T 0179/05 30-11-2006

I. The grant of the European patent No. 0 835 885 in the name of Nippon Shokubai Co., Ltd, in respect of European patent application No. 97 117 334.9 filed on 7 October 1997 and claiming priority of the Japanese patent application JP 27094996 filed on 14 October 1996 was announced on 27 February 2002 (Bulletin 2002/09) on the basis of 11 claims.

Independent Claims 1 to 5, and 8 to 11 read as follows:

"1. A water-swellable crosslinked polymer, which has a total pore volume of pores with a pore size in gels of 5.1-27 nm of 60 v/v % or more relative to the entire amount of a physiological salt solution absorbed into the polymer, wherein the pore volume of pores with a pore size in gels of 5.1-27 nm (PV (5.1-27 nm)) is defined by a method comprising the following steps of:

A. allowing a water-swellable crosslinked polymer (W1 g), which stands in an equilibrium state swollen with a physiological salt solution (W2 ml), to fall again into an equilibrium state by adding a physiological salt solution (W3 ml, concentration Ci %) of a thread-ball-shaped molecule with molecular diameter R to the polymer; and then filtering off the polymer as swollen with the physiological salt solution; and then measuring concentration Cf % of the thread-ball-shaped molecule in the resultant filtrate;

B. defining PV (0-R) (ml/g) as PV (0-R) (ml/g) = (W2+W3) [1-{W3/(W2+W3)} x (Ci/Cf)]/W1;

C. determining PV (0-5.1 nm) and PV (0-27 nm) using a thread-ball-shaped molecule with R of 5.1 nm and a thread-ball-shaped molecule with R of 27 nm and

D. defining PV (5.1-27 nm) as PV (5.1-27 nm) = PV (0-27 nm) - PV (0-5.1 nm).

2. A water-swellable crosslinked polymer, which has a total pore volume of pores with a pore size in gels of 5.1-27 nm of 80 v/v% or more relative to the entire amount of an ion-exchanged water absorbed into the polymer, wherein the pore volume of pores with a pore size in gels of 5.1-27 nm (PVW (5.1-27 nm)) is defined by a method comprising the following steps of:

E. allowing a water-swellable crosslinked polymer (W1 g), which stands in an equilibrium state swollen with ion-exchanged water (W4 ml), to fall again into an equilibrium state by adding an ion-exchanged water solution (W5 ml, concentration Ci%) of a thread-ball-shaped molecule with molecular diameter R to the polymer; and

then filtering off the polymer as swollen with the ion-exchanged water; and then measuring concentration Cf% of the thread-ball-shaped molecule in the resultant filtrate;

F. defining PVW (0-R) (ml/g) as PVW (0-R) (ml/g) = (W4+W5) [1-{W5/(W4+W5)}x(Ci/Cf)]/W1;

G. determining PVW (0-5.1 nm) and PVW (0-27 nm) using a thread-ball-shaped molecule with R of 5.1 nm and a thread-ball-shaped molecule with R of 27 nm; and

H. defining PVW (5.1-27 nm) as PVW (5.1-27 nm) = PVW (0-27 nm) - PVW (0-5.1 nm).

3. A water-swellable crosslinked polymer, which has an average pore size in gels of 10-30 nm and a standard deviation of 11.5 or less in pore size in gels when the polymer is swollen with ion-exchanged water, wherein the average pore size is defined by a method comprising the following steps of:

I. allowing a water-swellable crosslinked polymer (W1 g), which stands in an equilibrium state swollen with ion-exchanged water (W4 ml), to fall again into an equilibrium state by adding an ion-exchanged water solution (W5 ml, concentration Ci%) of a thread-ball-shaped molecule with molecular diameter R to the polymer; and

then filtering off the polymer as swollen with the ion-exchanged water; and then measuring concentration Cf% of the thread-ball-shaped molecule in the resultant filtrate;

J. defining PVW (0-R) (ml/g) as PVW (0-R) (ml/g) = (W4+W5) [1-{W5/(W4+W5)}x(Ci/Cf)/W1;

K. determining PVW (0-5.1 nm), PVW (5.1-9 nm), PVW (9-11.8 nm), PVW (11.8-27 nm), PVW (27-56 nm), and PVW (0-56 nm) using a thread-ball-shaped molecule with R of 5.1 nm, a thread-ball-shaped molecule with R of 9 nm, a thread-ball-shaped molecule with R of 11.8 nm, a thread-ball-shaped molecule with R of 27 nm, and a thread-ball-shaped molecule with R of 56 nm; and

L. defining the average pore size as:

average pore size = [2.55 x PVW (0-5.1 nm)

+ 7.05 x PVW (5.1-9 nm)

+ 10.4 x PVW (9-11.8 nm)

+ 19.4 x PVW (11.8-27 nm)

+ 41.5 x PVW (27-56 nm)]

/[PVW (0-56 nm)].

4. A process for producing a water-swellable crosslinked polymer as claimed in claim 1, comprising the steps of subjecting a hydrophilic high molecule to a crosslinking reaction in an aqueous solution, wherein the crosslinking reaction is carried out in such a manner that the change in the concentration of a solid content falls within the range of ±30 %.

5. A process for producing a water-swellable crosslinked polymer as claimed in claim 1, comprising the steps of subjecting a hydrophilic high molecule to a crosslinking reaction in an aqueous solution, wherein the crosslinking reaction is carried out in such a manner that the concentration of a solid content falls within the range of 2 to 40 %.

8. A method for measuring a pore volume of pores with a specific range of size in a water-swellable crosslinked polymer as claimed in claim 1, which is swollen with a physiological salt solution, comprising the steps of:

allowing said swellable crosslinked polymer (W1 g), which stands in an equilibrium state swollen with physiological salt solution (W2 ml), to fall again into an equilibrium state by adding a physiological salt solution (W3 ml, concentration Ci%) of a thread-ball-shaped molecule with molecular diameter R to the polymer; and then filtering off the polymer as swollen with physiological salt solution; and then measuring concentration Cf% of the thread-ball-shaped molecule in the resultant filtrate; and

thereby determining volume PV (O-R) of physiological salt solution, as absorbed into pores having a size of O-R in a state swollen with physiological salt solution, from the following equation:

PV (0-R) (ml/g) = (W2+W3) [1-{W3/(W2+W3)} x (Ci/Cf)]/W1.

9. An absorbent article which comprises a water-swellable crosslinked polymer, wherein the water-swellable crosslinked polymer has a total pore volume of pores with a pore size in gels of 5.1-27 nm of 60 v/v% or more relative to the entire amount of a physiological salt solution absorbed into the polymer, wherein the pore volume of pores with a pore size in gels of 5.1-27 nm (PV (5.1-27 nm)) is defined by a method comprising the following steps of:

A. allowing a water-swellable crosslinked polymer (W1 g), which stands in an equilibrium state swollen with a physiological salt solution (W2 ml), to fall again into an equilibrium state by adding a physiological salt solution (W3 ml, concentration Ci%) of a thread-ball-shaped molecule with molecular diameter R to the polymer; and then filtering off the polymer as swollen with the physiological salt solution; and then measuring concentration Cf % of the thread-ball-shaped molecule in the resultant filtrate;

B. defining PV (0-R) (ml/g) as PV (0-R) (ml/g) = (W2+W3) [1-{W3/(W2+W3)}x(Ci/Cf)]/W1;

C. determining PV (0-5.1 nm) and PV (0-27 nm) using a thread-ball-shaped molecule with R of 5.1 nm and a thread-ball-shaped molecule with R of 27 nm and

D. defining PV (5.1-27 nm) as PV (5.1-27 nm) = PV (0-27 nm) - PV (0-5.1 nm).

10. An absorbent article which comprises a water-swellable crosslinked polymer, wherein the water-swellable crosslinked polymer has a total pore volume of pores with a pore size in gels of 5.1-27 nm of 80 v/v % or more relative to the entire amount of an ion-exchanged water absorbed into the polymer, wherein the pore volume of pores with a pore size in gels of 5.1-27 nm (PV (5.1-27 nm)) is defined by a method comprising the following steps of:

E. allowing a water-swellable crosslinked polymer (W1 g), which stands in an equilibrium state swollen with ion-exchanged water (W4 ml), to fall again into an equilibrium state by adding an ion-exchanged water solution (W5 ml, concentration Ci%) of a thread-ball-shaped molecule with molecular diameter R to the polymer; and then filtering off the polymer as swollen with the ion-exchanged water; and then measuring concentration Cf % of the thread-ball-shaped molecule in the resultant filtrate;

F. defining PVW (0-R) (ml/g) as PVW (0-R) (ml/g) [sic] (W4+W5) [1-{W5/(W4+W5)}x(Ci/Cf)]/W1;

G. determining PVW (0-5.1 nm) and PVW (0-27 nm) using a thread-ball-shaped molecule with R of 5.1 nm and a thread-ball-shaped molecule with R of 27 nm; and

H. defining PVW (5.1-27 nm) as PVW (5.1-27 nm) = PVW (0-27 nm - PVW (0-5.1 nm).

11. An absorbent article which comprises a water-swellable crosslinked polymer, wherein the water-swellable crosslinked polymer has an average pore size in gels of 10-30 nm and a standard deviation of 11.5 or less in pore size in gels when the polymer is swollen with ion-exchanged water, wherein the average pore size is defined by a method comprising the following steps of:

I. allowing a water-swellable crosslinked polymer (W1 g), which stands in an equilibrium state swollen with ion-exchanged water (W4 ml), to fall again into an equilibrium state by adding an ion-exchanged water solution (W5 ml, concentration Ci%) of a thread-ball-shaped molecule with molecular diameter R to the polymer; and

then filtering off the polymer as swollen with the ion-exchanged water; and then measuring concentration Cf% of the thread-ball-shaped molecule in the resultant filtrate;

J. defining PVW (0-R) (ml/g) as PVW (0-R) (ml/g) = (W4+W5) [1-{W5/(W4+W5)}x(Ci/Cf)]/W1;

K. determining PVW (0-5.1 nm), PVW (5.1-9 nm), PVW (9-11.8 nm), PVW (11.8-27 nm), PVW (27-56 nm), and PVW (0-56 nm) using a thread-ball-shaped molecule with R of 5.1 nm, a thread-ball-shaped molecule with R of 9 nm, a thread-ball-shaped molecule with R of 11.8 nm, a thread-ball-shaped molecule with R of 27 nm, and a thread-ball-shaped molecule with R of 56 nm; and

L. defining the average pore size as:

average pore size = [2.55 x PVW (0-5.1 nm)

+ 7.05 x PVW (5.1-9 nm)

+ 10.4 x PVW (9-11.8 nm)

+ 19.4 x PVW (11.8-27 nm)

+ 41.5 x PVW (27-56 nm)]

/ [PVW (0-56 nm)]."

Claims 6 and 7 were process claims directed to elaborations of the subject-matter claimed in Claims 4 and 5.

II. Two Notices of Opposition were filed against the patent, as follows:

(i) by Stockhausen GmbH & Co. KG (Opponent I), on 27 November 2002 and

(ii) by Kimberly Clark Worldwide, Inc. (Opponent II), on 27 November 2002.

Both Opponents requested the revocation of the patent on the grounds of lack of novelty and lack of inventive step (Article 100(a) EPC), and of insufficient disclosure (Article 100(b) EPC).

These objections were supported inter alia by the following documents:

Dl: Dextran Fractions; Amersham Biosciences data file 18-1153-41 AA, 2001-11;

D2: US-A-4 090 013;

D4: US-A-5 230 958;

D7: Declaration of Joy Holgerson, dated November 22, 2002;

D8: Declaration of Hoa Wilhelm, dated November 26, 2002;

D9: Martin M. Chui et al, "Measurement of the Porous Microstructure of Hydrogels by Nuclear Magnetic Resonance" Journal of Colloid and Interface Science, Vol. 174, 1995, pages 336-344;

D10: W0-A-95/12632;

Dl1: EP-B-0 105 634; and

Dl3: Declaration of Michael Niemeyer, dated 27 November 2002.

III. By a decision announced orally on 24 November 2004 and issued in writing on 6 December 2004, the Opposition Division rejected the oppositions.

According to the decision of the Opposition Division, the grounds of opposition raised by the Opponents did not prejudice the maintenance of the patent as granted. According to the decision the subject-matter of the granted claims met the requirements of Article 83 EPC, since the examples clearly indicated how to obtain a water swellable crosslinked polymer having a total pore volume falling within the meaning of the claims, and since the method for determining the pore volume of pores was completely reported in Claims 1 and 3. The Opposition Division did not accept the arguments of the Opponents that it was impossible to determine the pore volume according to the method disclosed in the patent in suit with precision and accuracy, since the tests carried out by the Opponents having been carried on a commercial product (Favor 880) and not on a polymer resulting from the examples of the invention were not an exact repetition of the specific embodiments indicated in the opposed patent.

According to the decision the subject-matter of the claims was novel over documents D2, D4, D9, D10, and D11. Furthermore, according to the decision, it had not been shown by the Opponents that the prior use of the product Favor 880 (cf. D13) complied with the requirements of the claims of the disputed patent.

Concerning inventive step, it was held that none of the cited documents suggested that the use of polymer having a total pore volume with a pore size in gels as indicated in Claims 1 to 3 would result in an improvement of the absorbency as shown by the examples. Furthermore, the method of measuring the pore volume according to Claim 8 had not been disclosed nor suggested by the cited documents.

IV. Notices of Appeal were filed on 4 February 2005 by Appellant I (Opponent I) and on 9 February 2005 by Appellant II (Opponent II) with simultaneous payment of the prescribed fee.

V. With its Statement of Grounds of Appeal filed on 15 April 2005, Appellant II submitted the following documents:

D17: Graph showing the maximal concentration of Dextran (thread-ball shaped molecule) in the filtrate as a function of the swelling capacity of the polymer; and

Annex 2: Test Data for samples prepared according to D2.

It also presented arguments concerning insufficiency of disclosure which may be summarized as follows:

(i.1) It had been held in the decision under appeal that the opposed patent satisfied the requirements of Article 83 EPC since it contained examples of the synthesis of polymers which allegedly satisfied the requirements of the test procedures set out in Claims 1 to 3.

(i.2) Claims 1 to 3 however were not limited to the particular swellable polymers synthesized in the Examples.

(i.3) During the opposition procedure, both Opponents had submitted test data demonstrating that the tests referred to in the claims did not produce meaningful results in relation to the prior art product Favor 880.

(i.4) Favor 880 water-swellable polymer tested by the Opponents was a crosslinked partially neutralised polyacrylic acid as in the Examples in the opposed patent.

(i.5) The Patent Proprietor had provided no explanation as to why the claimed tests did not work with Favor 880.

(i.6) The very small difference in concentration of the Dextran for 0% and 100% exclusion could not be measured reliably using the method of the patent.

(i.7) Blank measurements showed that there was an inherent error in the method of at least about 0.6%.

(i.8) As shown by Annex 2, there was a standard deviation of 0.004% in the filtrate concentration.

(i.9) This would imply a grand total estimate of error equal to about 1.4%.

(i.10) For a superabsorbent having a capacity of 60 g/g no exclusion of the Dextran would give a concentration of 0.5000% whereas total exclusion would give a concentration of 0.5051% (see also D17).

(i.11) Thus, for a 60 g/g capacity superabsorbent, and taking into account the error of 1.4%, it was impossible to distinguish between complete exclusion and none at all using the method of the patent.

(i.12) Repeating the analysis for the case of 100 g/g superabsorbent capacity, the error in determining excluded volume would be massive i.e. 84.5%. With a polymer having a 290 g/g capacity, the error in excluded volume would be reduced to 26%.

(i.13) However, a swelling capacity of 290 g/g was significantly higher than the swelling capacity of the vast majority of known superabsorbent polymers.

(i.14) The test procedures set out in Claims 1 to 3 were therefore flawed in that by their very nature they could not provide meaningful results for the vast majority of absorbent polymers.

(i.15) Further tests had been carried on samples of absorbent polymer prepared according to D2. The process disclosed in Examples I and II of D2 fell within at least Claims 4, 5 and 7 of the opposed patent (cf. Annex 2).

(i.16) These results further confirmed that the claimed tests were fundamentally flawed and hence that the patent was insufficient.

(i.17) They also showed that even a polymer prepared according to the process claimed in the opposed patent did not fall within Claims 1 to 3.

(i.18) In view of the evidence submitted, the burden of proving sufficiency should be shifted to the Patent Proprietor.

(i.19) Insufficiency arguments set out in the letter dated 24 September 2004 relating to the term "thread-ball-shaped molecule with molecular diameter R" in Claims 1 to 3 of the patent in suit were also maintained.

VI. With its Statement of Grounds of Appeal filed on 18 April 2005, Appellant I submitted the following documents:

Tables A and B: tests results on Samples 9 and 10 of D2; and

D18: Declaration of Dr. H. Schmidt dated 15 April 2005.

The arguments concerning insufficiency of disclosure presented by Appellant I in its Statement of Grounds of Appeal may be summarized as follows:

(i.1) The pore volume test of the patent in suit was neither exact nor sound and of course not reproducible. It yielded for example negative pore volumes or percentages above 100%.

(i.2) Samples 9 and 10 of D2 were state of the art samples which exactly followed the teaching of the patent in suit (cf. Claim 5).

(i.3) The pore volume tests carried out by Appellant II on these Samples clearly showed that meaningless results were obtained.

(i.4) The Appellants had sufficiently proved lack of enablement.

(i.5) According to numerous decisions of the Technical Boards of Appeal of the EPO the patent in suit must contain sufficient information to carry out the invention within the whole area that was claimed, i.e. not only with respect to the examples given in the patent in suit.

(i.6) Sample 9 of D2 clearly showed with a V/V% average of 46.53 (cf. Table A) that the claimed range of 60% or more was not fulfilled. Therefore, the claims in general and in particular Claims 1 and 5 were not sufficiently disclosed.

(i.7) Furthermore, the measurements in ion-exchange water of Samples 9 and 10 showed that they neither exhibited a V/V% average of 80% or more nor possessed an average of the Average Pore Size of 10-30 nm. Consequently, the subject-matter of Claims 2 and 3 was likewise not sufficiently disclosed, since both samples were however embodiments of the patent in suit.

(i.8) Reference was made in that respect to decision T 226/85 in which it was stated "it is, however, important to note that for sufficiency not only the exemplified specific embodiments must be reproducible but any embodiment which falls within the ambit of the claim."

(i.9) The Appellants had provided numerous pieces evidence that the pore volume tests of the patent in suit did not work.

(i.10) The Patent Proprietor had failed to submit evidence showing that the tests gave meaningful results.

(i.11) The shift of burden of proof to the Patent Proprietor was justified.

VII. In its letter dated 2 August 2005, the Respondent argued essentially as follows concerning insufficiency of disclosure:

(i.1) The tests carried out by the Appellants could not be considered as objective because they were not an exact repetition of the specific embodiments indicated in the patent in suit.

(i.2) The tests on Samples 9 and 10 of document D2, as provided by Appellant I, did not present in detail all the necessary operational data.

(i.3) A polymer usually had a molecular weight range and a molecular weight distribution. The test experiments provided by Appellant I did not show such data.

(i.4) Appellants I and II had argued that the burden of proof had been transferred to the patentee to provide evidence supporting that the method for determining the pore size volume was sufficiently disclosed.

(i.5) It was however the permanent jurisdiction of the Boards of Appeal in the European Patent Office that for proving an insufficient disclosure of an invention lack of reproducibility of the examples provided in the respective patent in suit was to be demonstrated.

(i.6) Any experimental data provided in respect of a sample of super absorbent Favor 880 could not be considered as providing objective evidence that the embodiments described in the present patent were objectionable under Article 83 EPC.

VIII. In a communication dated 8 August 2006 annexed to the summons to oral proceedings scheduled to take place on 30 November 2006, the Board drew the attention of the Parties to issues concerning the determination of the pore volume and the manufacture of the claimed products in view of the disclosure of document D2.

IX. With its letter dated 26 October 2006, the Respondent submitted a first auxiliary request consisting of six claims and a second auxiliary request consisting of a single claim.

Independent Claims 1 and 6 of the first auxiliary request corresponded to granted Claims 2 and 10. Independent Claims 2 and 3 and dependent Claims 4 to 5 were said to be based on granted Claims 4 and 5, and on granted Claims 6 and 7.

Claim 1 of the second auxiliary request corresponded to Claim 10 as granted.

It also presented arguments concerning insufficiency of disclosure which may be summarized as follows:

(i.1) Neither Appellant had exactly repeated the specific embodiments described in the patent in suit with respect to the measurement method of the pore volume of a water-swellable crosslinked polymer as claimed in claims 1 to 11 of the patent in suit as granted.

(i.2) Therefore, due to the lack of evidence, sufficiency of disclosure of the patent in suit should be acknowledged.

(i.3) According to the permanent jurisdiction in the EPO, the only requirement with respect to information not explicitly disclosed in a patent with respect to the requirements of sufficiency of disclosure was that information which was not explicitly disclosed in a patent sufficiently, was obvious to a person skilled in the art in a way that a detailed description of said information was superfluous in the light of the general knowledge of a skilled person.

(i.4) This applied to the way of determining the total amount of absorption for physiological salt solution and to the temperature at which the absorbency should be determined.

(i.5) Reference was made to paragraph [0029] of the patent in suit and to the standard procedures to determine the absorbency of super absorbent materials EDANA 442.1-99 and 441.1-99 as well as JIS K 7224-1996 according to which the parameters were measured by swelling the super absorbent materials or polymers at 23 ± 2 ºC.

(i.6) The same applied with respect to the so-called thread-ball shaped molecules which were used in the measurement of the pore volume as described in the present patent. Reference was also made to the letter of Appellant I dated November 27, 2002, page 5, second paragraph).

(i.7) The molecular diameter of said thread-ball- shaped molecules was known to a person skilled in the art for example from catalogues of commercially available products of said thread-ball-shaped molecules.

(i.8) The Respondent contradicted the allegations of Opponent II with respect to the high measurement errors (about 1.4 %).

X. The arguments presented by Appellant I in its letter dated 27 October 2006 and concerning insufficiency of disclosure may be summarized as follows:

(i.1) Reference was made to decision T 172/99 of 7 March 2002 (not published in OJ EPO).

(i.2) It had been shown that the pore volume test was not sufficiently disclosed for at least two polymers which were covered by the claim language.

(i.3) Contrary to the Patent Proprietor's assertion, the test experiments carried out by Appellant I provided both the film swell index for Samples 9 and 10 and the weight average molecular weight of the polyacrylate precursor prepared according to Example I of D2 (cf. D18).

XI. In its letter dated 27 October 2006, Appellant II argued essentially as follows:

(i) All the claims in the opposed patent referred either directly or indirectly to pore volume as measured by a particular non-standard test procedure.

(ii) It was for the Patent Proprietor to demonstrate that the patent in suit contained a full disclosure of the method by which the parameter was to be measured.

(iii) Claim 3 of the granted patent referred to an average pore size and a standard deviation in pore size. There was no indication whatsoever either in the claim or in the description of the patent as to how the standard deviation in pore size should be calculated.

(iv) Furthermore, a calculation made by Appellant II, showed that apart from comparative Example 3, the values for the average pore size reported in Table 2 of the patent in suit did not agree with those calculated using the equation given in Claim 3.

XII. Oral proceedings took place before the Board on 30 November 2006.

At the oral proceedings the discussion essentially focussed on the question of sufficiency of disclosure in view of the methods for determining the pore volumes used for characterizing the polymers according to granted Claims 1 and 2, of the determination of the average pore size and standard deviation thereof, and the method for determining the pore volume of water swellable polymer according to granted Claim 8.

(a) The Appellants, while having indicated that they essentially relied on the arguments and evidence presented in that respect during the written phase of the appeal for supporting their objection of insufficient disclosure, made additional submissions in that respect which may be summarized as follows:

(a.1) The methods for determining pore volumes as disclosed in granted Claims 1, 2 and 8 were not restricted to polymers meeting the requirements of Claims 1, 2 and 3. They should also be applicable to water swellable polymers of the prior art.

(a.2) Favor 880 and SXM 9543 which had been used in the tests carried out by Appellant II were superabsorbent polymers, based on partially neutralized polyacrylic acid as the polymers used in the Examples of the patent in suit.

(a.3) The patent in suit did not define the thread-ball shaped molecule used for carrying out the test for determination of pore volume.

(a.4) Document D1, which referred to Dextran products did not even refer to this term. Furthermore, the diameters which could be calculated from the Stoke's radii indicated in D1 (page 2) for the various Dextran products did not correspond to the diameters indicated in the patent in suit for the Dextran products used as "thread-ball shaped molecule".

(a.5) Stoke's radius might be determined in two different ways, either using a dynamic method (diffusion) or a static method (light scattering). These methods did not lead to the same results.

(b) The Respondent, while also essentially relying on the arguments presented in the written phase of the appeal made further submissions in order to support its view that the patent in suit did not lack sufficiency of disclosure in these respects. They may be summarized as follows.

(b.1) The criteria for sufficiency of disclosure was the possibility of repeating the examples of the patent in suit.

(b.2) The Respondent had no difficulties for carrying out the tests. The accuracy of the test was about 1%.

(b.3) The skilled person would know what was meant by "thread ball shaped molecules" and by the diameter of such molecules.

(b.4) An explanation to the problems encountered by the Appellants could have been that they had used polymers with an insufficient absorbency.

(b.5) As shown by document D17, the difference in the Dextran concentration in the filtrate between a 0% exclusion and a 100% exclusion increased with the absorbency of the polymer.

(b.6) The patent in suit was concerned with superabsorbent polymers which were known to have a high absorbency in physiological solution, e.g. more than 100g/g.

(b.7) Furthermore, the absorbency of these polymers was known to be even higher in ion-exchanged water than in physiological solution.

(b.8) The Respondent had developed its own method for calculating an average pore size of water swellable crosslinked polymer. Nevertheless, the standard deviation would however be determined as known by the skilled person.

XIII. The Appellants requested that the decision under appeal be set aside and the patent be revoked.

The Respondent requested that the appeals be dismissed, or, in the alternative, that the decision under appeal be set aside and the patent be maintained on the basis of Claims 1 to 6 of the first auxiliary request, or on the basis of Claim 1 of the second auxiliary request, both submitted with letter dated 26 October 2006.