T 593/09 – Sufficiently Clear

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

Claim 1 of the main request before the Board was identical to claim 1 as granted and read:

1. Polyethylene terephthalate resin covered metal sheet, wherein a biaxially oriented film consisting of polyethylene terephthalate having a low temperature crystallization temperature ranging from 130 to 165°C is covered at least on one side of a metal sheet by heat bonding.

The OD held that, as corroborated by A3, the low temperature crystallization (LTC) temperature depended to a substantial degree on the heating rate applied during differential scanning calorimetry (DSC). The ISO standard D8 did not give unambiguous advice on the heating rate but merely suggested a heating rate. Furthermore, no information regarding the heating rate could be found in the opposed patent or in the prior art cited therein. Also, the proprietor had not been able to convincingly show that this information was part of the common general knowledge (CGK). Finally, it was not possible to determine the required heating rate by applying DSC measurements to commercial polymers with given LTC values because, as confirmed by the proprietor, the LTC temperature also depended on the polymerisation catalyst, the molecular weight, the heat treatment and the amount of stretching of the film. As a consequence the skilled person, when having to decide whether a specific polyethylene terephthalate fell within the claimed range or not, did not have enough information to do so. The opposed patent therefore was insufficiently disclosed.

The discussion of this matter by the Board is quite interesting:

[3.1] The essence of the [opponent’s] attack on sufficiency of disclosure was that the LTC temperature range covered by claim 1 of the main request was not well-defined, since any information with regard to the heating rate to be applied during the heating step for the determination of the LTC temperature was missing. As the skilled person therefore did not know whether he was working within or outside of the scope of claim 1, sufficiency of disclosure had to be denied.

[3.2] Accordingly, it has to be analysed whether the skilled person indeed lacks information as to what heating rate to apply when determining the LTC temperature of the polyethylene terephthalate in claim 1. In this regard, (i) the information available from the opposed patent as filed and (ii) the CGK at the filing date of the opposed patent must be taken into account.

[3.3] As regards point (i), all that is contained in the opposed patent as filed with regard to the determination of the LTC temperature is the indication on page 4, lines 16-20 that an exothermic peak appears when quenched polyethylene terephthalate films are gradually heated using differential scanning calorimetry (DSC). Consequently, all that the skilled person learns from the opposed patent as filed is that the LTC temperature of the polyethylene terephthalate in claim 1 is measured by means of DSC, applying gradual heating. In particular, no information as to the heating rate to be applied during this gradual heating is contained in the opposed patent.

[3.3.1] The [patent proprietor] argued in this respect that according to page 11, lines 36-37 of the opposed patent, polyethylene terephthalate on the market had an LTC temperature of 128°C. In order to identify the heating rate applied in the opposed patent, the skilled person therefore simply had to calibrate the DSC measurement and in particular the heating rate with the help of the polyethylene terephthalate resin on the market such that an LTC temperature of 128°C resulted. The heating rate thereby determined was the heating rate applied in the opposed patent. The [patent proprietor’s] argument logically implies that at the filing date of the opposed patent either only one polyethylene terephthalate resin was available on the market or all polyethylene terephthalate resins available on the market had the same LTC temperature of 128°C. As set out by the [opponent] and as also acknowledged by the [patent proprietor], this was however not the case. Actually, “polyethylene terephthalate resin” constitutes a family of materials, each member having different properties, depending e.g. on its molecular weight, the presence and type of nucleating agents, and the intrinsic viscosity. Therefore, contrary to the [patent proprietor’s] allegation, a skilled person could not identify the heating rate to be applied in the opposed patent for the determination of the LTC temperature with the help of those polyethylene terephthalate resins which were available on the market at the filing date of the opposed patent.

[3.3.2] The [patent proprietor] additionally argued that it followed from page 3, lines 56-57 of the opposed patent that polyethylene terephthalates with an LTC temperature above 165°C could not be produced. In the [patent proprietor’s] view, the upper limit of the claim was, therefore, inherently given by the polyethylene terephthalate with the highest LTC temperature available on the market.

However, page 3, lines 56-57 in fact discloses that

“ … it is extremely difficult in the sense of economy to manufacture a Homo polymer film consisting of polyethylene terephthalate resin having a low temperature crystallisation temperature more than 165°C alone.” (emphasis added).

Consequently, what may be deduced from the opposed patent is that polyethylene terephthalates with an LTC temperature above 165°C are expensive to produce. This does however not mean that such polyethylene terephthalates were not available to the skilled person, be it on the market or otherwise. Hence, also this argument of the [patent proprietor] must fail.

[3.3.3] On the basis of the information present in the opposed patent as filed, the skilled person would thus not know what heating rate to apply for the determination of the LTC temperature.

[3.4] It remains to be examined whether this information was available to the skilled person on the basis of the CGK at the filing date of the opposed patent (point (ii) above).

[3.4.1] The [patent proprietor] argued in this respect that the skilled person would deduce from the norm D8 that, by default, a heating rate of 20°C/min had to be applied for the determination of the LTC temperature in the opposed patent.

First of all, as the date of D8 (15 March 1999) is significantly later than the filing date of the opposed patent, the information present in D8 cannot, in the absence of any further evidence, be considered to have been part of the CGK at the filing date of the opposed patent. Hence, D8 is not to be taken into account when deciding on the question what heating rate the skilled person would use in order to determine the LTC temperature in the opposed patent.

Quite apart from that, D8 does not refer to the determination of the LTC temperature and for this reason also it cannot be relevant to the question of what heating rate the skilled person would apply for the determination of the LTC temperature in the opposed patent. In particular, the procedure applied in D8 (point 9) contains only the steps of:

• performing a preliminary thermal cycle at a rate of 20°C/min, thereby heating the sample to a temperature high enough to erase the test material’s previous thermal history,
• holding the temperature for 5 minutes,
• performing a cooling cycle at a rate of 20°C/min to approximately 50°C below the extrapolated end crystallisation temperature, thereby determining the crystallisation temperature,
• holding the temperature for 5 minutes, and
• performing a second heating cycle at a rate of 20°C/min to approximately 30°C higher than the extrapolated end melting temperature, thereby determining the melting temperature.

Hence, what are determined in D8 are the melting and the crystallisation temperatures, but not the low temperature crystallisation (LTC) temperature, i.e. a temperature where crystallisation is observed in a heating cycle after a prior quenching step.

The [patent proprietor’s] argument that the skilled person would use a heating rate of 20°C/min on the basis of D8 in order to determine the LTC temperature in the opposed patent is thus not convincing.

[3.4.2] Like D8, and for the same reasons, the norm D10 (from 2007) does not reflect the CGK at the filing date of the opposed patent. Moreover, again like D8, D10 refers to the determination of a melting temperature (point 3.1 of table 2) rather than the LTC temperature. The same applies to documents D11 (from 1999) and D12 (from 2000) which are equally post-published and refer to the determination of melting points (D11, last paragraph of page 2) and “melting start points” (D12, point 2.3), rather than the determination of the LTC temperature. Hence, like D8, D10-D12 are not relevant to the question of what heating rate the skilled person would apply when determining the LTC temperature in the opposed patent.

[3.4.3] In fact, the only documents on file which were available to the skilled person at the filing date of the opposed patent and which relate to the measurement of the LTC temperature are D7 and D9.

D7 is a patent application with a publication date of 9 April 1997, which is prior to the filing date of the opposed patent (10 April 1997). This document describes on page 11, lines 14-17 the measurement of a thermal crystallisation parameter DeltaTcg. This parameter represents the difference between the peak temperature of crystallisation in DSC (Tc) and the glass transition temperature in DSC (Tg) (formula on top of page 6 of D7). The measurement comprises the steps of drying a polyester, melting it, quickly cooling it, and subsequently measuring the glass transition and crystallisation temperatures by DSC at a heating rate of 16°C/min. Due to the fact that the crystallisation temperature is determined after melting and quickly cooling the sample, this temperature is in fact the LTC temperature of the sample. So, what is determined in D7 is the LTC temperature, and to do so, a heating rate of 16°C/min is applied.

The [patent proprietor] argued in this respect that exceptionally a heating rate below 20°C/min had been used in D7 because, apart from the LTC temperature, also the glass transition temperature was determined, which was difficult to measure and which therefore required a lower heating rate. However, no evidence was provided for this allegation and, for this reason alone, the [patent proprietor’s] argument must fail.

D9 is a scientific article published in 1987, i.e. before the filing date of the opposed patent. Figure 7 of this document discloses DSC patterns of laminated polyethylene terephthalate films. These patterns show exothermic recrystallisation peaks that are obtained upon heating a rapidly quenched polyethylene terephthalate sample. The recrystallisation temperature (which is synonymous with the LTC temperature) thereby determined lies in the range of 110-130°C (first sentence of point 3 on page 641). The heating rate applied during the DSC measurement is 10°C/min (first sentence of point 2 on page 638).

[3.4.4] Consequently, the only documents on file dealing with the measurement of the LTC temperature (and being available at the filing date of the opposed patent), i.e. D7 and D9, do not teach one single but rather two different heating rates, namely 16°C/min and 10°C/min, and both heating rates are different from the one to be applied in the opposed patent according to the [patent proprietor], namely 20°C/min.

[3.5] In summary, neither from the opposed patent as filed nor on the basis of his CGK at the filing date of the opposed patent, would the skilled person know what heating rate to apply when determining the LTC temperature.

[3.6] In view of the fact that the LTC temperature strongly depends on the heating rate applied (see point 2.5 above) and in the absence of any knowledge of what heating rate to apply, the skilled person thus is not able to establish whether a given polyethylene terephthalate film has an LTC temperature as required according to the opposed patent in order to obtain the desired peel, permeation and impact resistance. Hence, because of the unclear “heating rate” parameter, the crucial LTC temperature is so ill-defined that the skilled person, when trying to carry out the invention underlying the opposed patent, is left with having to test each individual polyethylene terephthalate as to its peel, permeation and impact resistance. In view of the numerous polyethylene terephthalates with different properties on the market (see point [3.3.1] above) and the even greater number of polyethylene terephthalates which can be synthesized using e.g. different reaction conditions or catalysts, this amounts to an undue burden to solve the problem addressed in the opposed patent. Its teaching thus in effect is at most a suggestion to perform a research program in order to identify suitable materials.

[3.7] This has the consequence that the invention underlying the opposed patent is insufficiently disclosed within the meaning of A 100(b), because the requirement is not met that the invention is disclosed “in a manner sufficiently clear and complete for it to be carried out by a person skilled in the art”. Consequently, the main request must be refused.

A 83 versus A 84

[4.1] Though arriving at the same conclusion as the OD […], the board does not share the OD’s reasoning that led to this conclusion, namely that claim 1 of the patent did not comply with A 83 because the skilled person did not have enough information when having to decide whether a specific polyethylene terephthalate “falls into the claimed range or not” […].

[4.1.1] A 100(b) or A 83 requires a European patent or a European patent application to disclose the invention in a manner sufficiently clear and complete for it to be carried out by the skilled person. (As the disclosure standard given in A 100(b) is identical to that prescribed by A 83 and the same factual and legal criteria as well as the relevant jurisprudence apply, for the sake of conciseness, henceforth reference is made to the latter provision, i.e. A 83 only).

[4.1.2] The requirement of sufficient or “enabling” disclosure in the sense of A 83 is, as such, different from and independent from the clarity requirement pursuant to A 84, namely that the claims, which define the matter for which protection is sought, “shall be clear and concise”.

This distinction e.g. underlies decision T 1062/98 [2.1.4], where the board said:

“Firstly, the question whether the skilled person is capable of determining whether a certain feature would be infringing a feature claimed is not a matter of sufficiency of disclosure as required by A 83. … Whether there is infringement is … a matter to be decided by the national courts. Secondly, the determination of the scope of the claim … relates in fact to the question whether the claims properly define the matter for which protection is sought. …. These are, however, the requirements imposed by A 84 and R 29(1), which do not form grounds of opposition … ”

[4.1.3] There is thus a distinction between the meaning of “clear” in A 83, which concerns the disclosure (the “technical teaching”) of the application or the patent on the one hand, and in A 84, where that expression relates to the claims, which “shall define the matter for which protection is sought” on the other hand. In short, there is a distinction between clarity of what has been disclosed and clarity of what is claimed. This distinction is, however, not always properly made, in particular in respect of so called “ambiguous parameters”, i.e. parameters present in the description and/or claims, whose exact definition and/or applicable measuring method remains doubtful.

For example, there exist numerous decisions of the boards of appeal according to which the, or at least one, relevant criterion for sufficiency of a disclosure containing an ill-defined parameter is whether the skilled person knows if he is working within or outside of the scope of the claim (e.g., T 256/87 [10]; T 387/01 [2.2.1-4]; T 252/02 [2.2.1-5] and T 18/08 [4.2.1-4]). It is however, not always apparent from the reasoning of these decisions whether or not this criterion was meant to be the sole or the decisive one.

On the other hand, decisions exist that consider the question of whether or not the skilled person knows if he is working within or outside of the scope of the claims not to be a matter of sufficiency of disclosure but rather a matter of A 84 (see, e.g. T 396/02 [4.8.2-3], and T 1033/02 [11.4]).

[4.1.4] It is certainly true that where the disclosure is insufficient within the meaning of A 83 due to the presence of an ill-defined parameter, claims defined by reference to this parameter - in the present case the LTC temperature - would lack clarity under A 84, since establishing the exact scope of the claim would then be impossible. But that does not allow the reverse conclusion to be drawn, namely that there is insufficient disclosure in the sense of A 83 whenever the scope of the claims is unclear, i.e. not properly defined.

The position is as follows: where a claim contains an ill-defined (“unclear”, “ambiguous”) parameter and where, as a consequence, the skilled person would not know whether he was working within or outside of the scope of the claim, this, by itself, is not a reason to deny sufficiency of disclosure as required by A 83. Nor is such a lack of clear definition necessarily a matter for objection under A 84 only. What is decisive for establishing insufficiency within the meaning of A 83 is whether the parameter, in the specific case, is so ill-defined that the skilled person is not able, on the basis of the disclosure as a whole and using his CGK, to identify (without undue burden) the technical measures (e.g. selection of suitable compounds) necessary to solve the problem underlying the patent at issue.

[4.1.5] This rationale underlies e.g. T 608/07 [2.5.2] and T 815/07 [headnote], where the following statements are contained:

“Although the board accepts that, depending upon the circumstances, such an ambiguity may very well lead to an insufficiency objection, it should be born in mind that this ambiguity also relates to the scope of the claims, i.e. A 84. Since, however, A 84 is in itself not a ground of opposition, care has to be taken that an insufficiency objection arising out of an ambiguity is not merely a hidden objection under A 84. It is the conviction of this board that for an insufficiency arising out of ambiguity it is not enough to show that an ambiguity exists, e.g. at the edges of the claims. It will normally be necessary to show that the ambiguity deprives the person skilled in the art of the promise of the invention.” (T 608/07)

“The purpose of a parameter contained in a claim is to define an essential technical feature of the invention. Its significance is that the presence of this technical feature contributes to the solution of the technical problem underlying the invention. The method specified for determining the parameter should therefore be such as to produce consistent values, so that the skilled person will know when he carries out the invention whether what he produces will solve the problem or not.” (T 815/07).

The same rationale also underlies the decision in Kirin-Amgen Inc v. Hoechst Marion Roussel Ltd [2004] UKHL 46 of the United Kingdom House of Lords, where Lord Hoffmann said (the other members all agreeing):

“[if] … finding out which ones work will need extensive experiments, then that in my opinion is not merely lack of clarity; it is insufficiency. The lack of clarity does not merely create a fuzzy boundary between that which will work and that which will not. It makes it impossible to work the invention at all until one has found out what ingredient is needed.” (point 126).

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