T 0593/09 20-12-2011

Reasons for the Decision

1. The appeal is admissible.

2. The invention underlying the opposed patent

2.1 The opposed patent is directed to polyethylene terephthalate resin covered metal sheets from which metal containers can be produced (page 2, lines 5-12). The opposed patent in particular addresses the problem of providing low-cost polyethylene terephthalate films that have

- an excellent adhesion to the metal sheet such that it does not peel off therefrom, in particular under the severe conditions during the manufacturing of the container (referred to herein below as "peel resistance"),

- excellent permeation resistance such that the content of the metal container can not permeate through the film and corrode the metal substrate, and

- excellent impact resistance such that upon mechanical impact, no cracks are formed in the film (page 2, lines 23-57 and lines 50-51).

2.2 According to claim 1 of the opposed patent, the polyethylene terephthalate film is characterised by a "low temperature crystallisation temperature" (hereinafter also referred to as "LTC temperature") ranging from 130-165ºC.

As to the relevance of the LTC temperature for the solution of the problem addressed in the opposed patent, the following is stated on page 3, line 44 through page 4, line 5 of the opposed patent:

"In case where a polyethylene terephthalate resin having a low temperature crystalization temperature less than 130 DEG C, the crystallization velocity is large, which causes the great change of the biaxial orientation of the film by a slight change of the temperature of the metal sheet during the film covering process. Resultantly, the biaxial orientation widely varies in the film. When the biaxial orientation in the portion near the metal substratum is not lost enough, peeling-off of the film or origination of cracks in the film is caused in the forming of the polyethylene terephthalate resin covered metal sheet and as a result it can not be formed into a can. On the other hand, when the biaxial orientation is almost wholly lost in the entire film, the polyethylene terephthalate resin covered metal sheet can be formed into a can. However, when a content is packed in such a can and it is stored for a certain period of time, the content permeates the film and corrodes the metal substratum, or slight impact to the can causes cracks in the film. That is, When [sic] such a resin is used, the temperature range of a metal sheet to obtain a polyethylene terephthalate resin covered metal sheet having a favorable orientation structure of the film is so narrow that the operability is extremely poor.

On the other hand, it is extremely difficult in a sense of economy to manufacture a Homo polymer film consisting of polyethylene terephthalate resin having a low temperature crystallization temperature more than 165 DEG C alone." (emphasis added).

From the above statement, it can be deduced that polyethylene terephthalate covered metal sheets with an LTC temperature below 130ºC have poor peel, permeation and impact (crack) resistance and cannot be formed into a can. On the other hand, polyethylene terephthalate covered metal sheets with LTC temperatures above 165ºC are extremely difficult to manufacture economically, ie at low cost.

This is confirmed by comparative examples 1-3 (table 3) and 16-18 (erroneously numbered 7-9, table 4), where an LTC temperature of 128ºC (see table 1) results in insufficient peel and impact resistance.

2.3 It thus follows from the opposed patent that an LTC temperature of 130-165ºC, ie as required by claim 1, is crucial in order to solve the problem addressed in the opposed patent, ie to obtain a low-cost polyethylene terephthalate covered metal sheet suitable to be formed into a metal container and having excellent peel, permeation and impact resistance.

2.4 Low temperature crystallisation occurs if a crystallisable polymeric material such as polyethylene terephthalate is first heated above its melting point, such that all crystals are melted, and then quenched, ie rapidly cooled, such that the polymer chains are "frozen" and crystallisation is suppressed. Upon subsequent heating, the chains are "unfrozen", ie they regain their mobility, such that they can crystallise, resulting in an exothermic peak when using differential scanning calorimetry (DSC). This crystallisation occurs at a lower temperature than "ordinary" crystallisation, which takes place upon slowly cooling a previously molten material; therefore it is termed "low temperature crystallisation" (LTC) and the temperature at which it occurs is the "low temperature crystallisation temperature" ("LTC temperature").

2.5 As is evidenced by A3 (figure 4 and first paragraph of the left-hand column on page 30), the values obtained for the LTC temperature shift by nearly 21ºC if the heating rate applied to determine the LTC temperature (in the step denoted as "subsequent heating" above) is changed from 2ºC to 16ºC/min. This implies that, depending on the heating rate applied, the LTC temperature can vary by more than 21ºC for one and the same polyethylene terephthalate, which variation represents more than 60% of the LTC temperature range as claimed (130ºC-165ºC).

Main request (granted claims)

3. Sufficiency of disclosure (Article 100(b) EPC)

3.1 The essence of the respondent'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 common general knowledge 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 appellant 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 128ºC. 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 128ºC resulted. The heating rate thereby determined was the heating rate applied in the opposed patent. The appellant'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 128ºC. As set out by the respondent and as also acknowledged by the appellant, this was however not the case. Actually, "polyethylene terephthalate resin" constitutes a family of materials, each member having different properties, depending eg on its molecular weight, the presence and type of nucleating agents, and the intrinsic viscosity. Therefore, contrary to the appellant'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 appellant additionally argued that it followed from page 3, lines 56-57 of the opposed patent that polyethylene terephthalates with an LTC temperature above 165ºC could not be produced. In the appellant'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 165ºC alone." (emphasis added). Consequently, what may be deduced from the opposed patent is that polyethylene terephthalates with an LTC temperature above 165ºC 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 appellant 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 common general knowledge at the filing date of the opposed patent (point (ii) above).

3.4.1 The appellant argued in this respect that the skilled person would deduce from the norm D8 that, by default, a heating rate of 20ºC/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 common general knowledge 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 20ºC/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 20ºC/min to approximately 50ºC 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 20ºC/min to approximately 30ºC 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, ie a temperature where crystallisation is observed in a heating cycle after a prior quenching step.

The appellant's argument that the skilled person would use a heating rate of 20ºC/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 common general knowledge 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 16ºC/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 16ºC/min is applied.

The appellant argued in this respect that exceptionally a heating rate below 20ºC/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 appellant's argument must fail.

D9 is a scientific article published in 1987, ie 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 110-130ºC (first sentence of point 3 on page 641). The heating rate applied during the DSC measurement is 10ºC/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), ie D7 and D9, do not teach one single but rather two different heating rates, namely 16ºC/min and 10ºC/min, and both heating rates are different from the one to be applied in the opposed patent according to the appellant, namely 20ºC/min.

3.5 In summary, neither from the opposed patent as filed nor on the basis of his common general knowledge 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 eg 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 Article 100(b) EPC, 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.

4. Article 83 EPC versus Article 84 EPC

4.1 Though arriving at the same conclusion as the opposition division (point 3 of the Reasons of the opposition division's decision), the board does not share the opposition division's reasoning that led to this conclusion, namely that claim 1 of the patent did not comply with Article 83 EPC 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" (point 2.5 of the Reasons, see point III, above).

4.1.1 Article 100(b) EPC or Article 83 EPC 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 Article 100(b) EPC is identical to that prescribed by Article 83 EPC 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, ie Article 83 EPC only).

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

This distinction eg underlies decision T 1062/98, where in point 2.1.4 of the Reasons, 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 Article 83 EPC. ... 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 Article 84 EPC and Rule 29(1) EPC, which do not form grounds of opposition..."

4.1.3 There is thus a distinction between the meaning of "clear" in Article 83 EPC, which concerns the disclosure (the "technical teaching") of the application or the patent on the one hand, and in Article 84 EPC, 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 (eg, T 256/87 of 26 July 1988, point 10; T 387/01 of 13 January 2004, points 2.2.1, 2.2.3 and 2.2.4; T 252/02 of 7 December 2004, points 2.2.1 and 2.2.5 and T 18/08 of 17 August 2010, points 4.2.1-4.2.4; none of which published in OJ EPO). 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 Article 84 EPC (see, eg T 396/02 of 2 August 2005, point 4.8.2 and 4.8.3, and T 1033/02 of 26 April 2006, point 11.4, neither of which published in OJ EPO).

4.1.4 It is certainly true that where the disclosure is insufficient within the meaning of Article 83 EPC 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 Article 84 EPC, 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 Article 83 EPC 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 Article 83 EPC. Nor is such a lack of clear definition necessarily a matter for objection under Article 84 EPC only. What is decisive for establishing insufficiency within the meaning of Article 83 EPC 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 common general knowledge, to identify (without undue burden) the technical measures (eg selection of suitable compounds) necessary to solve the problem underlying the patent at issue.

4.1.5 This rationale underlies eg T 608/07 of 27 April 2009, point 2.5.2 and T 815/07 of 15 July 2008, headnote, (neither of which is published in OJ EPO), 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, ie Article 84 EPC. Since, however, Article 84 EPC 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 Article 84 EPC. 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, eg 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).

First auxiliary request

5. Sufficiency of disclosure (Article 100(b) EPC)

Claim 1 of the first auxiliary request differs from claim 1 of the main request in that the feature "wherein the low temperature crystallisation temperature is measured by differential scanning calorimetry" has been added. This addition does not alter the fact that the heating rate to be applied for the differential scanning calorimetry (DSC) measurement is not known to the skilled person. The arguments presented above with regard to sufficiency of disclosure of the main request therefore equally apply to the first auxiliary request. Sufficiency of disclosure has therefore to be denied for the first auxiliary request as well (Article 100(b) EPC).

Fourth auxiliary request

6. Sufficiency of disclosure (Article 100(b) EPC)

Claim 1 of the fourth auxiliary request differs from claim 1 of the first auxiliary request in that the LTC temperature range has been restricted to 140ºC-150ºC.

The restriction of the LTC temperature range does not change the finding made with regard to the main request that this range is ill-defined and that this results in a lack of sufficiency of disclosure. Therefore, sufficiency of disclosure has to be denied also for the fourth auxiliary request (Article 100(b) EPC).

Second, third, fifth and sixth auxiliary requests

7. Sufficiency of disclosure (Article 100(b) EPC)

Claim 1 of these auxiliary requests (see point VIII above) differs from claim 1 of the first and fourth auxiliary requests by way of the following amendments:

(a) incorporation of the feature "wherein the planar orientation coefficient of said film consisting of polyethylene terephthalate resin after being covered on said metal sheet by heat bonding ranges from 0 to 0.05 at the contacting portion of said film to said metal sheet (n1), and ranges from 0.03 to 0.15 at the surface portion of said film (n2)";

and/or

(b) incorporation of the feature "wherein the biaxial orientation of the film of said polyethylene terephthalate resin after being covered on said metal sheet by heat bonding is gradually increasing from the contacting portion of said film to said metal sheet to the surface portion of said film".

No evidence has been provided by the appellant that by selecting a planar orientation coefficient and/or a gradual increase of biaxial orientation as required according to the above amendments (a) and/or (b), the skilled person is able to select those low-cost polyethylene terephthalate covered metal sheets having the desired peel, permeation and impact resistance, thereby overcoming the objection under Article 100(b) EPC. In fact, the opposite is true. The orientation coefficients of samples 2 and 3 in table 3 and of samples 16-18 in table 4 (erroneously referred to as samples 7-9) are as required according to amendment (a) above. Nevertheless, these samples are all denoted "Comparative Example" in these tables and none of these samples has the desired peel and impact resistance.

Hence, the selection of a planar orientation coefficient and/or a gradual increase of orientation as required in claim 1 of the second, third, fifth or sixth auxiliary requests cannot be assumed to assist the skilled person in obtaining the effects aimed at by the opposed patent. Therefore, sufficiency of disclosure must also be denied for these requests (Article 100(b) EPC).