Tuesday, 13 October 2015

T 2249/10 - Lack of sufficiency for combination of parameters




The  polyethylene composition in Claim 24 in this opposition appeal is defined by a combination of parameters. Claim 24 according to the main request reads (simplified and formatted)

An injection moulded pipe fitting comprising a polyethylene composition (...)
- the flow rate ratio FRR21/5 of the polyethylene composition (...)  is within the range of 15-28
- the melt flow rate MFR5/190°C of the polyethylene composition (...) is within the range of 0.5-1.1 g/10 min, 
- the composition has a shear thinning index (SHI) (...) within the range of 10-60 (...)

The proprietor had successfully argued that  the flow rate ratio and melt flow ratio ranges do not imply a shear thinning index within the claimed range. The application gives two examples 1 and 2 which do have the required parameters. Unfortunately, the board does not see how the preparation of these examples differs from that of the comparative examples.


The claim is rejected for lack of sufficiency.


Reasons for the Decision
1. The appeal is admissible.


Main Request

Sufficiency of disclosure

2. The question to be answered when assessing sufficiency of disclosure of the injection moulded pipe-fitting of claim 24 of the main request, is whether it is possible to prepare substantially all polyethylene compositions meeting the parametric definition required by that claim. In particular, the question arises whether a person skilled in the art has sufficient information in the patent in suit and/or based on his general knowledge to obtain polyethylene compositions meeting the combination of a flow rate ratio FRR21/5 within the range of 15-28 and a shear thinning index (SHI2.7/210) within the range of 10-60.

2.1 According to the patent in suit, both the FRR21/5 and the SHI2.7/210 relate to the molecular weight distribution of the polyethylene composition. According to paragraph [0024] decreasing values for FRR21/5 indicate a decreasing width of the molecular weight distribution. According to paragraph [0040], the shear thinning gets more pronounced the broader the molecular weight distribution is.

2.2 According to the statement in D19 by one of the inventors of the patent in suit, "SHI is a rheological measurement of the molecular weight distribution by means of a plate-plate (...) Rheometer (as described in EP1655335) the measurement relation is covering a very large part of the viscosity curve (...) and hence has a good relation to the molecular weight distribution. The reason is that the lower the shear rate the bigger the influence of the high molecular weight portion and the higher the shear rate the bigger the influence from the low molecular weight part, meaning that to get as accurate picture as possible means that as big as possible range should be chosen. Contrary to this, the FRR21/5 is covering a much smaller portion of the viscosity curve and the lowest shear rate is considerably higher than the lower shear rate point in the plate-plate measurement. On top of this the FRR is a rheological measurement using a capillary measurement principal. That means that FRR is a less accurate rheological estimation of MWD and also added that other structural factors may come into play." In other words, the ratio FRR21/5 covers a much narrower range on the viscosity curve than does the ratio SHI2.7/210 and is a less accurate estimation of the molecular weight distribution than that on the basis of the complex viscosities.

2.3 The absence of a simple relation between FRR21/5 and SHI2.7/210 was argued by the appellant and is also shown by the measurements carried out on a variety of commercial resins or previously commercial resins the results of which are reported in D19. Measurements on the polyethylene resins "ME3440", "HE3494-FL" and "HE2470", indicated as bimodal, give FRR21/5 values of 27,0, 26,0 and 26,5 respectively, whereas the corresponding SHI2.7/210 exhibits values of 32,5, 50 and 37 respectively. The bimodal polyethylene resins "HE3490-LS" and "PE100-pilot" have FRR21/5 values of 38,0 and 38,6, whereas their SHI2.7/210 values are 61 and 94, respectively. The absence of a simple relationship between FRR21/5 and SHI2.7/210 is also confirmed by examples 1 and 2 and comparative examples 1 and 2 of the patent in suit.

2.4 Hence, the appellant's argument (brought forward in relation to novelty) that a polyethylene composition having a FRR21/5 and a melt flow rate MFR5/190°C within the presently claimed ranges does not necessarily also have the shear thinning index (SHI2.7/210) within the claimed value, can be accepted.

2.5 It follows from the above that it is not sufficient to find a method for preparing a polyethylene composition having a molecular distribution that would result either in the required FRR21/5 or the required SHI2.7/210 values, but that it is necessary to the find specific conditions to prepare the polyethylene composition meeting both parameters.

3. The patent in suit does not provide any explicit indication of the measures that have to be taken in order to achieve the combination of FRR21/5 and SHI2.7/210 values defined in the present claims. Apart from the combination of dependent claim 7 with either independent claim 1 or independent claim 2 of the patent in suit, examples 1 and 2, as well as comparative examples 1 and 2 are the only instances in the patent in suit concerning compositions defined by a combination of SHI2.7/210 and FRR21/5. Whereas the polyethylene compositions of examples 1 and 2 concern a combination of SHI2.7/210 and a FRR21/5 values as defined in present claim 24, the compositions of comparative examples 1 and 2 do not.

3.1 The appellant referred to the steps of the preparatory method defined in claims 16 to 19 of the patent in suit in order to explain which measures the skilled person should take to obtain the combination of SHI2.7/210 and FRR21/5 values defined in present claim 24. Those steps are however very generally described. In their most detailed form they consist of the polymerisation in a loop reactor of ethylene monomers and optionally one or more alpha-olefin comonomers in the presence of a Ziegler-Natta catalyst to obtain a first ethylene homo- or copolymer fraction (A), a second ethylene homo- or copolymer fraction (B) having a higher average molecular weight than fraction (A) being obtained in a gas phase reactor by polymerizing ethylene monomers and optionally one or more alpha-olefin comonomers in the presence of a Ziegler-Natta catalyst and the polymerization product of the first step, said process comprising before the polymerization step in the loop reactor a prepolymerisation step. These steps, however, are not specific for the method of the patent in suit as they have been also employed for comparative examples 1 and 2 of the patent in suit. They can therefore not serve as sufficient support for distinguishing a process for obtaining the combination of values defined in present claim 1 from a process that does not result in the claimed values.

3.2 A comparison of the process measures recommended for providing the polyethylene composition of the patent in suit with the process measures used in comparative examples 1 and 2 does not provide any indication on the measures or process steps leading to the values defined in claim 24, in particular does it not give any clue as to what should be changed in comparative examples 1 and 2 in order to arrive at the composition used in claim 24.

3.2.1 Concerning the type of Ziegler-Natta catalyst to be used in the process method of the invention, additional information is provided in paragraphs [0067] and [0068] of the specification. In paragraph [0068] reference is made to to EP 0 688 794 for the preparation of the catalyst that is preferably used. However, that same type of Ziegler-Natta catalyst is also used in comparative examples 1 and 2 (paragraphs [0118] and [0121]). Therefore, a difference in catalyst cannot be the reason why in comparative examples 1 and 2 the combination of FRR21/5 and SHI2.7/210 values defined in claim 24 of the main request is not achieved.

3.2.2 Furthermore, not only in the examples according to the patent in suit but also in the comparative examples the other measures recommended in the specification for the production of a polyethylene composition in accordance with claim 24 are used. Those measures concern the choice of a two step polymerisation, each with specific polymerisation conditions (temperature, pressure, content of hydrogen), the type and amount of comonomer (paragraphs [0089] and [0090]), the regulation of the molecular weight of the polymer produced in each step (paragraphs [0070], [0071] and [0088]), of the weight fraction of the first and second fraction (paragraph [0046]), as well as the choice of the density of the base resin (paragraph [0048]).

3.3 In the presence of only two examples and the comparatively large number of process measures and conditions indicated for those examples that may influence the molecular weight distribution and the resulting parametric values FRR21/5 and SHI2.7/210, it is also not possible for the skilled person, on the basis of those examples and the general description of the process steps indicated above, to detect a more specific teaching for the above mentioned general preparatory method that would enable to achieve the specific combination of FRR21/5 and SHI2.7/210 defined in claim 24.

3.4 Moreover, a comparison of the various process measures or conditions defined on the one side in examples 1 and 2 and on the other side in comparative examples 1 and 2 does not provide any information on the influence of any particular measure or condition favourable to obtain the combination of FRR21/5 and SHI2.7/210 values of claim 24, because several conditions were varied between any of those examples and comparative examples. It has also to be considered that the polyethylene compositions of those examples and comparative examples contain additional compounds in addition to the base resin - as shown in Table 2 by a difference in density between the various final polyethylene compositions and their respective base resins -, which was confirmed by the appellant. However, the nature of those additional compounds and their amounts are unknown, which renders a comparison between the process conditions and the parameters of the final compositions even more difficult. In this respect, the data provided in Tables 1 and 2 in particular for Example 2 regarding the base resin and the final composition comprising the additives demonstrate that additives can have an effect on MFR5/190°C that may not always be neglected.

3.5 In view of the above, the skilled person is not in a position to identify, within the general instructions provided in the patent in suit, the specific conditions necessary to obtain a base resin with a molecular weight distribution resulting in a polyethylene resin composition meeting both the FRR21/5 and SHI2.7/210 conditions specified in claim 24 of the main request. There are also no sufficient instructions regarding the measures to be taken in case of a failure, i.e. what to change in case the FRR21/5 or SHI2.7/210 value of the polyethylene does not satisfy the requirements of claim 24.

3.6 The appellant also did not indicate any relevant general knowledge that might enable the skilled person to select appropriate conditions for preparing a base resin resulting in a polyethylene resin composition meeting both the FRR21/5 and SHI2.7/210 conditions specified in claim 24 of the main request.

4. Therefore the patent does not disclose a technical concept fit for generalisation that makes available to the skilled person the polyethylene compositions necessary for preparing the injection moulded pipe fitting of claim 24. Under these circumstances, it is concluded that the person skilled in the art is left on his own to find out which sets of process conditions enable him to meet the requirements set out in claim 24, which amounts to an undue burden. Thus, pursuant to Article 83 EPC , the patent cannot be maintained on the basis of the main request.
(...)Order
For these reasons it is decided that:
The appeal is dismissed.


This decision T 2249/10 (pdf) has European Case Law Identifier: ECLI:EP:BA:2014:T224910.20141127. The file wrapper can be found here. Photo "Combination lock close-up" by aotaro obtained via Flickr under CC BY 2.0 license (no changes made).

No comments :

Post a Comment

Statcounter