 not only fails to disclose the size of the relevant gel pieces, but also the specific form of energy input (chopping or grinding) required by the patent in suit for obtaining them.

4.3.4. The argument of the Respondent, that the manner of comminution, and the size of the resulting particles have no significance for the nature of the product, is not convincing, since it has not been shown that different sizes during the drying step would in fact have no impact on the final product.

On the contrary, it was strongly argued by the Appellant, that energy intensive mechanical treatment of a polymer such as chopping or grinding would indeed have an effect on the structure of the resulting product, in particular, as it will result in a reduction of the molecular weight.

Moreover, the size of the gel pieces to be dried determines the ratio of their surface area, which serves as an interface for the water evaporation from the solid polymer phase to the surrounding gas phase (eg air), to their volume, and it is this ratio, which has an important influence on the drying time and on the heat energy to be imposed on the polymer: the lower the said ratio, the more unfavourable the necessary drying conditions, ie longer drying time or a higher amount of thermal energy needed, imparting higher thermal stress on the polymer and undoubtedly affecting its properties.

4.3.5. The further argument of the Respondent, that there were no limits in the subject-matter of the patent in suit on the amount of energy input does not alter the fact that no such step (in compliance with step (d) as defined in the patent in suit) is disclosed in D10, and the presence of such a step must be presumed, for the reasons given above, to have an effect on the resulting polymer which is not made available by D10.

4.3.6. Consequently, the Board has come to the conclusion that D10 does not anticipate the subject-matter of the independent claims of the main, first or second auxiliary requests.

4.4. The requirements of Articles 52(1) and 54 EPC are therefore met by the main and both auxiliary requests.

5. Problem and Solution

5.1. The patent in suit concerns a microcellular superabsorbent polymer.

5.2. Such a product is known from D2 which the Board regards as representing the closest state of the art. D1 cannot adequately fulfil this function, if only because it fails to disclose a microcellular polymer (see section 4.2.5, above).

Document D2 relates to improved superabsorbent polymer compositions, useful as absorbents for water and/or aqueous body fluids when incorporated into absorbent structures such as diapers, incontinence pads and sanitary napkins, and a process for their preparation. These absorbents are capable of retaining the absorbed fluids under moderate pressures (page 2, lines 1 to 14).

The superabsorbent polymers are, in general, based on polymerisable unsaturated carboxylic acids or their derivatives, such as acrylic and/or methacrylic acid and/or their water soluble salts, rendered water insoluble by crosslinking. The speed and/or rate of such water absorption of superabsorbent, substantially water insoluble, slightly crosslinked partially neutralised hydrogel forming polymer compositions is improved by carrying out, during their production, a sequence of steps 1 to 5, which are identical to steps (a) to (f) as defined in Claim 1 of the patent in suit (sections I and IX, above; D2: page 2, lines 14 to 21 and 51 to page 3, line 12 and page 5, lines 28 to 41). The resulting polymers show an improved rate of absorption of aqueous fluids while essentially retaining the gel strength and capacity of conventional superabsorbents made in the absence of carbonate blowing agents (D2: page 6, Table I and lines 33 to 40; page 7, Table II). This is confirmed in the patent in suit (page 4, lines 19 to 26), which refers to this polymer as "core polymer" as described in US-A-5 154 713 and 5 118 719, both of which are derived from the same US patent application 781526 as D2.

The disclosure of D2 differs from the patent in suit in that it is silent with respect to an additional surface treatment of the superabsorbent "core" polymer.

5.3. In line with the arguments of the Appellant (see eg sections V(i) and V(ii), above) and with the introductory statements in the patent specification, the technical problem underlying the patent in suit may thus be seen in imparting high liquid permeability under pressure (APUP), high absorbency under pressure (AUP) and swell rate (absorption speed) to the superabsorbent polymer without seriously affecting gel strength and absorption capacity (patent in suit: page 2, and in particular page 3, lines 3/4, 26 to 34 and 41/42).

5.4. According to the patent in suit, this problem is solved by mixing and reacting the polymer obtained in steps (a) to (f), as referred to above, in further steps (g) and (h) with 0.001 to 30 parts by weight of a surface crosslinking agent (in all experimental data provided by the Appellant: ethylene carbonate or glycerol).

5.5. In order to demonstrate that this problem was actually solved by the subject-matter claimed in the patent in suit, the Appellant pointed, in addition to the examples in the patent in suit, to the experimental results in Annexes 1/1 to 2/4, mentioned above, in particular to Example 1 and Table 1 therein. In order to put more emphasis on its arguments based on these results, the results were presented on the said "Sheet of data" in a different form.

On this sheet, changes in the swell rate, gel strength, absorption capacity, AUP and APUP of polymer samples are shown in order to demonstrate the effect of the addition of BA (sodium carbonate) or SCL (ethylene carbonate) or both in steps (b) and (g), respectively, of the method as defined in the independent claims of the patent in suit in comparison to polymers prepared in the absence of SCL (ie without steps (g) and (h)) or BA or both.

Thus, on the one hand, the comparison of samples 3 and 4. demonstrates that the addition of the said SCL results in a reduction of both the swell rate and absorption capacity, whilst the gel strength, AUP and APUP increase. On the other hand, the addition of the said BA in sample 5 (in comparison to sample 3) shows the opposite results, ie increased swell rate and absorption capacity, and decreased gel strength, AUP and APUP. Sample 6 demonstrates that a polymer sample prepared with sodium carbonate (BA) and ethylene carbonate (SCL) in comparison to a product prepared in the presence of only the said BA (sample 5) exhibits significant increases in swell rate (absorption speed), gel strength, AUP and APUP, although, according to Appellant, a reduction of the swell rate had been expected by a person skilled in the art.

Consequently, according to the data provided by the Appellant, the above technical problem was credibly solved by the subject-matter of the independent claims. The Respondent has neither filed any results of experimental data of its own nor disputed the above results.

6. Obviousness

It remains to be decided whether this solution was obvious to a person skilled in the art having regard to the state of the art relied upon by the Respondent.

6.1. It is evident from the above considerations that D2 by itself does not provide the teaching necessary to solve the technical problem referred to above.

6.2. Main request

6.2.1. According to D6a, the characteristic properties expected in superabsorbent resins include high absorption capacity, high absorption rate, liquid permeability, and large gel strength (page 2, lines 16/17). For use as constituent material for sanitary goods which absorbs body fluid, the polymer should not only have good absorption rate, liquid permeability and absorption capacity under no pressure, but these properties are also required under pressure (page 2, lines 3/4 and 36 to 40). In order to obtain such an absorbent polymer, the resin having a carboxylic group is mixed with 0.01 to 30 parts by weight of a polyhydric alcohol, such as glycols and glycerols (page 3, lines 38 to 43), as a surface crosslinking agent, per 100 parts by weight of the absorbent resin, and its surface is then reacted therewith. In four out of six examples, glycerol is used.

6.2.2. During the oral proceedings, the Respondent argued that the solution offered by the patent in suit was obvious vis-à-vis the combination of D2 and D6a and found this argument supported by the results in Example 3 (Table 3) of Annexes 1/1 to 2/4, already mentioned above, which confirmed the teaching of D6a by demonstrating, in particular, that the use of glycerol as a surface crosslinking agent provided a superabsorbent having the desired properties (such as an increased swell rates under normal pressure, gel strength, capacity, AUP and APUP) and, thus, solved the above technical problem. This fact was conceded by the Appellant.

6.2.3. In view of these facts, confirmed by the above experimental data (which are based on Table 3 of the patent in suit and Table 3 of Annexes 1/1 to 2/4 mentioned above), the Board comes to the conclusion that D6a provides the teaching necessary to solve the above technical problem. The incentive to impart high liquid permeability under pressure (APUP), high absorbency under pressure (AUP) and swell rate (absorption speed) to the superabsorbent "core" polymer (obtainable in accordance with D2) without seriously affecting gel strength and absorption capacity is clearly derivable from D6a.

6.2.4. It follows that the subject-matter claimed according to the main request is obvious to a person skilled in the art in view of D2 and D6a. Consequently, the main request cannot be successful. It is therefore refused.

6.3. Auxiliary request 1

The teaching of D6a is clearly limited to the surface treatment of superabsorbent carboxy-functional polymer powders with polyhydric alcohols. Surface crosslinking agents of this type are, however, excluded from the claims according to auxiliary request 1. In view of the differences between the experimental results in the above Annexes 1/1 to 2/4 (Table 1 and Table 3) obtained with different surface crosslinking agents, which results are not in dispute between the parties, it is evident that results obtained with one SCL cannot be extrapolated to another SCL. Consequently, the combination of D2 and D6a cannot render the subject-matter of auxiliary request 1 obvious. Thus, it remains to be examined whether the subject-matter claimed according to this auxiliary request is rendered obvious by the other prior art relied upon by the Respondent in these proceedings.

6.3.1. Document D4 explains the importance of, on the one hand, swell capacity and, on the other hand, gel strength in superabsorbent polymers and the influence of the gel strength in such polymers on the distribution and absorption of further fluid under pressure, to ensure fluid absorption, fluid transport and dry feel - despite any pressure exerted on the absorbent, eg by the load of a body (page 2, lines 31 to 42). More particularly, according to D4, hitherto known superabsorbent polymers have to be improved with respect to the retention and absorption capacities as well as the gel strength (page 2, lines 49 to 58) in order to dispense with the necessity of the use of high volume fluff in sanitary and hygienic goods, such as diapers, and to allow the volume of the article to be reduced. This aim has been achieved in D4 by surface treating a partially neutralised, crosslinked superabsorbent polymer on the basis of polymerisable unsaturated acid monomers with 0.1 to 5% by weight of an alkylene carbonate (Claims 1 and 10). This surface treatment results in an improved absorption of fluid under pressure as regards rate and capacity with simultaneous achievement of high retention capacity ("TB"), high gel strength and high absorbency under load ("AUL"), and storage modulus G' (page 3, lines 21 to 24; page 4, line 37 et seq., the examples).

6.3.2. The document is, however, silent about the swell rate under normal pressure. The Appellant has demonstrated in Table 1 in the patent in suit and in Annexes 1/1 to 2/4, mentioned above (in particular, the reduction of the swell rate in sample 4 of Table 1 to 81% in comparison to sample 3, see the "Sheet of data"), that the addition of a surface crosslinking agent to a superabsorbent polymer results in a reduction of the swell rate unless specific measures are taken to prevent this decrease.

D4 does not provide any information about additional features necessary to avoid this deterioration of properties, it does not even address this deficiency caused by the surface crosslinking.

6.3.3. Therefore, the Board is convinced that D4 does not provide any incentive to overcome the relevant technical problem by modifying the "core" polymer obtainable in accordance with D2 by means of ethylene carbonate as a surface crosslinking agent with a reasonable expectation of success. The reduction of the swell rate due to surface crosslinking by means of ethylene carbonate, mentioned above, rather teaches away from the solution found in the patent in suit. Moreover, a synergistic effect between the blowing agent and the surface crosslinking agent as asserted and proven by the Appellant during the oral proceedings on the basis of the above experiments (in particular with respect to sample 6 in comparison to sample 5 of Table 1: increase of the swell rate by a factor of 1.13, in addition to significant increases at the same time in gel strength, AUP and APUP) could not be foreseen from the document.

6.3.4. Furthermore, the different results obtained with ethylene carbonate, on the one hand, and glycerol, on the other, demonstrate that reliable conclusions cannot be drawn from the above opposite results (in Tables 1 and 3 of the Annexes 1/1 to 2/4, above) obtained with these two compounds as to the properties of a superabsorbent prepared instead with another surface crosslinking agent such as the other SCL compounds listed in the independent claims of the first auxiliary request (see section 6.3, above).

6.3.5. Nor does D1 add anything to D2 which would be significant for the solution of the technical problem, since it (a) does not relate to a microcellular core polymer and (b) discloses that superabsorbent polymer powder surface-treated with polyquaternary amines shows (in subsequent measurements) an increased initial water absorbency (under a certain pressure), a higher total water absorbency (under less pressure) and an increased total water retention (under the initially applied pressure again) than the untreated polymer and (c) the influence of different amounts of further non-polar comonomers incorporated in the polymer such as styrene and methyl methacrylate on these properties. There is no hint to an improvement in APUP, let alone swell rate.

6.3.6. According to established case law of the Board of appeal, the onus is on the Opponent in opposition proceedings convincingly to demonstrate that the claimed subject-matter is obvious with respect to the state of the art and/or that the technical problem is not solved in the whole range of the claims under consideration (see Case Law of the Boards of Appeal of the EPO, 4th edition, VI.J.6 et seq.). No such convincing argument or evidence has been produced by the Respondent (Opponent).

6.4. Consequently, the Board is satisfied that the subject-matter of independent Claims 1, 12 and 23 involves an inventive step, because neither D2 by itself, nor any combination of D2 with D4 and/or D6a and/or D1 provides an incentive to solve the technical problem so as to arrive at something within the ambit of these claims.

6.5. Claims 2 to 11, which relate to preferred embodiments of the polymer of Claim 1, Claims 13 to 22, which concern preferred of elaborations of the method according to Claim 12, and Claim 24, which further specifies the method of Claim 23, are supported by the patentability of the independent claims to which they are appendant and are thus also allowable.

6.6. Consequently, the Board has come to the conclusion that the subject-matter of the patent in suit as defined in the claims according to auxiliary request 1 meets the requirements of the EPC.

7. Auxiliary request 2

Since auxiliary request 1 is successful, there is no need to consider auxiliary request 2 any further.