The patent proprietor filed an appeal after the Opposition Division had revoked the opposed patent, in particular on the grounds of insufficiency of disclosure and lack of compliance with A 123(2).
Claim 1 before the Board read:
1. A composition comprising aqueous fluid absorbent polymer particles which have been heat-treated at temperatures greater than 170ºC for more than 10 minutes, wherein the composition has been remoisturized, after the heat-treatment, with an aqueous additive solution containing a mono- or multivalent metal salt in the absence of an organic solvent or water-insoluble, non-swellable powder, wherein the composition comprises 1 to 10 percent by weight, based on the total weight of the composition, water and wherein the composition is characterized by the ability to absorb at least 20 grams of a 0.9 weight percent aqueous saline solution under a pressure of 0.3 psi (21,000 dynes/cm2), that is, a 60 minute 0.3 psi (21,000 dynes/cm2) absorption under load (AUL) greater than 20 grams/gram. (my emphasis)
The Board found the request on file to comply with A 123(2) and then examined its compliance with A 83:
[3] The objections raised under A 83 essentially concerned the parameter “a 60 minutes 0.3 psi (21,000 dynes/cm2) absorption under load (AUL) greater than 20 grams/gram.
The [opponents] argued that the contested European patent did not disclose the invention in a manner sufficiently clear and complete for it to be carried out by a person skilled in the art because:
- the above parameter did not define the AUL of the entire absorbent polymer composition;
- the open-end range of AUL did not allow the skilled person to perform the patent over the whole claimed range; and
- the patent did not disclose the invention in a manner such that the skilled person could systematically obtain compositions satisfying the AUL-parameter.
The [opponents] raised an additional objection under A 83 concerning an alleged contradiction between Claim 1 (absence of organic solvent) and Claims 6 and 11 (further comprising propoxylated polyol, which is an organic solvent).
Method of measuring AUL
[3.1.1] The board acknowledges that the claims do not comprise a definition of the method to be used for the measurement of the AUL of the composition. Nevertheless, the patent specification […] provides a clear and unambiguous disclosure of the method to be used, stating that the composition is characterised by the ability to absorb 20 grams of a 0.9 weight per cent aqueous solution under a pressure of 0.3 psi, that is:
“a 60 minutes 0.3 psi (21,000 dynes/cm2) AUL greater than 20 grams/gram as measured in accordance with the Absorption Under Load Test set forth in U.S. Patent No. 5,147,343”. [This document corresponds to D1 of the appeal proceedings].
The board is satisfied that D1 […] discloses this test in full detail and thus enables the skilled person to carry out this test – something which was not contested by the [opponents]. The board, however, acknowledges the potential artificiality of this test, which is actually the origin of the dispute between the parties, namely that it does not use all polymer granules from the claimed composition in the measurement of AUL but only a fraction thereof. Thus a sample is prepared by pre-screening the granules through a U.S. standard #30 mesh and keeping only those retained on a U.S. standard #50 mesh. The AUL is then determined by measurements carried out on this fraction, which thus contains only particles with a size ranging between around 300 and around 600 mym. As a matter of convention, the AUL-value measured for this particular fraction is then attributed to the sample composition as a whole, i.e. to a composition including all polymer granule fractions.
The board observes that neither D1 nor any other of the cited documents provides a technical explanation for the selection of the specific particle size fraction in the AUL measuring method. Nor could such an explanation be provided by the parties at the oral proceedings. This is, however, immaterial since D1 gives the skilled person clear instructions how to carry out the measurement.
[3.1.2] The board acknowledges that the potential artificiality underlying the AUL-test described in D1 may be even more artificial in the present case. In particular, Claim 1 relates to a composition comprising aqueous fluid absorbent polymer particles but attributes the AUL to the whole composition. The board accepts that the AUL-value measured on a particular particle fraction of such a composition may indeed be even less representative for a composition comprising, besides the absorbent polymer particles, further components (e.g. non-absorbents) than for a composition essentially consisting of only absorbent polymer particles. Nevertheless, the convention or artificiality stemming from D1 is not invalidated by this fact.
[3.1.3] In the Board’s view, this convention cannot be validly objected to under A 83. A person trying to repeat the invention has merely to pre-screen the composition through a U.S. standard # 30 mesh, to retain the particles on a U.S. standard # 50 mesh, carry out the AUL-test on the retained sample of granules and then attribute the resulting value - in accordance with the convention - to the composition as a whole.
Under these circumstances it is not necessary to further consider whether the AUL-value depends on the particle size.
[3.1.4] In the board’s view there can also be no doubt that the claim requires that the composition indeed comprises particles of the required size. If no such particles are present in the composition, no AUL-value can be measured using the prescribed method, so that such a composition would in any case not fall within the scope of the claims.
[3.1.5] However, the particularity of the AUL-test may lead to the parameter as defined in Claim 1 being, at least to a certain extent, technically meaningless. For example, a composition may have, in accordance with the convention of the AUL-test, the required AUL-value, but may in fact have a rather “bad” absorbency under load in practice, for example because the composition contains only a very small amount of the material responsible for it. In the board’s view, however, this aspect relates not to insufficiency of disclosure, but rather is to be evaluated in the assessment of inventive step.
[3.1.6] Finally the board does not consider that the conclusions of T 137/01 on sufficiency of disclosure apply by analogy to the present case. In T 137/01 the claimed invention was also defined by parameters of the superabsorbent material, namely the “Resistance to Deformation Under Load” and the “Wicking Index”, although these are different from the AUL parameter used to define the present invention. In T 137/01, the patent, as with the present patent, only disclosed how to measure the parameters for absorbent particles with sizes between 300 and 600 mym.
In T 137/01 [2.2.1] the board took the view that since the claim was not limited to composites only having absorbent particles lying within this range, and since the patent did not disclose how much of the absorbent material should consist of particles lying within this range, there was not enough information enabling the skilled person to say that the absorbent material as a whole would be suitable for achieving the desired effects, these effects being achieved when the measured values of the parameter of the “whole superabsorbent material [fell] within specific numerical ranges.”.
[3.1.7] The present board reads the present patent differently. The board considers that it would be apparent to the skilled person that the AUL-value to be attributed to the composition for the purpose of the claimed invention cannot be the actual AUL-value for the “whole” composition because the stipulated AUL determination method requires sieving, as already explained. Since the composite is likely to have also absorbent particles with sizes lying outside the 300 - 600 mym range (see e.g. the reference to the problem of polymer particles in the form of dust […]) the AUL-value obtained is at best only likely to be representative of the actual AUL characteristics of the composite (except in the unlikely case of the composite comprising only polymer particles falling within the claim range). How representative the value will be for the whole composition will depend on the particular circumstances, in particular on the nature of the absorbent polymer used and the constitution of the composition as a whole. But the parameter is, nevertheless, capable of being measured and the skilled person will be able to tell if any particular composition falls within the claimed parameter value range. As already indicated, however, the stipulated method of determining the AUL-value will clearly become highly relevant when it comes to evaluating inventive step.
AUL value defined as an open-ended range
[3.2.1] The composition referred to in the claims (see for example Claim 1) must have an AUL-value of greater than 20 g/g. In essence it was argued that this open-ended range was unduly broad so that it would embrace values of AUL which were not yet known and/or it was not known how they could be achieved. In fact, the highest AUL-value in the examples of the contested patent is 30.5 g/g […]. However, the Board does not construe the AUL-value range as claimed, i.e. without defining a specific upper-end, as being unlimited.
[3.2.2] This objection is based on an erroneous interpretation of the subject-matter covered by the claims. It is clear for a skilled reader that a claim such as present Claim 1 including an open-ended range is limited in practice. In fact, values of the parameter not obtainable in practice would not be regarded by the skilled reader as being covered by the claim and thus could not justify an objection of insufficiency of disclosure (see Case Law of the Boards of Appeal of the EPO, 6th edition 2010, Section II.A. 6.1; see also point 2.3 of T 1018/05 [2.3] and T 297/90 [2.2]). The use of an open-end formulation simply seeks to embrace values which should be as high as can be technically attained above the specified minimum, given the other parameters of the claim.
In the present case there is a clear teaching in the patent specification, including numerous examples, how to achieve compositions with the desired value of absorbency under load greater than 20 g/g. Moreover Claim 1 includes process features (heat treatment of a starting material and its remoisturization with a specific aqueous additive solution), so that the skilled reader would immediately understand the practical repercussions of these limitations, namely that the starting material and the method for the preparation of the water-absorbent powder set the practical limitations for the value of absorption under load.
[3.2.3] The [opponents] did not question the examples in the patent in suit nor did they submit any experimental evidence showing that the invention could not be performed. Consequently, the board is satisfied that the requirement of sufficiency of disclosure with regard to the open-ended range for the AUL is met.
[3.2.4] In reaching this conclusion the board has also considered the decision T 1008/02 [3.3-4]. There, the board concluded that the auxiliary request under consideration did not fulfil the requirements of sufficiency because none of the examples showed the claimed properties, in particular an absorbency under load of “at least 27 ml/g”, and no evidence had been produced that a superabsorbent having inter alia this property was available to the skilled person. Thus, the situation in that case differs from the present case where the patent provides various examples with values of absorbency substantially greater than 20 g/g (e.g., 30.5 g/g).
Performance of the invention so that AUL values
systematically fall within the claimed range
[3.3.1] The board is satisfied that the experimental part of the contested patent exemplifies compositions with an AUL falling within the claimed range. The board does not dispute the fact that a comparison of the examples in the patent in suit with regard to the AUL-values before and after remoisturization indicates that the AUL-value can either increase […] or decrease […] or even remain the same […]. Nevertheless, the board observes that in all these examples referred to by the [opponents], the measured AUL has a value falling within the claimed range. Thus sufficiency of disclosure cannot be plausibly contested. In particular since commercial products are used as the starting materials […].
[3.3.2] Even if remoisturizing were to decrease AUL of the heat-treated polymer particles, it appears to be an obvious measure to use heat-treated polymer particles with a sufficiently high AUL-value in the first place so that despite a decrease after remoisturizing the AUL-value would still be above the lower limit.
The contradiction between Claim 1 and Claims 6 and 11
[3.4.1] According to independent Claim 1 the composition is remoisturized with a specific aqueous additive solution in the absence of an organic solvent. On the other hand, Claims 6 and 11, both dependent on Claim 1, specify that the aqueous additive solution further comprises a propoxylated polyol, which is, as pointed out by the [opponents], normally considered to be an organic solvent.
[3.4.2] The board accepts that there is a prima facie contradiction between Claim 1 (absence of organic solvent) and Claims 6 and 11 (further comprising propoxylated polyol). Nevertheless, the board considers that a skilled person would understand from reading the claims that, in the context of the present patent, propoxylated polyols are not considered to be organic solvents which have to be excluded. This is in fact supported by paragraph [0017] of the patent specification which describes, in addition to sodium, potassium or aluminium ions, propoxylated polyols as suitable additives, in particular to further bind the fine dust of the final superabsorbent polymer. Thus, the patent specification attributes to the propoxylated polyols a particular function different from the “normal” solvent function.
[3.4.3] In fact this issue relates to clarity, namely the interpretation of the terms used in the claims, rather than to sufficiency of disclosure. In any event, the apparent contradiction is resolvable, as explained above.
Admissibility of additional arguments regarding sufficiency of disclosure
[4.1] With its letter dated 13 January 2011 [opponent 1] filed numerous additional arguments relating to sufficiency of disclosure. The most relevant among these arguments concerned the absence of any disclosure of the method of measuring the water-content of the claimed composition. According to Claim 1 the composition comprises 1 to 10 percent by weight water, based on the total weight of the composition.
[4.2] These new arguments were filed long after [opponent 1’s] reply to the statement of grounds of appeal (filed with letter dated 10 October 2008) and also after the board had issued the summons to attend oral proceedings (11 August 2010). These arguments and lines of attack were therefore submitted very late and would have required amendment to [opponent 1’s] case (Article 13(1) RPBA), as well as prolonging and complicating the appeal. Furthermore, these new arguments are not prima facie relevant. In particular with regard to the method of measuring the required water-content of 1 to 10 wt%, the board observes that the originally filed application […] and the patent specification […] disclose that the moisture-content of the superabsorbent polymer resin is determined by weight loss at 105ºC for 3 hours. This method corresponds exactly to the disclosure of D28 where the following is stated […]:
“Traditionally the determination of moisture in superabsorbent polymers has been obtained gravimetrically after heating the sample at 105ºC for 3 h.”
Thus, apart from the fact that the method of measuring the water-content is disclosed in the patent specification itself, this method even appears to belong to the common general knowledge of a person skilled in the art.
[4.3] In view of the above considerations, the board exercising its discretion power under Articles 13(1) RPBA decided not to allow [opponent] 1 to amend its case and thus to admit the additional arguments relating to sufficiency into the proceedings.
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