T 1719/19 13-04-2022
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RANDOM PROPYLENE COPOLYMER FOR BOTTLES WITH GOOD OPTICAL PROPERTIES
Late-filed documents
Late-filed document - admittance
Inventive step - (yes)
I. The present appeal lies against the decision of the opposition division rejecting the opposition against European patent No. 2 920 217.
II. The independent claims 1 and 3 as granted read as follows:
"1. Propylene copolymer having
(a) a melt flow rate MFR2 (230 °C) measured according to ISO 1133 in the range of more than 1.0 to below 2.5 g/10min,
(b) a xylene cold soluble content (XCS) determined according ISO 16152 (25 °C) in the range of 25.0 to 35.0 wt.-%, and
(c) a comonomer content in the range of more than 7.5 to 12.0 wt.-%, wherein further
(d) the comonomer content of xylene cold soluble (XCS) fraction of the propylene copolymer is in the range of 16.0 to 28.0 wt.-%, and
(e) the intrinsic viscosity (IV) determined according to DIN ISO 1628/1 (in decalin at 135 °C) of the xylene cold soluble (XCS) fraction of the propylene copolymer is in the range of more than 1.2 to below 2.5 dl/g".
"3. Propylene copolymer having
(a) a melt flow rate MFR2 (230 °C) measured according to ISO 1133 in the range of more than 1.0 to below 2.5 g/10min,
(b) a xylene cold soluble content (XCS) determined according ISO 16152 (25 °C) in the range of 25.0 to 35.0 wt.-%, and
(c) a comonomer content in the range of more than 7.5 to 12.0 wt.-%, wherein further
(d) the comonomer content of xylene cold soluble (XCS) fraction of the propylene copolymer is in the range of 16.0 to 28.0 wt.-%, and
(e) the xylene cold insoluble (XCI) fraction of the propylene copolymer has a polydispersity (Mw/Mn) of more than 4.9 to 10.0".
III. The decision of the opposition division was based inter alia on documents D3 (WO 03/046021 A1) and D9 (Declaration of Markus Gahleitner dated 10 January 2019).
IV. The decision of the opposition division can be summarized as follows:
- D9 was not admitted into the proceedings.
- D3 disclosed visbroken materials for products with good optical properties and represented the closest prior art. Granted claim 1 of the patent in suit differed from D3 in the melt flow rate of 1.0-2.5 g/10 min, the examples of D3 disclosing instead melt flow rates in the range of 6.9-7.5 g/10 min.
- The patent in suit did not provide evidence of an effect attributable to the melt flow rate of the composition being in the range of 1.0-2.5 g/10 min according to granted claim 1. The problem was thus to provide polypropylene composition suitable for blow molded articles.
- In order to arrive at a material for blow molded bottles according to the granted claims starting out from optically clear cast films prepared from a composition with a MFR2 of 3-30 g/10 min as disclosed in D3, the skilled man would have needed a pointer that bottles could be prepared from resins with a lower melt flow rate than cast films. There was no evidence that the skilled person had that knowledge before the priority date of the patent in suit. Claim 1 involved therefore an inventive step over D3.
V. The opponent (appellant) lodged an appeal against that decision. D12 (Declaration Mr. Tartari dated 24 July 2019) and D13 (Handbook of Polypropylene and Polypropylene Composites, Second Edition, Harutun G.Karian, Taylor & Francis e-Library, 2009, page 26) were filed with the statement setting out the grounds of appeal.
VI. The patent proprietor (respondent) filed four sets of claims as first to fourth auxiliary requests and documents D14-D17 with their reply to the statement of grounds of appeal.
VII. Oral proceedings were held on 13 April 2022.
VIII. The appellant requested that the decision of the opposition division be set aside and the patent be revoked.
IX. The respondent requested that the appeal be dismissed (main request), in the alternative that the patent in suit be maintained in the form of one of the first to fourth auxiliary requests submitted with the reply to the statement setting out the grounds of appeal.
X. The arguments of the appellant may be summarized as follows:
Admittance of documents
- D12 was a rework of the composition of example 3 of D3 that should be admitted into the appeal proceedings.
- D13 represented the common general knowledge and should be admitted into the appeal proceedings.
Inventive step
- The visbroken composition of example 3 of D3 represented the closest prior art. Claim 1 of the main request differed from the composition of example 3 of D3 in the melt flow rate. No effect was shown for that feature. The problem was the provision of alternative propylene compositions suitable for blow molding applications. D13 taught that for blow molding applications the melt flow rate had to be of about 2 g/10min. That value could be obtained with an appropriate visbreaking of the precursor of the composition. When doing so, the other features of the composition would stay in the ranges defined in claim 1 of the main request. A similar reasoning applied to claim 3 as granted. Granted claims 1 and 3 lacked therefore an inventive step over D3.
XI. The arguments of the respondent may be summarized as follows:
Admittance of documents
- D12 should have been filed in the first instance proceedings. D12 was therefore late filed and should not be admitted into the appeal proceedings.
- There was no objection against the admittance of D13.
Inventive step
- D3 was not in the same technical field of application of blow molding as the patent in suit. D3 was remote to the patent in suit but it could nevertheless be considered as the closest prior art. Claim 1 of the main request not only differed from the composition of example 3 of D3 in the melt flow rate but also in xylene cold soluble content, the comonomer content of the xylene cold soluble fraction as well as the intrinsic viscosity of the xylene cold soluble fraction. D9 showed an effect on optical properties. The problem was to provide polypropylene compositions suitable for blow molding having improved optical performance. The teaching of D13 concerned polymers that did not correspond to the heterophasic compositions of the patent in suit. Applying the teaching of D13 to D3 could only be done with hindsight. A similar reasoning applied to claim 3 as granted, the polydispersity of the xylene cold insoluble fraction constituting an additional distinguishing feature. Granted claims 1 and 3 involved therefore an inventive step.
1. Admittance of documents
1.1 D12 and D13 were filed by the appellant with the statement setting out the grounds of appeal.
1.2 D12 is a declaration containing a rework of example 3 of D3 which is intended to show that the visbroken composition of example 3 of D3 fulfilled the conditions (b) to (e) as defined in granted claim 1. It is clear from the reply of the patent proprietor to the notice of opposition dated 12 October 2017 (page 7, sections 5.3 and 5.4) that that point had already been contested at the very beginning of the opposition procedure. There is thus no apparent reason as to why D12 was first filed in the appeal proceedings and not earlier in the opposition proceedings nor was such a reason provided by the appellant. The Board considers therefore that D12 should have been filed in opposition proceedings and thus finds it appropriate to exercise its discretion under Article 12(4) RPBA 2007 (which applies in view of Article 25(2) RPBA 2020) by not admitting D12 into the appeal proceedings.
1.3 D13 is filed to show the common general knowledge in extrusion blow molding and was filed in reply to a point regarding inventive step first made in the decision of the opposition division (page 8, sixth paragraph). The filing of D13 can be seen therefore as a legitimate reaction to the decision and the Board thus finds it appropriate to exercise its discretion under Article 12(4) RPBA 2007 (which applies in view of Article 25(2) RPBA 2020) by admitting D13 into the appeal proceedings.
1.4 The admittance of further documents (D9 and D14-D17) was discussed and decided upon at the oral proceedings before the Board but since these documents are not relevant to the present decision, there is no need to deal with the issue in any further detail.
2. Inventive step
2.1 The patent in suit concerns propylene copolymers for extrusion blow molded articles (paragraph 1) and in particular bottles (paragraphs 65-67). The propylene copolymers according to granted claims 1 and 3 have a melt flow rate (MFR2 as defined in claim 1) of more than 1.0 to below 2.5 g/10min.
2.2 The decision of the opposition division was based on D3 as the closest prior art. D3 concerns the preparation of propylene polymer compositions that are particularly suitable for the manufacture of films (second paragraph, page 1). The propylene compositions of D3 have a melt flow rate from 3 to 30 g/10min and are composed of one or more propylene copolymer(s) (A) and a copolymer of propylene and ethylene (B) (claim 1).
2.3 While the patent in suit and D3 concern different end applications, both parties considered in appeal that D3 and in particular its example 3 represented the closest prior art. The cast film prepared in example 3 of D3 is based on a propylene composition prepared by polymerizing propylene and ethylene under continuous conditions in a plant comprising a gas-phase polymerization apparatus and then subjected the thus obtained composition to degradation (visbreaking) to produce a final composition (page 11, lines 3-6). The properties of the visbroken propylene composition are reported in Table 1 of D3. The melt flow rate of the visbroken propylene composition is 6.9 g/10min.
2.4 On this basis, a distinguishing feature of the subject-matter of granted claims 1 and 3 with respect to example 3 of D3 which was acknowledged by the parties is the value of the melt flow rate MFR2 (230°C). Granted claims 1 and 3 define a melt flow rate MFR2 (230°C) in the range of more than 1.0 to below 2.5 g/10 min, which differs from the disclosed value of 6.9 g/10min of example 3 of D3.
2.5 In addition to the melt flow rate MFR2 (230°C) (feature (a) in granted claims 1 and 3), the respondent also argued that the xylene cold soluble (XCS) content (feature (b) in granted claims 1 and 3), the ethylene content of the xylene cold soluble (XCS) fraction (feature (d) in granted claims 1 and 3), the intrinsic viscosity (IV) of the xylene cold soluble (XCS) fraction (feature (e) in granted claim 1) and the polydispersity of the xylene cold insoluble (XCI) fraction of the propylene copolymer (feature (e) in granted claim 3) constituted further distinguishing features over the composition of example 3 of D3, which was disputed by the appellant. As the Board however arrives at the conclusion that the subject-matter of granted claims 1 and 3 is inventive over D3 already on the basis of the difference in melt flow rate, there is no necessity to consider features (b), (d) and (e) in the assessment of inventive step.
2.6 Paragraph 11 of the patent in suit sets out that the problem was to provide propylene copolymers having a high bottle appearance factor (BAF), a parameter that is related to the optical properties of the propylene composition. It is also apparent from Table 3 of the patent in suit that compositions according to granted granted claims 1 and 3 (IE1 and IE2) have BAF values over 20, which correspond to the highest values of the definition provided in paragraph 27. These high BAF values however cannot be attributed specifically to the melt flow rate MFR2 (230°C) being in the range defined in operative claims 1 and 3 since the comparative composition (CE1) has also a melt flow rate MFR2 (230°C) according to granted claims 1 and 3. The problem over D3 is thus the provision of alternative propylene compositions for blow molded articles with satisfactory optical properties.
2.7 The appellant argued that starting from the visbroken propylene composition applied to films in example 3 of D3 the skilled person knew that the melt flow rate of the composition had to be adapted to use it for blow molding applications. To this aim the appellant cited document D13 which concerned propylene compositions for blow molding applications and taught that the melt flow rate of choice for propylene homopolymers and random copolymers was about 2 g/10min for extrusion blow molding (page 26, section 2.9.6, third paragraph). D13 therefore taught a melt flow rate according to granted claim 1 for the application described in the patent in suit.
2.8 The Board cannot agree to this approach. The closest prior art D3 is a document directed to propylene compositions that are heterophasic propylene compositions used for making films. To that effect the propylene composition must be subjected to a chemical degradation treatment (visbreaking) in order to increase its melt flow rate to the desired range of 3-30 g/10min (fifth paragraph on page 1 and third full paragraph on page 2). By contrast, the passage on extrusion blow molding in D13 is of a generic nature and does not concern heterophasic propylene compositions (homopolymers and random copolymers are cited in D13), nor possible modifications of compositions produced for other purposes. The skilled person starting from D3 would thus have no reason to consider the generic teaching of D13 concerning different propylene polymers as those disclosed in D3 for a different application, all the more as the range of melt flow rate taught in D3 excludes the one taught in D13.
2.9 Thus, it is only with the benefit of hindsight that a skilled person would adjust the melt flow rate of the propylene composition of example 3 of D3 from 6.9 g/10min to a value in the range of more than 1.0 to below 2.5 g/10min in view of the disclosure of D13 as argued by the appellant.
2.10 In view of the above the board concludes that the subject-matter of granted claims 1 and 3 meets the requirements of Article 56 EPC.
For these reasons it is decided that:
The appeal is dismissed.