T 1478/07 (Multimodal polyethylene/BOREALIS TECHNOLOGY OY) 19-02-2010

Summary of Facts and Submissions

I. The decision of the opposition division to maintain European patent No. 0 837 915 on the basis of the first auxiliary request has been appealed by the patent proprietor and by the two opponents.

II. The oppositions sought revocation of the patent in suit in its entirety for lack of novelty and lack of inventive step (Article 100(a) EPC). At the oral proceedings, the opposition division introduced the ground of opposition under Article 100(c) EPC.

III. The following documents were cited before the opposition division:

(1) EP-A-369 436

(2) EP-B-057 420

(3) EP-A-603 935 instead of EP-A-940 411

(4) WO-A-92/12182

(5) EP-A-302 242

(6) JP-A-58 210 947 (abstract in English)

(6a) JP-A-58 210 947

(6b) Translation in English of table 2 of (6a)

(6c) Machine translation of (6a)

(6d) Certified translation in English of (6a) submitted by Opponent I at the oral proceedings and re- submitted by Appellant I (proprietor of the patent) at the oral proceedings before the Board

(7) Mannesman MAPEC 3-Schichten-Korrosionsschutz für Stahlleitungsrohre, Januar 1983

(8) K. Omori and T. Kimura, Plastic coated pipes with high density polyethylene, 4th International Conference on the internal and external protection of pipes, 15-17 September 1981

(9) CAN/CSA-Z245.21-M92 External Polyethylene Coating for Pipes, March 1992

(10) WO-A-97/03124

(11) SE 9502508 (priority document of (10) and EP-A-837 915)

(12) PCT/FI 96/00405 (priority document of (10) and EP-A-837 915)

(13) Table of experiments submitted by Opponent 02 with letter of 11 April 2007

(14) Experimental report submitted by the patentee with letter of 8 June 2007

Documents (6a) to (6c) and (7) to (9) were cited in the course of the written opposition proceedings (after the nine-month opposition period). Documents (6d), (10), (11) and (12) were submitted during the oral proceedings before the opposition division (see point 19 of the decision).

Documents (6a) and (6d) were admitted into the proceedings. Documents (6b) and (6c) were not admitted as no longer relevant vis-à-vis document (6d). Documents (7) to (9) were admitted as relevant for inventive step. Documents (10) to (12) were only relevant for the main request which eventually failed under Article 123(2) EPC. They were no longer relevant.

IV. The opposition division found that the claimed subject-matter of the main request (granted version of the patent) gave rise to objection under Article 100(c) EPC. The first auxiliary request was deemed to fulfil the requirements of Articles 123(2)(3), 84, 83, 54 and 56 EPC and the patent in suit was maintained accordingly (see point I above).

V. In the appeal proceedings further documents or evidence were submitted:

(15) WO-A-96/02583

(16) Borstar - Advanced New Generation Polyethylene

Technology from Borealis, 1995

submitted by Appellant II (Opponent I) with the statement of grounds of appeal.

(17) Experimental report submitted by Appellant II with letter of 28 March 2008 in response to the statement of grounds of appeal of Appellant I.

(18) Advanced polymerisation process for tailor-made pipe resins, plastic pipes IX, 18-21 September 1995, pp. 433-441, submitted with letter of 2 July 2009.

(19) On-line inference of polymer properties in an industrial polyethylene reactor, AIChE Journal, Vol. 37, no. 6, pages 825-835, K. McAuley and J. McGregor, submitted with letter dated 12 February 2010.

(20) Prediction of melt flow rate (MFR) of bimodal polyethylenes based on MFR of their components, in: Conference on polymer processing (the Polymer Processing Society), Extended Abstracts and Final Programme, Gothenburg, August 19-21, 1997, 4:13, submitted with letter dated 12 February 2010.

(21) Effect of blending on the molecular weight distribution of polymers, Journal of Polymer Science: Part A , Vol. 2, pp. 2977-3007 (1964), submitted with letter dated 12 February 2010.

(22) G 7/93

Annex 1 (not numbered), submitted with letter

dated 12 February 2010.

VI. The present decision is based on the thirteen sets of claims filed by Appellant I (proprietor of the patent) during the appeal proceedings.

Claim 1 of the main request submitted with letter of 16 May 2008 read as follows:

"1. Use of a coating composition for the coating of a metal pipe, preferably an iron or a steel pipe, which coating composition has an environmental stress cracking resistance (ESCR, F20, ASTM, 1693/A) of at least 2000 h, comprises a multimodal ethylene polymer containing from 80 to 100% by weight of ethylene repeating units and from 0 to 20% by weight of C3-C10 alpha-olefin repeating units, having a density of between 0.915 g/cm**(3)and 0.955 g/cm**(3), characterized in that said coating composition is obtainable by a process comprising

- a first ethylene polymer having a first average molecular weight, a first molecular weight distribution and a first melt flow rate MFR**(1)2 of between 50 g/10 min and 2000 g/10 min, is prepared by polymerizing ethylene in the presence of a catalyst system in a first step and

- a second ethylene polymer having a second average molecular weight, a second molecular weight distribution and a second melt flow rate MFR**(2)2, which is lower than said first melt flow rate, is prepared by polymerizing ethylene in the presence of a catalyst system in second step,

said steps being performed in any order and the ethylene polymer of each step being present in the following step or steps, and producing a blend of 20 to 80% by weight said first and 80 to 20% by weight of said second ethylene polymer, said blend having a third melt flow rate MFR**(3)2 of between 0.1 g/10 min to 50 g/10 min."

Claim 1 of the first auxiliary request submitted with letter of 16 May 2008 read as follows:

"1. Use of a coating composition for the coating of a metal pipe, preferably an iron or a steel pipe, which coating composition has an environmental stress cracking resistance (ESCR, F20, ASTM, 1693/A) of at least 2000 h, comprises a multimodal ethylene polymer containing from 80 to 100% by weight of ethylene repeating units and from 0 to 20% by weight of C3-C10 alpha-olefin repeating units, having a density of between 0.915 g/cm**(3) and 0.955 g/cm**(3), characterized in that said coating composition is obtained by a process comprising at least two steps in which

- a first ethylene polymer having a first average molecular weight, a first molecular weight distribution and a first melt flow rate MFR**(1)2 of between 50 g/10 min and 2000 g/10 min, is prepared by polymerizing ethylene in the presence of a catalyst system and an amount of chain transfer agent which gives said melt flow rate in a first step and

- a second ethylene polymer having a second average molecular weight, a second molecular weight distribution and a second melt flow rate MFR**(2)2, which is lower than said first melt flow rate, is prepared by polymerizing ethylene in the presence of a catalyst system in second step,

said steps being performed in any order and the ethylene polymer of each step being present in the following step or steps, and producing a blend of 20 to 80% by weight said first and 80 to 20% by weight of said second ethylene polymer, said blend having a third melt flow rate MFR**(3)2 of between 0.1 g/10 min to 50 g/10 min."

Claim 1 of the second auxiliary request submitted with letter of 12 February 2010 read as follows:

"1. Use of a coating composition for the coating of a metal pipe, preferably an iron or a steel pipe, which coating composition has an environmental stress cracking resistance (ESCR, F20, ASTM, 1693/A) of at least 2000 h, comprises a multimodal ethylene polymer containing from 80 to 100% by weight of ethylene repeating units and from 0 to 20% by weight of C3-C10 alpha-olefin repeating units, having a density of between 0.915 g/cm**(3)and 0.955 g/cm**(3), characterized in that said coating composition is obtainable by a process comprising at least two steps in which

- a first ethylene homopolymer having a first average molecular weight, a first molecular weight distribution and a first melt flow rate MFR**(1)2 of between 50 g/10 min and 2000 g/10 min, is prepared by polymerizing ethylene in the presence of a catalyst system and an amount of chain transfer agent which gives said melt flow rate in a first step and

- a second ethylene copolymer having a C3-C10 alpha-olefin content of 1.0 to 25% by weight having a second average molecular weight, a second molecular weight distribution and a second melt flow rate MFR**(2)2, which is lower than said first melt flow rate, is prepared by polymerizing ethylene in the presence of a catalyst system in second step,

said steps being performed in any order and the ethylene polymer of each step being present in the following step or steps, and producing a blend of 20 to 80% by weight said first and 80 to 20% by weight of said second ethylene polymer, said blend having a third melt flow rate MFR**(3)2 of between 0.1 g/10 min to 50 g/10 min."

Claim 1 of the second auxiliary request A submitted with letter of 12 February 2010 differs from claim 1 of the second auxiliary request only in that the figure "50g/10min" was replaced with "20g/10min".

Claim 1 of the third auxiliary request submitted with letter of 16 May 2008 read as follows:

"1. A process for producing a metal pipe comprising a coating composition, said process comprising:

applying to said pipe a primer, like an epoxy lacquer, covering said pipe, a layer of a coupling agent, like carboxy modified polyethylene, covering said primer, and a coating composition of said coupling agent layer,

wherein the coating composition has an environmental stress cracking resistance (ESCR, F20, ASTM, 1693/A) of at least 2000 h, comprises a multimodal ethylene polymer containing from 80 to 100% by weight of ethylene repeating units and from 0 to 20% by weight of C3-C10 alpha-olefin repeating units, having a density of between 0.915 g/cm**(3)and 0.955 g/cm**(3),

and wherein the coating composition is produced in a process,

said process comprises at least two steps in which

- a first ethylene homopolymer having a first average molecular weight, a first molecular weight distribution and a first melt flow rate MFR**(1)2 of between 50 g/10 min and 2000 g/10 min, is prepared by polymerizing ethylene in the presence of a catalyst system and an amount of chain transfer agent which gives said melt flow rate in a first step and

- a second ethylene copolymer having a C3-C10 alpha-olefin content from 1.0 to 25% by weight, having a second average molecular weight, a second molecular weight distribution and a second melt flow rate MFR**(2)2, which is lower than said first melt flow rate, is prepared by polymerizing ethylene in the presence of a catalyst system in a second step,

said steps being performed in any order and the ethylene polymer of each step being present in the following step or steps, and producing a blend of 20 to 80% by weight said first and 80 to 20% by weight of said second ethylene polymer, said blend having a third melt flow rate MFR**(3)2 of between 0.1 g/10 min to 50 g/10 min."

Claim 1 of the fourth auxiliary request submitted with letter of 16 May 2008 read as follows:

"1. A process for producing a metal pipe comprising a coating composition, said process comprising:

applying to said pipe a primer, like an epoxy lacquer, covering said pipe, a layer of a coupling agent, like carboxy modified polyethylene, covering said primer, and a coating composition of said coupling agent layer,

wherein the coating composition has an environmental stress cracking resistance (ESCR, F20, ASTM, 1693/A) of at least 2000 h, comprises a multimodal ethylene polymer containing from 80 to 100% by weight of ethylene repeating units and from 0 to 20% by weight of C3-C10 alpha-olefin repeating units, having a density of between 0.915 g/cm**(3)and 0.955 g/cm**(3),

and wherein the coating composition is produced in a process,

said process comprises at least two steps in which

- a first ethylene homopolymer having a first average molecular weight, a first molecular weight distribution and a first melt flow rate MFR**(1)2 of between 50 g/10 min and 2000 g/10 min, is prepared by polymerizing ethylene in the presence of a catalyst system and an amount of chain transfer agent which gives said melt flow rate in a first step and

- a second ethylene copolymer having a C3-C10 alpha-olefin content of 1.0 to 25% by weight, having a second average molecular weight, a second molecular weight distribution and a second melt flow rate MFR**(2)2, which is lower than said first melt flow rate, is prepared by polymerizing ethylene in the presence of a catalyst system in a second step,

said steps being performed in any order and the ethylene polymer of each step being present in the following step or steps, and producing a blend of 20 to 80% by weight said first and 80 to 20% by weight of said second ethylene polymer, said blend having a third melt flow rate MFR**(3)2 of between 0.1 g/10 min to 50 g/10 min, and wherein the melt flow rate ratio FRR21/5 of said blend according to ISO1133 is between 15 and 40."

Claim 1 of the fifth auxiliary request submitted with letter of 16 May 2008 read as follows:

"1. A process for producing a metal pipe comprising a coating composition, said process comprising:

applying to said pipe a primer, like an epoxy laquer, covering said pipe, a layer of a coupling agent, like carboxy modified polyethylene, covering said primer, and a coating composition of said coupling agent layer,

wherein the coating composition has an environmental stress cracking resistance (ESCR, F20, ASTM, 1693/A) of at least 2000 h, comprises a multimodal ethylene polymer containing from 80 to 100% by weight of ethylene repeating units and from 0 to 20% by weight of C3-C10 alpha-olefin repeating units, having a density of between 0.915 g/cm**(3)and 0.955 g/cm**(3),

and wherein the coating composition is produced in a process,

said process comprises at least two steps in which

- a first ethylene homopolymer having a first average molecular weight, a first molecular weight distribution and a first melt flow rate MFR**(1)2 of between 50 g/10 min and 2000 g/10 min, is prepared by polymerizing ethylene in the presence of a catalyst system and an amount of chain transfer agent which gives said melt flow rate in a first step and

- a second ethylene copolymer having a C3-C10 alpha-olefin content of 1.0 to 25% by weight, having a second average molecular weight, a second molecular weight distribution and a second melt flow rate MFR**(2)2, which is lower than said first melt flow rate, is prepared by polymerizing ethylene in the presence of a catalyst system in second step,

said steps being performed in any order and the ethylene polymer of each step being present in the following step or steps, and producing a blend of 20 to 80% by weight said first and 80 to 20% by weight of said second ethylene polymer, said blend having a third melt flow rate MFR**(3)2 of between 0.1 g/10 min to 50 g/10 min, said polymerisation step being a combination of slurry polymerisation and gas phase polymerisation."

Claim 1 of the sixth auxiliary request submitted on 19 February 2010 read as follows:

"1. Use of a coating composition for the coating of a metal pipe, preferably an iron or a steel pipe, which coating composition has an environmental stress cracking resistance (ESCR, F20, ASTM, 1693/A) of at least 2000 h, comprises a multimodal ethylene polymer containing from 80 to 100% by weight of ethylene repeating units and from 0 to 20% by weight of C3-C10 alpha-olefin repeating units, having a density of between 0.915 g/cm**(3)and 0.955 g/cm**(3), characterized in that said coating composition is obtainable by a process comprising at least two steps in which

- a first ethylene homopolymer having a first average molecular weight, a first molecular weight distribution and a first melt flow rate MFR**(1)2 of between 50 g/10 min and 2000 g/10 min, is prepared by polymerizing ethylene in the presence of a catalyst system and an amount of chain transfer agent which gives said melt flow rate in a first step and

- a second ethylene copolymer having a C3-C10 alpha-olefin content of 1.0 to 25% by weight having a second average molecular weight, a second molecular weight distribution and a second melt flow rate MFR**(2)2, which is lower than said first melt flow rate, is prepared by polymerizing ethylene in the presence of a catalyst system in second step,

said first steps being performed first and the ethylene polymer of the first step being present in the following step or steps, and producing a blend of 20 to 80% by weight said first and 80 to 20% by weight of said second ethylene polymer, said blend having a third melt flow rate MFR**(3)2 of between 0.1 g/10 min to 50 g/10 min."

Claim 1 of the seventh auxiliary request submitted on 19 February 2010 read as follows:

"1. A process for producing a metal pipe comprising a coating composition, said process comprising:

applying to said pipe a primer, like an epoxy lacquer, covering said pipe, a layer of a coupling agent, like carboxy modified polyethylene, covering said primer, and a coating composition on said coupling agent layer,

wherein the coating composition has an environmental stress cracking resistance (ESCR, F20, ASTM, 1693/A) of at least 2000 h, comprises a multimodal ethylene polymer containing from 80 to 100% by weight of ethylene repeating units and from 0 to 20% by weight of C3-C10 alpha-olefin repeating units, having a density of between 0.915 g/cm**(3)and 0.955 g/cm**(3),

and wherein the coating composition is produced in a process,

said process comprises at least two steps in which

- a first ethylene homopolymer having a first average molecular weight, a first molecular weight distribution and a first melt flow rate MFR**(1)2 of between 50 g/10 min and 2000 g/10 min, is prepared by polymerizing ethylene in the presence of a catalyst system and an amount of chain transfer agent which gives said melt flow rate in a first step and

- a second ethylene copolymer having a C3-C10 alpha-olefin content from 1.0 to 25% by weight, having a second average molecular weight, a second molecular weight distribution and a second melt flow rate MFR**(2)2, which is lower than said first melt flow rate, is prepared by polymerizing ethylene in the presence of a catalyst system in second step,

whereby said first ethylene polymer is prepared in a first step and said second ethylene polymer is prepared in a succeeding second step and in said first step of the polymerization process, an amount of chain transfer agent is used which gives said melt flow rate MFR**(1)2 and the ethylene polymer of each step being present in the following step or steps, and producing a blend of 20 to 80% by weight said first and 80 to 20% by weight of said second ethylene polymer, said blend having a third melt flow rate MFR**(3)2 of between 0.1 g/10 min to 50 g/10 min."

Claims 1 and 7 of the eighth auxiliary request submitted on 16 May 2008 read as follows:

"1. A process for producing a metal pipe comprising a coating composition, said process comprising:

applying to said pipe a primer, like an epoxy lacquer, covering said pipe, a layer of a coupling agent, like carboxy modified polyethylene, covering said primer, and a coating composition on said coupling agent layer,

wherein the coating composition has an environmental stress cracking resistance (ESCR, F20, ASTM, 1693/A) of at least 2000 h, comprises a multimodal ethylene polymer containing from 80 to 100% by weight of ethylene repeating units and from 0 to 20% by weight of C3-C10 alpha-olefin repeating units, having a density of between 0.915 g/cm**(3)and 0.955 g/cm**(3),

and wherein the coating composition is produced in a process,

said process comprises at least two steps in which

- a first ethylene homopolymer having a first average molecular weight, a first molecular weight distribution and a first melt flow rate MFR**(1)2 of between 50 g/10 min and 2000 g/10 min, is prepared by polymerizing ethylene in the presence of a catalyst system and an amount of chain transfer agent which gives said melt flow rate in a first step and

- a second ethylene copolymer having a C3-C10 alpha-olefin content from 1.0 to 25% by weight, having a second average molecular weight, a second molecular weight distribution and a second melt flow rate MFR**(2)2, which is lower than said first melt flow rate, is prepared by polymerizing ethylene in the presence of a catalyst system in second step,

whereby said first ethylene polymer is prepared in a first step and said second ethylene polymer is prepared in a succeeding second step and in said first step of the polymerization process, an amount of chain transfer agent is used which gives said melt flow rate MFR**(1)2 and the ethylene polymer of each step being present in the following step or steps, and producing a blend of 20 to 80% by weight said first and 80 to 20% by weight of said second ethylene polymer, said blend having a third melt flow rate MFR**(3)2 of between 0.1 g/10 min to 50 g/10 min, and wherein the melt flow rate ratio FRR21/5 of said blend according to ISO1133 is between 15 and 40."

"7. A process according to any of claims 2 to 5, characterized in that in said second ethylene polymer, the C3-C10 alpha-olefin, which is preferentially 1-butene or 1-hexene, repeating unit content is from 1 to 25% by weight, preferentially from 2 to 15% by weight, of said second ethylene polymer."

Claim 1 of the ninth auxiliary request submitted on 16 May 2008 read as follows:

"1. A process for producing a metal pipe comprising a coating composition, said process comprising:

applying to said pipe a primer, like an epoxy lacquer, covering said pipe, a layer of a coupling agent, like carboxy modified polyethylene, covering said primer, and a coating composition on said coupling agent layer,

wherein the coating composition has an environmental stress cracking resistance (ESCR, F20, ASTM, 1693/A) of at least 2000 h, comprises a multimodal ethylene polymer containing from 80 to 100% by weight of ethylene repeating units and from 0 to 20% by weight of C3-C10 alpha-olefin repeating units, having a density of between 0.915 g/cm**(3)and 0.955 g/cm**(3),

and wherein the coating composition is produced in a process,

said process comprises at least two steps in which

- a first ethylene homopolymer having a first average molecular weight, a first molecular weight distribution and a first melt flow rate MFR**(1)2 of between 50 g/10 min and 2000 g/10 min, is prepared by polymerizing ethylene in the presence of a catalyst system and an amount of chain transfer agent which gives said melt flow rate in a first step and

- a second ethylene copolymer having a C3-C10 alpha-olefin content from 1.0 to 25% by weight, having a second average molecular weight, a second molecular weight distribution and a second melt flow rate MFR**(2)2, which is lower than said first melt flow rate, is prepared by polymerizing ethylene in the presence of a catalyst system in second step,

whereby said first ethylene polymer is prepared in a first step and said second ethylene polymer is prepared in a succeeding second step and in said first step of the polymerization process, an amount of chain transfer agent is used which gives said melt flow rate MFR**(1)2 and the ethylene polymer of each step being present in the following step or steps, and producing a blend of 20 to 80% by weight said first and 80 to 20% by weight of said second ethylene polymer, said blend having a third melt flow rate MFR**(3)2 of between 0.1 g/10 min to 50 g/10 min, said polymerisation step being a combination of slurry polymerisation and gas phase polymerisation."

The wording of claim 7 of the ninth auxiliary request is identical to the wording of claim 7 of the eighth auxiliary request.

Claim 1 of the tenth auxiliary request submitted on 16 May 2008 read as follows:

"1. A process for producing an iron or steel pipe comprising a coating composition, said process comprising: applying to said pipe a primer, like an epoxy lacquer, covering said pipe and a coupling agent, like carboxy modified polyethylene, covering said primer, wherein the coating composition has an environmental stress cracking resistance (ESCR, F2, ASTM, 1693/A) of at least 2000 h, comprises a multimodal ethylene polymer containing from 80 to 100% by weight of ethylene repeating units and from 0 to 20% by weight of C3-C10 alpha-olefin repeating units, having a density of between 0.915 g/cm**(3)and 0.955 g/cm**(3), characterized in that said process comprises at least two steps in which

- a first ethylene polymer having a first average molecular weight, a first molecular weight distribution and a first melt flow rate MFR**(1)2 of between 50 g/10 min and 2000 g/10 min, is prepared by polymerizing ethylene in the presence of a catalyst system in a first step and

- a second ethylene copolymer having a C3-C10 alpha-olefin content of 1.0 to 25% by weight having a second average molecular weight, a second molecular weight distribution and a second melt flow rate MFR**(2)2, which is lower than said first melt flow rate, is prepared by polymerizing ethylene in the presence of a catalyst system in a second step, whereby said first ethylene polymer is prepared in a first step in a slurry polymerization and said second ethylene polymer is prepared in a succeeding second step in a gas-phase polymerization and in said first step of the polymerization process, an amount of chain transfer agent, preferentially hydrogen, is used which gives said melt flow rate MFR**(1)2 and the ethylene polymer of each step being present in the following step or steps, and producing a blend of 20 to 80% by weight of said first and 80 to 20% by weight of said second ethylene polymer, said blend having a third melt flow rate MFR**(3)2 of between 0.1 g/10 min to 50 g/10 min, and wherein the melt flow rate ratio FRR**(3)21/5 of said blend is between 15 and 40."

The wording of dependent claim 7 of the tenth auxiliary request is identical to the wording of dependent claim 7 of the eighth auxiliary request.

Claim 1 of the eleventh auxiliary request submitted on 16 May 2008 read as follows:

"1. A process for producing an iron or steel pipe comprising a coating composition, said process comprising: applying to said pipe a primer, like an epoxy lacquer, covering said pipe and a coupling agent, like carboxy modified polyethylene, covering said primer, wherein the coating composition has an environmental stress cracking resistance (ESCR, F20, ASTM, 1693/A) of at least 2000 h, comprises a multimodal ethylene polymer containing from 80 to 100% by weight of ethylene repeating units and from 0 to 20% by weight of C3-C10 alpha-olefin repeating units, having a density of between 0.915 g/cm**(3)and 0.955 g/cm**(3), characterized in that said process comprises at least two steps in which

- a first ethylene polymer having a first average molecular weight, a first molecular weight distribution and a first melt flow rate MFR**(1)2 of between 50 g/10 min and 2000 g/10 min, is prepared by polymerizing ethylene in the presence of a catalyst system in a first step and

- a second ethylene copolymer having a C3-C10 alpha-olefin content of 1.0 to 25% by weight having a second average molecular weight, a second molecular weight distribution and a second melt flow rate MFR**(2)2, which is lower than said first melt flow rate, is prepared by polymerizing ethylene in the presence of a catalyst system in second step, whereby said first ethylene polymer is prepared in a first step in a loop reactor and said second ethylene polymer is prepared in a succeeding second step in a gas-phase reactor and in said first step of the polymerization process, an amount of chain transfer agent, preferentially hydrogen, is used which gives said melt flow rate MFR**(1)2 and the ethylene polymer of each step being present in the following step or steps, and producing a blend of 20 to 80% by weight of said first and 80 to 20% by weight of said second ethylene polymer, said blend having a third melt flow rate MFR**(3)2 of between 0.1 g/10 min to 50 g/10 min, and wherein the melt flow rate ratio FRR**(3)21/5 of said blend is between 15 and 40, the molecular weight distribution curve showing several peaks or a broad peak lacking small fractions of extremely high molecular weight material."

The wording of claim 7 of the eleventh auxiliary request is identical to the wording of claim 7 of the eighth auxiliary request.

VII. The arguments of appellant I (patent proprietor) as far as they are relevant for the present decision can be summarised as follows:

- In accordance with decision G 10/91 (OJ EPO 1993, 420) of the Enlarged Board of Appeal, the introduction of a ground of opposition not raised initially was to be seen as an exception to the principle established by the Enlarged Board of Appeal and such a new ground was to be admitted only if it was prima facie relevant.

- In decision of the Enlarged Board of Appeal G 9/91 (OJ EPO 1993, 408), it was stated that the introduction of a new ground of opposition before the opposition division should take place only if there were clear reasons to believe that this ground would prejudice the maintenance of the patent in suit. No discussion as to the prima facie relevance of such a ground had taken place and therefore the admission of this ground by the opposition division without asking the parties to present their comments constituted a violation of Article 113(1) EPC. It was conceded that after the admittance of such a ground by the opposition division, a discussion of the arguments had taken place as recited by the minutes of the oral proceedings (see point 9). As the patent proprietor was not given the opportunity to comment as to the prima facie relevance of this new ground, a violation of the requirements of Article 113(1) had taken place. A remittal to the department of the first instance was justified, since the requirements of Article 113(1) EPC were infringed by the opposition division.

- An objection based on Article 83 EPC was raised during oral proceedings by the opposition division without making a decision to admit this new ground of opposition. This was a procedural mistake, because this objection was unfounded and no discussion took place before its admission. Thus the right to be heard had been violated.

- In view of the procedural mistakes made by the opposition division, a remittal of the case to a differently composed opposition division, which should be experienced in handling ethylene polymer composition and the reimbursement of the appeal fee were requested.

- The melt flow rate of the first polymer, which is the polymer with low molecular weight, is originally disclosed in claim 6 and in the application as originally filed on page 4, lines 4 to 8. This feature is disclosed in such a way that the first step is performed before the second step. The reason is that the melt flow rate can be directly measured only if the first step is performed before the second step. This does not mean that there is no disclosure of the melt flow rate if the low molecular weight component is prepared in a second step. The specification makes it clear that the preferred embodiment is to prepare the low molecular weight component first (see claim 3 and page 3, lines 13 to 18). The general principle is however that the steps can be performed in any order (see page 3, lines 12-13). Therefore, if according to the general teaching, the low molecular weight component can be produced in the second step, the question is what information the person skilled in the art can deduce from the original application in respect of the melt flow rate of this low molecular weight component. It is common general knowledge that the low molecular weight component can be produced in the first or the second step. Therefore, the disclosure of the melt flow rate, when the low molecular weight component is prepared in the first step, in the understanding of the person skilled in the art automatically also applies to the embodiment in which the low molecular weight component is prepared in the second step. The information provided in the application as filed on the range of the melt flow rate characterises the molecular weight range of the low molecular weight component. It is a property of the polymer material itself and has nothing to do with the step sequence. It is irrational to assume that the person skilled in the art will deduce from the application that the low molecular weight component will have a different melt flow rate if produced in the second step. On the contrary, the person skilled in the art will understand that precisely the same preferred melt flow rate of 50 g/10min to 2000 g/10min will apply if the low molecular weight component is prepared in the second step. The difficulties of calculating the MFR of a polymer prepared in a second step are irrelevant. The disclosure is not a question of difficulty of measurements. The original disclosure is what a person skilled in the art understands from the original application. If the person skilled in the art understands that the MFR of the first polymer also if prepared in the second step should be in the range of 50 to 2000, then it is irrelevant whether such feature can be accurately measured or whether different methods might lead to different results.

- Regarding inventive step of the seventh auxiliary request, document (6d) could be regarded as the closest state of the art because it was also concerned with a coating composition for steel pipes and disclosed an ethylene polymer composition which is similar to that of the present invention. However, one of the essential features is the requirement to limit the copolymer content of the polymer to 20%, the polymer being a multimodal polymer where the low molecular weight component is a homopolymer and the high molecular weight component is a copolymer with a

C3-C10 alpha-olefin content of 1 to 25%. From the F50 value set out in Example 2 of document (6d), i.e. > 1000, it could be assumed that the F20 values of document (6d) were well below 1000 h. (Note of the board: F20 is the time where 20% of the samples have failed. F50 is the time where 50% of the samples have failed.) A disclosure of a value of above 2000 in a manner which is clear and beyond any reasonable doubt cannot be taken from document (6d). A second reason why Example 2 of document (6d) would have an ESCR F20 value well below 2000 is the fact that this polymer is a copolymer/copolymer composition. Evidence has been provided in document (14) that in the preferred embodiment, where the first ethylene polymer is a homopolymer, surprisingly extremely high ESCR values are obtained, whereas when the first polymer is a copolymer as well, the values are much lower. In Example A (copo/copo) a value of 1559 was determined. From these considerations it is evident that Example 2 of document (6d) will not provide high ESCR values and it is safe to assume that they are well below 2000. Therefore, there is no clear and unambiguous disclosure in document (6d) of ESCR F20 values of >2000. From the examples (Examples 1, 2, 3 and 4) of the patent, the person skilled in the art obtains the information that a combination of a homopolymer for the low molecular weight component and a copolymer for the high molecular weight component leads to coating compositions which have an excellent ESCR, namely an F20 value of above 2000. In all examples 1 to 7 (Example 7 having a comonomer in both the low molecular weight and high molecular weight) the winding speed is dramatically higher compared to a commercial steel pipe material as can be seen from Tables 1, 2 and 4 of the patent. The maximum winding speed is an essential property for excellent coating materials. The technical problem in document (6d) can be formulated as providing a coating composition to be used for coating pipes which exhibits exceptionally high ESCR values and by which pipes can be coated in a fast and reliable way. No hint was given in document (6d) for improving the environmental stress cracking resistance (ESCR). Document (6d) does not provide any teaching that it is important to restrict the comonomer content. Nowhere in document (6d) was it mentioned that the C3-C10 alpha-olefin content had to be lower than 20%. Density cannot be directly connected with the C3-C10 alpha-olefin content. Document (14) showed a noticeable improvement of the ESCR for the multimodal polymers made according to the patent in suit when compared to multimodal polymers in which the first and the second polymer were copolymers.

- The other documents did not provide any information as to improving the ESCR. Document (2) discloses on page 13 the coating of a steel pipe and mentions properties, namely low temperature resistance, impact resistance and resistance to environmental stress cracking. No experimental data is given for these properties. High winding speed is not disclosed in that document and no teaching can be derived from it as to how such high speeds as given in Table 1 of the patent can be obtained. Document (4) is not concerned with coating compositions to be coated on pipes. This document is silent in respect of high environmental stress cracking resistance and high winding speed of an extruded material. Document (5) is not concerned with coating of metal pipes either. Although stress cracking resistance is mentioned, no values above 2000 h are disclosed. The document is silent in respect of high winding speed. Document (3) has a completely different object, namely to produce polymer components with markedly different melt flow rates so that final compositions with different molecular weight distributions can be made, allowing a polymer with a very high melt flow rate to be produced for the production of pipes. Stress-cracking but not environmental stress-cracking is mentioned. Moreover, values for the comonomer content are disclosed but it seems that the total amount is 25% higher than the amount in the claim. Such a document would not be considered by the person skilled in the art.

VIII. The arguments of both Appellant II (Opponent 1) and Appellant III (Opponent 2) as far as they are relevant for the present decision can be summarised as follows:

The passage of the application on page 4, lines 5 to 8, clearly indicates that the MFR**(1)2 of the first ethylene polymer is from 50 to 2000 g/10min only inter alia when the first step is performed before the second step. Appellant I's arguments that it would be possible to carry out the steps in the reverse order on the basis of the passage on page 3, line 12, which indicates that that the steps can be performed in any order and that the melt flow rate is a property of the polymer material itself and has nothing to do with the sequence of the steps are irrelevant. The question of whether subject-matter was added to the application after it was filed is one based on the actual disclosure and not on what one skilled in the art may deduce. Appellant I seems to be arguing that embodiments equivalent to one disclosed would be obvious for, or could be deduced by, the skilled person. The standard of Article 123(2) EPC, however, is one of "direct and unambiguous disclosure". Thus if a feature, as in the present case, is disclosed only in association with a particular sequence of steps, it is added subject-matter to disclose that feature with a different sequence of steps. Moreover, only the melt flow rate of the polymer produced in the first reactor and the melt flow rate of the composition that exists in the second reactor can be measured directly. The methods for calculating the melt flow rate of the polymer produced in the second reactor are not reliable. Reference was made to experimental report (17).

Regarding inventive step, document (6d) is the closest state of the art. It discloses the use of a composition for coating a steel pipe, which has a density of 0.935-0.950 g/cm**(3), an MFR2 of 0.1-1.0 g/10 min and contains 30-60 parts by weight of component A which is an ethylene polymer having an MFR2 of 5-2000 g/10 min and 70-40 parts by weight of component (b) which is an ethylene copolymer having an MFR2 lower than component (a). The preferred way of making this polymer composition is a two-stage polymerisation method. The compositions have excellent anti-stress crack property.

In Example 2, a coating composition is disclosed which is made by a sequential two-stage polymerisation process. In the first reactor an ethylene polymer having an MFR2 of 430 g/10 min and a density of 0.970 g/cm**(3) is made to give a final composition having an MFR2 of 0.2 and a density of 0.945. The second component as produced in the second reactor thus has a lower MFR2 (0.009) and a density of 0.921. From the density of both components and of the final composition one can calculate that the weight ratio is about 50:50. No explicit information is given in Example 2 for the 1-butene content of the composition. Thus what needs to be assessed is whether the composition of Example 2 has a butene-1 comonomer content of between 0 and 20%. It is well known that there is a relationship between density and comonomer content as evidenced by documents (17) and (18).

Table 3, page 4 of document (17) provides data for various ethylene compositions prepared in two stages, which compositions had different densities. For these compositions the hexene-1 content varied between 0.9 wt% for the highest density composition and 3.6 wt% for the lowest.

FORMULA/TABLE/GRAPHIC

While the effect of butene-1 as comonomer is slightly different, it is unthinkable that a composition as prepared in Example 2 has a butene-1 content >20 wt%. Furthermore, in the examples of the patent in suit, no comonomer percentages are provided for either the components or the composition.

As further evidence on the density vs. comonomer relationship for bimodal compositions, document (18), figure 2, shows the typical relationship between the short chain branches level and density for bimodal compositions. At the density of 0.945, the branching level will be between 4 and 5 branches per 1000 carbon atoms. For butene-1, this would result in a weight percentage of 1.6 to 2.1.

Given the density and the similarity in composition of example 2 of document (6d) with those of the examples of the patent, the comonomer content is not higher than 20 wt.%. This is also shown by document (3), which indicates on page 5, lines 15 to 22, that the alpha-olefin content of the low melt-index component of a two-part composition is 0.5 to 20% by weight or, alternatively, the alpha-olefin content of the high melt-index polymer does not exceed 5% by weight. Using either of these results in a composition which contains less than 20 wt% alpha-olefin units. Document (3) indicates that the compositions are suitable for any pipe uses (see page 6, lines 15 and 18).

Table 2 of document (6d) indicates that the ESCR of the composition of example 2 is greater than 1000 hours. This is a minimum value, and it may well be higher than 2000 hours.

Regarding example A of document (14), butene was introduced in the reactor but it is not stated how much is actually incorporated in the polymer. Furthermore, the same C4/C2 was fed, which is likely to lead to similar comonomers levels in both the LMW and HMW components. This is known to affect the ESCR performance. In addition, the fact that example A does not meet the ESCR requirements (>2000) does not necessarily mean that any composition of two copolymers will behave badly.

Document (6d) does not explicitly disclose the coating of a steel pipe with a primer and a coupling agent. However, to improve the adhesiveness to the coating, the steel pipe may be pretreated and furthermore, adhesives or binders may be used as intervening agents. Moreover, those two components are not precisely defined and belong to the general knowledge of the person skilled in the art, who knows from documents (7), (8) and (9) that a three-layer sheet for protection against the corrosion of steel pipe is used, said sheet comprising an Epoxy-Typ as primary layer, an adhesive layer (PE-Copo) and an outer layer of PE. One skilled in the art knows that the use of an epoxy primer and adhesive coating, i.e. a coupler, on a steel pipe provides good peel strength. The patent in suit does not mention any benefits associated with the use of a primer and coupling agent on a steel or iron pipe.

Document (5) discloses that bimodal compositions have improved properties, relating to processability and stress crack resistance. The compositions are suitable for extrusion and blow extrusion and have excellent processability as end use properties. The compositions are made in a two-stage process with different molecular weights. Copolymer may be included up to 10 wt.%, with the comonomer preferably introduced in the polymer with the higher molecular weight. The excellent properties may be used in making films and tapes. As mentioned in document (8), the pipe coating processes either utilise a film or a sheet or utilise a sort of tape which is wound around the pipe.

Document (3) discloses that bimodal PE with good mechanical properties contains a part of homopolymer of low molecular weight and a part of copolymer of high molecular weight. The alpha-olefin content of the low melt-index component of the two-part composition is 0.5 to 20% by weight. The alpha-olefin content of the high

melt-index polymer does not exceed 1 wt%. The compositions have good ESCR, and bimodal PE is useful for any pipe uses (see page 6, lines 15 to 18).

Document (4) discloses in Example 6 a bimodal polyethylene that contains a homopolymer of low molecular weight and a copolymer of high molecular weight. The density is 0.955 g/cm**(3) and the melt index 0.8 g/10 min.

IX. In its provisional opinion, the board let the parties know that it could not be inferred from decisions G 9/91, G 10/91 and T 433/93 that a reason for the prima facie relevance for the introduction of a new ground of opposition must be discussed.

X. Appellants II and III (opponents) requested that the decision under appeal be set aside and that European patent No. 0837915 be revoked.

XI. Appellant I (patent proprietor) requested that the decision under appeal be set aside and that the patent be maintained on the basis of the main request, dated 16 May 2008, or on the basis of the first auxiliary request, dated 16 May 2008, or on the basis of the second auxiliary request or second auxiliary request A, dated 12 February 2010, or on the basis of the third to fifth auxiliary requests, dated 16 May 2008, or on the basis of the sixth or seventh auxiliary requests, filed at the oral proceedings or on the basis of one of the eighth to eleventh auxiliary requests, dated 16 May 2008. The appellant further requested: not to admit the grounds of opposition under Article 100(b) and 100(c) EPC or otherwise to remit the case back to the opposition division; to remit the case to a differently composed opposition division; to remit the case back to an opposition division experienced in handling ethylene polymer compositions; to reimburse the appeal fee; to dismiss the appeal of the opponents; not to admit documents D10-D18 into the proceedings and not to admit the four documents and annex 1 filed on 12 February 2010 into the proceedings.

XII. At the end of the oral proceedings, the decision of the board was announced.