Thursday, 17 May 2012

T 1051/09 – Too Particular

This appeal was against the revocation of the patent under consideration by the Opposition Division (OD).

Claim 1 of the main request before the Board read:
A process for preparing paper comprising:
(A) a resin treatment step for reducing the AOX content of a starting water-soluble wet-strength resin comprising azetidinium ions and tertiary aminohalohydrin, comprising treating said resin in aqueous solution with base to form treated resin, wherein at least 90% of the tertiary aminohalohydrin present in the starting resin is converted into epoxide, the level of azetidinium ion is substantially unchanged, and the effectiveness of the treated resin in imparting wet strength is at least as great as that of said starting wet strength resin; and
(B) a paper-making step comprising:
(a) providing aqueous pulp slurry
(b) adding to the aqueous pulp slurry the treated resin produced in step (A)
(c) sheeting and drying the aqueous pulp slurry to produce paper.
In what follows the Board examined this request in view of sufficiency of disclosure.

[2] The claimed process is defined in a functional manner, i.e. by its outcome. Since the claimed subject-matter is not limited to particular water-soluble wet-strength resins, the question to be answered with respect to A 83 is whether the way to achieve that outcome for any possible water-soluble wet-strength resin is disclosed in the patent in suit in such a manner that it is fit for generalisation beyond the specific examples disclosed.

[2.1] The only general information relating to the nature of the resin is provided in paragraph [0034] of the patent in suit which states that the amount of base varies widely from resin to resin and teaches that this is dependent on :
  •  resin type
  • amount and type of polymeric aminochlorohydrin
  • the amount of epi by-products
  • the amount of stabilisation acid in the resin
  • the conditions used to activate the resin.
There are however no further explanations, analyses or discussions of any of these factors, their interrelationship and how they affect the outcome. Thus all that this paragraph provides is a disclosure which while comprehensive in scope is almost devoid of any relevant information. In particular this paragraph does not amount to the provision of a teaching of a concept fit for generalisation since no consideration is presented of how the identified factors might, even in a very general manner, influence the outcome or interact with the treatment system.

According to paragraph [0035], the treatment temperature ranges from 0° to 100°C, the time from 1 minute to 24 hours and the resin solids content for base treatment from 1% up to 40%. These are very broad ranges and again there is no discussion or appreciation of their interdependence or relationship to other resin properties.

Paragraph [0038] provides the general statement that treatment conditions can be optimized for each resin to a given set of conditions, but that other conditions also give good results and that if shorter reaction time is desired then higher temperatures are needed. Thus the sum total of the general teaching is that it is necessary to select conditions that are neither “too mild” nor “too harsh”, but are “moderate” or “just right” and that the conditions have to be adapted to the resin and a list of factors which influence the reaction, in line with the argumentation of the [patent proprietor].

[2.2] As submitted by the [patent proprietor], and not disputed by the [opponent], the patent in suit does indeed contain a great many examples. It is also the case that a number of different resins are employed in these examples. However the outcome of these is variable – some provide the required outcome in terms of reduction of AOX content (and also conversion of aminohalohydrin to epoxide) and retention of azetidinium groups, whereas others do not.

[2.2.1] The [patent proprietor] drew attention in particular to the family of examples 25, 26 and 28, which would reveal that the required “moderate” conditions to obtain simultaneously the required reduction of AOX and retention of azetidinium were provided by example 25, in which Kymene® 736 resin was treated:
  • at 55°C for 5 minutes
  • with 4.3 mmole NaOH/g resin and peak pH of 10.8
resulting in a percentage AZE of 38, a percentage aminochlorohydrin (ACH) of <2 and 165 ppm AOX.

The conditions of example 26 were however “too harsh”, leading to a too great reduction in azetidinium:
  • carrying out reaction under the same conditions of temperature and time, i.e. 55°C for 5 minutes
  • but with 5.1 mmol NaOH/g resin and a maximum pH of 11.1
resulting in a percentage AZE of 32, a percentage ACH of <2 and an undetectable amount of AOX.

Example 28, according to the [patent proprietor], demonstrated conditions that were “too mild”, i.e. did not lead to the required reduction of AOX:
  • 25°C for 5 minutes
  • same base concentration as example 25, i.e. 4.3 mmole NaOH/g resin but higher maximum pH namely 11.8
resulting in a percentage AZE of 37, a percentage ACH of <2 and 770 ppm of AOX.

As the respective values of the starting resin were 42%, 30% and 4820 ppm the reduction was (rounded):

Example 25: 10% AZE, >93% ACH, 96% AOX
Example 26: 34% AZE, >93% ACH, 100% AOX
Example 28: 12% AZE, >93% ACH, 84% AOX.

Apparently, from the [patent proprietor’s] submissions, a reduction of 10% or 12% of AZE is still considered as being “substantially unchanged”.

[2.2.2] Further, the [patent proprietor] drew attention to examples 24 to 26 in which the effect of the “harshness” of treatment on AZE retention was demonstrated. In example 24, treatment was carried out at
  • 55°C for 5 minutes
  • 3.9 mmole NaOH/g resin, peak pH 10.3
which resulted in hardly any loss of AZE with a percentage of 41, a percentage ACH of <2 and an undetectable amount of AOX. Hence, the reduction was:

Example 24: 2% AZE, >93% ACH, 100% AOX.

[2.2.3] The effect of the nature of the treatment on reduction in AOX content was stated by the [patent proprietor] to be demonstrated by examples 17 and 18, in which however Kymene® 557LX resin, hence a different resin from that of examples 24-26 and 28, was employed:

Example 17:
  • temperature/time conditions of 55°C/5 minutes
  • a base concentration of 2.4 mmole NaOH/g resin
  • the reaction reaching a peak pH of 10.9
resulting in a percentage AZE of 47.5 and a percentage ACH of 0.0 and 200 ppm of AOX.

In example 18 the same temperature/time conditions were employed but with 2.0 mmole NaOH/g resin, and a peak pH of 10.4, leading to a percentage AZE of 51.0, a percentage ACH of 1.5 and 663 ppm of AOX.

The values of the starting material being 51.6%, 8.8% and 3200 ppm, the reduction can be calculated:

Example 17: 8% AZE, 100% ACH and 94% AOX
Example 18: 1% AZE, 83% ACH and 79% AOX.

The conditions used in these examples differ significantly from those of examples 24-28, also in the concentration of base. Therefore, examples 17 and 18 cannot be compared or combined with examples 24-28 in order to obtain general information about how to achieve the result now being claimed.

[2.3] Furthermore, in the arguments presented with respect to examples 17 and 18 the [patent proprietor] focused solely on the AOX content, and omitted to explain what information these examples provide about other properties of the resin.

Accordingly, and apart from the question of the interpretation of “substantially unchanged” for the level of AZE, not only has the [patent proprietor] discussed unrelated examples in combination, it has furthermore restricted consideration of these examples to certain aspects in isolation. This approach is however inconsistent with the requirements of the claimed subject-matter: to obtain a set of properties in combination.

[2.4] Other evidence, not invoked by the [patent proprietor], undermines the conclusions presented by the [patent proprietor] regarding appropriate conditions based on example 25, showing these not to be generally applicable. Thus in comparative example 5 a polyamino-polyamide-epi resin containing about 13 mole% of AZE was prepared and in the related examples 21 and 22 it was base treated. In the results and discussion of examples 21 and 22 it is stated that treatment at 55°c for 5 minutes at a base concentration of 5.0 mmole NaOH/g resin and a peak pH of 11.6, i.e. a higher NaOH concentration and peak pH than employed in example 25, leads to the desired properties of the treated resin (a percentage AZE of 11.8, a percentage ACH of 0.0 and 244 ppm of AOX). According to example 22 however, the same temperature/time conditions but with a base concentration of 4.3 mmole NaOH/g resin and a peak pH of 11.2, i.e. the same base concentration as example 25 but a higher peak pH, do not lead to a desirable product, with a percentage AZE of 12.8, a percentage ACH of 5.1 and 759 ppm of AOX.

The starting resin having values of 13,1%, 54,8% and 9600 ppm, respectively, the reduction can be calculated:

Example 21: 10% AZE, 100% ACH and 97% AOX
Example 22: 2% AZE, 89% ACH and 92% AOX.

The evidence of these examples in relation to example 25 is that similar reaction conditions can lead to greatly differing outcomes in the case of different resins. The patent in suit however provides no explanation of the underlying factors leading to these differences.

[2.5] For the sake of completeness, the Board also notes that the teaching of the patent in suit with respect to the requirement of claim 1 of maintenance of the effectiveness of the resin at imparting wet-strength properties is also insufficient. There is a discrepancy between the results depending on the aging of the paper. Only in the case of examples 21 and 22 is a consistent improvement shown. For many other examples the requirement that the wet-strength should be at least that imparted by the starting resin is not fulfilled.

[2.6] The only conclusion that can be drawn from the above is that the conditions necessary to meet the varying requirements of the resin, in particular conversion of AOX and retention of AZE as well as maintenance of the effectiveness of the resin at imparting wet-strength properties, cannot be generalised but need to be adapted for each starting resin to be treated.

[2.7] Accordingly the patent in suit provides no indication or teaching for the skilled person on how starting from a given resin it is possible in a directed and structured manner to identify an appropriate set of conditions. Nor does the patent provide any indication or guidance to assist the skilled person in evaluating the outcome of unsuccessful trials to identify which modifications need to be made in order to progress towards conditions which give the desired result.

Each set of examples in the patent in suit relates to a specific resin. The [patent proprietor] has failed to show that the information given in the patent relating to the nature of the resins and conditions employed would provide the skilled person with the insight sufficient to understand the interaction between these factors and how they influence the outcome so that it would be possible in a directed way, without undue burden, to converge on a set of conditions which for any given resin would yield the desired result. Accordingly the technical teaching of the patent amounts to little more than a report that it has been found possible to provide optimised conditions enabling the various competing requirements to be met and some examples of special cases in which this was achieved. What is lacking is a generalisable teaching applicable within the scope of the claims, i.e. beyond the specific examples (cf. decisions T 435/91 [2.2.1] and T 226/85).

[2.8] The main request […] therefore does not meet the requirements of A 83 and is refused.

Should you wish to download the whole decision, just click here.

To have a look at the file wrapper, click here.