T 0864/12 03-12-2015

1. Inventive step

1.1 The novelty of claim 1 of the present request over the same disclosure of example 16 of D1 has been addressed and has been decided upon by the board in decision T 859/06. It appears to the board in its present composition that the facts of the case have not changed since that decision. The decision provided in T 859/06 on novelty is res judicata and the present board consequently has no power to reconsider whether the requirements of Article 54 EPC have been met.

1.2 The patent in suit relates to a polypropylene composition obtained by polymerisation with a metallocene catalyst and displaying flexibility, low temperature impact-strength, heat-resisting property and rigidity (paragraphs 1 and 59). The polypropylene is required to have:

(1) a ratio of isotactic pentad (mmmm) is 0.900 - 0.949,(2) a 2,1- and 1,3-propylene units in the polymer chain is 0.2-0.5 mol%,

(3) a weight average molecular weight (Mw) is 40,000-1,000,000,

(4) a ratio of a weight average molecular weight (Mw) to a number average molecular weight (Mn), i.e. (Mw)/(Mn) is 1.5-3.8,

(5) in case of elevating the temperature of o-dichlorobenzene continuously or stepwise up to a given temperatures to measure the amount of eluted polypropylene at each temperature, the position of a main elution peak is 95-110°C and the amount of components existing in the range of ±10°C of the main elution peak is at least 90% of the total amounts of components eluted at a temperature higher than 0°C,

(6) The melting point is ranging from 152 to 158°C (claim 1).

1.3 D1 relates to metallocenes containing aryl-substituted indenyl derivatives as ligands which can be used as catalysts components in the preparation of polyolefins of high isotacticity, narrow molecular weight distribution and very high molecular weight (page 1, lines 9 to 12). Example 16 of D1 discloses the polymerisation of propylene with such a catalyst. Example 16 of D1 was considered by the parties to be the most relevant disclosure for the subject-matter of the patent in suit.

1.4 According to the decision G 7/95 of the Enlarged Board of Appeal, an allegation that the claims lack novelty in view of the closest prior art document may be considered in the context of deciding upon the ground of inventive step (G 7/95, Order, second paragraph). Therefore, a finding of lack of novelty in these circumstances may inevitably result in such subject-matter being unallowable on the ground of lack of inventive step. Although the circumstances of the present case differ from those of G 7/95 and the associated decision G 1/95, in that the reasons for the lack of availability of the ground pursuant to Article 54 EPC are not the same, the Board is of the opinion that the conclusion drawn up by the Enlarged Board of Appeal may be applied here. Following the decision G 7/95, should Example 16 of D1 be found to disclose a composition according to claim 1 of the patent in suit, that claim may be found to lack an inventive step.

1.5 In the process of example 16 of D1, liquid propylene is polymerized in the presence of a toluene solution of methylaluminoxane. Hydrogen was introduced in the gas space of the reactor and methylphenylsilylbis(2-methyl-4-phenylindenyl) zirconium dichloride rac-7 was added to the reactants in a toluene solution of methylaluminoxane before carrying out the 1st polymerization step for 5 hours at 50°C. Gas was released from the reactor to reduce the pressure, ethylene gas was introduced and the polymerization was continued for a further 14 hours at 40°C before the reaction was terminated. A block copolymer was obtained wherein the melting point of the polymer of the first polymerization step was 159°C and the glass transition temperature of the polymer of the second polymerization step was -38°C. Fractionation of the product gave the following composition: 69% by weight of homopolymer, 31% by weight of copolymer, the copolymer having an ethylene content of 15% by weight.

1.6 Example 16 of D1 discloses therefore the preparation of a polypropylene composition comprising 69% of a polypropylene homopolymer and 31% of a propylene-ethylene copolymer. The ratio of ethylene in the copolymer was 15%, which is within the claimed range of 10 to 90% specified for component [II] of claim 1 of the operative request. Example 16 of D1 does however not disclose any of the properties (1) to (5) of homopolymer [I] required in claim 1 of the patent in suit.

1.7 D27 is an experimental report relating to a repetition of the preparation disclosed in example 16 of D1. The polymer was prepared according to the procedure disclosed in example 16 with the difference that it was scaled down from a reactor volume of 150dm**(3) to 5dm**(3). There is no reason to doubt that the repeat provided in D27 was representative of the process disclosed in example 16 of D1. That was also not disputed by the patent proprietor during the appeal procedure. The polypropylene homopolymer fraction obtained in D27 was isolated and analysed.

1.8 The analysis of the homopolypropylene with the sample number S-2009-003860 obtained in D27 is provided on pages 6 and 7 of D27 as well as in D28.

1.8.1 The determination of the ratio of isotactic pentad (mmmm) as well as the amount of 2,1- and 1,3-propylene units in the polymer chain of the homopolypropylene was carried out by C**(13)-NMR run at 130°C and according to a procedure disclosed on page 4 of D27. The method used in D27 to determine these parameters is very close to that disclosed in paragraphs 22 to 25 of the patent in suit. The ratio of isotactic pentad (mmmm) of the polypropylene was 0.9476 mol% and is within the claimed range of 0.900 to 0.949. The amount of 2,1- and 1,3-propylene units in the polymer chain was measured to be 0.253 which is within the claimed range of 0.2 to 0.5 mol%. The homopolypropylene according to D1, example 16, fulfils therefore the conditions (1) and (2) of claim 1 of the operative request.

1.8.2 The weight average molecular weight (Mw) and the ratio of Mw/Mn of the homopolypropylene was determined by GPC (page 3) according to a method close to that disclosed in paragraph 28 of the patent in suit. The value of the weight average molecular weight (Mw) was 256,600 g/mol, within the claimed range of 40,000 to 1,000,000 g/mol and the ratio of Mw/Mn was calculated to be 2.8, within the claimed range of 1.5 to 3.8. The homopolypropylene according to D1, example 16, fulfils therefore also the conditions (3) and (4) of claim 1 of the operative request.

1.8.3 The characteristic factor (5) of the homopolypropylene according to D1, example 16, was determined by the temperature raising elution fractionation procedure. That procedure was conducted at 140°C in o-dichlorobenzene at 1 ml/min flow rate, corresponding to the method disclosed in paragraph 35 of the patent in suit. The position of the main elution peak was at 108.3°C, within the claimed range of 95°C to 110°C and the amount of components existing in the range of ±10°C of the main elution peak was 96.1%, at least 90% of the total amounts of components eluted at a temperature higher than 0°C as claimed. The homopolypropylene according to D1, example 16, fulfils therefore also the condition (5) of claim 1 of the operative request.

1.8.4 Claim 1 of the operative request requires a melting point ranging from 152°C to 158°C for the polypropylene [I]. The method of measurement of the melting point is however not indicated in the claim. The method of determination of the melting point is only disclosed in paragraph 32 of the patent in suit. There it is disclosed that the melting point of the polymers or copolymers was measured by a DSC7 type Differential Scanning Calorimeter (manufactured by Perkin-Elmer Inc.) according to the method wherein polypropylene is heated from room temperature at a heat-elevation rate of 30°C/min up to 230°C, maintained at the same temperature for 10 minutes, then depressed in temperature at a rate of -20°C/min down to -20°C, maintained at the same temperature for 10 minutes and again heated at a rate of 20°C/min whereby a temperature showing a peak of melting is determined as melting point (Tm). The size of the sample used to perform the measurement is not defined in the patent in suit. Both parties acknowledged that the size of the sample used for the determination of the melting point with a DSC7 Calorimeter had an influence on the value of the melting point obtained. The patent proprietor argued in that respect that different melting points for the same polypropylene would be obtained from a sample size of 2mg and a sample size of 5mg (page 3 of the reply to the statement of the grounds of appeal) and that the sample size employed in D28 had been selected such that a value of the melting point within the scope of the operative claim would be obtained. The dependence of melting point on sample size is indeed experimentally confirmed on page 2 of D28 wherein the same sample S-2009-003860 was subjected to two melting point determinations using the DSC7 calorimeter and a method equivalent to that used in the patent in suit, the first determination being performed on a sample size of 2mg (melting point of 157.78°C) and the second on a sample size of 5mg (melting point of 158.95°C). The results provided in D28 show that depending on the sample size chosen for the determination of the melting point by DSC, the same polypropylene [I] otherwise satisfying the conditions (1) to (5) of claim 1 of the operative request would be considered to be within the ambit of claim 1 when a sample size of 2mg was used and outside when a sample size of 5mg was used instead. This demonstrates that the sample size chosen for the determination of the melting point by DSC is critical to the definition of the melting point in claim 1 of the operative request. The absence of a definition of the sample size to be used for the determination of the melting point in claim 1 therefore means that this parameter has to be broadly interpreted, to the extent that any applicable sample size for use with the DSC7 instrument has to be considered as appropriate for carrying out the determination, with a consequent spread of obtained values for one and the same polymer.

1.8.5 The description of the patent in suit contains no information or guidance about the sample size to be used when performing the melting point determination according to the method of paragraph 32. The operating variables of the DSC7 calorimeter from Perkin Elmer used in the patent in suit are disclosed in ER6. The typical sample size range recommended for the DSC7 calorimeter is found in section 7.4 on page 7-3. In that section, it is disclosed that the size of samples that can be analyzed with the DSC7 calorimeter is only limited by the volume of the sample pan that is in use, keeping in mind that the sample size in conjunction with the scanning rate and the sensitivity (Y Range) will affect the quality of the results. A typical range of sample size run on the DSC7 is stated to vary from 0.5mg to 30mg. The sample sizes employed in D28 i.e. 2mg and 5mg are both within the boundaries of the sample size that can be used with a DSC7 calorimeter.

1.8.6 ER2 is an extract of a textbook on thermal analysis of plastics that was published in 2004, after the priority date of the patent in suit. The teaching of ER2 however, as far as it concerns the sample size used in DSC analysis, was acknowledged by both parties to have been part of the common general knowledge of the person skilled in the art before the priority date of the patent in suit. Though ER2 does not specifically address the parameters of the DSC7 calorimeter described in the patent in suit, it nevertheless provides some guidance about the experimental parameters that can be used for the determination of the thermal properties of polymers by DSC analysis. In the table of page 41 of ER2, the sample size chosen for melting point determination using DSC is said to vary between 5mg and 10mg, whereby it is stated in a footnote that a sample size of 1mg to 2mg is also adequate provided the instrument is sensitive enough. That passage therefore teaches that provided the instrument is sensitive enough, a sample size ranging from 1mg to 10mg can be used for melting point determination by DSC. Further on page 42 of ER2, it is disclosed that in order to be able to follow melting processes as precisely as possible and to minimize lag and heat conduction effects, it is best to keep the sample size at between 1mg and 2mg, provided the instrument is sensitive enough. Since the sample size disclosed in ER6 for the DSC7 calorimeter can be as low as 0.5mg, it is concluded that the DSC7 calorimeter as used in the patent in suit and in D28 is sensitive enough to be operated with a sample size of 2mg as well as 5mg.

1.8.7 Even if a sample size of 5mg was common in the art for the determination of the melting point of polymers using a DSC7 calorimeter, the documents D28 and ER6 show that a value of 2mg was equally operative. The absence of any definition in the patent in suit of the sample size to be employed, and the resulting consequent uncertainty regarding the melting point as defined in claim 1, cannot be overcome with help of the supplementary documentation provided during the appeal procedure. In assessing the scope of claim 1, the claimed subject-matter must therefore be given its broadest possible meaning within what can still be considered technically reasonable in that art. On the basis of D28 and ER6, the Board concludes that the melting point of 157.78°C measured in D28 on a DSC7 calorimeter with a sample size of 2mg (Table on page 2) fulfils condition (6) of claim 1 of the operative request. D28 therefore shows that the sample S-2009-003860 provided in D27, corresponding to example 16 of D1 and fulfilling the conditions (1) to (5) fulfils also condition (6). As a result, it was convincingly shown by the repetition of D1, example 16 submitted in D27 that the polypropylene composition disclosed in example 16 of D1 was according to claim 1 of the operative request.

1.9 In G 7/95, it was decided that if the closest prior art document destroys the novelty of the claimed subject matter, such subject-matter obviously cannot involve an inventive step. A finding of lack of novelty in such circumstances was then considered to result in such subject-matter being inevitably unallowable on the ground of lack of inventive step.

As shown above, the subject matter of claim 1 cannot be distinguished from example 16 of D1 which represents the closest prior art. The subject matter of claim 1, following the considerations of G 7/95 therefore lacks an inventive step.

The operative request does not fulfil the requirements of Article 56 EPC.